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1.
Curr Microbiol ; 79(4): 99, 2022 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-35150334

RESUMO

Mycotoxins may be present in nuts, coffee, cereals, and grapes, among other products. Increasing concerns about human health and environmental protection have driven the application of biological control techniques that can inhibit fungal contaminants. In this study, the growth inhibition of the ochratoxigenic fungus Aspergillus carbonarius Ac 162 was evaluated using 5 lactic acid bacteria (LAB). The LAB studied were Lactobacillus plantarum MZ801739 (J), Lactobacillus plantarum MZ809351 (31) and Lactobacillus plantarum MZ809350 (34), isolated in the Ivory Coast, and Lactobacillus plantarum MN982928 (3) and Leuconostoc citreum MZ801735 (23), isolated in Mexico. J, 31, 34, 3 and 23 are the internal strain codes from our laboratory. LAB were cultivated in De Man, Rogosa and Sharpe (MRS) broth, and different polyols (glycerol, mannitol, sorbitol, and xylitol) were added to the culture broth to stimulate the production of antifungal compounds. The fungal inhibition studies were performed using the poisoned food technique. The highest inhibition of A. carbonarius growth was obtained by cultivating L. plantarum MZ809351 in the presence of xylitol and glycerol. Under these conditions, 1 L of the L. plantarum MZ809351 cultures were used to identify antifungal compounds. The compounds were concentrated by solid-phase extraction and then characterized by GC-MS. In addition to 9-octadecenoic acid, 3 diketopiperazines or cyclic dipeptides were identified, including cyclo (Leu-Leu), cyclo (Pro-Gly) and cyclo (Val-Phe), which were compounds related to microbial antifungal activities. Xylitol and glycerol induced the production of these antifungal compounds against A. carbonarius Ac 162. On the other hand, adding xylitol and glycerol to the MRS broth reduced the Ochratoxin A (OTA) content to 56.8 and 54.7%, respectively. This study shows the potential for using L. plantarum MZ809351 as a biocontrol agent to prevent the growth of A. carbonarius and reduce the production of OTA in foods.


Assuntos
Lactobacillus plantarum , Micotoxinas , Antifúngicos/farmacologia , Humanos , Polímeros
2.
Chemosphere ; 295: 133792, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35104543

RESUMO

miRNAs are responsible for the regulation of many cellular processes such as development, cell differentiation, proliferation, apoptosis, and tumor growth. Several studies showed that they can also serve as specific, stable, and sensitive markers of chemical exposure. In this review, current experimental and epidemiological data evidencing deregulation in miRNA expression in response to fungicides, insecticides or herbicides were analyzed. As shown by Venn's diagrams, miR-363 and miR-9 deregulation is associated with fungicide exposure in vitro and in vivo, while let-7, miR-155, miR-181 and miR-21 were found to be commonly deregulated by at least three different insecticides. Furthermore, let-7, miR-30, miR-126, miR-181 and miR-320 were commonly deregulated by 3 different herbicides. Notably, these 5 miRNAs were also found to be deregulated by one or more insecticides, suggesting their participation in the cellular response to pesticides, regardless of their chemical structure. All these miRNAs have been proposed as potential biomarkers for fungicide, insecticide, or herbicide exposure. These results allow us to improve our understanding of the molecular mechanisms of toxicity upon pesticide exposure, although further studies are needed to confirm these miRNAs as definitive (not potential) biomarkers of pesticide exposure.


Assuntos
Fungicidas Industriais , Herbicidas , Inseticidas , MicroRNAs , Praguicidas , Fungicidas Industriais/toxicidade , Herbicidas/toxicidade , MicroRNAs/genética , Praguicidas/toxicidade
3.
Appl Biochem Biotechnol ; 194(3): 1327-1339, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-34699041

