Isolation and characterization of lactic acid bacteria from sugarcane waste

Aims@#Researchers are focusing more on the isolation of new probiotic bacteria to increase varieties for the growing market demand. This study aimed to isolate lactic acid bacteria (LAB) strains from sugarcane waste materials and evaluate its characteristic. @*Methodology and results@#In the present study, two strains of LAB (Isolates A and B) were isolated from sugarcane waste and investigated in vitro for their characteristics as potential probiotics. These isolates were evaluated on their characteristics based on four biochemical tests (acid tolerance, bile tolerance, microbial adhesion, and phenol resistance), with the commercial strain Lactobacillus isolated from Yakult ® served as a positive control. Both isolated strains (>8 log10 CFU/mL) displayed higher survivability than control (>6 log10 CFU/mL) in simulated gastrointestinal conditions at pH 2.0 and pH 6.9 after 24 h. Furthermore, both isolated LABs were resistant to inhibitory substances which are 0.05-0.3% bile and 0.4% phenol. For bile tolerance, isolate A (OD 6.83) had a higher absorbance at 0.3% bile concentration as compared to isolate B (OD 2.20). However, isolate B (7.49 log10 CFU/mL) showed higher resistance towards 0.4% phenol than isolate A (7.11 log10 CFU/mL) after 24 h. Both isolate A and isolate B displayed low cell surface hydrophobicity, strong electron donor, and basic characteristic.@*Conclusion, significance and impact of study@#Both isolates were able to survive under gastrointestinal stress conditions, implying their potential as probiotics. This study demonstrated that valuable products such as probiotic strain could be isolated from sugarcane wastes to use in food production or medical treatment.

Hydroalcoholic Extract of Eugenia uniflora as Denture Disinfectant: Antimicrobial Activity and Effect on the Physical Properties of Polymethylmethacrylate

Abstract To the moment, there is no ideal substance for home-based denture disinfection. This study assessed in vitro the antimicrobial effect of the hydroalcoholic extract of Eugenia uniflora and the effect on the physical properties of denture polymethylmethacrylate (PMMA). Candida albicans, Staphylococcus aureus, and Klebsiella oxytoca were isolated from samples of saliva collected from denture wearers. The extracts were produced in three concentrations, according to the Brazilian Pharmacopeia. One hundred eighty-eight disc-shaped specimens of thermopolymerizable PMMA were prepared and randomly allocated to five treatment groups: sterile saline solution (0.85%; control); chlorhexidine digluconate (0.2%); and hydroalcoholic extract of E. uniflora (0.2%, 0.8%, and 1.16%). The specimens were disinfected for 8 hours/day for 30 days. Adherence of microorganisms to the surface, PMMA surface roughness, and color stability were assessed. Inferential statistics were performed with one- and two-way ANOVA/Tukey test, and Kruskal Wallis, Mann-Whitney U, and paired t-tests, at α=0.05. The extract of E. uniflora at 0.2% and 1.16% reduced the microbial load of K. oxytoca, while chlorhexidine digluconate significantly reduced microbial load of all microrganisms. Microbial adherence at day 10 was reduced by all experimental substances (p<0.001). Surface roughness was not affected by the disinfecting substances (p>0.05). Nevertheless, all experimental groups produced unacceptable color change at the end of the disinfection protocol (p<0.001). The non-adherent potential against microorganisms isolated from the oral cavity confirm the potential of use of the hydroalcoholic extract of E. uniflora as a denture disinfectant. Yet, unacceptable color changes may occur, regardless of extract concentration.

Microbial Adhesion of Salmonella Muenster, Salmonella Kentucky, Salmonella Newport and Salmonella Kiel: Effect of Ionic Strength on Physicochemical Surface Properties

Aims: The aim of this study was to investigate the ability of adhesion of different Salmonella’s serovars (S. Newport, S. Muenster, S. Kentucky and S. Kiel) isolated from food surfaces under two ionic strengths (0.1M; 0.001M), in order to understand the influence of environmental characteristics on their adhesion behaviour. Place and Duration of Study: Laboratory of bioprocesses and biointerfaces; Sciences and technologies Faculty (FST) between February 2015 and July 2015. Methodology: Physicochemical properties (hydrophobicity, electron donor- electron acceptor) of cells surfaces and substratum surface were determined using contact angle method. The adhesion of Salmonellastrains on glass was studied using optical microscope and Matlab program. Results: Salmonella strains showed similar cell surface physicochemical properties under low and high ionic strength except for S. Newport and S. Kentucky at low ionic strength. In addition, all Salmonella strains presented strong adhesion ability at low ionic strength (0,001M) especially for S. Newport and S. Kentuckyserovars. Conclusion: The results presented in this work could contribute to understand and control the microbial adhesion of Salmonella serovars to inert surface depending on environmental conditions.

