Ethanol tolerance of thermotolerant yeasts cultivated on mixtures of sucrose and ethanol

The final levels of ethanol (levels of ethanol produced plus that added initially to the media) reached by the thermotolerant yeasts were highest (16.5-20.3%, v/v) at 8% initial ethanol. The thermotolerant yeasts were found to have the following characteristics: constant levels of ethanol formation (10.5-12.3%, v/v), fog additions of external ethanol within the range 2-8% (v/v) of initial ethanol; constant values of product coefficients when initial ethanol was in the range of 2-6%, which increased or decreased, depending on the strain, when initial ethanol exceeded 6%; growth activity was inhibited at different levels of addition of external ethanol when final biomass and specific rate of growth were compared; significant differences among the yeast strains in the amount of external ethanol capable of reducing biomass formation by one half. In addition, the viability of the strains (early stationary phase) varied with the amount of external ethanol, the lowest viabilities occurring at concentrations of initial ethanol ranging from 4 to 7% and the highest in the range of 7 to 8% (v/v). The relative levels of trehalose (with/without 7% ethanol added initially) in the yeast strains (the stationary phase) ranged from 1.03 to 1.75, suggesting that the effect of produced ethanol on trehalose accumulation was stronger than that of external ethanol. The levels of final ethanol shown by the yeast strains were also correlated with the cellular levels of glycerol-3-phosphate dehydrogenase (increase in enzyme levels with decrease in final ethanol) for cells harvested at the stationary phase.

Response of the stingless bee manduri do mato grosso (Melipona favosa orbignyi, Hymenoptera, Apidae) to variable concentrations of sucrose in artificial feeding sources of different colors

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Influence of diltiazem in combination with a sucrose-rich diet on gingival alterations in rats

The aim of this study was to evaluate the influence of diltiazem in combination with a sucrose-rich diet on gingival alterations in rats. One hundred and twenty male Holtzman rats were randomly assigned to 10 groups (n = 12), being 2 control groups treated with saline and 8 test groups treated with diltiazem in daily doses of 5, 25, 50 and 100 mg/kg during 40 or 60 days. Afterwards, the mandibles were removed for macroscopic, histologic and histometric analyses of the buccal gingiva of the mandibular right first molar. No macroscopic characteristic of gingival overgrowth was observed in any of the groups. The microscopic analysis showed characteristics of normality with inflammatory cells only adjacent to the crevicular epithelium in all groups for both periods. The histometric analysis showed significant differences only for the epithelial tissue area in the 40-day period (Kruskal-Wallis; P = 0.032). Comparing the periods, significant differences regarding the connective and epithelial tissue areas were observed only in the group treated with a 25 mg/kg dose (Mann-Whitney; P = 0.004 and P = 0.007, respectively). Oral administration of diltiazem in combination with a sucrose-rich diet did not induce gingival alterations in rats. © 2009 Sociedade Brasileira de Pesquisa Odontológica.

High-sucrose effect on bone structure, hardness and biomechanics in an obesity model using Wistar male rats

Introduction: Excessive consumption of sugar-sweetened beverage is positively related to overweight. Despite the epidemic of childhood obesity, body mass can have a positive or negative effect on bone health. Material and methods: Wistar rats 8 weeks olds were randomly assigned to consume water (Control group, n = 10), sucrose 30% (HS group, n = 10) and water + sucrose 30% (WHS group, n = 14) for 8 weeks. All animals received standard laboratory chow ad libitum. Femur measurements included microhardness, bone mineral density (BMD) by DXA, mechanical compression test and microcomputed tomography (microCT) analysis. Results: We observed significant difference in final body weight in HS and WHS groups, significant increase in triacylglycerol/fructosamine in HS and WHS groups, significantly high BMD in WHS group, increased periosteal/endosteal cortical microhardness in WHS group. Compared with control, microCT parameters evidenced lower amount of connected trabecular bone, decreased bone volume, lower trabecular number with high trabecular separation in distal epiphysis in WHS animals. Conclusion: High-sucrose consumption causes obesity induced by a liquid diet with negative effects on cancellous bone.

Osmotic Dehydration of Pineapple with Impregnation of Sucrose, Calcium, and Ascorbic Acid

Mass transfer was evaluated during osmotic dehydration of pineapple in solutions with until four components aiming to investigate the solutes concentration influence on impregnation. In the first step, the experimental trials for optimization of solution concentration were based on 23 factorial design. In the second step, effective diffusion coefficients were determined. Equations representing the influence of the concentration of sucrose, calcium lactate, and ascorbic acid in osmotic solutions on water loss and gains of sucrose, calcium, and vitamin C were found. Results showed that both calcium lactate and sucrose concentration affected calcium and sucrose gain. On the other hand, only vitamin C gain was significantly affected by the ascorbic acid concentration in the studied concentration range. However, when comparing diffusivities in pineapple immersed in sucrose solutions, with and without calcium lactate, with and without ascorbic acid, it was possible to verify that diffusivities of water, sugar, and calcium increased in presence of ascorbic acid in solution. Calcium in solution diminished the water and sucrose diffusivities. High calcium and vitamin C contents were obtained in 1 h immersion in the solutions studied. © 2013 Springer Science+Business Media New York.

