title: Sigma Factor Regulated Cellular Response in a Non-solvent ProducingClostridium beijerinckiiDegenerated Strain: A Comparative Transcriptome Analysis.
abstract: Clostridium beijerinckiiDG-8052, derived from NCIMB 8052, cannot produce solvent or form spores, a phenomenon known as degeneration. To explore the mechanisms of degeneration at the gene level, transcriptomic profiles of the wild-type 8052 and DG-8052 strains were compared. Expression of 5168 genes comprising 98.6% of the genome was assessed. Interestingly, 548 and 702 genes were significantly up-regulated in the acidogenesis and solventogenesis phases of DG-8052, respectively, and mainly responsible for the phosphotransferase system, sugar metabolic pathways, and chemotaxis; meanwhile, 699 and 797 genes were significantly down-regulated, respectively, and mainly responsible for sporulation, oxidoreduction, and solventogenesis. The functions of some altered genes, including 286 and 333 at the acidogenesis and solventogenesis phases, respectively, remain unknown. Dysregulation of the fermentation machinery was accompanied by lower transcription levels of glycolysis rate-limiting enzymes (pfkandpyk), and higher transcription of cell chemotaxis genes (cheA, cheB, cheR, cheW, andcheY), controlled mainly by σ54at acidogenesis. Meanwhile, abnormal spore formation was associated with repressedspo0A, sigE, sigF, sigG, andsigKwhich are positively regulated by σ70, and correspondingly inhibited expression of CoA-transferase at the solventogenesis phase. These findings indicated that morphological and physiological changes in the degeneratedClostridiumstrain may be related to altered expression of sigma factors, providing valuable targets for strain development ofClostridiumspecies.
authors.affiliation: School of Medicine, Institute for Genome Sciences, University of Maryland, Baltimore MD, USA.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: School of Public Health, Health Science Center, Xi'an Jiaotong University Xi'an, China.
authors.forename: Shengyin
authors.initials: S
authors.lastname: Jiao
authors.affiliation: School of Public Health, Health Science Center, Xi'an Jiaotong University Xi'an, China.
authors.forename: Jia
authors.initials: J
authors.lastname: Lv
authors.affiliation: School of Public Health, Health Science Center, Xi'an Jiaotong University Xi'an, China.
authors.forename: Renjia
authors.initials: R
authors.lastname: Du
authors.affiliation: School of Public Health, Health Science Center, Xi'an Jiaotong University Xi'an, China.
authors.forename: Xiaoni
authors.initials: X
authors.lastname: Yan
authors.affiliation: Department of Bioengineering, University of Missouri, Columbia MO, USA.
authors.forename: Caixia
authors.initials: C
authors.lastname: Wan
authors.affiliation: School of Public Health, Health Science Center, Xi'an Jiaotong University Xi'an, China.
authors.forename: Ruijuan
authors.initials: R
authors.lastname: Zhang
authors.affiliation: School of Public Health, Health Science Center, Xi'an Jiaotong University Xi'an, China.
authors.forename: Bei
authors.initials: B
authors.lastname: Han
keywords: Clostridium beijerinckii NCIMB8052; microarray; sigma factor; strain degeneration; transcriptome analysis