title: Augmented production of alginate oligosaccharides by the Pseudomonas mendocina NK-01 mutant.
abstract: Pseudomonas mendocina NK-01 can simultaneously synthesize medium-chain-length polyhydroxyalkanoate (PHA(MCL)) and alginate oligosaccharides (AO) from glucose under conditions of limited nitrogen. In this study, the PHA(MCL) synthesis pathway was blocked by a deletion of approximately 57% of the sequence of PHA synthase operon mediated by the suicide plasmid, pEX18TcC1ZC2Amp. Deletion of the PHA synthase operon in P. mendocina NK-01 was confirmed by polymerase chain reaction (PCR) and antibiotic resistance assays to form the gene knockout mutant, P. mendocina C7. Shake-flask and 30 L fermentor cultures of P. mendocina C7 showed a 2.21-fold and 2.64-fold accumulation of AO from glucose, respectively, compared with the wild-type strain. Mass spectrometry and gel permeation chromatography characterization revealed that P. mendocina C7 and P. mendocina NK-01 produced AO were identical in terms of monomer composition and average molecular weight (M(W)). Thus, the mutant P. mendocina C7 has potential use in large scale fermentation of AO. Furthermore, it was demonstrated that the PHA(MCL) and AO synthesis pathways compete for the use of carbon sources in P. mendocina NK-01.
authors.affiliation: Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China.
authors.forename: Wenbin
authors.initials: W
authors.lastname: Guo
authors.forename: Jun
authors.initials: J
authors.lastname: Feng
authors.forename: Weitao
authors.initials: W
authors.lastname: Geng
authors.forename: Cunjiang
authors.initials: C
authors.lastname: Song
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Wang
authors.forename: Ning
authors.initials: N
authors.lastname: Chen
authors.forename: Shufang
authors.initials: S
authors.lastname: Wang
mesh_terms: D000217:Acyltransferases / Q000235:genetics / Q000378:metabolism; D000464:Alginates / Q000737:chemistry*; D005285:Fermentation; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D009154:Mutation; D009844:Oligosaccharides / Q000096:biosynthesis* / Q000737:chemistry* / Q000378:metabolism; D009876:Operon / Q000235:genetics; D010957:Plasmids / Q000235:genetics; D054813:Polyhydroxyalkanoates / Q000378:metabolism; D044203:Pseudomonas mendocina / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism*; D017384:Sequence Deletion
chemical_list: D000464:Alginates; D006603:Hexuronic Acids; D009844:Oligosaccharides; D054813:Polyhydroxyalkanoates; D020723:Glucuronic Acid; D000217:Acyltransferases; C077225:poly(3-hydroxyalkanoic acid) synthase