Beta-glycosidase (amygdalase and linamarase) from Endomyces fibuliger (LU677): formation and crude enzyme properties

Polyphasic Characterization of Yeasts and Lactic Acid Bacteria Metabolic Contribution in Semi-Solid Fermentation of Chinese Baijiu (Traditional Fermented Alcoholic Drink): Towards the Design of a Tailored Starter Culture

Chinese Baijiu is principally produced through a spontaneous fermentation process, which involves complex microorganism communities. Among them, yeasts and lactic acid bacteria (LAB) are important communities. The study examined the isolated strains from fermented grains of Baijiu regarding their activity of α-amylase and glucoamylase, ethanol tolerance, glucose utilization, as well as metabolite production in the process of laboratory-scale sorghum-based fermentation. Selected strains (Saccharomycopsis fibuligera 12, Saccharomyces cerevisiae 3, and Pediococcus acidilactici 4) were blended in different combinations. The influence of selected strains on the metabolic variation in different semi-solid fermentations was investigated by gas chromatography–mass spectrometry (GC–MS) accompanied by multivariate statistical analysis. According to the principal component analysis (PCA), the metabolites produced varied in different mixtures of pure cultures. S. fibuligera produced various enzymes, particularly α-amylase and glucoamylase, and exhibited a better performance compared with other species regarding the ability to convert starch to soluble sugars and positively affect the production process of volatile compounds. S. cerevisiae had a high fermentation capacity, thereby contributing to substrates utilization. Lactic acid bacteria had a good ability to produce lactic acid. This study attaches importance to the special functions of S. fibuligera, S. cerevisiae, and P. acidilactici in Chinese Baijiu making, and investigates their metabolic characteristics in the process of lab-scale semi-solid fermentation.

Complex microbiota of a Chinese "Fen" liquor fermentation starter (Fen-Daqu), revealed by culture-dependent and culture-independent methods

Daqu is a traditional fermentation starter that is used for Chinese liquor production. Although partly mechanized, its manufacturing process has remained traditional. We investigated the microbial diversity of Fen-Daqu, a starter for light-flavour liquor, using combined culture-dependent and culture-independent approaches (PCR-DGGE). A total of 190 microbial strains, comprising 109 bacteria and 81 yeasts and moulds, were isolated and identified on the basis of the sequences of their 16S rDNA (bacteria) and 26S rDNA and ITS regions (fungi). DGGE of DNA extracted from Daqu was used to complement the culture-dependent method in order to include non-culturable microbes. Both approaches revealed that Bacillus licheniformis was an abundant bacterial species, and Saccharomycopsis fibuligera, Wickerhamomyces anomalus, and Pichia kudriavzevii were the most common yeasts encountered in Fen-Daqu. Six genera of moulds (Absidia, Aspergillus, Mucor, Rhizopus, Rhizomucor and Penicillium) were found. The potential function of these microorganisms in starters for alcoholic fermentation is discussed. In general the culture-based findings overlapped with those obtained by DGGE by a large extent. However, Weissella cibaria, Weissella confusa, Staphylococcus saprophyticus, Enterobacter aerogenes, Lactobacillus sanfranciscensis, Lactobacillus lactis, and Bacillus megaterium were only revealed by DGGE.

Hydrolysis of terpenyl glycosides in grape juice and other fruit juices: a review

The importance of monoterpenes on varietal flavour of must and other fruit juices has been reviewed. These compounds were mainly found linked to sugar moieties in grape juice and wines, showing no olfactory characteristics. In this way, analytical techniques developed to study these compounds, in both free or glycosidically forms, are discussed. Mechanisms to liberate terpenes were studied, making a comparative study between acidic and enzymic hydrolysis of terpene glycosides; as enzymic hydrolysis seems to be the most natural way to liberate terpenes, the ability to use glycosidases from grapes, yeasts, bacterial or exogenous, i.e. fungal commercial preparations, were reviewed. Re-arrangements of terpenes after acidic hydrolysis of glycoconjugated are discussed as well as potential adverse effects of enzyme preparations.

Degradation of cyanogenic glycosides by Lactobacillus plantarum strains from spontaneous cassava fermentation and other microorganisms

Strains of Lactobacillus plantarum, Leuconostoc mesenteroides, Candida tropicalis and Penicillium sclerotiorum were screened for 19 enzymatic activities using the commercial kit API zym (Bio Mérieux). This activity was compared to the ability of degrading the toxic cyanogenic glycosides amygdalin, linamarin, and linseed cyanogens (a mixture of linustatin and neolinustatin). Good correlation between the beta-glucosidase activity found in the API zym screening and the ability to degrade the cyanogenic glycosides was found for the first three species mentioned. P. sclerotiorum strains exhibited very high activity in the API zym test (substrate: 6-Br-2-naphthyl-beta-D-glucopyranoside), but proved unable to degrade any of the cyanogenic substrates. Among the seven strains of L. plantarum tested, a great variation was seen in the beta-glucosidase activity as well as in the ability to degrade the cyanogens. This was also the case for the strains of C. tropicalis. However, all the glucosidase positive strains of these species were also able to degrade all of the cyanogens tested and at approximately the same rate. A co-culture of the most active strain of L. plantarum and C. tropicalis seemed to degrade linamarin faster than the mono cultures. L. plantarum LPI (originally isolated from fermented cassava) was investigated in further detail. The hydrolytic activity of this strain was intracellular or cell bound, and beta-bis-glycosides such as amygdalin were hydrolysed by a two-stage sequential mechanism as follows: (1) amygdalin to prunasin and (2) prunasin to cyanohydrin. Finally, inoculation of extracted linseed meal (containing linustatin and neolinustatin) with L. plantarum LPI resulted in hydrolysis of the glycosides.