| Many thermophilic bacteria have now been identified. Only a few of these bacteria are alkalithermophiles, which grow at temperatures above 50°C and at pH levels above 8.0 In an effort to identify and characterize additional alkalithermophilic bacteria, 25 samples were collected from 6 different alkaline hot springs and thermally heated areas within Yellowstone National Park (YNP). Microbial isolates were obtained by streak and enrichment cultures on different selective media. Five of the six sampling sites yielded alkalithermophilic bacteria. Phylogenetic analysis of 16S rDNA indicated that the majority of these isolates were members of the genus Anoxybacillus. On the basis of morphology and biochemical characteristics, one of the isolates, designated B-25 was further characterized. B-25 is a gram positive, sporulating, rod-shaped bacterium. B-25 can utilize a wide range of nutrient sources, including glucose, maltose, sucrose, and starch, as well as grow on both dilute and high concentrations of organic media. Isolate B-25's optimal growth conditions were determined to be at a pH of 9.0 and at a temperature of 60°C. Isolate B-25 had a very high growth rate (20 minute generation time) and sporulates with a high efficiency. It is highly susceptible to a number of commercial antibiotics and produces the following enzymes: amylase, catalase, and oxidase. 16S rDNA gene sequence analysis on B-25 showed that it is most closely related to Anoxybacillus kualawohkensis and Anoxybacillus kamchatkensis which were recently isolated from hot springs in Malaysia and Russia respectively. Our results suggest that Isolate B-25 is a new species of Anoxybacillus. |