RESUMO

Invertase from Aspergillus niger C28B25 was produced by solid-state fermentation (SSF). Fermented solids were used directly as a biocatalyst for batch and continuous hydrolysis of sucrose in a packed-bed reactor under different operational conditions with various temperatures, sucrose concentrations, and feed flow rates. The SSF allowed obtaining a biocatalyst with an invertase activity of 82.2 U/g db. The biocatalyst maintained its activity in the range of 40 to 70 °C for at least 70 h of continuous operation. In a 20-mL packed bed reactor, the highest hydrolysis rate (12.3 g/g db h) was obtained at 40 °C with 2 M sucrose. Continuous hydrolysis in 20-mL and 200-mL reactors at 60 °C led to sucrose hydrolysis above 60% (8.5 residence times) and above 55% (4.5 residence times), respectively. The auto-immobilised biocatalyst produced by SSF without recovery, purification, and immobilisation stages offers an economical alternative for developing accessible biocatalysts that can be applied in batch or continuous sucrose hydrolysis processes. This study shows the potential of biocatalyst production by SSF for other enzymatic systems.


Assuntos
Aspergillus niger
4.
J Environ Manage ; 299: 113614, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34523542

RESUMO

The Mexican Caribbean is a vital nesting destination for loggerhead (Caretta caretta) and green (Chelonia mydas) sea turtles. Since 2015, massive periodical landings of pelagic Sargassum species (sargasso) have affected coastal ecosystems. Dense accumulations of sargasso on the shoreline may preclude access to sea turtles' preferred nesting areas and compromise hatching. In this study, we assess whether the number of nests and hatches of loggerhead and green sea turtles has been affected by the massive influx of sargasso. We compare data from before (2010-2014) and after (2015-2019) the first sargasso event, obtained from the same 17 marine turtle camps, which collectively account for 72.3 km of sampling distance over a 210 km section of shoreline. No differences in preferences on nesting beaches were recorded between periods for the two species. The mean number of nests per kilometer of coastline remained without statistically significant changes between periods in 16 camps and increased significantly in one camp for each species. Overall, the mean annual number of nests per kilometer of beach was 37% higher in the period after massive landings of sargasso began. The mean number of hatchlings increased significantly in one camp for C. mydas and in three for C. caretta. Periodical massive landings of sargasso from 2015 to 2019 do not appear to have compromised nesting and hatching of loggerhead and green sea turtles along the Mexican Caribbean coast.


Assuntos
Sargassum , Tartarugas , Animais , Região do Caribe , Ecossistema , Comportamento de Nidação
5.
Bioresour Technol ; 320(Pt A): 124222, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33171346

RESUMO

Surfactants are multipurpose products found in most sectors of contemporary industry. Their large-scale manufacturing has been mainly carried out using traditional chemical processes. Some of the chemical species involved in their production are considered hazardous and some industrial processes employing them categorised as "having potential negative impact on the environment". Biological surfactants have therefore been generally accepted worldwide as suitable sustainable greener alternatives. Biosurfactants exhibit the same functionalities of synthetic analogues while having the ability to synergize with other molecules improving performances; this strengthens the possibility of reaching different markets via innovative formulations. Recently, their use was suggested to help combat Covid-19. In this review, an analysis of recent bibliography is presented with descriptions, statistics, classifications, applications, advantages, and challenges; evincing the reasons why biosurfactants can be considered as the chemical specialities of the future. Finally, the uses of the solid-state fermentation as a production technology for biosurfactants is presented.


Assuntos
COVID-19 , Características da Família , Fermentação , Humanos , Pandemias , SARS-CoV-2 , Tensoativos , Tecnologia
6.
Bioresour Technol ; 265: 52-58, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29879651

RESUMO

Lipases produced by solid-state fermentation were used directly as biocatalysts for continuous synthesis of ethyl oleate in a continuously stirred tank reactor. The effect of biocatalyst reutilisation, molar ratio of substrates, agitation rate and feed rate on the esterification of oleic acid with ethanol were investigated. The catalyst maintained 90% conversion for four batch cycles with a 1:2 molar ratio (oleic acid:ethanol). Mechanical agitation at 200 and 300 rpm during 12 h of continuous reaction did not affect the biocatalytic conversion, allowing substrate conversions greater than 90% that were obtained with 50 mM oleic acid at a molar ratio of 1:2 during 14 h reaction. In contrast, substrate conversion was 70% with 100 mM oleic acid at a flow rate of 2 mL/min during 25 h of reaction. These results are promising and offer a technical alternative for the development of accessible biocatalysts that can be used in continuous operations.


