title: Isolation of thermophilic L-lactic acid producing bacteria showing homo-fermentative manner under high aeration condition.
abstract: By applying non-sterile open fermentation of food waste, various thermotolerant l-lactic acid-producing bacteria were isolated and identified. The predominant bacterial isolates showing higher accumulation of l-lactic acid belong to 3 groups of Bacillus coagulans, according to their 16S rRNA gene sequence similarities. B. coagulans strains M21 and M36 produced high amounts of l-lactic acid of high optical purity and lactic acid selectivity in model kitchen refuse medium and glucose-yeast extract-peptone medium. Other thermotolerant isolates resembling to Bacillus humi, B. ruris, B. subtilis, B. niacini and B. soli were also identified. These bacteria produced low amounts of l-lactic acid of more than 99% optical purity. All isolated strains showed the highest growth rate at temperatures around 55-60°C. They showed unique responses to various oxygen supply conditions. The majority of isolates produced l-lactic acid at a low overall oxygen transfer coefficient (KLa); however, acetic acid was produced instead of l-lactic acid at a high KLa. B. coagulans M21 was the only strain that produced high, consistent, and reproducible amounts of optically pure l-lactic acid (>99% optical purity) under high and low KLa conditions in a homo-fermentative manner.
authors.affiliation: Department of Microbiology, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand. Electronic address: saoton@kku.ac.th.
authors.forename: Saowanit
authors.initials: S
authors.lastname: Tongpim
authors.affiliation: Department of Microbiology, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand. Electronic address: ratchanu@live.kku.ac.th.
authors.forename: Ratchanu
authors.initials: R
authors.lastname: Meidong
authors.affiliation: Department of Bioscience and Biotechnology, Graduate School of Bioresources and Bioenvironmental Sciences, Kyushu University, Fukuoka 812-8581, Japan. Electronic address: poudel.pm@gmail.com.
authors.forename: Pramod
authors.initials: P
authors.lastname: Poudel
authors.affiliation: Department of Bioscience and Biotechnology, Graduate School of Bioresources and Bioenvironmental Sciences, Kyushu University, Fukuoka 812-8581, Japan. Electronic address: faucon-pelerin_2.17@hotmail.co.jp.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Yoshino
authors.affiliation: Department of Bioscience and Biotechnology, Graduate School of Bioresources and Bioenvironmental Sciences, Kyushu University, Fukuoka 812-8581, Japan. Electronic address: okugawa@agr.kyushu-u.ac.jp.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Okugawa
authors.affiliation: Department of Bioscience and Biotechnology, Graduate School of Bioresources and Bioenvironmental Sciences, Kyushu University, Fukuoka 812-8581, Japan. Electronic address: tashiro@agr.kyushu-u.ac.jp.
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Tashiro
authors.affiliation: Department of Materials Science and Technology, Faculty of Engineering, Niigata University, Niigata 950-2181, Japan. Electronic address: mtanig@eng.niigata-u.ac.jp.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Taniguchi
authors.affiliation: Department of Bioscience and Biotechnology, Graduate School of Bioresources and Bioenvironmental Sciences, Kyushu University, Fukuoka 812-8581, Japan. Electronic address: kensak@agr.kyushu-u.ac.jp.
authors.forename: Kenji
authors.initials: K
authors.lastname: Sakai
mesh_terms: D000332:Aerobiosis; D001407:Bacillus / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D005285:Fermentation; D005735:Garbage; D005947:Glucose / Q000378:metabolism; D019344:Lactic Acid / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D013696:Temperature
chemical_list: D012336:RNA, Ribosomal, 16S; D019344:Lactic Acid; D005947:Glucose; D010100:Oxygen
keywords: Aerotolerant; Bacillus coagulans; Food waste; Homo-fermentative; K(L)a; Thermotolerant; l-Lactic acid