Wine is a complex beverage, comprising thousands of metabolites that are produced through the action of a plethora of yeasts and bacteria during fermentation of grape must. These microbial communities originate in the vineyard and the winery and reflect the influence of several factors including grape variety, geographical location, climate, vineyard spraying, technological practices, processing stage and season (pre-harvest, harvest, post-harvest). Vineyard and winery microbial communities have the potential to participate during fermentation and influence wine flavour and aroma. Therefore, there is an enormous interest in isolating and characterising these communities, particularly non-Saccharomyces yeast species to increase wine flavour diversity, while also exploting regional signature microbial populations to enhance regionality. In this review we describe the role and relevance of the main non-Saccharomyces yeast species found in vineyards and wineries. This includes the latest reports covering the application of these species for winemaking; and the biotechnological characteristics and potential applications of non-Saccharomyces species in other areas. In particular, we focus attention on the species for which molecular and genomic tools and resources are available for study. Copyright © 2016 John Wiley & Sons, Ltd.

Yeasts found in vineyards and wineries.

We are pleased to dedicate this paper to Dr Julian E Davies. Julian is a giant among microbial biochemists. He began his professional career as an organic chemistry PhD student at Nottingham University, moved on to a postdoctoral fellowship at Columbia University, then became a lecturer at the University of Manchester, followed by a fellowship in microbial biochemistry at Harvard Medical School. In 1965, he studied genetics at the Pasteur Institute, and 2 years later joined the University of Wisconsin in the Department of Biochemistry. He later became part of Biogen as Research Director and then President. After Biogen, Julian became Chair of the Department of Microbiology at the University of British Columbia in Vancouver, Canada, where he has contributed in a major way to the reputation of this department for many years. He also served as an Adjunct Professor at the University of Geneva. Among Julian's areas of study and accomplishment are fungal toxins including α-sarcin, chemical synthesis of triterpenes, mode of action of streptomycin and other aminoglycoside antibiotics, biochemical mechanisms of antibiotic resistance in clinical isolates of bacteria harboring resistance plasmids, their origins and evolution, secondary metabolism of microorganisms, structure and function of bacterial ribosomes, antibiotic resistance mutations in yeast ribosomes, cloning of resistance genes from an antibiotic-producing microbe, gene cloning for industrial purposes, engineering of herbicide resistance in useful crops, bleomycin-resistance gene in clinical isolates of Staphylococcus aureus and many other topics. He has been an excellent teacher, lecturing in both English and French around the world, and has organized international courses. Julian has also served on the NIH study sections, as Editor for several international journals, and was one of the founders of the journal Plasmid. We expect the impact of Julian's accomplishments to continue into the future.

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Production of valuable compounds by molds and yeasts.

Bioprospecting non-conventional yeasts for ethanol production from rice straw hydrolysate and their inhibitor tolerance

Production of xylitol by expressing xylitol dehydrogenase and alcohol dehydrogenase from Gluconobacter thailandicus and co-biotransformation of whole cells.

Arabitol is a low-calorie sugar alcohol with anti-cariogenic properties. Enzymatic hydrolysate of soybean flour is a new renewable biorefinery feedstock containing hexose, pentose, and organic nitrogen sources. Arabitol production by Debaryomyces hansenii using soybean flour hydrolysate was investigated. Effects of medium composition, operating conditions, and culture stage (growing or stationary phase) were studied. Production was also compared at different culture volumes to understand the effect of dissolved oxygen concentration (DO). Main factors examined for medium composition effects were the carbon to nitrogen concentration ratio (C/N), inorganic (ammonium) to organic nitrogen ratio (I/O-N), and sugar composition. Arabitol yield increased with increasing C/N ratio and a high I/O-N (0.8–1.0), suggesting higher yield at stationary phase of low pH (3.5–4.5). Catabolite repression was observed, with the following order of consumption: glucose > fructose > galactose > xylose > arabinose. Arabitol production also favored hexoses and, among hexoses, glucose. DO condition was of critical importance to arabitol production and cell metabolism. The yeast consumed pentoses (xylose and arabinose) only at more favorable DO conditions. Finally, arabitol was produced in fermentors using mixed hydrolysates of soy flour and hulls. The process gave an arabitol yield of 54%, volumetric productivity of 0.90 g/L-h, and specific productivity of 0.031 g/g-h.

