Genetic and Physiological Diversity of Marine Actinobacteria from the Okha Coast, Gujarat, India

Abstract

Saline and alkaline habitats of the Okha coastline, Gujarat, India, were explored for the diversity of actinobacteria. Based on the phenotypic and genotypic heterogeneity, nine haloalkaliphilic actinobacterial strains were characterized and identified. The PCR amplification of 16S rDNA using universal and genus-specific primers corroborated the trends that emerged through cultural and physiological characterization. Streptomyces was the most abundant genus amplified with the Streptomyces-specific primers (StreptB/E, StreptB/F), whereas other actinobacterial strains were amplified by the universal primers U1 and U2. Further molecular diversity was investigated by the gradient PCR-DGGE as a fingerprinting tool that generated group-specific DGGE patterns. Based on the nucleotide homology and phylogenetic analysis, strains OK-1 and OK-2 were identified as Streptomyces somaliensis. At the same time, OK-3 and OK-7 were detected as Streptomyces sp., while OK-5, OK-6, OK-8, OK-9, and OK-10 belonged to Nocardiopsis alba. Further, the cluster analysis using the UPGMA method generated 3 clusters based on biochemical characterization, sugar utilization, and enzyme production. The dendrogram based on the DGGE band pattern created with Jaccard-distance revealed two major clades with 33.33% similarity. Further, the study of alpha diversity calculation using phenotypic characteristics discloses highly diverse sugar utilization abilities. Moreover, a stress value of 0.1236 was obtained based on the NMDS analysis of the plots using Bary-Curties dissimilarity. Overall, the distinct phenotypic, metabolic, and molecular profiling illustrated the diversity among marine actinobacteria.