Isolation and Characterization of Rhizospheric Soil Microorganisms from Pennisetum purpureum for Enzyme Production: Amylase, Lipase, and Protease.

Abstract

The rhizospheric soil of Pennisetum purpureum (elephant grass) harbors a diverse community of microorganisms with the potential for enzyme production. This study focuses on the isolation and characterization of these microorganisms for the production of industrially significant enzymes: amylase, lipase, and protease. Soil samples were collected from the rhizosphere of P. purpureum and subjected to serial dilution and plating on selective media to isolate distinct microbial colonies. Pure cultures were obtained and screened for enzyme production through qualitative assays. Amylase activity was detected using starch agar plates, lipase activity was assessed on tributyrin agar, and protease activity was evaluated on casein agar plates. The promising isolates exhibiting significant enzyme activity were further characterized using morphological, biochemical, and molecular techniques. The bacterial strains were identified through 16S rRNA gene sequencing, while fungal strains were identified via ITS region sequencing. Phylogenetic analysis confirmed the identity and diversity of the isolates. Quantitative enzyme assays were conducted to measure the specific activity of amylase, lipase, and protease under various conditions, including pH, temperature, and substrate concentration, to determine the optimal production parameters. Among the isolates, Bacillus sp., Pseudomonas sp., and Aspergillus sp. demonstrated high enzyme activities. The amylase from Bacillus sp. showed optimal activity at pH 6.5 and 55°C, while lipase from Pseudomonas sp. exhibited maximum activity at pH 8.0 and 37°C. Protease from Aspergillus sp. had peak activity at pH 7.0 and 50°C. The enzymes also exhibited stability over a range of conditions, making them suitable for various industrial applications, such as in the food, detergent, and pharmaceutical industries. The findings highlight the rhizospheric soil of P. purpureum as a valuable source of microbial diversity with significant potential for enzyme production. This study not only enhances our understanding of soil microbiota associated with P. purpureum but also opens avenues for the biotechnological exploitation of these microbes for sustainable industrial enzyme production.