title: Genes encoding the production of extracellular polysaccharide bioflocculant are clustered on a 30-kb DNA segment in Bacillus licheniformis.
abstract: Bioflocculants are special high-molecular weight polymers produced by microorganisms. Despite the fact that several types of bioflocculants from different species of bacteria have been reported, there is a large gap in our knowledge regarding the molecular machine responsible for the production of bioflocculants. To investigate genes involved in bioflocculant synthesis, a fosmid library was generated from Bacillus licheniformis genomic DNA and screened for the production of bioflocculant. Four positive clones with distinct flocculation were isolated by a two-pooling scheme. The clone with 662 U ml(-1) flocculating activity was sequenced. As a result, a 30-kb fragment with 26 hypothetical genes was identified in the bioflocculant-producing clone. Most of the predicted proteins encoded by the inserted genes showed significant homology with enzymes involved in the biosynthesis of polysaccharide. Based on these homologies, a biosynthesis pathway and two gene clusters involved in the production of the polysaccharide bioflocculant were proposed with the integration of functional descriptions of individual genes by metabolic databases, and a glucose-sensitive glycosidases was predicted. This research supplied significant data for potential application of bioflocculant-producing strains in wastewater refining and industrial downstream treatments.
authors.affiliation: Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, People's Republic of China.
authors.forename: Shan
authors.initials: S
authors.lastname: Yan
authors.forename: Na
authors.initials: N
authors.lastname: Wang
authors.forename: Zhen
authors.initials: Z
authors.lastname: Chen
authors.forename: Yuanpeng
authors.initials: Y
authors.lastname: Wang
authors.forename: Ning
authors.initials: N
authors.lastname: He
authors.forename: Yajuan
authors.initials: Y
authors.lastname: Peng
authors.forename: Qingbiao
authors.initials: Q
authors.lastname: Li
authors.forename: Xu
authors.initials: X
authors.lastname: Deng
mesh_terms: D001407:Bacillus / Q000235:genetics* / Q000378:metabolism; D005427:Flocculation; D005798:Genes, Bacterial; D005810:Multigene Family; D011134:Polysaccharides / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D011134:Polysaccharides