title: Enhancement of welan gum production in Sphingomonas sp. HT-1 via heterologous expression of Vitreoscilla hemoglobin gene.
abstract: Welan gum is a microbial polysaccharide produced by Sphingomonas sp. Its production is limited by the dissolved oxygen levels in the highly viscous fermentation. A strategy of heterologous expression of the Vitreoscilla hemoglobin gene in Sphingomonas sp. HT-1 was investigated to alleviate oxygen limitation and improve the yield of welan gum. Ultimately, the welan gum production increased from 25.3g/L to 34.6g/L, whereas the rheological behavior of welan gum solutions remained virtually unchanged. The transcriptional levels of the key genes in the electron transfer chain, TCA cycle and welan gum synthesis pathway, as well as ATP level revealed that the VHb expression in Sphingomonas sp. HT-1 enhanced welan gum biosynthesis by improving respiration and ATP supply. This study would pave the genetic manipulation way for enhancing welan gum yield, and it's also of great importance for the industrial applications of welan gum under harsh conditions.
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, No. 30 South Puzhu Road, Pukou District, Nanjing 211816, PR China; College of Food Science and Light Industry, Nanjing Tech University, No. 30 South Puzhu Road, Pukou District, Nanjing 211816, PR China.
authors.forename: Xiaoliu
authors.initials: X
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, No. 30 South Puzhu Road, Pukou District, Nanjing 211816, PR China; College of Food Science and Light Industry, Nanjing Tech University, No. 30 South Puzhu Road, Pukou District, Nanjing 211816, PR China.
authors.forename: Ping
authors.initials: P
authors.lastname: Zhu
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, No. 30 South Puzhu Road, Pukou District, Nanjing 211816, PR China; College of Food Science and Light Industry, Nanjing Tech University, No. 30 South Puzhu Road, Pukou District, Nanjing 211816, PR China.
authors.forename: Ruifan
authors.initials: R
authors.lastname: Jiang
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, No. 30 South Puzhu Road, Pukou District, Nanjing 211816, PR China; College of Food Science and Light Industry, Nanjing Tech University, No. 30 South Puzhu Road, Pukou District, Nanjing 211816, PR China.
authors.forename: Lingtian
authors.initials: L
authors.lastname: Wu
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, No. 30 South Puzhu Road, Pukou District, Nanjing 211816, PR China; College of Food Science and Light Industry, Nanjing Tech University, No. 30 South Puzhu Road, Pukou District, Nanjing 211816, PR China.
authors.forename: Xiaohai
authors.initials: X
authors.lastname: Feng
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, No. 30 South Puzhu Road, Pukou District, Nanjing 211816, PR China; College of Food Science and Light Industry, Nanjing Tech University, No. 30 South Puzhu Road, Pukou District, Nanjing 211816, PR China. Electronic address: lisha@njtech.edu.cn.
authors.forename: Sha
authors.initials: S
authors.lastname: Li
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, No. 30 South Puzhu Road, Pukou District, Nanjing 211816, PR China; College of Food Science and Light Industry, Nanjing Tech University, No. 30 South Puzhu Road, Pukou District, Nanjing 211816, PR China. Electronic address: xuh@njut.edu.cn.
authors.forename: Hong
authors.initials: H
authors.lastname: Xu
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D005285:Fermentation; D007218:Industrial Microbiology; D000074041:Microorganisms, Genetically-Modified / Q000378:metabolism; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis*; D020578:Sphingomonas / Q000235:genetics / Q000378:metabolism*; D054793:Truncated Hemoglobins / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D011135:Polysaccharides, Bacterial; D054793:Truncated Hemoglobins; C082613:hemoglobin protein, Vitreoscilla; C068570:welan
keywords: Fermentation; Rheological behavior; Vitreoscilla hemoglobin gene; Welan gum