title: The optimization of l-lactic acid production from sweet sorghum juice by mixed fermentation of Bacillus coagulans and Lactobacillus rhamnosus under unsterile conditions.
abstract: The cost reduction of raw material and sterilization could increase the economic feasibility of l-lactic acid fermentation, and the development of an cost-effective and efficient process is highly desired. To improve the efficiency of open fermentation by Lactobacillus rhamnosus based on sweet sorghum juice (SSJ) and to overcome sucrose utilization deficiency of Bacillus coagulans, a mixed fermentation was developed. Besides, the optimization of pH, sugar concentration and fermentation medium were also studied. Under the condition of mixed fermentation and controlled pH, a higher yield of 96.3% was achieved, compared to that (68.8%) in sole Lactobacillus rhamnosus fermentation. With an optimized sugar concentration and a stepwise-controlled pH, the l-lactic acid titer, yield and productivity reached 121gL(-1), 94.6% and 2.18gL(-1)h(-1), respectively. Furthermore, corn steep powder (CSP) as a cheap source of nitrogen and salts was proved to be an efficient supplement to SSJ in this process.
authors.affiliation: National energy R&D center for biorefinery, Beijing University of Chemical Technology, Beijing 100029, PR China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Wang
authors.affiliation: National energy R&D center for biorefinery, Beijing University of Chemical Technology, Beijing 100029, PR China.
authors.forename: Changjing
authors.initials: C
authors.lastname: Chen
authors.affiliation: National energy R&D center for biorefinery, Beijing University of Chemical Technology, Beijing 100029, PR China.
authors.forename: Di
authors.initials: D
authors.lastname: Cai
authors.affiliation: National energy R&D center for biorefinery, Beijing University of Chemical Technology, Beijing 100029, PR China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Wang
authors.affiliation: National energy R&D center for biorefinery, Beijing University of Chemical Technology, Beijing 100029, PR China. Electronic address: qinpy@mail.buct.edu.cn.
authors.forename: Peiyong
authors.initials: P
authors.lastname: Qin
authors.affiliation: National energy R&D center for biorefinery, Beijing University of Chemical Technology, Beijing 100029, PR China.
authors.forename: Tianwei
authors.initials: T
authors.lastname: Tan
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000070000:Bacillus coagulans / Q000378:metabolism*; D001628:Beverages; D005285:Fermentation; D006863:Hydrogen-Ion Concentration; D007477:Ions; D019344:Lactic Acid / Q000096:biosynthesis*; D052201:Lacticaseibacillus rhamnosus / Q000378:metabolism*; D008670:Metals / Q000032:analysis; D009584:Nitrogen / Q000032:analysis; D010758:Phosphorus / Q000032:analysis; D045868:Sorghum / Q000737:chemistry*; D013242:Sterilization; D003313:Zea mays / Q000737:chemistry
chemical_list: D000596:Amino Acids; D007477:Ions; D008670:Metals; D010758:Phosphorus; D019344:Lactic Acid; D009584:Nitrogen
keywords: Corn steep powder; Mixed fermentation; Sweet sorghum juice; l-Lactic acid