Use of flow cytometry with fluorescent antibodies in real-time monitoring of simultaneously inoculated alcoholic-malolactic fermentation of Chardonnay

AIMS: To monitor in real-time the changes in microbial populations and chemistry of grape juice simultaneously inoculated with Saccharomyces cerevisiae and Oenococcus oeni. METHODS AND RESULTS: Viable populations of S. cerevisiae and O. oeni in Chardonnay fermentations were identified and quantified using fluorescent dyes and fluorescently labelled antibodies in a flow cytometric assay. Fermentation chemistry was monitored using Fourier transform infrared (FTIR) spectroscopy, except for malic acid which was measured enzymatically. Malic acid utilization by O. oeni was greatest in the presence of the yeast Cepage. Growth of O. oeni was substantially slower in the presence of the yeast VL1. The three yeasts had similar fermentation rates in the presence and absence of O. oeni. CONCLUSIONS: Viable and nonviable yeast and bacterial populations can be rapidly discriminated in simultaneous malolactic-alcoholic wine fermentations using antibodies, fluorescent dyes and flow cytometry. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study using fluorescently labelled antibodies to discriminate and monitor yeast and bacterial populations in wine fermentations and offers a new approach to investigating microbial interactions in wine fermentations.     

Dynamics of the yeast transcriptome during wine fermentation reveals a novel fermentation stress response

In this study, genome-wide expression analyses were used to study the response of Saccharomyces cerevisiae to stress throughout a 15-day wine fermentation. Forty per cent of the yeast genome significantly changed expression levels to mediate long-term adaptation to fermenting grape must. Among the genes that changed expression levels, a group of 223 genes was identified, which was designated as fermentation stress response (FSR) genes that were dramatically induced at various points during fermentation. FSR genes sustain high levels of induction up to the final time point and exhibited changes in expression levels ranging from four- to 80-fold. The FSR is novel; 62% of the genes involved have not been implicated in global stress responses and 28% of the FSR genes have no functional annotation. Genes involved in respiratory metabolism and gluconeogenesis were expressed during fermentation despite the presence of high concentrations of glucose. Ethanol, rather than nutrient depletion, seems to be responsible for entry of yeast cells into the stationary phase.     

Determination of Growth and Glycerol Production Kinetics of a Wine Yeast Strain Saccharomyces cerevisiae Kalecik 1 in Different Substrate Media

Summary Glycerol has been known as an important by-product of wine fermentations improving the sensory quality of wine. This study was carried out with an endogenic wine yeast strain Saccharomyces cerevisiae Kalecik 1. The kinetics of growth and glycerol biosynthesis were analysed at various initial concentrations of glucose, fructose, and sucrose in a batch system. Depending on the determined values of Monod constants, glucose (K_s = 28.09 g/l) was found as the most suitable substrate for the yeast growth. Initial glucose, fructose and sucrose concentrations necessary for maximum specific yeast growth rate were determined as 175 g, 100 l, and 200 g/l, respectively. The yeast produced glycerol at very high concentrations in fructose medium. Fructose was determined as the most suitable substrate for glycerol production while the strain showed low tendency to use it for growth. S. cerevisiae Kalecik 1 could not produce glycerol below 200 g/l initial sucrose concentration. When natural white grape juice was used as fermentation medium, maximum glycerol concentration and dry weight of the yeast were determined as 9.3 g/l and 11.8 g/l, respectively.     

Production and Characterization of Wine from Mango Fruit (Mangifera indica L)

Summary Mango (Mangifera indica L) is the most popular and the choicest fruit of India. A major portion (nearly 60–70%) of the total quantity produced is locally consumed and a sizable portion is exported to other countries. In the present study, six varieties of mango, which are abundantly available in the region were selected for wine production and the conditions for juice extraction were optimized. It was found that the mango juices were similar to grape juice in terms of sugar and acidity. After fermentation, the ethanol concentration was 7–8.5% w/v, the methanol concentration was slightly higher than that of grape wines and other volatile compounds were present in comparable amounts. From the physicochemical characteristics of the mango wine produced, it was observed that aromatic components were comparable in concentration to those of grape wine.     

