title: Direct starch fermentation to L-lactic acid by a newly isolated thermophilic strain, Bacillus sp. MC-07.
abstract: A newly isolated Bacillus sp. MC-07 showed 99.2 % 16S rRNA gene sequence similarity with the Bacillus thermoamylovorans LMG 18084(T). It demonstrated optimum and maximum growth temperatures of 50 and 62 °C, respectively. The ability of MC-07 to produce optically pure L-lactic acid via direct fermentation of starch without enzymatic hydrolysis was investigated at different pH values (6.0-8.0) by intermittent adjustments every 12 h. During batch fermentation in mineral salt medium containing 0.001 % yeast extract at pH 7.0, 20 g/L of soluble starch was utilized to produce 16.6 g/L L-lactic acid at 50 °C within 24 h of fermentation, with 100 % optical purity, 92.1 % lactic acid selectivity, and an L-lactic acid yield of 0.977 g/g. Direct starch fermentation at pHs 6.0, 6.5, 7.5, and 8.0 resulted in considerably lower concentrations of lactic acid than did at pH 7.0. Compared with B. thermoamylovorans LMG 18084(T), the ability of strain MC-07 to produce L-lactic acid was superior.
authors.affiliation: Laboratory of Soil Microbiology, Division of Systems Bioengineering, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School of Bioresources and Bioenvironmental Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan.
authors.forename: Pramod
authors.initials: P
authors.lastname: Poudel
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Tashiro
authors.forename: Hirokuni
authors.initials: H
authors.lastname: Miyamoto
authors.forename: Hisashi
authors.initials: H
authors.lastname: Miyamoto
authors.forename: Yuki
authors.initials: Y
authors.lastname: Okugawa
authors.forename: Kenji
authors.initials: K
authors.lastname: Sakai
mesh_terms: D001407:Bacillus / Q000302:isolation & purification / Q000378:metabolism*; D005285:Fermentation; D006868:Hydrolysis; D019344:Lactic Acid / Q000378:metabolism*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D013213:Starch / Q000378:metabolism*; D013696:Temperature
chemical_list: D012336:RNA, Ribosomal, 16S; D019344:Lactic Acid; D013213:Starch