Molecular Identification, Bioactivity Screening and Metabolic Fingerprinting of the Actinomycetes of Chenab River Sediments

Abstract

Aims: The mortality, morbidity and health cost have been increased due to multiple antimicrobial drug resistance in pathogens across the world. So it is important to discover new active compounds. This study was designed to screen the Chenab river actinomycetes for antimicrobial activity against various MDR bacterial pathogens and preliminary cytotoxicity. Study Design: Collection of water and sediments samples, sample enrichment and selective isolation of the actinomycetes, laboratory scale cultivation, solvent extraction, determination of antimicrobial activity and cytotoxicity, chemical profiling and metabolic fingerprinting by TLC and HPLC-UV. Place and Duration: All the work was done during July 2013 to July 2015 in the Department of Microbiology and Molecular Genetics, University of the Punjab Lahore, Pakistan. Methodology: The water and sediments samples of Chenab river were collected from the Sialkot region (Punjab, Pakistan) and were processed for the selective isolation of actinomycetes. The isolated strains were identified by morphological, biochemical, physiological characterization and by 16S rRNA gene sequencing. The selected strains were screened for antimicrobial activity and cytotoxicity using agar diffusion assays and by microwell cytotoxicity assay against Artemia salina larvae. For metabolic fingerprinting the methanolic crude extracts obtained from the selected strains were analyzed by thin layer chromatography (TLC) and high performance liquid chromatography (HPLC-UV). Results: A total of 30 actinomycetes strains were isolated and were identified as different species of genus Streptomyces. Among all the selected strains, the isolates M72, M1, M71, W38, W108 and M93 were found to exhibit potent antimicrobial activity against the test strains including Klebsiella sp., methiciliin resistant Staphylococcus aureus (MRSA), Acinetobacter sp., E. coli, and B. cereus. Similarly, the isolates M54, W19 and M81 demonstrated significant cytotoxicity (up to 80% larval mortality) against Artemia salina. Conclusion: The study suggested that actinomycetes flora of Chenab river is rich source of useful natural compounds and should be continuously isolated characterized and investigated for novel antibiotics and other chemotherapeutic agents.