Isolation and selection of thermophilic microorganisms from hot springs with the ability to produce thermostable chitinase

Abstract

Hot mineral springs are the primary habitats of thermophilic microorganisms, and serve as sources of many important biologically active substances used in industry, especially heat-stable enzymes. This study aimed to isolate and screen thermophilic bacterial strains capable of producing thermostable chitinase from Truong Xuan hot spring in Ninh Hoa town, Khanh Hoa province. A total of 63 bacterial isolates were obtained from 20 samples of water, mud, and soil collected from the hot spring area, of which 18 demonstrated chitinase-producing activity. Among them, TX9 exhibited the highest chitinase activity, with a clear zone on a chitin agar plate of 25.33 ± 0,58 mm. TX9 produced the highest activity when incubated at 50^oC in a 180 rpm rotary shaker for 48 hours. This crude chitinase retained thermal stability within the temperature range of  50^oC to 70^oC for 60 minutes. Results of Gram staining and biochemical tests identified TX9 strain as Gram-positive, rod-shaped, catalase-positive, and spore-forming bacterium. Based on 16S rRNA gene sequence analysis, strain TX9 was identified as Bacillus licheniformis with 99.85% sequence similarity. These findings indicate that Bacillus licheniformis TX9 is a promising thermophilic bacterium  for thermostable chitinase production, with potential industrial applications, especially in environmental treatment.

DOI: https://doi.org/10.53818/jfst.04.2025.602