Biotransformation of sucrose into 5-hydroxy-2-hydroxymethyl-γ-pirone by Aspergillus flavus

Foram investigadas a hidrólise da sacarose e a preferência pela glicose frente à frutose no processo de produção do 5-hidroxi-2-hidroximetil-γ-pirona (HHMP) na presença de Aspergillus flavus IOC 3974 cultivado em meio líquido Czapeck. Quantidades de 0,5g de pelletes foram utilizadas como inóculo. Doze frascos cônicos de 250 ml contendo 100 ml de meio de cultura com diferentes concentrações de sacarose foram utilizados. Os microrganismos foram cultivados a 120 rpm e 28"C por 16 dias sem ajuste do pH. O maior rendimento do HHMP foi 26g l^-1 em 120g l^-1 de sacarose. Nestas condições, A. flavus, foi capaz de produzir uma invertase possibilitando a hidrólise de 65% da concentração total de sacarose em 24 horas, conjuntamente com a produção de uma isomerase que foi capaz de converter a frutose em glicose. Este trabalho está focalizado preferencialmente no consumo da glicose frente à frutose por A. flavus e na estratégia de produção do HHMP.

Ethanol production by Zymomonas mobilis during sucrose fermentation: Optimization of culture conditions using factorial design

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Sucrose utilization by Zymomonas mobilis: Levan production optimization using submerged fermentation

Levan is an extracellular polysaccharide (EPS), constituted by linked fructose units β (2,6), obtained by transfructosilation reaction during fermentation of microorganisms in a sucrose rich culture medium. The bacterial levan production is a good alternative of fructose source, besides having certain functional characteristics in the human body, such as a hypocholesterolemic and an anticarcinogenic agent. In the food industry, the levan can be used to fix colors and flavors, as well as to thickening and stabilizing agent in foods. This work aimed to analyze the kinetic parameters for levan production by Zymomonas mobilis CCT 4494, using submerged fermentation. The response surface methodology (RSM), was utilized to predict the optimization of medium for exopolymer production and the independent variables studied were: initial pH, incubation temperature, sucrose, KCl, K2SO4, MgSO4 and CaCl2. It was observed that the bacterium Z. mobilis CCT 4494 well adapted in medium containing high concentrations of sucrose.

Obesity induced by a sucrose-rich diet promotes deficits in bone mineralization and microarchitecture

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Femoral Biomechanic and microtomography from male rats submitted to dietary restricition supplemented with sucrose

Food restriction reduces body weight and influence bone mass and also is correlated with bone mineral density (BMD). Mechanisms have been proposed for the loss of BMD after body weight reduction, including reduced energy intake. Growing 8 wk-old Wistar male rats were randomly divided into Control and Calorie restriction associated with sucrose 30% (CRS). These animals were subjected to intermittent food restriction during 8 weeks and had free access to tap water and sucrose30% in distilled water. The rats were euthanized at the end of week 8, blood collected from abdominal aorta artery, femurs cleaned of adherent soft tissues, scanned using dual energy X-ray absorptiometry, structural and material properties determined by three-point bending testing in the mid-diaphyseal region, bone surface tested in a microhardness tester and microstructure was assessed in a microcomputer tomography. In CRS animals body weight decreased significantly relative to the Control animals. There was a clear option for high-sucrose beverage in CRS animals. No difference was observed in biochemical, densitometric and biomechanical analyzes. Results from micro CT showed only significant difference in connectivity of trabecular bone. It has been suggested that rats submitted to food restriction consumed sugar not because of its inherent palatability, but in order to alter their macronutrient balance and animals need to meet energy demands in high-sucrose.

Relationship between ethanol and sucrose self-administration and schedule-induced polydipsia

Studies have suggested a relationship between drug abuse and compulsive behaviors. The present experiments investigated the relationship between schedule-induced polydipsia (SIP) and self-administration (SA) of ethanol and sucrose. SIP served as a model of compulsive behavior. and oral self-administration on a progressive-ratio (PR) schedule of reinforcement assessed the reinforcing value of either a 10% ethanol solution or an isocaloric sucrose solution. Rats first were exposed to PR sessions in which break points were the dependent variable and then switched to SIP sessions. with number of licks as the dependent variable. Results showed a positive relationship between PR and SIP for sucrose but not for ethanol: higher and lower PRs for sucrose were associated with higher and lower SIP levels. The order of the sessions then was reversed, such that SIP sessions were run before PR sessions. An opposite relationship was observed in which high and low SIP animals exhibited low and high PR break points, respectively. The relationship between SIP and SA was dependent on the reinforcing value of the substance and on prior SIP exposure. These results may reflect a common dopaminergic substrate and suggest that prior experience in coping with stress may reduce vulnerability to substance abuse behavior. (c) 2008 Published by Elsevier Inc.

