title: Influence of geosmin-producing Streptomyces on the growth and volatile metabolites of yeasts during chinese liquor fermentation.
abstract: Diverse Streptomyces species act as geosmin producers in the Chinese liquor-making process, causing an earthy, off-odor containment. Through microbiological and metabolite analyses, this paper investigates the influence of several geosmin-producing Streptomyces on the microbial community of a brewing system. The antifungal activity against functional liquor-brewing microbes was assayed by an agar diffusion method. Several Streptomyces, most notably Streptomyces sampsonii QC-2, inhibited the growth of the brewing functional yeasts and molds in pure culture. In a simulated coculture, Streptomyces spp. reduced the flavor compounds (alcohols and esters) contributed by yeasts. Nine components in Streptomyces sampsonii QC-2 broth were detected by ultraperformance liquid chromatography coupled with photo diode array (UPLC–PDA), with characteristic ultraviolet absorptions at 360, 380, and 400 nm. The main products of Streptomyces sampsonii QC-2 were identified by ultraperformance liquid chromatography–quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF–MS/MS), and confirmed by standard mass spectrometry. The antifungal active components were revealed as a series of heptaene macrolide antibiotics.
authors.forename: Hai
authors.initials: H
authors.lastname: Du
authors.forename: Hu
authors.initials: H
authors.lastname: Lu
authors.forename: Yan
authors.initials: Y
authors.lastname: Xu
mesh_terms: D000434:Alcoholic Beverages / Q000032:analysis / Q000382:microbiology*; D005285:Fermentation; D005421:Flavoring Agents / Q000378:metabolism; D009284:Naphthols / Q000378:metabolism*; D013302:Streptomyces / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D055549:Volatile Organic Compounds / Q000378:metabolism*; D015003:Yeasts / Q000254:growth & development* / Q000378:metabolism*
chemical_list: D005421:Flavoring Agents; D009284:Naphthols; D055549:Volatile Organic Compounds; C001278:geosmin