title: High-throughput system for screening of high L-lactic acid-productivity strains in deep-well microtiter plates.
abstract: For strain improvement, robust and scalable high-throughput cultivation systems as well as simple and rapid high-throughput detection methods are crucial. However, most of the screening methods for lactic acid bacteria (LAB) strains were conducted in shake flasks and detected by high-performance liquid chromatography (HPLC), making the screening program laborious, time-consuming and costly. In this study, an integrated strategy for high-throughput screening of high L-lactic acid-productivity strains by Bacillus coagulans in deep-well microtiter plates (MTPs) was developed. The good agreement of fermentation results obtained in the MTPs platform with shake flasks confirmed that 24-well U-bottom MTPs could well alternate shake flasks for cell cultivation as a scale-down tool. The high-throughput pH indicator (bromocresol green) and L-lactate oxidase (LOD) assays were subsequently developed to qualitatively and quantitatively analyze L-lactic acid concentration. Together with the color halos method, the pH indicator assay and LOD assay, the newly developed three-step screening strategy has greatly accelerated the screening process for LAB strains with low cost. As a result, two high L-lactic acid-productivity mutants, IH6 and IIIB5, were successfully screened out, which presented, respectively, 42.75 and 46.10 % higher productivities than that of the parent strain in a 5-L bioreactor.
authors.affiliation: State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, P.O. Box 329, Shanghai, 200237, China.
authors.forename: Xiangyun
authors.initials: X
authors.lastname: Lv
authors.affiliation: State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, P.O. Box 329, Shanghai, 200237, China.
authors.forename: Jiali
authors.initials: J
authors.lastname: Song
authors.affiliation: State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, P.O. Box 329, Shanghai, 200237, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Yu
authors.affiliation: State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, P.O. Box 329, Shanghai, 200237, China.
authors.forename: Huilan
authors.initials: H
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, P.O. Box 329, Shanghai, 200237, China.|Shanghai Institute of Biomanufacturing Technology & Collaborative Innovation Center, 130 Meilong Road, P.O. Box 329, Shanghai, 200237, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Li
authors.affiliation: State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, P.O. Box 329, Shanghai, 200237, China. ypzhuang@ecust.edu.cn.|Shanghai Institute of Biomanufacturing Technology & Collaborative Innovation Center, 130 Meilong Road, P.O. Box 329, Shanghai, 200237, China. ypzhuang@ecust.edu.cn.
authors.forename: Yingping
authors.initials: Y
authors.lastname: Zhuang
authors.affiliation: State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, P.O. Box 329, Shanghai, 200237, China. yhwang@ecust.edu.cn.|Shanghai Institute of Biomanufacturing Technology & Collaborative Innovation Center, 130 Meilong Road, P.O. Box 329, Shanghai, 200237, China. yhwang@ecust.edu.cn.
authors.forename: Yonghong
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000070000:Bacillus coagulans / Q000254:growth & development*; D001426:Bacterial Proteins / Q000378:metabolism*; D019344:Lactic Acid / Q000096:biosynthesis*; D006899:Mixed Function Oxygenases / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D019344:Lactic Acid; D006899:Mixed Function Oxygenases; C021497:lactate 2-monooxygenase
keywords: 24-well MTPs; Bromocresol green; High-throughput screening; L-lactate oxidase assay; L-lactic acid