Premium
Temperature‐induced mutagenesis‐based adaptive evolution of Bacillus amyloliquefaciens for improving the production efficiency of menaquinone‐7 from starch
Author(s) -
Liu Ning,
Ruan Haozhe,
Liu Liming,
Zhang Weiguo,
Xu Jianzhong
Publication year - 2021
Publication title -
journal of chemical technology and biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.64
H-Index - 117
eISSN - 1097-4660
pISSN - 0268-2575
DOI - 10.1002/jctb.6615
Subject(s) - starch , bacillus amyloliquefaciens , strain (injury) , fermentation , food science , hydrolysis , chemistry , amylase , carbon source , carbon fibers , yield (engineering) , mutagenesis , biochemistry , biology , enzyme , mutant , materials science , gene , composite number , metallurgy , composite material , anatomy
BACKGROUND Starch can be used as a carbon source for producing menaquinone‐7 (MK‐7) by Bacillus sp., but the final titer and productivity are unsatisfactory because starch cannot be effectively hydrolyzed to fermentable sugars. This article focuses on developing thermo‐tolerable MK‐7 high‐producing strains by temperature‐induced mutagenesis‐based adaptive evolution. RESULTS Here, we isolated a thermo‐tolerable MK‐7 high‐producing strain B. amyloliquefaciens MK50‐36 after multi‐rounds of acclimation at high temperature. Strain MK50‐36 showed a large growth with soluble starch as carbon source at 50 °C. Compared with the parental strain B. amyloliquefaciens H.β.D.R.‐5 cultivated at 37 °C, MK‐7 yield of strain MK50‐36 increased about twofold at 50 °C when soluble starch was used as the sole carbon resource (17.5 ± 1.5 mg L –1 versus 37.1 ± 2.1 mg L –1 ). In addition, strain MK50‐36 showed an improvement in starch utilization rate as compared with strain H.β.D.R.‐5 because α‐amylase activity of strain MK50‐36 was the highest at 50 °C. Moreover, MK‐7 yield of strain MK50‐36 was further increased by feeding fresh broth to control the amount of fermentation liquid in fed‐batch fermentation because fermentation broth will be easy to volatilize and thus affect the production of MK‐7 at high temperature, which reached up to 52.7 ± 4.6 mg L –1 . CONCLUSION These results indicated that soluble starch can act as an effective carbon source for producing MK‐7, and strain MK50‐36 has a superior capacity to produce MK‐7 from soluble starch. © 2020 Society of Chemical Industry