Assuntos
Lipase/metabolismo , Ácidos Oleicos , Rhizopus/enzimologia , Esterificação , Fermentação , Ácido Oleico
7.
Bioresour Technol ; 247: 412-418, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-28961447

RESUMO

The present work describes the monitoring of CO2 production by Aspergillus niger GH1 in a bioprocess for the production of ellagitannase (EAH) and ellagic acid by solid state fermentation. Pomegranate ellagitannins, mainly punicalagin, were used as carbon source and EAH inducer. A second condition, using ellagitannins and maltose as growth promoting carbon source, was tested. The ellagic acid production was quantified and the EAH activity was assayed. The accumulated metabolites were identified by HPLC-ESI-MS/MS. Higher CO2 production (7.79mg/grams of dry material) was reached in media supplemented with maltose. Short-time lag phase (7.79h) and exponential phase (10.42h) were obtained using only ellagitannins, despite its lower CO2 production (3.79mg/grams of dry material). Without the use of maltose lower ellagic acid (11.85mg/L/h) and EAH (21.80U/L/h) productivities were reached. The use of maltose enhances the productivity of EA (33.18mg/L/h) and EAH (33.70U/L/h). Besides of punicalin and ellagic acid, two unknown compounds with mass weight of 702 and 290g/mol (ions 701 and 289m/z in negative mode, respectively) were identified and characterized by HPLC-ESI-MS/MS analysis.


Assuntos
Aspergillus niger , Ácido Elágico , Fermentação , Lythraceae , Espectrometria de Massas em Tandem
8.
J Agric Food Chem ; 62(31): 7869-76, 2014 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-25008987

RESUMO

The contents of soluble and bound hydroxycinnamates (HCAs) were analyzed in coffee pulp (CP) of seven cultivars of Coffea arabica at three different ripening stages. Methodologies for the extraction and analysis of HCAs were evaluated and improved. HCAs were present mainly in the soluble fraction (68-97%). Chlorogenic acid was the main phenolic acid (94-98%) in the soluble fraction, whereas caffeic acid was the most abundant HCA found in the bound fraction (72-88%). Small amounts of free and bound ferulic and p-coumaric acids were also detected. The content of total HCAs in CP reached the maximum concentration at the semiripe stage (7.4-25.5 mg/g CP, dw) but decreased at the ripe stage for six of the seven cultivars. These findings suggest that unripe or semiripe coffee cherries, considered as defective cherries, are a potential inexpensive source of phenolic compounds, such as chlorogenic and caffeic acids.


Assuntos
Coffea/química , Ácidos Cumáricos/análise , Sementes/química , Sementes/crescimento & desenvolvimento , Ácidos Cafeicos/análise , Ácidos Cafeicos/isolamento & purificação , Ácido Clorogênico/análise , Ácido Clorogênico/isolamento & purificação , Ácidos Cumáricos/química , Ácidos Cumáricos/isolamento & purificação , Solubilidade , Especificidade da Espécie
9.
J Med Primatol ; 43(1): 44-7, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24033265

RESUMO

BACKGROUND: Congenital scoliosis (CS) is defined as lateral curvatures of the spine provoked by the anomalous development of the vertebral bodies. It is associated with neuromuscular anomalies, which can be genetic, caused by the compensation of discrepancies in the length of the extremities or intrarachidian anomalies. METHODS: This study was carried out in 2-year-old female, showed alterations in the gait, mainly in the hind limbs, a clumsy gait and a slight claudication in the right hindlimb. To perform the imaging study were: X-Ray projections and Computerized Axial Tomography, neurophysiological evaluation was performed by means somatosensory-evoked potentials of the tibial nerve (SEPTN). RESULTS: The results showed an enlargement of the latencies from the L5 to the cortex, mainly in the left afference, correlated with the imaging studies. CONCLUSIONS: There is no doubt that the concurrent use of different diagnostic tools complements knowledge regarding the physiopathogenesis of these osteopathologies.


