title: Transcriptome analysis guided metabolic engineering of Bacillus subtilis for riboflavin production.
abstract: A comparative transcriptome profiling between a riboflavin-producing Bacillus subtilis strain RH33 and the wild-type strain B. subtilis 168 was performed, complemented with metabolite pool and nucleotide sequence analysis, to rationally identify new targets for improving riboflavin production. The pur operon (purEKBCSQLFMNHD) together with other PurR-regulated genes (glyA, guaC, pbuG, xpt-pbuX, yqhZ-folD, and pbuO) was all down-regulated in RH33, which consequently limited the supply of the riboflavin precursors. As 5-phospho-ribosyl-1(a)-pyrophosphate (PRPP) strongly inhibits the binding of PurR to its targets, it was inferred that the reduced expression of PurR-regulated genes might be caused by a low PRPP pool, which was subsequently confirmed by metabolite analysis. Thus, we selected and co-overexpressed prs and ywlF genes in RH33, which are involved in the biosynthetic pathway of PRPP from ribulose-5-phosphate. This co-amplification led to an elevated PRPP pool and thus the increased transcript abundances of PurR-regulated genes participated in riboflavin precursor biosynthesis. The riboflavin titer was increased by 25% (up to 15 g l(-1)) in fed-batch fermentation.
authors.affiliation: Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China.
authors.forename: Shuobo
authors.initials: S
authors.lastname: Shi
authors.forename: Tao
authors.initials: T
authors.lastname: Chen
authors.forename: Zhigang
authors.initials: Z
authors.lastname: Zhang
authors.forename: Xun
authors.initials: X
authors.lastname: Chen
authors.forename: Xueming
authors.initials: X
authors.lastname: Zhao
mesh_terms: D001412:Bacillus subtilis / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D004269:DNA, Bacterial / Q000737:chemistry / Q000378:metabolism; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D005818:Genetic Engineering / Q000379:methods*; D008969:Molecular Sequence Data; D009876:Operon; D012256:Riboflavin / Q000096:biosynthesis*; D017422:Sequence Analysis, DNA
chemical_list: D004269:DNA, Bacterial; D012256:Riboflavin