Geobacillus thermodenitrifi cans subsp. calidus, subsp. nov., a thermophilic and αglucosidase producing bacterium isolated from Kizilcahamam, Turkey

Abstract

An α-glucosidase producing, thermophilic, facultatively anaerobic, and endospore-forming, motile, rod-shaped bacterial strain F84bT was isolated from a high temperature well-pipeline sedimentsample in Kizilcahamam, Turkey. The growth occurred at temperatures, pH and salinitiesranging from 45 to 69°C (optimum 60°C), 7.0 to 8.5 (optimum 8.0) and 0 to 5% (w/v) (optimum3.5%), respectively. Strain F84bT was able to grow on a wide range of carbon sources. Starchand tyrosine utilization, amylase, catalase and oxidase activities, nitrate reduction, and gas productionfrom nitrate were all positive. The G+C content of the genomic DNA was 49.6 mol%. Themenaquinone content was MK-7. The dominant cellular fatty acids were iso-C17:0, iso-C15:0,and C16:0. In phylogenetic analysis of 16S rRNA gene sequence, strain F84bT showed highsequence similarity to Geobacillus thermodenitrifi cans (99.8%) and to Geobacillus subterraneus(99.3%) with DNA hybridization values of 74.3% and 29.1%, respectively. In addition, theRep-PCR and the intergenic 16S 23S rRNA gene fi ngerprinting profi les differentiated strainF84bT from the Geobacillus species studied. The results obtained from the physiological andbiochemical characters, the menaquinone contents, the borderline DNA DNA hybridization homology,and the genomic fi ngerprinting patterns had allowed phenotypic, chemotaxonomic andgenotypic differentiation of strain F84bT from G. thermodenitrifi cans. Therefore, strain F84bT isassigned to be a new subspecies of G. thermodenitrifi cans, for which the name Geobacillusthermodenitrifi cans subsp. calidus, subsp. nov. is proposed (The type strain F84bT= DSM 22629T= NCIMB 14582T).