Evaluation of C. Albicans and S. Mutans adherence on different provisional crown materials

PURPOSE: Bacterial adhesion on provisional crown materials retained for a long time can influence the duration for which permanent prosthetic restorations can be healthily worn in the oral cavity. The aim of this study was to compare seven different commonly used provisional crown materials with regard to Streptococcus mutans and Candida albicans surface adhesion. MATERIALS AND METHODS: For each group, twenty specimens of the provisional fixed prosthodontic materials TemDent (Schütz), Imıdent (Imıcryl), Tab 2000 (Kerr), Structur Premium (Voco), Systemp (Ivoclar Vivadent), Acrytemp (Zhermack), and Takilon-BBF (Takilon) were prepared (diameter, 10.0 mm; height, 2.0 mm). Surface roughness was assessed by atomic force microscopy. Each group was then divided into 2 subgroups (n=10) according to the microbial suspensions used: S. mutans and C. albicans. The specimens were incubated at 37℃ with S. mutans or C. albicans for seven days. Bacterial adherence on surfaces was assessed using the 2,3-bis[2-methyloxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide (XTT) assay. RESULTS: S. mutans showed maximum adhesion to Structur, followed by Systemp, Acrytemp, Takilon, Tab 2000, Imident, and TemDent (P<.05). The highest vital C. albicans adhesion was noted on Takilon, followed by Imident and Tab 2000; the lowest adhesion was noted on Systemp (P<.05). CONCLUSION: The materials showed significant differences in the degree of bacterial adhesion. C. albicans showed higher surface adhesion than S. mutans on provisional crown and fixed partial denture denture materials.

Efecto del metronidazol suplementado con hidroquinona en la adherencia de Lactobacillus acidophilus en células vaginales ovinas / Effect of metronidazole supplemented with hydroquinone on the adhesion of Lactobacillus acidophilus in ovine vaginal cells

This work demonstrates that the addition of metronidazole together with a ubiquitous quinone compound reduces adherence of Lactobacillus acidophilus to ovine vaginal cells. Spectrophotometric and voltammetric studies have shown that neoformed compounds were observed in these systems; there were also changes in their electroactive composition, and the oxidant status had a significantly higher value compared to the control (p < 0.05). Based on reduction potential (E; mV), the distribution of electroactive compound concentrations suggests that the compounds with low reduction potential induce this behavior, which would indicate that the addition of metronidazole with a ubiquitous quinone compound to the vaginal system might increase the reductive capacity of these systems. This work shows that the study of behavior and fluctuations of the redox compounds that compose the vaginal environment, in terms of concentration and species of redox molecules, must be hierarchized in order to better understand the early stages of colonization by microorganisms.

Este trabajo demuestra que la incorporación de metronidazol conjuntamente con un compuesto quinónico ubicuo disminuye la adherencia de Lactobacillus acidophilus a células vaginales ovinas. Los estudios espectrofotométricos y voltamétricos mostraron que en estos sistemas aparecieron compuestos neoformados y que hubo modificaciones en la composición electroactiva; asimismo, el estatus oxidante presentó un valor significativamente superior con respecto al control (p < 0,05). Según los potenciales de reducción (E; mV), la distribución de las concentraciones de los compuestos electroactivos muestra que los compuestos con bajos potenciales de reducción inducen este comportamiento. Esto indicaría que la incorporación de esta mezcla al sistema vaginal aumentaría su capacidad reductora. El trabajo muestra que el estudio del comportamiento y las fluctuaciones de los compuestos redox que componen el ambiente vaginal, en términos de concentración y especies moleculares, debe ser jerarquizado para comprender mejor las primeras etapas de la colonización de este ambiente por parte de los microorganismos.