Assuntos
Potenciais Somatossensoriais Evocados , Macaca mulatta , Doenças dos Macacos/diagnóstico por imagem , Escoliose/veterinária , Animais , Vértebras Cervicais/diagnóstico por imagem , Vértebras Cervicais/patologia , Feminino , Fluoroscopia/veterinária , Vértebras Lombares/diagnóstico por imagem , Vértebras Lombares/patologia , Doenças dos Macacos/congênito , Doenças dos Macacos/fisiopatologia , Sacro/diagnóstico por imagem , Sacro/patologia , Escoliose/congênito , Escoliose/diagnóstico por imagem , Escoliose/fisiopatologia , Nervo Tibial/fisiopatologia , Tomografia Computadorizada por Raios X/veterinária
10.
Pest Manag Sci ; 70(4): 661-6, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23847155

RESUMO

BACKGROUND: In addition to high production levels of conidia, the success of entomopathogenic fungi as biological control agents depends both on their prevalence under the environmental conditions found in open fields (resistance to stress) and on the capacity of these conidia to infect pests. This study compares conidium production, infectivity and resistance to thermal and osmotic stress in two strains of Isaria fumosorosea (ARSEF 3302 and CNRCB1) grown either under a normal atmosphere (21% O2) or using enriched oxygen pulses (26% O2). RESULTS: After 180 h, the ARSEF 3302 strain with 26% O2 pulses increased conidium production nearly fivefold compared with the normal atmosphere, while conidium production by the CNRCB1 strain decreased by 50% under O2 pulses, relative to the values measured with the normal atmosphere. The conidia obtained with 26% O2 pulses had a greater germination rate and resistance to thermal and osmotic stress, in addition to improved infectivity against Galleria mellonella (Lepidoptera) larvae. These findings were associated with an increase in catalase activities for both strains. CONCLUSION: An enriched oxygen atmosphere increases the quality of conidia of both strains of I. fumosorosea, with a variable effect on conidium production.


Assuntos
Hypocreales/fisiologia , Mariposas/microbiologia , Controle Biológico de Vetores , Esporos Fúngicos/crescimento & desenvolvimento , Animais , Catalase/metabolismo , Hypocreales/patogenicidade , Pressão Osmótica , Oxigênio , Temperatura
11.
Braz. arch. biol. technol ; 56(3): 357-363, May-June 2013. ilus
Artigo em Inglês | LILACS | ID: lil-679181

RESUMO

In this work, fifty yeast strains, isolated from the spontaneous alcoholic fermentation of Agave duranguensis to produce mezcal, were tested using the double coupling system. These yeasts were from the genera Pichia, Torulaspora, Saccharomyces, Kluyveromyces, Deckera, Hanseniaspora, and Candida. P. fermentans ITD00165 was the best isoamyl acetate producer, yielding 0.38 g/L of ester after incubation for 24 h, while K. marxianus ITD00211 produced 0.32 g/L of ester. Thus P. fermentans TD00165 could be considered as an excellent choice for use in optimization studies of the culture medium and bioreactor operating conditions to develop a process for biotechnological production of isoamyl acetate.

12.
Biotechnol Prog ; 29(2): 337-45, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23341203

RESUMO

The highest enzymatic extraction of covalent linked chlorogenic (36.1%) and caffeic (CA) (33%) acids from coffee pulp (CP) was achieved by solid-state fermentation with a mixture of three enzymatic extracts produced by Aspergillus tamarii, Rhizomucor pusillus, and Trametes sp. Enzyme extracts were produced in a practical inexpensive way. Synergistic effects on the extraction yield were observed when more than one enzyme extract was used. In addition, biotransformation of chlorogenic acid (ChA) by Aspergillus niger C23308 was studied. Equimolar transformation of ChA into CA and quinic acids (QA) was observed during the first 36 h in submerged culture. Subsequently, after 36 h, equimolar transformation of CA into protocatechuic acid was observed; this pathway is being reported for the first time for A. niger. QA was used as a carbon source by A. niger C23308. This study presents the potential of using CP to produce enzymes and compounds such as ChA with biological activities.


