Aspergillus labruscus ITAL 22.223 xylanase - immobilization and application for the obtainment of corncob xylan targeting xylitol production.

Corncob is an agro-residue rich in lignocellulosic material that can be used for the xylitol production, through its enzymatic conversion obtaining fermentable sugars and their subsequent fermentation. In light of the above, this study targeted the immobilization of Aspergillus labruscus xylanase and the use of the derivative to hydrolyze the corncob xylan for the obtainment of xylose, and its subsequent use for the production of xylitol. The extracellular xylanase was immobilized using different supports (sodium alginate, DEAE-Cellulose, DEAE-Sephadex and CM-Sephadex). Among all supports used, the best results were obtained with the DEAE-Cellulose derivative showing an efficiency of immobilization of 97-99%, yield of 93-95% and recovered activity of 81-100%. The sodium alginate derivative showed 3 cycles of reuse, with drop in activity of about 65% in the 3rd cycle using both CaCl2 and MnCl2 as crosslinkers. The best enzymatic activity for the DEAE-Cellulose derivative was observed at 55ºC and pH 5.0. This derivative presented reuse of 10 cycles using commercial xylan as substrate, and 4 cycles using corncob xylan. This derivative was used in an enzymatic reactor to hydrolyze corncob xylan, obtaining 2.7 mg/mL of xylose after 48 h of operation under optimal condition of temperature and pH. The xylose obtained from the corncob was fermented by Candida tropicalis for 96 h with consumption of 60%. The HPLC analyses indicated a production of 1.02 mg/mL of xylitol with 48 h of fermentation. In conclusion, this is the first report on the immobilization of the A. labrucus xylanase as an alternative for the obtainment of xylose from corncob xylan, and the subsequent production of xylitol.

Exploring xylose metabolism in non-conventional yeasts: kinetic characterization and product accumulation under different aeration conditions.

d-Xylose is a metabolizable carbon source for several non-Saccharomyces species, but not for native strains of S. cerevisiae. For the potential application of xylose-assimilating yeasts in biotechnological processes, a deeper understanding of pentose catabolism is needed. This work aimed to investigate the traits behind xylose utilization in diverse yeast species. The performance of 9 selected xylose-metabolizing yeast strains was evaluated and compared across 3 oxygenation conditions. Oxygenation diversely impacted growth, xylose consumption, and product accumulation. Xylose utilization by ethanol-producing species such as Spathaspora passalidarum and Scheffersomyces stipitis was less affected by oxygen restriction compared with other xylitol-accumulating species such as Meyerozyma guilliermondii, Naganishia liquefaciens, and Yamadazyma sp., for which increased aeration stimulated xylose assimilation considerably. Spathaspora passalidarum exhibited superior conversion of xylose to ethanol and showed the fastest growth and xylose consumption in all 3 conditions. By performing assays under identical conditions for all selected yeasts, we minimize bias in comparisons, providing valuable insight into xylose metabolism and facilitating the development of robust bioprocesses. ONE-SENTENCE SUMMARY: This work aims to expand the knowledge of xylose utilization in different yeast species, with a focus on how oxygenation impacts xylose assimilation.

Spathaspora marinasilvae sp. nov., a xylose-fermenting yeast isolated from galleries of passalid beetles and rotting wood in the Amazonian rainforest biome.

Four yeast isolates were obtained from rotting wood and galleries of passalid beetles collected in different sites of the Brazilian Amazonian Rainforest in Brazil. This yeast produces unconjugated allantoid asci each with a single elongated ascospore with curved ends. Sequence analysis of the internal transcribed spacer-5.8 S region and the D1/D2 domains of the large subunit ribosomal RNA (rRNA) gene showed that the isolates represent a novel species of the genus Spathaspora. The novel species is phylogenetically related to a subclade containing Spathaspora arborariae and Spathaspora suhii. Phylogenomic analysis based on 1884 single-copy orthologs for a set of Spathaspora species whose whole genome sequences are available confirmed that the novel species represented by strain UFMG-CM-Y285 is phylogenetically close to Sp. arborariae. The name Spathaspora marinasilvae sp. nov. is proposed to accommodate the novel species. The holotype of Sp. marinasilvae is CBS 13467 T (MycoBank 852799). The novel species was able to accumulate xylitol and produce ethanol from d-xylose, a trait of biotechnological interest common to several species of the genus Spathaspora.

Characterization of a symbiotic beverage based on water-soluble soybean extract fermented by Lactiplantibacillus plantarum ATCC 8014.

The health benefits of functional foods are associated with consumer interest and have supported the growth of the market for these types of foods, with emphasis on the development of new formulations based on plant extracts. Therefore, the present study aimed to characterize a symbiotic preparation based on water-soluble soy extract, supplemented with inulin and xylitol and fermented by Lactiplantibacillus plantarum ATCC 8014. Regarding nutritional issues, the symbiotic formulation can be considered a source of fiber (2 g/100 mL) and proteins (2.6 g/100 mL), and it also has a low-fat content and low caloric value. This formulation, in terms of microbiological aspects, remained adequate to legal standards after storage for 60 days under refrigeration and also presented an adequate quantity of the aforementioned probiotic strain, corresponding to 9.11 Log CFU.mL-1. These viable L. plantarum cells proved to be resistant to simulated human gastrointestinal tract conditions, reaching the intestine at high cell concentrations of 7.95 Log CFU.mL-1 after 60 days of refrigeration. Regarding sensory evaluation, the formulation showed good acceptance, presenting an average overall impression score of 6.98, 5.98, and 5.16, for control samples stored for 30 and 60 days under refrigeration, respectively. These results demonstrate that water-soluble soy extract is a suitable matrix for fermentation involving L. plantarum ATCC 8014, supporting and providing data on the first steps towards the development of a symbiotic functional food, targeting consumers who have restrictions regarding the consumption of products of animal origin, diabetics, and individuals under calorie restrictions.

