title: Diversity of two-domain laccase-like multicopper oxidase genes in Streptomyces spp.: identification of genes potentially involved in extracellular activities and lignocellulose degradation during composting of agricultural waste.
abstract: Traditional three-domain fungal and bacterial laccases have been extensively studied for their significance in various biotechnological applications. Growing molecular evidence points to a wide occurrence of more recently recognized two-domain laccase-like multicopper oxidase (LMCO) genes in Streptomyces spp. However, the current knowledge about their ecological role and distribution in natural or artificial ecosystems is insufficient. The aim of this study was to investigate the diversity and composition of Streptomyces two-domain LMCO genes in agricultural waste composting, which will contribute to the understanding of the ecological function of Streptomyces two-domain LMCOs with potential extracellular activity and ligninolytic capacity. A new specific PCR primer pair was designed to target the two conserved copper binding regions of Streptomyces two-domain LMCO genes. The obtained sequences mainly clustered with Streptomyces coelicolor, Streptomyces violaceusniger, and Streptomyces griseus. Gene libraries retrieved from six composting samples revealed high diversity and a rapid succession of Streptomyces two-domain LMCO genes during composting. The obtained sequence types cluster in 8 distinct clades, most of which are homologous with Streptomyces two-domain LMCO genes, but the sequences of clades III and VIII do not match with any reference sequence of known streptomycetes. Both lignocellulose degradation rates and phenol oxidase activity at pH 8.0 in the composting process were found to be positively associated with the abundance of Streptomyces two-domain LMCO genes. These observations provide important clues that Streptomyces two-domain LMCOs are potentially involved in bacterial extracellular phenol oxidase activities and lignocellulose breakdown during agricultural waste composting.
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha, People's Republic of China.
authors.forename: Lunhui
authors.initials: L
authors.lastname: Lu
authors.forename: Guangming
authors.initials: G
authors.lastname: Zeng
authors.forename: Changzheng
authors.initials: C
authors.lastname: Fan
authors.forename: Jiachao
authors.initials: J
authors.lastname: Zhang
authors.forename: Anwei
authors.initials: A
authors.lastname: Chen
authors.forename: Ming
authors.initials: M
authors.lastname: Chen
authors.forename: Min
authors.initials: M
authors.lastname: Jiang
authors.forename: Yujie
authors.initials: Y
authors.lastname: Yuan
authors.forename: Haipeng
authors.initials: H
authors.lastname: Wu
authors.forename: Mingyong
authors.initials: M
authors.lastname: Lai
authors.forename: Yibin
authors.initials: Y
authors.lastname: He
mesh_terms: D000383:Agriculture; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D014644:Genetic Variation; D008031:Lignin / Q000378:metabolism*; D008969:Molecular Sequence Data; D010088:Oxidoreductases / Q000235:genetics* / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D017385:Sequence Homology; D012987:Soil; D012988:Soil Microbiology; D013302:Streptomyces / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development; D018505:Waste Management
chemical_list: D004269:DNA, Bacterial; D012987:Soil; C036909:lignocellulose; D008031:Lignin; D010088:Oxidoreductases