Assuntos
Aspergillus/enzimologia , Ácido Clorogênico/metabolismo , Coffea/metabolismo , Proteínas Fúngicas/metabolismo , Microbiologia Industrial/métodos , Rhizomucor/enzimologia , Trametes/enzimologia , Aspergillus/metabolismo , Biotransformação , Ácidos Cafeicos/metabolismo , Ácido Clorogênico/isolamento & purificação , Coffea/química , Fermentação , Proteínas Fúngicas/química , Resíduos Industriais/análise , Rhizomucor/metabolismo , Trametes/metabolismo
13.
J Med Primatol ; 41(3): 163-71, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22620269

RESUMO

BACKGROUND: It has been widely documented that quadrupedal animals rarely display natural spontaneous scoliotic rachis deviations of the spinal column. The objective was to determine spinal deformities developed by geriatric monkeys of the Macaca mulatta species, by radiographical and tomographical studies of the vertebral column correlating morphological changes with altered physiological parameters and electrical neurosensorial conductivity of somatosensory-evoked potentials (SEPs). MATERIALS AND METHODS: A cohort of six geriatric monkeys was used: three non-scoliotic subjects and three monkeys with naturally acquired true scoliosis. RESULTS: Radiographic and tomographic studies depicted a thoracic curvature displaying a left-sided thoracic vertebral rotation. The evaluation of physiological parameters demonstrated significant differences in the respiratory rate, as it was observed for the diastolic blood pressures, which showed a decrease in the monkeys with scoliosis compared with healthy monkeys. Regarding the SEPs studies, the non-parametric test for independent samples Mann-Whitney U test displayed a significant difference observed at the left and right thoracic derivative in P1; while regarding the study of upper limbs, a significant difference was seen at the Erb's point derivative, left afferency in P1, showing in all the derivatives an increase in latency in monkeys with scoliosis versus monkeys in the control group. CONCLUSIONS: This study has demonstrated that quadrupedal animals can develop true scoliosis showing an analogous way to that occurring in humans.


Assuntos
Cardiopatias/veterinária , Macaca mulatta , Doenças dos Macacos/patologia , Doenças Respiratórias/veterinária , Escoliose/veterinária , Envelhecimento , Animais , Potenciais Somatossensoriais Evocados/fisiologia , Cardiopatias/etiologia , Doenças Respiratórias/etiologia , Escoliose/complicações , Escoliose/patologia
14.
J Am Assoc Lab Anim Sci ; 50(3): 401-3, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21640038

RESUMO

In subclavian steal phenomenon (SSP), the subclavian artery develops a stenoocclusive disease proximal to the origin of the vertebral artery, leading to pronounced hemodynamic changes such as arterial flow reversal. Although SSP is a common echographic finding in humans, the phenomenon occurs only rarely in animals; consequently its physiologic features have not been reported previously. Here we describe the clinical and morphologic features of a spontaneous left SSP that was an incidental finding in an 18-y-old female rhesus macaque (Macaca mulatta). Our findings were documented through high-quality imaging studies obtained by using a computerized 3D tomography apparatus and clinical assessment of systolic and diastolic blood pressures.


Assuntos
Achados Incidentais , Doenças dos Macacos/diagnóstico , Doenças dos Macacos/fisiopatologia , Síndrome do Roubo Subclávio/veterinária , Angiografia , Animais , Velocidade do Fluxo Sanguíneo/fisiologia , Pressão Sanguínea/fisiologia , Feminino , Macaca mulatta , Doenças dos Macacos/diagnóstico por imagem , Artéria Subclávia/diagnóstico por imagem , Artéria Subclávia/fisiopatologia , Síndrome do Roubo Subclávio/diagnóstico , Síndrome do Roubo Subclávio/fisiopatologia , Tomografia Computadorizada por Raios X , Artéria Vertebral/diagnóstico por imagem , Artéria Vertebral/fisiopatologia
15.
Braz. arch. biol. technol ; 53(4): 771-777, July-Aug. 2010. graf, tab
Artigo em Inglês | LILACS | ID: lil-554769