葡萄酒工业酵母生孢特性研究

孢子是单倍体配子,由于具有遗传型与表现型相一致的优点,是遗传学上常用的材料。用工业化葡萄酒活性干酵母进行生孢试验,结果表明,供试8支菌种均可生孢,但生孢率与孢子形态相差较大。其中,17#生孢最强,30#、29#、27#次之,28#、18#、26#渐弱,32#生孢最弱。子囊多为圆形大细胞,孢子多为球形或卵圆形,子囊内一般含2~4个孢子,但29#中可见5~6个孢子。     

基因重组酵母在葡萄酒酿造中的应用前景

基因重组技术是菌种改良的重要手段。就基因重组酵母在葡萄酒酸度调解、增香、抗氧化及果胶分解方面的潜在应用价值及近年来相关研究成果进行了概述。     

Screening of <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> wine strains for the production of acetic acid

In this study 80 wine strains of Saccharomyces cerevisiae were characterized for the production of acetic acid. A significant variability in the production levels was determined among the strains, which produced from a few mg/l to more than 1 g/l. Fifteen strains, differing in acetic acid production, were tested in fermentation of grape musts of different varieties (Aglianico Basilicata, Aglianico Apulia, Cannonau, Bombino nero, Nero d'Avola, Vermentino, Fiano). The results emphasized a great strain variability, but the best strain behaviour was strictly related to the must composition, which is a determinant factor on the expression of the best strain potentiality. Therefore, this study, confirming the high/low production of acetic acid as a strain characteristic, demonstrated also that the inoculated fermentation becomes more advantageous when the starter culture is chosen in relation to the interaction of yeast strain/vine variety.     

Alcohol Consumption in the Severely Obese: Relationship with the Metabolic Syndrome

Objective: The aim of this study was to examine the association between the clinical and biochemical features of the metabolic syndrome and quantity and type of alcohol intake in the severely obese. Research Methods and Procedures: A cross‐sectional study was performed in 486 consecutive severely obese subjects. Data on alcohol consumption was collected by serial clinical interviews and a questionnaire. The relationship between alcohol intake and the clinical and serum chemistry features of the metabolic syndrome was analyzed by multiple statistical techniques. Laboratory measures included lipid profile, fasting blood glucose, hemoglobin A1c, and fasting serum insulin. An indirect index of insulin resistance was calculated using the log‐transformed fasting insulin and glucose product. Results: There were 486 subjects, 84% women, with a mean age of 40.6 ± 10 years (range, 16 to 71 years) and a body mass index of 45.3 ± 7 kg/m² (range, 34 to 77 kg/m²). Alcohol consumers (N = 276) showed a marked reduction in the adjusted odds ratio of type 2 diabetes (odds ratio = 0.29; 95% confidence interval, 0.16 to 0.55) compared with rare or nonconsumers (N = 210). There was a U‐shaped relationship between the amount and frequency of alcohol consumption and fasting triglyceride, fasting glucose, hemoglobin A1c, and index of insulin resistance measurements. Consumers of <100 g/wk had more favorable measures. The effect was attenuated when diabetics were excluded from the analysis. Timing of alcohol consumption did not influence outcome measures. Discussion: Light‐to‐moderate alcohol consumption is associated with a lower prevalence of type 2 diabetes, reduced insulin resistance, and more favorable vascular risk profile in the severely obese. We would propose that light to moderate alcohol consumption should not be discouraged in the severely obese.     

Preliminary characterization of wine lactobacilli able to degrade arginine

Lactobacillus strains able to degrade arginine were isolated and characterized from a typical red wine. All the strains were gram-positive, catalase-negative and produced both D- and L-lactate from glucose. Strains L2, L3, L4, and L6 were able to produce CO₂ from glucose; however, production of CO₂ from glucose was not observed in strains L1 and L5, suggesting that they belong to the homofermentative wine lactic acid bacteria (LAB) group. All of the lactobacilli were tested for their ability to ferment 49 carbohydrates. The sugar fermentation profile of strain L1 was unique, suggesting that this strain belonged to Lactococcus lactis ssp. cremoris, a non-typical wine LAB. Furthermore, a preliminary typing was performed by using a random amplified polymorphic DNA analysis (RAPD-PCR analysis).     

Formation of biogenic amines as criteria for the selection of wine yeasts

This work deals with biogenic amine production by yeast strains isolated from grapes and wines. A total of 50 strains were tested for their capacity to produce biogenic amines in wine. In general, all the species produced very low or non-detectable amounts of histamine, whereas methylamine and agmatine were formed by all the species considered. The highest concentration of total biogenic amines was formed by Brettanomyces bruxellensis, with an average value of 15 mg/l, followed by Saccharomyces cerevisiae with an average of 12.14 mg/l. The other species formed less than 10 mg of total biogenic amines per litre. Wines fermented with the most fermentative strains of S. cerevisiae species had the highest contents of ethanolamine, from 2.3 to 16 mg/l, and of agmatine, from 3.1 to 7.5 mg/l. The strains of the other species, which exhibited a low fermentative ability, Kloeckera apiculata, B. bruxellensis and Metschnikowia pulcherrima, varied in the production of agmatine and phenylethylamine. A significant variability in the production of cadaverine was characteristic of Candida stellata strains, which varied also in ethanolamine production. Our results emphasize the importance of using selected strains of S. cerevisiae, not only for the expression of desirable technological traits, but also to avoid potentially negative effects on human health. Therefore, the characterization of strains of S. cerevisiae for the 'production of biogenic amines' becomes of applicative interest.