Morphological, biochemical and molecular characterization of culturable epilithic and endolithic bacteria from rocks of Ayubia (Murree), lower Himalaya, Pakistan

Abstract

Murree and Ayubia hills are parts of the lower Himalaya Mountain range in Pakistan. The rocks of these hills are younger and mostly limestone in nature. In this study, geomicrobiological investigation of the selected samples collected from Murree and Ayubia hills was carried out. The rock samples were spread on nutrient agar plates and endolithic and epilithic bacteria were isolated on the basis of colony morphology and studied further. All the isolates were screened for different industrially important hydrolytic enzymes. Study isolates were identified through 16S rRNA gene sequencing. These endoliths and epiliths were assayed for antimicrobial activities against clinical isolates S. aureus, P. aeuroginosa and E. coli. Total 31 bacterial isolates were recovered of which 15 were endolithic and 16 were epilithic. 16S rRNA gene sequencing revealed major culturable groups colonizing these rocks were clustered in four major groups, Proteobacteria, Firmicutes, Actinobacteria and Bacteroidetes which inlcude Alcaligenes, Lysinibacillus, Actinobacteria, Pseudomonas, Pusillimonas, Streptomyces, Fluviicola, Serratia, Flavobacterium, Stenotrophomonas and Brevindomonas species. The sequences were deposited in NCBI for acquisition of accession numbers. The bacterial isolates were efficient producers of oxidase, catalase, protease, amylase and gelatinase. The endolithic isolates N4 (Pseudomonas sp. KT223616) and N28 (Streptomyces sp. KT004386) exhibited good activity against all the three clinically isolated target strains. The study revealed the rocks of Murree and Ayubia hills have a rich microbial ecology that besides having an important role in weathering and mineralization processes may also be potential source of biotechnological applications.