Xylitol associated or not with fluoride: Is the action the same on de- and remineralization?

OBJECTIVES: This study evaluated the effect of xylitol combined or not with fluoride (F) on reduction of demineralization and increase of remineralization of shallow and deep artificial enamel lesions. METHODS: Bovine enamel samples were allocated to the following solutions groups: no xylitol (negative control), 5% xylitol, 10% xylitol, 20% xylitol, 500 ppm F (as NaF), 5% xylitol+F, 10% xylitol+F or 20% xylitol+F (n = 12-15). For the demin study, a pH-cycling model (demineralization-6 h, pH 4.7/remineralization 18 h, pH 7.0) was employed for 7 days. Treatments were applied 2 × 1 min. In the remin study, specimens were pre-demineralized for 2, 5 or 10 days. Afterwards, a pH-cycling protocol was conducted (2 h demineralizing and 22 h remineralizing solution/day for 8 days) and the same treatments were done. The response variables were percentage surface hardness loss (%SHL) and transverse microradiography. Data were analyzed by RM ANOVA/Tukey or Kruskal-Wallis/Dunn (p < 0.05) RESULTS: F and Xylitol combined with F reduced the %SHL (23-30%) compared to the negative control (61.5%). The integrated mineral loss and the lesion depth were not reduced by any treatment. Surface hardness recovery was seen only for shallow lesions in case of 20% xylitol+F compared to negative control. No lesion depth recovery, but significant mineral recovery was seen for F (2-days and 10-days lesion). CONCLUSIONS: All concentrations of xylitol+F reduced enamel surface demineralization, while only 20% xylitol+F improved surface remineralization of shallow lesions in vitro. CLINICAL SIGNIFICANCE: Our results suggest that while F or any concentration of xylitol + F reduces surface demineralization, only 20% xylitol+F improves surface remineralization of shallow lesions in vitro. Therefore, xylitol may be added into oral products, combined to F, to control dental caries.

Avaliação antimicrobiana de uma resina Bulk Fill Fluida com inserção do xilitol / Antimicrobial evaluation of a Fluid Bulk Fill resin with xylitol insertion

Introdução: As resinas Bulk Fill apresentam uma boa procura pelos profissionais, pois o seu uso diminui o tempo clínico, como também a melhora qualidade das restaurações, porém não possuem atividade antibacteriana, sendo um dos fatores que ainda causam impacto negativo na vida das pessoas. A biomodificação com o xilitol tem o sentido de produzir ação microbiana e com isso aperfeiçoar as suas características clínicas. Objetivo: Avaliar a ação antimicrobiana de uma resina Bulk Fill flow após a inserção do xilitol. Metodologia: A resina Tetric® N-Flow Bulk Fill foi misturada às concentrações de xilitol (0% [Controle], 2,5% e 5% p/p). Amostras cilíndricas (n=5 do grupo controle e n=3 dos demais grupos experimentais) foram confeccionadas em moldes acrílicos de diâmetro de 2mm espessura, fotoativadas por 10s e armazenadas a 37ºC por 24h. Os espécimes foram esterilizados por luz ultravioleta por 20 minutos antes de serem acomodadas em uma placa de 48 poços estéril, sendo adicionado em cada poço 0,5mL de caldo Mueller Hinton. Então, adicionou-se 50µL do inóculo de S. mutans nos poços correspondentes. A placa foi incubada a 37 ± 1 ˚C durante 48 horas. Após o período de incubação, os espécimes foram gentilmente removidos e o crescimento microbiano foi indicado pela adição de 100µL da solução aquosa de resazurina (SigmaAldrich) a 0,01% com a posterior incubação a 37 ± 1 ˚C por duas horas. Micro-organismos viáveis reduzem o corante mudando sua coloração azul para rosa e a CIM foi definida como a menor concentração da substância que inibiu a mudança de coloração da resazurina. Em um poço contendo o grupo controle foi acrescentado clorexidina a 0,12% com o intuito de comparar o resultado gerado dos grupos testes. Resultado: Não houve inibição do crescimento bacteriano nos poços com inóculos que continham S. mutans e corpo de prova de resina acrescida de xilitol. Conclusão: Esse estudo mostrou que o acréscimo de 2,5% e 5% de Xilitol à resina Tetric® N-Flow Bulk Fill não apresentou inibição do crescimento bacteriano (AU).

Introduction: Bulk Fill resins are in good demand among professionals, as their use reduces clinical time and improves the quality of restorations, but they do not have antibacterial activity, which is one of the factors that still hurt people's lives. Biomodification with xylitol aims to improve its clinical characteristics. Objective: To evaluate the antimicrobial action of a Bulk Fill flow resin after inserting xylitol. Methodology: Tetric® N-Flow Bulk Fill resin was mixed with xylitol concentrations (0% [Control], 2.5% and 5% w/w). Cylindrical samples (n=5 from the control group and n=3 from the other groups) were made in acrylic molds with a diameter of 2 mm thick, light-cured for 10 s and stored at 37ºC for 24h. The specimens were sterilized by ultraviolet light for 20 minutes before being placed in a sterile 48-well plate, with 0.5 mL of Mueller Hinton broth added to each well. The plate was incubated at 37 ± 1 ˚C for 48 hours. After the incubation period, the specimens were gently removed, and microbial growth was indicated by adding 100 µL of 0.01% resazurin aqueous solution with subsequent incubation at 37 ± 1 ˚C for two hours. Viable microorganisms reduce the dye, changing its color from blue to pink. The MIC was defined as the lowest concentration of the substance that inhibited the color change of resazurin. In 0.12%, chlorhexidine was added to a well containing the control group to compare the results generated from the test groups. Result: There was no inhibition of bacterial growth in the wells with inocula containing S. mutans and the resin specimen with xylitol added. Conclusion: This study showed that adding 2.5% and 5% Xylitol to the Tetric® N-Flow Bulk Fill resin did not inhibit bacterial growth (AU).

