title: Use of whey lactose from dairy industry for economical kefiran production by Lactobacillus kefiranofaciens in mixed cultures with yeasts.
abstract: To evaluate the feasibility of producing kefiran industrially, whey lactose, a by-product from dairy industry, was used as a low cost carbon source. Because the accumulation of lactic acid as a by-product of Lactobacillus kefiranofaciens inhibited cell growth and kefiran production, the kefir grain derived and non-derived yeasts were screened for their abilities to reduce lactic acid and promote kefiran production in a mixed culture. Six species of yeasts were examined: Torulaspora delbrueckii IFO 1626; Saccharomyces cerevisiae IFO 0216; Debaryomyces hansenii TISTR 5155; Saccharomyces exiguus TISTR 5081; Zygosaccharomyces rouxii TISTR 5044; and Saccharomyces carlsbergensis TISTR 5018. The mixed culture of L. kefiranofaciens with S. cerevisiae IFO 0216 enhanced the kefiran production best from 568 mg/L in the pure culture up to 807 and 938 mg/L in the mixed cultures under anaerobic and microaerobic conditions, respectively. The optimal conditions for kefiran production by the mixed culture were: whey lactose 4%; yeast extract 4%; initial pH of 5.5; and initial amounts of L. kefiranofaciens and S. cerevisiae IFO 0216 of 2.1×10(7) and 4.0×10(6)CFU/mL, respectively. Scaling up the mixed culture in a 2L bioreactor with dissolved oxygen control at 5% and pH control at 5.5 gave the maximum kefiran production of 2,580 mg/L in batch culture and 3,250 mg/L in fed-batch culture.
authors.affiliation: Department of Industrial Biotechnology, Faculty of Agro-Industry, Prince of Songkla University, Hat-Yai 90112, Thailand. benjamas.che@psu.ac.th
authors.forename: Benjamas
authors.initials: B
authors.lastname: Cheirsilp
authors.forename: Sirilaor
authors.initials: S
authors.lastname: Radchabut
mesh_terms: D003612:Dairying; D019649:Food Industry; D007778:Lactobacillus / Q000254:growth & development*; D007785:Lactose / Q000494:pharmacology*; D011134:Polysaccharides / Q000096:biosynthesis*; D013549:Sweetening Agents / Q000494:pharmacology*; D015003:Yeasts / Q000254:growth & development*
chemical_list: D011134:Polysaccharides; D013549:Sweetening Agents; C050180:kefir grain polysaccharide; D007785:Lactose