title: Enhancement of riboflavin production with Bacillus subtilis by expression and site-directed mutagenesis of zwf and gnd gene from Corynebacterium glutamicum.
abstract: Zwf (code for glucose-6-phosphate dehydrogenase) and gnd (code for 6-phosphogluconate dehydrogenase) genes from Corynebacterium glutamicum were firstly cloned, and then site-directed mutagenesis was successfully introduced to remove allosteric inhibition by intracellular metabolites. Expression of the mutant zwf and gnd in Bacillus subtilis RH33 resulted in significant enhancement of riboflavin productivity, while the specific growth rate decreased slightly and the specific glucose uptake rate was unchanged. Introduction of the mutant zwf and gnd led to approximately 18% and 22% increased riboflavin production, respectively. An improvement by 31% and 39% of the riboflavin production was obtained by co-expression of the mutated dehydrogenases in shaker flask and fed-batch cultivation. Intracellular metabolites analysis indicated that metabolites detected in pentose phosphate pathway or riboflavin synthesis pathway of engineered strains showed higher concentration, while TCA cycle and glycolysis metabolites detected were lower abundance than that of parent strain.
authors.affiliation: Key Laboratory of Systems Bioengineering, Ministry of Education, Tianjin University, Tianjin 300072, People's Republic of China.
authors.forename: Zhiwen
authors.initials: Z
authors.lastname: Wang
authors.forename: Tao
authors.initials: T
authors.lastname: Chen
authors.forename: Xianghui
authors.initials: X
authors.lastname: Ma
authors.forename: Zhuo
authors.initials: Z
authors.lastname: Shen
authors.forename: Xueming
authors.initials: X
authors.lastname: Zhao
mesh_terms: D001412:Bacillus subtilis / Q000235:genetics* / Q000378:metabolism*; D018533:Biomass; D002952:Citric Acid Cycle; D048230:Corynebacterium glutamicum / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D005838:Genotype; D005947:Glucose / Q000378:metabolism; D005954:Glucosephosphate Dehydrogenase / Q000235:genetics*; D007700:Kinetics; D016297:Mutagenesis, Site-Directed; D010427:Pentose Phosphate Pathway; D010734:Phosphogluconate Dehydrogenase / Q000235:genetics* / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D012256:Riboflavin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D013696:Temperature
chemical_list: D010734:Phosphogluconate Dehydrogenase; D005954:Glucosephosphate Dehydrogenase; D005947:Glucose; D012256:Riboflavin