title: Improved production of carotenoid-free welan gum in a genetic-engineered Alcaligenes sp. ATCC31555.
abstract: OBJECTIVE
  To improve the production of welan gum and obtain a carotenoid-free strain while reducing the fermentation and post-treatment costs.
  
  
  RESULTS
  The vitreoscilla globin (vgb) gene combined with the β-galactosidase (lacZ) promoter was inserted into the phytoene synthase (crtB) gene region of the chromosome in Alcaligenes sp. ATCC31555. When the recombinant strain was grown in a 5 l fermentor, welan gum was produced at 24 ± 0.4 g l(-1) compared to 21 g ± 0.4 g l(-1) in the wild type. Furthermore, the carotenoid-free welan gum produced using Alcaligenes sp. ATCC31555 VHb strain was less expensive with improved properties.
  
  
  CONCLUSIONS
  Alcaligenes sp. ATCC31555 VHb strain was a better neutral welan-producing strain with a higher production than the wild-type strain.
authors.affiliation: Key Laboratory of Molecular Microbiology Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, 300071, China.
authors.forename: Wenwen
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Molecular Microbiology Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, 300071, China.
authors.forename: Zhaohui
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Key Laboratory of Molecular Microbiology Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, 300071, China.
authors.forename: Mengmeng
authors.initials: M
authors.lastname: Wu
authors.affiliation: Key Laboratory of Molecular Microbiology Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, 300071, China.
authors.forename: Zhong
authors.initials: Z
authors.lastname: Shi
authors.affiliation: Key Laboratory of Molecular Microbiology Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, 300071, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Zhu
authors.affiliation: Key Laboratory of Molecular Microbiology Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, 300071, China.
authors.forename: Guoqiang
authors.initials: G
authors.lastname: Li
authors.affiliation: Key Laboratory of Molecular Microbiology Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, 300071, China. tingma@nankai.edu.cn.
authors.forename: Ting
authors.initials: T
authors.lastname: Ma
mesh_terms: D000421:Alcaligenes / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D019149:Bioreactors; D001709:Biotechnology / Q000295:instrumentation / Q000379:methods; D002338:Carotenoids / Q000235:genetics / Q000378:metabolism; D005285:Fermentation; D015964:Gene Expression Regulation, Bacterial; D055786:Gene Knockout Techniques; D005818:Genetic Engineering / Q000379:methods*; D051232:Geranylgeranyl-Diphosphate Geranylgeranyltransferase / Q000235:genetics / Q000378:metabolism; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D011401:Promoter Regions, Genetic; D054793:Truncated Hemoglobins / Q000235:genetics / Q000378:metabolism; D014783:Viscosity; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D011135:Polysaccharides, Bacterial; D054793:Truncated Hemoglobins; C082613:hemoglobin protein, Vitreoscilla; D002338:Carotenoids; C068570:welan; D051232:Geranylgeranyl-Diphosphate Geranylgeranyltransferase; D001616:beta-Galactosidase
keywords: Alcaligenes sp.; Carotenoid-free strain; Gene expression; Phytoene synthase gene; Vitreoscilla hemoglobin; Welan gum