Culturable and culture-independent bacterial diversity and the prevalence of cold-adapted enzymes from the Himalayan mountain ranges of India and Nepal.

Abstract

Bacterial diversity of soil samples collected from different geographical regions of Himalayan mountains was studied through culturable (13 samples) and culture-independent approaches (5 samples based on abundance of diversity indices in each ecological niche). Shannon-Wiener diversity index and total bacterial count ranged from 1.50 ± 0.1 to 2.57 ± 0.15 and 7.8 ± 1.6 × 10(5) to 30.9 ± 1.7 × 10(5) cfu ml(-1) of soil, respectively. Based on morphology and pigmentation, 406 isolates were selected by culturing in different cultivable media at various strengths and concentrations. All the strains were subjected to amplified ribosomal DNA restriction analysis and the representative isolates from each cluster were chosen for 16S rRNA gene sequence-based identification. Soil habitat in Himalayan foot hills was dominated by the genera Arthrobacter, Exiguobacterium, Bacillus, Cedecea, Erwinia, and Pseudomonas. Five 16S rRNA gene libraries from the selected five samples yielded 268 clones and were grouped into 53 phylotypes covering 25 genera including the genus of Ferribacterium, Rothia, and Wautersiella, which were reported for the first time in Himalayan tracks. Principal coordinates analysis indicates that all the clone libraries were clearly separated and found to be significantly different from each other. Further, extracellular investigation of cold-active enzymes showed activity of cellulase (23.71%), pectinase (20.24%), amylase (17.32%), phytase (13.87%), protease (12.72%), and lipase (23.71%) among the isolates. Four isolates namely Exiguobacterium mexicanum (BSa14), Exiguobacterium sibiricum (BZa11), Micrococcus antarcticus (BSb10), and Bacillus simplex (BZb3) showed multiple enzyme activity for five different types of enzymes. In addition, various genera like Exiguobacterium, Erwinia, Mycetecola, Cedecea, Pantoea, and Trichococcus have also shown novel hydrolytic enzyme activity in the Himalayan foothills.