16S rRNA phylogenetic analysis of actinomycetes isolated from Eastern Ghats and marine mangrove associated with antibacterial and anticancerous activities

Abstract

Morphologically 238 different marine and terrestrial actinomycete strains were chosen by screening of the antagonistic activity using human pathogens and cancerous cell lines, for which 185 sediments/rhizosphere soil samples were collected from the different sites of Manakkudi estuary of south-west coastal regions and Yercaud hills of eastern Ghats of Tamil Nadu, India. The present study aimed at the evaluation of biologically diverse strains of actinomycetes from soil samples, for the production of wide spectrum of bioactive secondary metabolites. Most of the isolated strains belong to the genus namely Streptomyces (68%), followed by Actinobacterium (28%) and Nocardiopsis (4%). Among the different strains purified, about 10 strains exhibited high antagonistic activity. An attempt was made to study the bioactive compounds extracted from the Act2 strain isolated from marine mangrove sediments, which showed the highest antibacterial and anticancerous activities. The partially purified fifth active fraction was analyzed by Gas chromatography-mass spectrometry (GC-MS) and the possible closely related compounds were identified as Silane, Pyridine, 2,4,6-trimethyl, Amino malonic acid, 4-benzoxazin, Tris methyl and Cyclohexydimethoxy methyl compounds. Studies were conducted to extract the genomic DNA from the selected strains, amplified through polymerase chain reaction (PCR) and subjected to 16S rRNA sequence analysis. Subsequently, phylogenetic tree was constructed using suitable bioinformatics tools to identify the similarity which showed 97% similarity between strains. Moreover, all the selected strains of actinomycetes were subjected to study the protein and plasmid DNA expression profiles which showed prominent bands with genetically excellent relationship between strains in the profiles.

Key words: Marine mangrove, Yercaud hills, actinomycetes, antibacterial activity, anticancerous activity, bioactive compounds, 16S rRNA sequence, phylogenetic tree.