title: Permeabilization of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus with ethanol.
abstract: Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus cultures were treated with ethanol and tested for viability and beta-galactosidase activity. Exposure of the biomass of test cultures to 30%-55% ethanol (vol/vol) caused a 100% loss of viability and up to 15-fold increase in measurable beta-galactosidase activity in both streptococci and lactobacilli. Ethanol-treated cell suspensions could be stored for up to 6 months without loss of enzyme activity. The nonviable permeabilized biomass of the more active S. thermophilus was used to achieve up to 80% hydrolysis of lactose in aqueous solutions and non-fat milk.
authors.affiliation: U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 E. Mermaid Lane, Wyndmoor, PA 19038, USA.
authors.forename: G A
authors.initials: GA
authors.lastname: Somkuti
authors.forename: M E
authors.initials: ME
authors.lastname: Dominiecki
authors.forename: D H
authors.initials: DH
authors.lastname: Steinberg
mesh_terms: D000891:Anti-Infective Agents, Local / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004795:Enzyme Stability; D000431:Ethanol / Q000494:pharmacology*; D005947:Glucose / Q000378:metabolism; D007778:Lactobacillus / Q000187:drug effects* / Q000201:enzymology; D007785:Lactose / Q000378:metabolism; D010539:Permeability / Q000187:drug effects; D013291:Streptococcus / Q000187:drug effects* / Q000201:enzymology; D013696:Temperature; D001616:beta-Galactosidase / Q000187:drug effects* / Q000235:genetics
chemical_list: D000891:Anti-Infective Agents, Local; D000431:Ethanol; D001616:beta-Galactosidase; D005947:Glucose; D007785:Lactose