Jyotsna Begani1, Jyoti Lakhani2, Dharmesh Harwani1*
1Department of Microbiology, Maharaja Ganga Singh University, Bikaner, Rajasthan, India
2Department of Computer Science, Maharaja Ganga Singh University, Bikaner, Rajasthan, India
1Department of Microbiology, Maharaja Ganga Singh University, Bikaner, Rajasthan, India
*Address for corresponding author:
Dharmesh Harwani
Department of Microbiology, Maharaja Ganga Singh University, Bikaner, Rajasthan, India
Abstract
Objective: An attempt has been made in the present study to evaluate the efficacy of six selective isolation media in the isolation of bioactive thermophilic actinomycetes native to the Bikaner region of the Thar desert in Rajasthan and to characterize them at polyphasic and chemical levels. Material and methods: Selective isolation media were used to recover thermophilic actinobacteria from the soil samples collected at the Bikaner region of the Thar desert. The isolates were characterized for their phenotype and physiology using Bergey’s manual of determinative bacteriology. The molecular identification of actinobacteria was done using 16SrRNA sequence gene analysis and the nature of the bioactive chemical compound was determined by UV-visible absorption spectrum and thin layer chromatography. Results: Among different tested selective media, the highest plate counts (CFUs/gm of soil) of thermophilic actinomycetes were observed with Modified Actinomycete Selective (MAS)-DH-1 agar medium. The MAS-DH-1 agar medium permitted adequate growth of many different pigmented actinomycetes from the desert soil samples. Among various other bio-active actinomycetes strains, an actinobacterial strain D8 was identified on the basis of its broad-spectrum antibacterial and antifungal activities. The D8 strain was found to produce high levels of extracellular phosphatase, catalase, tyrosinase, lipase, cellulase, protease, amylase, and L-asparaginase enzymes. Conclusion: The polyphasic characterization of the isolate D8 assigned it to an anaerobic, Gram-positive, non-acid-fast, catalase-positive filamentous bacterium of the genus Nocardiopsis sp. (KM205637) in the order Actinomycetales that produces multiple enzymes of industrial and therapeutic use. The partial chemical characterization of the anti-microbial metabolite produced by the strain D8 revealed the presence of an aromatic ring compound.
Keywords: Thar desert, thermophilic actinomycetes, polyphasic characterization, phylogenetic tree, chromatography
