Identification, characterization and hydrolase producing performance of thermophilic bacteria: geothermal hot springs in the Eastern and Southeastern Anatolia Regions of Turkey

Abstract

In the last two decades, researchers have increasingly focused on the rich microorganism-based diversity of natural hot spring sources to explore the benefits of thermophiles in industrial and biotechnological fields. Within the scope of this study, a total of 83 thermophilic Bacilli strains were isolated from 7 different geothermal hot springs (at temperatures ranging between 40 and 85 °C) located in the Eastern and Southeastern Anatolia Regions of Turkey. The physiological, morphological, biochemical and molecular properties of the isolates were determined. As a result of the 16S rRNA gene sequence analysis, 5 different species (Bacillus licheniformis, Bacillus sp., Bacillus subtilis, Geobacillus kaustophilus, and Weizmannia coagulans,) were identified. B. licheniformis and B. subtilis were the most frequently encountered species among those obtained from the researched hot spring sources. Phylogenetic analysis was conducted to evaluate the phylogenetic relationships of the isolated species. The results showed that there was no significant difference between the groups and the bacteria in terms of the locations or optimum temperatures of the isolates. The bacterial isolates were screened for amylase, cellulase, lipase and protease hydrolytic enzyme activities. The hydrolytic enzyme production potentials among the isolates were identified in 68 (82%) isolates for amylase, 34 (41%) for cellulase, 69 (83%) for lipase and 73 (88%) for protease. All isolates were found to have at least one or more extracellular enzyme activities. Additionally, it was determined that 27 of the existing isolates (32.8%) were able to produce all of the aforementioned hydrolytic enzymes.