Isolation Of Actinobacteria From Coastal Wetlands And Screening Of Antimicrobial Activity Strains And Functional Genes

Actinobacteria are a treasure-house of resources for discovering a large number of medicinal natural products and occupy a very important position in the research of new microbial drugs.The special living environment of marine actinobacteria makes it have a unique metabolic pathway different from terrestrial actino bacteria.It has the potential to synthesize a variety of bioactive substances,and is an important source of natural medicinal active compounds.Many of the naturally derived antibiotics are produced by actinobacteria.Streptomyces in actinobacteria is widely used in the pharmaceutical industry because of its ability to produce secondary metabolites with good biological activity.Due to the rapid variability of pathogens and the development of drug resistance,the demand for new antibiotics continues to grow.Although considerable progress has been made in the field of chemical biosynthesis,nature is still the most abundant source of new antibiotics.Actinobacteria are found in a variety of ecosystems,are particularly rich in soil,and are abundant in freshwater and marine environments.Actinobacteria in undeveloped habitats are considered to be potential sources of novel bioactive natural products.The purpose of this study is to isolate actinobacteria with good antibacterial activity from the sediments of coastal wetlands,and lay the foundati on for the development and utilization of new natural products.In this study,the actinobacteria were isolated by pure culture method from the sediment samples of the Sanggou Bay Wetland and the Swan Lake Wetland in Weihai City,Shandong Province.Filter paper method was performed to determine the potential antimicrobial activities of the isolated actinobacteria strains against 7kinds of different indicator strains.The strains with better antibacterial activity were selected for the screening of polyketide synthase(PKS)and non-ribosomal peptide synthetase(NRPS)genes.A total of 109 actinobacteria were isolated from the wetland sediment samples from two locations,of which 49 were from the Sanggou Bay wetland and 60 from the Swan Lake wetland.Of 109 actinobacteria strains,104 actinobacteria strains inhibited at least one indicator bacteria,23 actinobacteria strains inhibited both indicator bacteria,19 actinobacteria strains inhibited three indicator bacteria,18 actinobacteria strains inhibited four indicator bacteria,and 7 actinobacteria strains inhibited five indicator bacteria.Among the PKS and NRPS gene screens of 35 strains of actinomycetes with good antibacterial activity,9 strains were screened for NRPS gene,7 strains were screened for PKS gene,and 3 strains(TEHA31,SGWA09 and SGWA47)were screened for PKS and NRPS genes simultaneously.The results showed that coastal wetland-derived actinomycetes have good antibacterial activity,and the strain has a novel PKS or NRPS gene,which has the ability to synthesize new secondary metabolites.