Bioelectrical impedance analysis and anthropometry for the determination of body composition in rats: effects of high-fat and high-sucrose diets

Objective The aim of the present study was to determine the impedance of Wistar rats treated with high-fat and high-sucrose diets and correlate their biochemical and anthropometric parameters with chemical analysis of the carcass. Methods Twenty-four male Wistar rats were fed a standard (AIN-93), high-fat (50% fat) or high-sucrose (59% of sucrose) diet for 4 weeks. Abdominal and thoracic circumference and body length were measured. Bioelectrical impedance analysis was used to determine resistance and reactance. Final body composition was determined by chemical analysis. Results Higher fat intake led to a high percentage of liver fat and cholesterol and low total body water in the High-Fat group, but these changes in the biochemical profile were not reflected by the anthropometric measurements or bioelectrical impedance analysis variables. Anthropometric and bioelectrical impedance analysis changes were not observed in the High-Sucrose group. However, a positive association was found between body fat and three anthropometric variables: body mass index, Lee index and abdominal circumference. Conclusion Bioelectrical impedance analysis did not prove to be sensitive for detecting changes in body composition, but body mass index, Lee index and abdominal circumference can be used for estimating the body composition of rats.

Switching the mode of sucrose utilization by Saccharomyces cerevisiae

Abstract Background Overflow metabolism is an undesirable characteristic of aerobic cultures of Saccharomyces cerevisiae during biomass-directed processes. It results from elevated sugar consumption rates that cause a high substrate conversion to ethanol and other bi-products, severely affecting cell physiology, bioprocess performance, and biomass yields. Fed-batch culture, where sucrose consumption rates are controlled by the external addition of sugar aiming at its low concentrations in the fermentor, is the classical bioprocessing alternative to prevent sugar fermentation by yeasts. However, fed-batch fermentations present drawbacks that could be overcome by simpler batch cultures at relatively high (e.g. 20 g/L) initial sugar concentrations. In this study, a S. cerevisiae strain lacking invertase activity was engineered to transport sucrose into the cells through a low-affinity and low-capacity sucrose-H+ symport activity, and the growth kinetics and biomass yields on sucrose analyzed using simple batch cultures. Results We have deleted from the genome of a S. cerevisiae strain lacking invertase the high-affinity sucrose-H+ symporter encoded by the AGT1 gene. This strain could still grow efficiently on sucrose due to a low-affinity and low-capacity sucrose-H+ symport activity mediated by the MALx1 maltose permeases, and its further intracellular hydrolysis by cytoplasmic maltases. Although sucrose consumption by this engineered yeast strain was slower than with the parental yeast strain, the cells grew efficiently on sucrose due to an increased respiration of the carbon source. Consequently, this engineered yeast strain produced less ethanol and 1.5 to 2 times more biomass when cultivated in simple batch mode using 20 g/L sucrose as the carbon source. Conclusion Higher cell densities during batch cultures on 20 g/L sucrose were achieved by using a S. cerevisiae strain engineered in the sucrose uptake system. Such result was accomplished by effectively reducing sucrose uptake by the yeast cells, avoiding overflow metabolism, with the concomitant reduction in ethanol production. The use of this modified yeast strain in simpler batch culture mode can be a viable option to more complicated traditional sucrose-limited fed-batch cultures for biomass-directed processes of S. cerevisiae.

Sucrose Substitutes Affect the Cariogenic Potential of Streptococcus mutans Biofilms

Streptococcus mutans is considered the primary etiologic agent of dental caries and contributes significantly to the virulence of dental plaque, especially in the presence of sucrose. To avoid the role of sucrose on the virulence factors of S. mutans, sugar substitutes are commonly consumed because they lead to lower or no production of acids and interfere with biofilm formation. This study aimed to investigate the contribution of sugar substitutes in the cariogenic potential of S. mutans biofilms. Thus, in the presence of sucrose, glucose, sucralose and sorbitol, the biofilm mass was quantified up to 96 h, the pH of the spent culture media was measured, the expression of biofilm-related genes was determined, and demineralization challenge experiments were conduct in enamel fragments. The presence of sugars or sugar substitutes profoundly affected the expression of spaP, gtfB, gtfC, gbpB, ftf, vicR and vicX in either biofilm or planktonic cells. The substitution of sucrose induced a down-regulation of most genes involved in sucrose-dependent colonization in biofilm cells. When the ratio between the expression of biofilm and planktonic cells was considered, most of those genes were down-regulated in biofilm cells in the presence of sugars and up-regulated in the presence of sugar substitutes. However, sucralose but not sorbitol fulfilled the purpose of reducing the cariogenic potential of the diet since it induced the biofilm formation with the lowest biomass, did not change the pH of the medium and led to the lowest lesion depth in the cariogenic challenge