Isolation and characterization of novel denitrifying alkalithermophiles, AT-1 and AT-2.

Two novel denitrifying alkalithermophilic bacteria, AT-1 and AT-2, were isolated from manure-amended soil. The isolates grew at 35-65 degrees C with an optimum temperature at 50-60 degrees C, and pH 6.5-10.0 with an optimum pH at 9.5. Both isolates were Gram-positive, facultative anaerobic, non-motile rod-shaped bacteria. A phylogenetic analysis based on 16S rRNA sequence data indicated that both AT-1 and AT-2 are members of the genus Anoxybacillus. DNA-DNA hybridization revealed moderate relatedness between AT-1 and AT-2 and one phylogenetically related strain, A. pushchinensis K1 (69.5 and 69.1%, respectively). Comparative analysis of morphology and biochemical characteristics of the two isolates also showed similarity to A. pushchinensis K1. Based on these results, we identified AT-1 and AT-2 as A. pushchinensis. To our knowledge, this is the first report of denitrifying bacterium isolated from alkalithermophilic Anoxybacillus spp.