Evaluation of Solutions Containing Fluoride, Sodium Trimetaphosphate, Xylitol, and Erythritol, Alone or in Different Associations, on Dual-Species Biofilms.

Although the association of polyols/polyphosphates/fluoride has been demonstrated to promote remarkable effects on dental enamel, little is known on their combined effects on biofilms. This study assessed the effects of solutions containing fluoride/sodium trimetaphosphate (TMP)/xylitol/erythritol on dual-species biofilms of Streptococcus mutans and Candida albicans. Biofilms were grown in the continuous presence of these actives alone or in different associations. Quantification of viable plate counts, metabolic activity, biofilm biomass, and extracellular matrix components were evaluated. Overall, fluoride and TMP were the main actives that significantly influenced most of the variables analyzed, with a synergistic effect between them for S. mutans CFUs, biofilm biomass, and protein content of the extracellular matrix (p < 0.05). A similar trend was observed for biofilm metabolic activity and carbohydrate concentrations of the extracellular matrix, although without statistical significance. Regarding the polyols, despite their modest effects on most of the parameters analyzed when administered alone, their co-administration with fluoride and TMP led to a greater reduction in S. mutans CFUs and biofilm biomass compared with fluoride alone at the same concentration. It can be concluded that fluoride and TMP act synergistically on important biofilm parameters, and their co-administration with xylitol/erythritol significantly impacts S. mutans CFUs and biomass reduction.

Profundidade de polimerização de uma resina bulk fill fluida após adição de xilitol / Depth of polymerization of a fluid bulk fill resin after addition of xylitol

Objetivo: Avaliar a profundidade de polimerização em diferentes espessuras da resina composta Tetric® N-Flow Bulk Fill com adição de xilitol em diferentes concentrações. Metodologia: A resina Tetric® N-Flow Bulk Fill foi misturada às concentrações do xilitol (0% [Controle], 2,5% e 5% g/g) por espatulação manual durante 1 min em uma câmara escura. Amostras cilíndricas foram confeccionadas em moldes de polimetilmetacrilato de 5 mm de diâmetro x 1 mm, 2 mm, 3 mm e 4 mm de espessura nas concentrações de xilitol propostas totalizando 12 grupos (n=3), fotoativadas por 10 s e armazenadas a 37º C por 24 h. Os espécimes foram submetidos ao teste de microdureza Vickers, sendo a profundidade de polimerização obtida por meio da razão base/topo. Foram utilizados testes não paramétricos de Kruskal Wallis para comparação das diferentes espessuras na mesma concentração e das diferentes concentrações na mesma espessura (p<0,05) através do software BioEstat 5.3. Resultados: Não houve diferença estatisticamente significativa entre as diferentes espessuras na mesma concentração, bem como entre as diferentes concentrações na mesma espessura (p=1,000). Todos os espécimes apresentaram profundidade de polimerização adequada (razão de dureza ≥80%), com exceção das amostras com 4 mm de espessura contendo 2,5 e 5% de xilitol, que apresentaram razão de dureza média de 79% e 74%, respectivamente. Conclusão: Nas condições deste estudo, pode-se concluir que a adição de xilitol a uma resina bulk fill fluida pode afetar a profundidade de polimerização em 4 mm (AU).

Objective: To evaluate the depth of cure at different thicknesses of the Tetric® NFlow Bulk Fill composite resin with the addition of xylitol at different concentrations. Materials and Methods: The Tetric™ N-Flow Bulk Fill resin was mixed with xylitol concentrations (0% [Control], 2.5%, and 5% g/g) by manual spatulation for 1 minute in a portable darkroom. Cylindrical samples were prepared in polymethyl methacrylate molds with diameters of 5 mm and thicknesses of 1 mm, 2 mm, 3 mm, and 4 mm at the proposed xylitol concentrations, totaling 12 groups (n=3), photoactivated for 10 seconds, and stored at 37°C for 24 hours. The specimens were subjected to Vickers microhardness testing, and the depth of cure was obtained by calculating the base/top ratio. Non-parametric Kruskal-Wallis tests were used to compare different thicknesses at the same concentration and different concentrations at the same thickness (p<0,05) using BioEstat 5.3 software. Results: There was no statistically significant difference between different thicknesses at the same concentration, as well as between different concentrations at the same thickness (p=1,000). All specimens exhibited adequate depth of cure (hardness ratio ≥80%), except for the samples with 4 mm thickness containing 2.5% and 5% xylitol, which showed average hardness ratios of 79% and 74%, respectively. Conclusion: Under the conditions of this study, it can be concluded that the addition of xylitol to a fluid bulk fill resin can affect the depth of cure at 4 mm (AU).

