Bacterial Diversity Analysis And Functional Gene Screening For The Mangrove Sediment

Mangrove swamps are unique inter-tidal wetland ecosystems found in sheltered tropical and subtropical shores, and represent rich and diverse living resources. Special mangrove sediment niches possess valuable microbial resources. Unfortunately, very few researches were carried out on the microbial communities comparing to much achievement on the study of plants in mangrove ecosystem. So far, there is very little knowledge on the mangrove soil microbial communities. It's urgent and significant to investigate the microbial communities and explore its potential resources.In this research, using the metagenomic strategy, a 16SrDNA gene library was constructed to investigate the bacterial diversity in the mangrove sediment collected in Fugong, Longhai, Fujian Province and a metagenomic library was also constructed to screen the cellulolytic genes. The results were as follows:1. The bacterial diversity in the mangrove sediment was characterized by analyzing the 16SrDNA gene library. 200 clones with different RFLP patterns showed abundant bacterial diversity in the sediment. Among them, 30 clones representing the dominant species with RFLP patterns occurred frequently were sequenced and phylogenetically identified as belonging to the Proteobacteria(70%),Unknown bacteria(20%),Planctomycetacia(3.3%),Bacteroidetes(3.3%) ,Verrucomicrobia(3.3%).2. Using the mangrove sediment sample, the total DNA was isolated directly from environment and a metagenomic library was constructed using the pUC19 plasmid as vector and E.coli DH5αas host. The library was named as pUC19-Hsemident .It contained 45,000 clones with average insert sizes of 5.4kb, covering 450Mb genomic DNA in the sediment.3. Using the function-driven screening model, 3 clones with extracellular cellulolytic activity were screened .They have inserts of 6.4kb, 2.6kb, 1.2kb respectively .The sequence analysis of these inserts is ongoing.Concluded from the results, it shows that the mangrove sediment holds great new microbial resources and the metagenomic strategy can be powerful exploiting the potential microbial resources from the environment.