Biofilmes microbianos na indústria de alimentos: uma revisão / Microbial biofilms in the food industry: a review

Biofilmes podem ser definidos como comunidades microbianas envoltas por uma matriz de polímeros extracelulares e aderidas a superfícies. Na indústria de alimentos, os microrganismos podem se aderir a resíduos orgânicos e inorgânicos presentes na superfície de equipamentos e utensílios, caso o processo de higienização seja aplicado incorretamente. Células sésseis, presentes no biofilme, além de reduzir a eficiência e vida útil de equipamentos, em função do fenômeno denominado corrosão microbiologicamente induzida, são mais resistentes ao processo de desinfecção. As células podem se desprender e contaminar os alimentos que passam pelo local, que causam prejuízos econômicos e risco de ocorrência de toxinfecções alimentares. A compreensão do conceito de biofilmes microbianos e de aspectos inerentes a sua estrutura e composição, bem como de seu processo de formação, são fundamentais para efetuar o desenvolvimento de estratégias de controle efetivas e entendimento do risco que estes representam para as indústrias de alimentos. Na presente revisão bibliográfica, estão descritos os principais aspectos de biofilmes microbianos de importância na indústria de alimentos: i) definição, estrutura e composição; ii) etapas envolvidas na formação; iii) mecanismos de resistência a antimicrobianos; iv) riscos; v) microrganismos envolvidos; vi)importância da higienização como ferramenta de controle.

Bacterial biofilms are defined as microbial communities surrounded by an extracellular matrix of polymers and adhered to surfaces. In food industry, the microorganisms can adhere to organic and inorganic waste occurring on the equipment and utensils surfaces, if the cleaning and sanitization procedures are done incorrectly. The presence of sessile cells in the biofilm reduces the efficiency and durability of equipments through the phenomenon called microbiologically induced corrosion. Additionally, they show muchgreater resistance to the sanitization process; the cells can be loosen and contaminate foods that pass through the place, causing economic losses and risk of occurrence of food borne diseases. Understanding the concept, the structure and composition inherent aspects, and also the producing process of microbial biofilms, are fundamental for establishing effective control strategies and being assured on the risks that they represent to the food industry. This article reviews the crucial aspects concerned with microbialbiofilms in the food industry i) definition, structure and composition; ii) steps involved in the formation; iii) mechanisms of resistance to antimicrobials; iv) risks; v) involved microorganisms; and vi) importance of hygienization as a control strategy.

Influência da sacarose, lactose e glicose + frutose no potencial cariogênico de S. mutans: estudo in situ e in vitro / Influence of sucrose, lactose and glucose + fructose on the cariogenic potential of S. mutans: an in situ and in vitro study

Objetivo: Este estudo determinou o efeito in situ de sacarose, lactose e glicose+frutose na colonização do esmalte por S. mutans e seu potencial cariogênico in vitro. Metodologia: Doze voluntários participaram da etapa in situ, tipo duplo-cego, cruzada, em quatro etapas de 48 horas. Dispositivos palatinos contendo três blocos de esmalte bovino receberam uma gota de substrato 4 vezes/dia. O biofilme formado foi inoculado em meio de cultura Mitis-Salivarius-Bacitracina (MSB) para determinação do número de colônias (UFC). No experimento in vitro, os açúcares e S. mutans foram adicionados ao meio Brain-Heart-Infusion; o pH foi aferido após 6, 12, 24, 48 horas; o peso úmido do biofilme foi determinado e inoculado em MSB. Resultados: Não houve diferença estatisticamente significante na colonização pelos microorganismos no modelo in situ. No estudo in vitro, os meios contendo sacarose e lactose apresentaram maior número de colônias e de peso úmido de biofilme que glicose+frutose (P<0,05). O pH reduzido do meio foi mantido por maior período de tempo na presença de sacarose (48h/pH=4,4). Conclusão: Embora não tenha havido diferença de colonização por S. mutans frente à sacarose e lactose neste delineamento in situ, o estudo in vitro mostrou potencial cariogênico distinto das soluções testadas.

Purpose: This study evaluated the in situ effect of sucrose, lactose, and glucose+fructose on dental enamel colonization by S. mutans and its in vitro cariogenic potential. Methods: Twelve volunteers participated in a crossover double-blind in situ study, comprising four 48-hour stages. Acrylic resin appliances with three bovine enamel blocks received a drop of experimental solution 4 times/day. The biofilm formed was inoculated in Mitis-Salivarius-Bacitracin (MSB) culture to determine the number of colonies (CFU). In the in vitro experiment, the solutions and S. mutans were added to the Brain-Heart-Infusion medium; the pH was measured after 6, 12, 24, and 48 hours; the biofilm-wet weight was determined and inoculated in MSB. Results: There was no in situ effect of any solution on S. mutans colonization. The in vitro results showed that sucrose and lactose yielded larger number of colonies and biofilm wet-weight than glucose+fructose solution (P<0.05); sucrose samples sustained reduced pH values for a longer period of time (48 hours/pH=4.4). Conclusion: Although there was no difference of S. mutans colonization under sucrose and lactose challenge in situ, the study vitro showed different cariogenic potential of the tested solutions.