Isolation and Molecular Identification of Xylanase and Glucose-Isomerase Producer Geobacillus and Brevibacillus Strains from Hot Springs in Turkey

Some hot springs located in west of Turkey were investigated with respect to presence of thermophilic microorganisms. Based on the 16S rRNA gene sequence analysis, the 7 isolates are members of the genus Geobacillus , the other 7 isolates are members of the genus Brevibacillus. Based on recN sequence similarity analysis, isolate EG1 is a strain of G. thermodenitficans and isolate SG1 is a strain of one of Group 3 species. The species identity for the isolates SG13, SG16, SG17, EG6, and HIG12 are uncertain. Based on hypervariable regions similarity analysis of the 16S rDNA, isolates HIG17, HIG27 and HIG29 are strains of B. thermoruber, B. parabrevis and B. borstelensis , respectively. Isolate HIG22 and HIG28 are strains of B. agri , while HIG11 is a strain of B. gelatini . Also HIG19 could be regarded as an independent species Brevibacillus . The presence of xylanase and glucose isomerase activities, their optimum temperature and pH were also investigated. These results showed that SG16 has both xylanase and glucose isomerase activity, 4 strains have only xylanase activity, 4 strains have only glucose isomerase activity, remaining 6 strains have neither of these activities. The isolate SG16 has the highest temperature optima (80°C), HIG11, HIG19 and SG16 isolates have the highest pH optima (pH 9) of xylanase. Isolate SG16, SG1 and HIG12 have optimum glucose isomerase activities at 80°C, and isolates SG16, SG17 and HIG12 have the lowest pH of 6.5. Therefore, the results of the study indicated that these bacteria and their enzymes can constitute important reservoirs for biotechnological researches.