Diversity of Xylanolytic Bacteria Isolated from Thai Sources

Twenty-three xylanolytic bacteria were isolated from soils, sediments and buffalo faeces collected in Thailand. They were divided into 10 groups based on the phenotypic and chemotaxonomic characteristics including 16S rRNA gene sequence analyses. Eleven isolates were Gram-positive, facultatively anaerobic, spore-forming, rod-shaped bacteria. They contained meso-diaminopimelic in cell wall peptidoglycan. Two isolates (Group IA) were identified as Bacillus subtilis, 4 isolates (Group IB) were B. licheniformis, 2 isolates (Group IC) were B. niabensis, one (Group ID) was B. nealsonii, and 2 isolates (Group IE) were B. cereus. Seven isolates were Gram-positive, non-spore-forming, rod-shaped bacteria and were identified as Isoptericola variabilis (2 isolates in Group II), as Jonesia denitrificans (2 isolates in Group III), as Microbacterium natoriense (2 isolates in Group IV), and one isolate as Nocardioides simplex (Group V). Five isolates were Gram-negative; facultatively anaerobic, non-spore-forming, rod-shaped bacteria and each of them were identified respectively as Acinetobacter junii (Group VI), Aeromonas enteropelogenes (Group VII), Pseudomonas stutzeri (Group VIII), Stenotrophomonas maltophilia (Group IX) and Zobellella denitrificans (Group X). The isolates produced xylanase activity ranged from 1.03 to 17.65±0.25 unit/ml.