Production of arabitol from enzymatic hydrolysate of soybean flour by Debaryomyces hansenii fermentation

A new strain producing high yield of d-arabitol was isolated from hyperosmotic environments and the ITS rDNA sequencing analysis revealed it as Zygosaccharomyces rouxii. In addition, using a pH control and repeated-batch fermentation strategy in a 5-L reactor, the maximum yield and the highest volumetric productivity of d-arabitol were 93.48 ± 2.79 g/L and 1.143 g/L h, respectively. Volumetric productivity was successfully improved from 0.86 to 1.143 g/L h, which was increased by 32.9 % after 72 h of fermentation. Z. rouxii JM-C46 has potential to be used for d-arabitol and xylitol production from glucose via d-arabitol route.

Enhanced d-arabitol production by Zygosaccharomyces rouxii JM-C46: isolation of strains and process of repeated-batch fermentation

Xylitol is the first rare sugar that has global market because of its excellent properties. Considering its superiority to chemosynthesis, biosynthesis of xylitol became hot issue in recent studies. The production of xylitol from glucose experienced a development from three-step process to two-step process, or even only one-step process. The microbial and enzymatic process involving key enzymes, molecular cloning and expression and transgenic bacteria construction is introduced in this paper. This study may provide novel thought to explore new resource for better control of biological reaction conditions and obtainment of higher xylitol yield.

Microbial Bioconversion Process of Glucose for the Production of Xylitol

D-Tagatose is a ketohexose monosaccharide and recognized as a low-calorie substitute sweetener that could be used in nonchronic drugs, foods, beverages and dietary supplements. Currently, the biological production of D-tagatose using L-arabinose isomerase has caused extensive attention. In the article, properties and recent researches about D-tagatose and L-arabinose isomerase are described. The industrial application and existing problems are also stated.

Biological Synthesis of D-Tagatose Using L-Arabinose Isomerase

Paeonol is one of main medicinal ingredients of Cortex Moutan. Paeonol has the functions of sedative, hypnosis, anti-bacterial, antibiosis, anti-inflammation, antioxidation, reducing blood pressure and so on. Paeonol has extensive biological activities and has broad prospects of exploitation and utilization. This paper reviews the latest progress of its pharmacology.

Pharmacology Research Progress of Paeonol

Glycerol can be biologically converted to 1,3-propanediol (1,3-PD), a key raw material required for the synthesis of polytrimethylene terephthalate and other polyester fibers. 1,3-propanediol oxidoreductase (PDOR) is the rate-limiting enzyme in 1,3-PD synthesis biologically pathway. In present study, the dhaT gene encoding PDOR was cloned from Citrobacter freundii and overexpressed in E. coli BL21. The recombinant enzyme was purified by nickel-chelate chromatography combined with gel filtration to study the enzymatic characterization. Specific activity of recombinant PDOR was 55.2 U/mg. Km and Vmax values were 8.9 mM, 40.2 U/mg respectively. Holoenzyme of PDOR maybe a decamer of which a monomer has a molecular mass of 43 kDa. This research may form a basis for the future work on biological synthesis of 1, 3-PD.

Fang Chen

Papers

Enhanced d-arabitol production by Zygosaccharomyces rouxii JM-C46: isolation of strains and process of repeated-batch fermentation

Microbial Bioconversion Process of Glucose for the Production of Xylitol

Biological Synthesis of D-Tagatose Using L-Arabinose Isomerase

Pharmacology Research Progress of Paeonol

Overexpression and Characterization of the Gene Encoding 1,3-Propanediol Oxidoreductase of Citrobacter freundii