Efeito da incorporação de xilitol na dureza de superfície de um compósito bulk fill fluido / Efeito da incorporação de xilitol na dureza de superfície de um compósito bulk fill fluido

Introdução: Frente à necessidade de maior longevidade das restaurações, o desenvolvimento de resinas antimicrobianas vem sendo necessário. O xilitol, um composto antimicrobiano natural e biocompatível, pode ser um aditivo em potencial para incluir esta propriedade em uma resina bulk fill fluida sem comprometer sua integridade. Objetivo: Avaliar a microdureza de superfície de uma resina antimicrobiana desenvolvida a partir da adição de xilitol (0% ou controle; 2,5%; 5%) em resina bulk fill fluida comercial (Tetric N-Flow Bulk Fill, Ivoclar Vivadent, Schaan, Liechtenstein). Metodologia: 3 grupos (n=12) foram obtidos através da variação da concentração de xilitol (0% ou controle; 2,5%; 5%). Para obter as resinas experimentais, xilitol em pó foi incorporado à resina fluida por espatulação manual por 1 min em uma câmara escura. A partir de um molde de acrílico, discos de 5 mm de diâmetro foram confeccionados através da fotoativação de um incremento único com um aparelho de LED de irradiância 1400 mW/cm² (Bluephase, Ivoclar Vivadent) por 10 s. Os discos foram submetidos à análise de microdureza Vickers (HMV-2, Shimadzu, Tokyo, Japan) na face superior, com uma carga estática de 300g e em um tempo de 10 s, obtendo uma média após três indentações por amostra. A análise estatística foi realizada através da variância ANOVA a um fator e teste de Tukey para a comparação entre os grupos (p < 0,05). Resultados: O grupo xilitol 5% mostrou a menor média de microdureza de superfície quando comparado aos grupos 0% e 2,5%. Conclusão: O xilitol afetou negativamente à dureza da restauração, principalmente quando foi utilizada uma concentração de 5% (AU).

Introduction: In view of the need for improved longevity of restorations, the development of antimicrobial resins has become necessary. Xylitol, a natural and biocompatible antimicrobial compound, may be a potential additive to include this property in a flowable bulk fill resin without compromising its integrity. Objective: To evaluate the surface microhardness of an antimicrobial resin developed by adding xylitol (0% or control; 2.5%; 5%) to a commercial flowable bulk fill resin (Tetric N-Flow Bulk Fill, Ivoclar Vivadent, Schaan, Liechtenstein). Methodology: 3 groups (n=12) were obtained by changing the xylitol concentration (0% or control; 2.5%; 5%). To obtain the experimental resins, xylitol powder was incorporated into the flowable resin by manual spatulation for 1 min in a darkroom. Based on an acrylic mold, 5 mm diameter disks were made by curing of a single increment with a 1400 mW/cm² irradiance LED device (Bluephase, Ivoclar Vivadent) for 10s. The disks were subjected to Vickers microhardness analysis (HMV-2, Shimadzu, Tokyo, Japan) on the upper face, with a static load of 300g and in a time of 10 s, obtaining an mean after three indentations for sample. Statistical analysis was performed using one-way ANOVA and Tukey's test for comparison between groups (p < 0.05). Results: The 5% xylitol group showed lower mean surface microhardness when compared to the 0% and 2.5% groups. Conclusion: Xylitol negatively affected restoration hardness mainly when a 5% concentration was used (p < 0.01) (AU).

Xylose Metabolization by a Saccharomyces cerevisiae Strain Isolated in Colombia.

Saccharomyces cerevisiae (S. cerevisiae) is the most widely used yeast in biotechnology in the world because its well-known metabolism and physiology as well as its recognized ability to ferment sugars such as hexoses. However, it does not metabolize pentoses such as arabinose and xylose, which are present in lignocellulosic biomass. Lignocellulose is a widely available raw material, with xylose content of approximately 35% of total sugars. This xylose fraction could be used to obtain high added-value chemical products such as xylitol. One of these yeasts isolated from a Colombian locality, designated as 202-3, showed interesting properties. 202-3 was identified through different approaches as a strain of S. cerevisiae, with an interesting consumption of xylose metabolizing into xylitol, in addition with excellent ability as a hexose fermenter with high ethanol yields and shows resistance to inhibitors present in lignocellulosic hydrolysates. The xylose metabolization by the 202-3 strain and their kinetics parameters had not been previously reported for any other natural strain of S. cerevisiae. These results suggest the great potential of natural strains for obtaining high value-added chemical products using sugars available in lignocellulosic biomass. Supplementary Information: The online version contains supplementary material available at 10.1007/s12088-023-01054-z.

Strategy to reduce acetic acid in sugarcane bagasse hemicellulose hydrolysate concomitantly with xylitol production by the promising yeast Cyberlindnera xylosilytica in a bioreactor.

The yeast Cyberlindnera xylosilytica UFMG-CM-Y309 has been identified as a promising new xylitol producer from sugarcane bagasse hemicellulosic hydrolysate (SCHH). However, SCHH pretreatment process generates byproducts, which are toxic to cell metabolism, including furans, phenolic compounds, and carboxylic acids, such as acetic acid, typically released at high concentrations. This research aims to reduce acetic acid in sugarcane hemicellulose hydrolysate concomitantly with xylitol production by yeast strain Cy. xylosilytica UFMG-CM-Y309 in a bioreactor by strategically evaluating the influence of volumetric oxygen transfer coefficient (kLa) (21 and 35 h-1). Experiments were conducted on a bench bioreactor (2 L volumetric capacity) at different initial kLa values (21 and 35 h-1). SCHH medium was supplemented with rice bran extract (10 g L-1) and yeast extract (1 g L-1). Cy. xylosilytica showed high xylitol production performance (19.56 g L-1), xylitol yield (0.56 g g-1) and, maximum xylitol-specific production rate (µpmáx 0.20 gxylitol·g-1 h-1) at kLa value of 21 h-1, concomitantly slowing the rate of acetic acid consumption. A faster acetic acid consumption (100%) by Cy. xylosilytica was observed at kLa of 35 h-1, concomitantly with an increase in maximum cellular growth (14.60 g L-1) and reduction in maximum xylitol production (14.56 g L-1 and Yp/s 0.34 g g-1). This study contributes to pioneering research regarding this yeast performance in bioreactors, emphasizing culture medium detoxification and xylitol production.

