Summary auto-generated
Researchers isolated seven thermophilic, spore-forming bacteria from hot springs in Turkey and characterized strain G2T as a novel species. The isolate is a Gram-positive rod that grows optimally at 55-60°C and facultatively anaerobic. It utilizes multiple carbon sources including xylose, glucose, and starch, and expresses xylose isomerase activity. Based on 16S rRNA gene sequencing showing 97% similarity to Anoxybacillus flavithermus, combined with distinct 16S-23S ITS patterns and DNA-DNA hybridization showing only 53.4% relatedness to A. flavithermus and 45% to A. pushchinoensis, the strain represents a new species. Additional supporting evidence includes unique protein profiles on SDS-PAGE and distinct physiological characteristics. The isolate has a DNA G+C content of 57 mol%, forms terminal spherical endospores, and can tolerate up to 4% NaCl. All characterization data—morphological, biochemical, enzymatic, and genetic—indicate this is a distinct species within the genus Anoxybacillus, proposed as Anoxybacillus gonensis sp. nov., with the type strain G2T suitable for industrial applications due to its xylose isomerase enzyme production.
Key findings
- Strain G2T is a moderately thermophilic, facultative anaerobe that forms endospores and utilizes xylose with high xylose isomerase activity
- 16S rRNA sequencing shows 97% similarity to A. flavithermus, but DNA-DNA hybridization reveals only 53.4% relatedness, indicating species-level distinction
- 16S-23S ITS PCR analysis and SDS-PAGE protein profiles differentiate G2T from related Anoxybacillus species
- DNA G+C content of 57 mol% and distinct physiological properties confirm designation as novel species Anoxybacillus gonensis
- All seven isolated strains belong to A. gonensis based on genetic relatedness, protein profiles, and biochemical characteristics
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Abstract
Seven closely related xylanolytic, thermophilic bacilli were isolated from mud and water samples from the Gonen and Diyadin hot springs, respectively located in the Turkish provinces of Balikesir and Agri. On the basis of morphology and biochemical characteristics, one of the isolates, designated strain G2T, was studied further. Strain G2T is a xylanolytic, sporulating, Gram-positive, rod-shaped bacterium. The isolate is a thermophilic (optimum temperature for growth, 5560 °C), facultative anaerobe that grows on a wide range of carbon sources, including glucose, starch, xylose and mannitol. It expressed a high level of xylose isomerase activity on xylose and also on glucose. 16S rRNA gene sequence analysis showed that this isolate resembled Anoxybacillus flavithermus DSM 2641T (>97 % similarity), but 16S23S rDNA internally transcribed spacer polymorphism PCR showed variation between DSM 2641T and isolate G2T. However, it is also known that analysis of 16S rRNA gene sequences may be insufficient to distinguish between some species. In DNADNA hybridization, thermophilic isolate G2T showed relatedness of 53·4 % to A. flavithermus and about 45·0 % to Anoxybacillus pushchinoensis, indicating that it is distinct at the species level. On the basis of the evidence presented, it is proposed that strain G2T (=NCIMB 13933T=NCCB 100040T) be designated as the type strain of Anoxybacillus gonensis sp. nov.