RESUMO

The aim of the present work was to study the effect of moisture content and inoculum on the growth and conidia production by Beauveria bassiana on wheat bran (WB).The highest growth rate of B. bassiana 885.2 on WB media was obtained at a w=1.0, with no detected growth at a w < 0.97. Solid-state fermentation (SSF) using WB (66 percent moisture; a w=1.0) achieved a maximal yield of 1.18x10 10 conidia per gram of dry substrate (gds). This yield decreased one order of magnitude with higher moisture contents or the addition of sugarcane bagasse (SCB) as a texturiser. In SSF using WB (66 percent humidity),the time to obtain a yield of 1x10(10) conidia/gds, referred to as t10, could be predicted using a model considering common inoculum levels and maximal yields. For instance, t10 was 285 h with an inoculum of 1x10(6) conidia/gds; however, t10 was reduced to 232 h and 148 for inocula of 7x10(6) and 5x10(7) conidia/gds, respectively. The estimation of t10 values allowed both comparison between the cultures and prediction of harvesting times in production processes. Values for hydrophobicity were within 90 and 92 percent, whereas viability averages were around 70 percent for all the cultures

16.
Bioresour Technol ; 101(12): 4721-4, 2010 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-20153180

RESUMO

Ferulic acid biotransformation has a number of interesting industrial uses. Ferulic acid biotransformation by the wild strain Aspergillus niger C28B25 and a diploid strain DAR2, obtained by parasexual recombination, was studied. The wild strain of A.niger C28B25 biotransforms ferulic acid to vanillic acid (VA); while the diploid strain DAR2 preferentially decarboxylates ferulic acid to 4-vinylguaiacol (4VG). The latter was identified by mass spectroscopy, (1)H and (13)C nuclear magnetic resonance spectroscopy, and quantified by HPLC. The diploid strain A.niger DAR2 and the wild strain showed a ferulic acid conversion of 64% and 36%, respectively. Molar yields show that the formation of 4VG was preferred, being as much as 4.4 times higher than the formation of VA in diploid strain cultures. Differential regulation of enzymes involved in the biotransformation of ferulic acid may explain the accumulation of 4VG by diploid DAR2. This strain produced both 4VG and VA.


Assuntos
Aspergillus niger/metabolismo , Ácidos Cumáricos/metabolismo , Guaiacol/análogos & derivados , Biotransformação , Ácidos Cumáricos/química , Guaiacol/química , Guaiacol/metabolismo , Ácido Vanílico/metabolismo
17.
Comp Med ; 60(5): 396-9, 2010 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21262126

RESUMO

Degenerative spinal disease is a leading cause of chronic disability both in humans and animals. Although widely seen as a normal occurrence of aging, degenerative spinal disease can be caused by various genetic, iatrogenic, inflammatory, and congenital factors. The objective of this study was to characterize the degenerative spine-related diseases and the age at onset in a random subpopulation of 20 captive rhesus monkeys (Macaca mulatta; male, 13; female, 7; age: range, 4 to 27 y; median, 18.5 y). Spinal radiographic evaluation (left lateral, right lateral, and ventrodorsal views) of the spinal column (C1 to S1) was performed, and spinal degenerative disease was scored. The incidence of osteopathology was higher in the 14- to 18-y-old group, but incidence did not differ according to sex. In the studied population, degenerative changes were present in monkeys as young as 9 y of age.


Assuntos
Macaca mulatta , Doenças dos Macacos/epidemiologia , Doenças da Coluna Vertebral/veterinária , Idade de Início , Envelhecimento , Animais , Feminino , Incidência , Masculino , Doenças dos Macacos/diagnóstico por imagem , Radiografia , Doenças da Coluna Vertebral/diagnóstico por imagem , Doenças da Coluna Vertebral/epidemiologia
18.
J Ind Microbiol Biotechnol ; 36(1): 11-20, 2009 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-18800233

RESUMO

Eighteen lactic acid bacteria (LAB) strains, isolated from coffee pulp silages were characterized according to both growth and gallic acid (GA) consumption. Prussian blue method was adapted to 96-well microplates to quantify GA in LAB microcultures. Normalized data of growth and GA consumption were used to characterize strains into four phenotypes. A number of 5 LAB strains showed more than 60% of tolerance to GA at 2 g/l; whereas at 10 g/l GA growth inhibition was detected to a different extent depending on each strain, although GA consumption was observed in seven studied strains (>60%). Lactobacillus plantarum L-08 was selected for further studies based on its capacity to degrade GA at 10 g/l (97%). MRS broth and GA concentrations were varied to study the effect on growth of LAB. Cell density and growth rate were optimized by response surface methodology and kinetic analysis. Maximum growth was attained after 7.5 h of cultivation, with a dilution factor of 1-1/2 and a GA concentration between 0.625 and 2.5 g/l. Results indicated that the main factor affecting LAB growth was GA concentration. The main contribution of this study was to propose a novel adaptation of a methodology to characterize and select LAB strains with detoxifying potential of simple phenolics based on GA consumption and tolerance. In addition, the methodology presented in this study integrated the well-known RSM with an experimental design based on successive dilutions.