In vitro effect of low-fluoride toothpaste supplemented with sodium trimetaphosphate, xylitol, and erythritol on enamel demineralization

Abstract Regular use of toothpaste with fluoride (F) concentrations of ≥ 1000 ppm has been shown to contribute to reducing caries increment. However, when used by children during the period of dental development, it can lead to dental fluorosis. Objective: In this study, we aimed to evaluate the in vitro effect of a toothpaste formulation with reduced fluoride (F) concentration (200 ppm) supplemented with sodium trimetaphosphate (TMP: 0.2%), Xylitol (X:16%), and Erythritol (E: 4%) on dental enamel demineralization. Methodology: Bovine enamel blocks were selected according to initial surface hardness (SHi) and then divided into seven experimental toothpaste groups (n=12). These groups included 1) no F-TMP-X-E (Placebo); 2) 16% Xylitol and 4% Erythritol (X-E); 3) 16% Xylitol, 4% Erythritol and 0.2%TMP (X-E-TMP); 4) 200 ppm F (no X-E-TMP: (200F)); 5) 200 ppm F and 0.2% TMP (200F-TMP); 200 ppm F, 16% Xylitol, 4% Erythritol, and 0.2% TMP (200F-X-E-TMP); and 7) 1,100 ppm F (1100F). Blocks were individually treated 2×/day with slurries of toothpastes and subjected to a pH cycling regimen for five days (DES: 6 hours and RE: 18 hours). Then, the percentage of surface hardness loss (%SH), integrated loss of subsurface hardness (ΔKHN), fluoride (F), calcium (Ca), and phosphorus (P) in enamel were determined. The data were analyzed by ANOVA (1-criterion) and the Student-Newman-Keuls test (p<0.001). Results: We found that the 200F-X-E-TMP treatment reduced %SH by 43% compared to the 1100F treatments (p<0.001). The ΔKHN was ~ 65% higher with 200F-X-E-TMP compared to 1100F (p<0.001). The highest concentration of F in enamel was observed on the 1100F treatment (p<0.001). The 200F-X-E-TMP treatment promote higher increase of Ca and P concentration in the enamel (p<0.001). Conclusion: The association of 200F-X-E-TMP led to a significant increase of the protective effect on enamel demineralization compared to the 1100F toothpaste.

Efectos del xilitol en el crecimiento bacteriano frente a Streptococcus sanguinis: Estudio in vitro

Streptococcus sanguinis forma parte del biofilm bucal, tiene función decisoria en el desarrollo de las enfermedades bucales prevalentes y a nivel sistémico actúa como patógeno oportunista. Objetivo: Evaluar in vitro los efectos del xilitol en el crecimiento bacteriano frente a Streptococcus sanguinis (ATCC 10556). Métodos: la muestra del estudio fue distribuida en 6 grupos: 4 grupos experimentales (xilitol 1M; 0,75M; 0,50M y 0,25M), un control negativo (agua destilada) y un control positivo (clorhexidina); el análisis estadístico se hizo mediante el software estadístico Infostat y se empleó las pruebas t-Student, ANOVA y Tukey para contrastar la hipótesis. Resultados: diferentes concentraciones de xilitol (0,25M; 0,50M; 0,75M y 1M) causaron un halo de inhibición entre 9,89 - 12,89 mm (24 horas) y 10,85 - 13,45 mm (48 horas). Conclusiones: diferentes concentraciones de xilitol inhiben el crecimiento bacteriano del Streptococcus sanguinis, este efecto inhibitorio aumenta a mayor concentración y tiempo de exposición.

Streptococcus sanguinis faz parte do biofilme oral, tem papel decisivo no desenvolvimento de doenças bucais prevalentes e atua como patógeno oportunista em nível sistêmico. Objetivo: Avaliar in vitro os efeitos do xilitol no crescimento bacteriano contra Streptococcus sanguinis (ATCC 10556). Métodos: A amostra do estudo foi distribuída em 6 grupos: 4 grupos experimentais (1M; 0,75M; 0,50M e 0,25M xilitol), um controle negativo (água destilada) e um controle positivo (clorexidina); a análise estatística foi feita com o software estatístico Infostat e os testes t-Student, ANOVA e Tukey para testar a hipótese. Resultados: diferentes concentrações de xilitol (0,25M; 0,50M; 075M e 1M) causou um halo de inibição entre 9,89 - 12,89 mm (24 horas) e 10,85 - 13,45 mm (48 horas). Conclusões: diferentes concentrações de xilitol inibem o crescimento bacteriano de Streptococcus sanguinis, este efeito inibitório aumenta com maior concentração e tempo de exposição.

Streptococcus sanguinis forms part of the oral biofilm, has a decisive role in the development of prevalent oral diseases and acts as an opportunistic pathogen at the systemic level. Aims: To evaluate in vitro the effects of xylitol on bacterial growth against Streptococcus sanguinis (ATCC 10556). Methods: The study sample was distributed into 6 groups: 4 experimental groups (1M; 0,75M; 0,50M and 0,25M xylitol), a negative control (distilled water) and a positive control (chlorhexidine). The statistical analysis was done using the statistical software Infostat and the tests used t-Student, ANOVA and Tukey to test the hypothesis. Results: different concentrations of xylitol (0,25M; 0,50M; 0,75M and 1M) caused an inhibition halo between 9,89 - 12,89 mm (24 hours) and 10,85 - 13,45 mm (48 hours). Conclusions: different concentrations of xylitol inhibit the bacterial growth of Streptococcus sanguinis, this inhibitory effect increases with higher concentration and exposure time.

