Phylogenetic Diversity and Anti-MRSA Activity of Halotolerant Actinobacteria from sediments in Great Salt Plains, Oklahoma.

Abstract

Studies have been surged on extreme environments and hypersaline ecosystems through the recent decades. Despite the apparent severity of the environmental conditions in the Great Salt Plain, recent phylogenetic studies carried on its soil samples have revealed a wide diversity of microorganisms. In this current study, we present the actinobacteria as one of the largest and important phenotypic groups. The Great Salt Plain of Oklahoma is an extreme region and a hypersaline environment from marine origin. Thirty soil samples were collected from vegetated and salt flat sites of the Great Salt Plain area and used for isolation. Actinomycetes were selectively isolated by employing four different media. A total of 358 actinomycetes isolates obtained from the Great Salt Plain soil samples. Based on morphological and physiological characterization 155 representative isolates were chosen for phylogenetic diversity, salt tolerance, and antimicrobial activities. Results from the 16S rRNA gene sequence analysis indicate that, the isolates could be grouped into two genera; phylotypes were detected at high frequency, and affiliated to the genus Streptomyces, and phylotypes were detected at low frequency, and affiliated to the genus Nocardiopsis. The majority of the isolates were of hypersaline or marine origin. 38% of actinomycetes isolates were able to grow at 10% salinity, and only 7% of actinomycetes shown salient ability at 15% salinity. Of the 155 isolates, 44 strains exhibited anti-MRSA bioactivities. To our knowledge, this research paper is the first report on the isolation of actinomycetes members from hypersaline environment of the Great Salt Plain of Oklahoma. This current study confirms that the Great Salt Plain harbors significant diversity of actinobacterial communities, and illustrates their potential for production biologically active molecules. Due to the high bioactivity percentage, broad bioactivities against both MRSA strains, the isolated actinomycetes presented their capability in pharmaceutical application.