Assuntos
Técnicas de Cultura , Ácido Gálico/metabolismo , Ácido Láctico/metabolismo , Lactobacillaceae/genética , Lactobacillaceae/metabolismo , Técnicas Bacteriológicas , Coffea/microbiologia , Meios de Cultura/química , Meios de Cultura/metabolismo , Cinética , Lactobacillaceae/química , Lactobacillaceae/isolamento & purificação
19.
Appl Biochem Biotechnol ; 151(2-3): 610-7, 2008 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-18592410

RESUMO

A study was carried out to select the conditions for cultivation of Kluyveromyces marxianus CDBBL 278 in solid-state culture (SSC) using polyurethane foam (PUF) as an inert support. PUF was impregnated with culture media containing lactose (50 g/L) as the carbon and energy source. Evaluation of culture parameters during different growth phases was carried out by respirometry. The effect of inoculum level, buffer capacity of the medium, and nitrogen source upon the yield of biomass on lactose (Yx/s) and production of lactase and inulinase was investigated. The highest lactase titre was achieved with an inoculum level of 1 x 10(7) cells per gram of wet matter (gwm) and 20% of the total nitrogen source provided as urea. The best biomass yield (0.37) was obtained when less than 40% of the total nitrogen was provided as urea. Using potassium phosphate allowed 90% substrate consumption in 30 h. In the best conditions, intracellular lactase and extracellular inulinase activities of 1147.7 IU/gX and 241.6 IU/gX were obtained, respectively, with a lag phase of 13.8 h and a rate of respiratory activity (microCO2) of 0.23 +/- 0.01 h(-1). To our knowledge, this is the first report on lactase production by K. marxianus CDBBL 278 in SSC. This study gives basic information about biomass yield and enzyme production using lactose as the sole carbon source in SSC on an inert support.


Assuntos
Kluyveromyces/metabolismo , Lactase/biossíntese , Soluções Tampão , Meios de Cultura , Kluyveromyces/crescimento & desenvolvimento , Lactose/metabolismo , Micologia/métodos , Nitrogênio/administração & dosagem , Poliuretanos
20.
Appl Biochem Biotechnol ; 151(2-3): 393-401, 2008 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-18392560

RESUMO

This paper reports a study of the enzymatic esterification of oleic acid and ethanol. The reaction was catalyzed by lipases produced by solid-state fermentation with Rhizopus sp. Olive oil and perlite were used as an inducer and inert support, respectively. Synthesis of ethyl oleate was carried out in a 10-mL batch reactor with magnetic stirring. The effects of substrate ratios, biocatalyst concentration, and temperature on the reaction rate and conversion efficiency were evaluated. The highest reaction rate (1.64 mmol/L min) was reached with an oleic acid/ethanol mol ratio of 1:5 (oleic acid 50 mM:ethanol 250 mM) and 1 g of biocatalyst. Conversions approaching 100% were obtained after 60 min of reaction at 45 degrees C with n-hexane as a solvent. The initial reaction rate increased proportionally with respect to biocatalyst concentration, which suggests that the reaction rate was not controlled by mass transfer. The biocatalyst retained more than 80% of its catalytic activity after 7 months of storage at 4 degrees C. The results demonstrate that the biocatalyst produced by Rhizopus sp. in solid-state fermentation can be successfully used for ethyl oleate synthesis over short reaction periods under conditions when ethanol is in excess.


Assuntos
Lipase/metabolismo , Ácidos Oleicos/biossíntese , Estabilidade Enzimática , Ésteres/síntese química , Etanol/metabolismo , Fermentação , Ácido Oleico/metabolismo , Rhizopus/enzimologia , Temperatura
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