Fermentation performance of a Mexican native Clavispora lusitaniae strain for xylitol and ethanol production from xylose, glucose and cellobiose.

Lignocellulose hydrolysates are rich in fermentable sugars such as xylose, cellobiose and glucose, with high potential in the biotechnology industry to obtain bioproducts of higher economic value. Thus, it is important to search for and study new yeast strains that co-consume these sugars to achieve better yields and productivity in the processes. The yeast Clavispora lusitaniae CDBB-L-2031, a native strain isolated from mezcal must, was studied under various culture conditions to potentially produce ethanol and xylitol due to its ability to assimilate xylose, cellobiose and glucose. This yeast produced ethanol under microaerobic conditions with yields of 0.451 gethanol/gglucose and 0.344 gethanol/gcellobiose, when grown on 1% glucose or cellobiose, respectively. In mixtures (0.5% each) of glucose:xylose and glucose:xylose:cellobiose the yields were 0.367 gethanol/gGX and 0. 380 gethanol/gGXC, respectively. Likewise, in identical conditions, C. lusitaniae produced xylitol from xylose with a yield of 0.421 gxylitol/gxylose. In 5% glucose or xylose, this yeast had better ethanol and xylitol titers and yields, respectively. However, glucose negatively affected xylitol production in the mixture of both sugars (3% each), producing only ethanol. Xylose reductase (XR) and xylitol dehydrogenase (XDH) activities were evaluated in cultures growing on xylose or glucose, obtaining the highest values in cultures on xylose at 8 h (25.9 and 6.22 mU/mg, respectively). While in glucose cultures, XR and XDH activities were detected once this substrate was consumed (4.06 and 3.32 mU/mg, respectively). Finally, the XYL1 and XYL2 genes encoding xylose reductase and xylitol dehydrogenase, respectively, were up-regulated by xylose, whereas glucose down-regulated their expression.

Rational engineering of industrial S. cerevisiae: towards xylitol production from sugarcane straw.

BACKGROUND: Sugarcane hemicellulosic material is a compelling source of usually neglected xylose that could figure as feedstock to produce chemical building blocks of high economic value, such as xylitol. In this context, Saccharomyces cerevisiae strains typically used in the Brazilian bioethanol industry are a robust chassis for genetic engineering, given their robustness towards harsh operational conditions and outstanding fermentation performance. Nevertheless, there are no reports on the use of these strains for xylitol production using sugarcane hydrolysate. RESULTS: Potential single-guided RNA off-targets were analyzed in two preeminent industrial strains (PE-2 and SA-1), providing a database of 5'-NGG 20 nucleotide sequences and guidelines for the fast and cost-effective CRISPR editing of such strains. After genomic integration of a NADPH-preferring xylose reductase (XR), FMYX (SA-1 hoΔ::xyl1) and CENPKX (CEN.PK-122 hoΔ::xyl1) were tested in varying cultivation conditions for xylitol productivity to infer influence of the genetic background. Near-theoretical yields were achieved for all strains; however, the industrial consistently outperformed the laboratory strain. Batch fermentation of raw sugarcane straw hydrolysate with remaining solid particles represented a challenge for xylose metabolization, and 3.65 ± 0.16 g/L xylitol titer was achieved by FMYX. Finally, quantification of NADPH - cofactor implied in XR activity - revealed that FMYX has 33% more available cofactors than CENPKX. CONCLUSIONS: Although widely used in several S. cerevisiae strains, this is the first report of CRISPR-Cas9 editing major yeast of the Brazilian bioethanol industry. Fermentative assays of xylose consumption revealed that NADPH availability is closely related to mutant strains' performance. We also pioneer the use of sugarcane straw as a substrate for xylitol production. Finally, we demonstrate how industrial background SA-1 is a compelling chassis for the second-generation industry, given its inhibitor tolerance and better redox environment that may favor production of reduced sugars.

Efectos de azúcares totales sustitutos de sacarosa en la salud bucal. Revisión bibliográfica / Effects of sucrose substitute total sugars on oral health. Bibliographic review

Se realizó una revisión bibliográfica sobre los efectos de azúcares totales sustitutos de sacarosa sobre el estado de salud bucal. Los artículos científicos fueron localizados en bases de datos científicas digitales: Scopus, PubMed, Web Of Science y Ovid. Las fuentes empleadas son de libre acceso, 49 de los manuscritos fueron descartados, quedando 23. El 43,5% de los artículos mostraban resultados de ensayos clínicos sobre las gomas de mascar con xilitol, el 39,1% acerca de otros compuestos (stevia, magnolia, eritritol, fostato de calcio), el 13% revisiones narrativas y el 4,4% metaanálisis. Las gomas de mascar hechas con sustitutos de sacarosa estimulan la producción salival, neutralizan y elevan su pH, reconociéndosele su función promotora de salud bucal en varias publicaciones científicas. Los efectos anticariogénicos del xilitol están establecidos en diversos estudios. No existen suficientes estudios sobre los efectos de las sustancias: stevia, d-tagatosa, magnolia, eritritol y fostato de calcio.

