Recovery of antibiotic resistance genes in natural environments

Abstract

Recently environmental metagenomics are useful methodology to study microbial diversity in the environment as well as functional metabolic genes. This study was also based on metagenomic method to discover antibiotic resistance genes from aquatic environments.  To create a metagenomic library, the environmental DNA was extracted from water and sediment sample of Thi Nghe canal, Ho Chi Minh City. Total DNA then was fragmented by sizes of 1-3 kb and inserted in to pUC19 plasmid. After transformation into E.coli DH5a host, transfomants were screened by growth on a minimal inhibition concentration (MIC) of antibiotics. Results showed that antibiotic MIC values for Ecoli DH5a/pUC19 used as a negative control are 5mg/ml gentamicin, 6mg/ml chloramphenicol, and 50mg/ml streptomycin and 30mg/ml tetracyclin. From a newly created environmental DNA library of 1.315 mega bases (337 transformants) 176 clones resistant to gentamicin and 284 clones resistant to chloramphenicol were found, but either recombinant resistant to streptomycin nor to tetracycline. Because of timing limited for a Msc. study, the sequences of clones have not been verified yet. However, primarily results showed here indicate that the antibiotic resistant gene(s) from an aquatic environment in Ho Chi Minh city could be cloned for further studies.