A bibliographic review was carried out on the effects of sucrose substitute total sugars on the state of oral health. The scientific articles were in the following digital scientific databases: Scopus, PubMed, Web of Science and Ovid. The sources used were freely accessible, 49 of the manuscripts gotten by the search were discarded and 23 were used. 43.5% of the articles inclu-ded showed results of clinical trials on chewing gums with xylitol, 39.1% about other com-pounds (stevia, magnolia, erythritol, calcium phosphate), 13% narrative reviews and the 4.4% meta-analysis. Chewing gums made with sucrose substitutes stimulate salivary production, neutralize and raise its pH. That is why, its role in promoting oral health is recognized in several scientific publications. The anticariogenic effects of xylitol were established in various studies. There were not enough studies on the effects of the substances: stevia, d-tagatose, magnolia, erythritol and calcium phosphate

Efecto de una pasta dental con xilitol sobre Streptcococcos mutans en pacientes con ortodoncia fija / Effect of a toothpaste with xylitol on Streptcococcus mutans in patients with fixed orthodontics / Efeito de um creme dental xilitol sobre Streptcococcus mutans em pacientes com ortodontia fixa

La terapia ortodóntica produce una mayor acumulación de placa bacteriana en los pacientes, observándose cambios ecológicos orales que causan aumento del número de estreptococos mutans, por lo que es importante una adecuada higiene bucal que ayude a disminuir las bacterias y prevenir la caries. Objetivo. El propósito fue comparar el efecto del uso de una pasta dental con xilitol, en el recuento de Streptcococcos mutans en pacientes con aparatología ortodóntica fija. Material y métodos. Se realizó un estudio cuasiexperimental de cegamiento simple. La muestra estuvo constituida por 34 pacientes adolescentes con aparatología ortodontica fija de ambo sexos que cumplieron los criterios establecidos, todos fueron instruidos en una técnica de cepillado y designados al azar a uno de los dos grupos: grupo experimental 17 pacientes que usaron una pasta dental con xilitol y 17 pacientes en el grupo control que utilizaron una pasta dental convencional con flúor. A ambos grupos se les tomó y procesó microbiológicamente placa bacteriana al inicio del estudio y a las 3 y 5 semanas para evaluar el recuento de streptococos mutans. Resultados. La prueba T-Student demostró que hubo menos unidades formadoras de colonias en los pacientes que utilizaron pasta dental con xilitol siendo significativa la diferencia en la quinta semana de uso (˂ 0.0001). Conclusiones. Existe mayor efectividad de la pasta dental con xilitol, en relación a la pasta dental solo con flúor en el recuento de Streptococos mutans, sin embargo, los pacientes de ambos grupos tuvieron menos unidades formadoras de colonias.

Orthodontic therapy produces a greater accumulation of bacterial plaque in patients, with oral ecological changes that cause an increase in the number of mutans streptococci, so it is important to have an adequate oral hygiene that helps to reduce bacteria and prevent caries. Objective. The purpose was to compare the effect of the use of a toothpaste with xylitol on the Streptococcus mutans count in patients with fixed orthodontic appliances. Material and methods. A single-blinded quasi-experimental study was carried out. The sample consisted of 34 adolescent patients with fixed orthodontic appliances of both sexes who met the established criteria. All were instructed in a brushing technique and randomly assigned to one of two groups: 17 patients in the experimental group used a toothpaste with xylitol and 17 patients in the control group used a conventional toothpaste with fluoride. Both groups had bacterial plaque taken and processed microbiologically at the beginning of the study and at 3 and 5 weeks to evaluate the streptococcus mutans count. Results. The T-Student test showed that there were fewer colony-forming units in patients who used xylitol toothpaste with the difference being significant at the fifth week of use (˂ 0.0001). Conclusions. There is greater effectiveness of toothpaste with xylitol in relation to toothpaste with fluoride alone in the Streptococcus mutans count; however, patients in both groups had fewer colony-forming units.

A terapia ortodôntica produz um maior acúmulo de placa bacteriana nos pacientes, com alterações ecológicas orais causando um aumento no número de estreptococos mutantes, razão pela qual uma higiene oral adequada é importante para ajudar a reduzir as bactérias e prevenir cáries. Objetivo. O propósito era comparar o efeito do uso de uma pasta de dentes com xilitol na contagem de Streptococcus mutans em pacientes com aparelhos ortodônticos fixos. Material e métodos. Foi realizado um estudo quase-experimental mono-cego. A amostra consistiu de 34 pacientes adolescentes com aparelhos ortodônticos fixos de ambos os sexos que preenchiam os critérios estabelecidos. Todos foram instruídos em uma técnica de escovação e distribuídos aleatoriamente em um dos dois grupos: 17 pacientes do grupo experimental que usaram uma pasta de dentes com xilitol e 17 pacientes do grupo controle que usaram uma pasta de dentes convencional com flúor. Ambos os grupos tiveram a placa bacteriana retirada e processada microbiologicamente na linha de base e com 3 e 5 semanas para avaliar a contagem de estreptococos mutantes. Resultados. O teste T-Student mostrou que havia menos unidades formadoras de colônias em pacientes que usavam pasta de dentes de xilitol, sendo a diferença significativa na quinta semana de uso (˂ 0,0001). Conclusões. A pasta de dente com xilitol é mais eficaz do que a pasta de dente com flúor apenas no Streptococcus mutans, entretanto, os pacientes de ambos os grupos tinham menos unidades formadoras de colônias.

Symptom assessment after nasal irrigation with xylitol in the postoperative period of endonasal endoscopic surgery / Avaliação dos sintomas após irrigação nasal com xilitol no período pós-operatório de cirurgias endoscópicas endonasais

Abstract Introduction: Chronic rhinosinusitis is an inflammatory condition of the nasal cavity and the paranasal sinuses that requires multifactorial treatment. Xylitol can be employed with nasal irrigation and can provide better control of the disease. Objective: To evaluate the association between the effects of nasal lavage with saline solution compared to nasal lavage with a xylitol solution. Methods: Fifty-two patients, divided into two groups (n = 26 in the "Xylitol" group and n = 26 in the "Saline solution" group) answered questionnaires validated in Portuguese (NOSE and SNOT-22) about their nasal symptoms and general symptoms, before and after endonasal endoscopic surgery and after a period of 30 days of nasal irrigation. Results: The "Xylitol" group showed significant improvement in pain relief and nasal symptom reduction after surgery and nasal irrigation with xylitol solution (p < 0.001). The "Saline solution" group also showed symptom improvement, but on a smaller scale. Conclusion: This study suggests that the xylitol solution can be useful in the postoperative period after endonasal endoscopic surgery, because it leads to a greater reduction in nasal symptoms.

Resumo Introdução: Rinossinusite crônica é um quadro de inflamação da cavidade nasal e dos seios paranasais que necessita de tratamento multifatorial. O xilitol pode ser associado às irrigações nasais e pode prover melhor controle da doença. Objetivo: Avaliar a relação entre os efeitos da lavagem nasal com solução fisiológica em comparação à lavagem nasal com solução de xilitol. Método: Divididos em dois grupos (n = 26 no grupo Xilitol e n = 26 no grupo Soro), 52 pacientes responderam à questionários validados em língua portuguesa (NOSE e SNOT-22) sobre seus sintomas nasais e sintomas gerais, antes e depois de cirurgia endoscópica endonasal e após um período de 30 dias de irrigação nasal. Resultados: O grupo Xilitol apresentou melhoria significativa dos sintomas de dor e sintomas nasais após a cirurgia e a irrigação nasal com solução de xilitol (p < 0,001). O grupo Soro também apresentou melhoria dos sintomas, porém em menor escala. Conclusão: Este estudo sugere que a solução de xilitol pode ser usada no período pós-operatório de cirurgia endoscópica endonasal por levar a uma maior redução nos sintomas nasais.

Antiplaque and antigingivitis efficacy of medicated and non-medicated sugar-free chewing gum as adjuncts to toothbrushing: systematic review and network meta-analysis.

OBJECTIVE: This network meta-analysis (NMA) assessed the antiplaque and anti-inflammatory efficacy of different sugar-free chewing gums (SFCG) as adjuncts to toothbrushing. MATERIAL AND METHODS: PubMed, Scopus, EMBASE, Web of Science, and CENTRAL databases were searched up to February 2021 to identify randomized controlled trials, involving adults, comparing antiplaque and anti-inflammatory effects of SFCG, with different active ingredients, as adjunctive to mechanical control of biofilm, with a minimum of 7-day of follow-up. Plaque and gingival indexes were assessed. The risk of bias assessment was performed with the RoB 2.0 tool. NMA, and pairwise meta-analyses were performed for both dental plaque and gingival indexes. RESULTS: Twelve studies were included, comprising 850 (antiplaque) and 1459 (gingival inflammation) subjects randomized into 9 interventions: (1) chlorhexidine; (2) chlorhexidine + xylitol (CHX+Xyl); (3) green tea + xylitol (GT+Xyl); (4) magnolia; (5) Lactobacillus reuteri; (6) vitamin C + xylitol; (7) vitamin + carbamide; (8) eucalyptus; and (9) negative control, sorbitol, gum base only, or no chewing gum. No statistically significant differences were detected among SFCG, with different active ingredients, for both antiplaque and anti-inflammatory efficacy (p > 0.05). However, SFCG with GT+XyL outperformed negative control gums regarding antiplaque efficacy (SMD, - 2.93; 95% CrI, - 0.45 to - 5.38). The SUCRA results showed that SFCG containing GT+Xyl was ranked first, for both antiplaque and anti-inflammatory outcomes. CONCLUSION: SFCG containing GT+Xyl showed better antiplaque effect over negative controls. However, cautious interpretation is required due to the low number of direct comparisons arms. These shortcomings underscore the need for RCTs with mostly head-to-head comparison that provide more conclusive evidence. CLINICAL RELEVANCE: There is no robust evidence for the clinical indications of sugar-free chewing gums as adjunct to toothbrushing for the control of biofilm or the treatment of gingivitis.

Analysis of glucose and xylose metabolism in new indigenous Meyerozyma caribbica strains isolated from corn residues.

Aiming to broaden the base of knowledge about wild yeasts, four new indigenous strains were isolated from corn residues, and phylogenetic-tree assemblings on ITS and LSU regions indicated they belong to Meyerozyma caribbica. Yeasts were cultivated under full- and micro-aerobiosis, starting with low or high cell-density inoculum, in synthetic medium or corn hydrolysate containing glucose and/or xylose. Cells were able to assimilate both monosaccharides, albeit by different metabolic routes (fermentative or respiratory). They grew faster in glucose, with lag phases ~ 10 h shorter than in xylose. The hexose exhaustion occurred between 24 and 34 h, while xylose was entirely consumed in the last few hours of cultivation (44-48 h). In batch fermentation in synthetic medium with high cell density, under full-aerobiosis, 18-20 g glucose l-1 were exhausted in 4-6 h, with a production of 6.5-7.0 g ethanol l-1. In the xylose medium, cells needed > 12 h to consume the carbohydrate, and instead of ethanol, cells released 4.4-6.4 g l-1 xylitol. Under micro-aerobiosis, yeasts were unable to assimilate xylose, and glucose was more slowly consumed, although the ethanol yield was the theoretical maximum. When inoculated into the hydrolysate, cells needed 4-6 h to deplete glucose, and xylose had a maximum consumption of 57%. Considering that the hydrolysate contained ~ 3 g l-1 acetic acid, it probably has impaired sugar metabolism. Thus, this study increases the fund of knowledge regarding indigenous yeasts and reveals the biotechnological potential of these strains.