Abstract: [Objective] One thermophilic bacterium was isolated from the hot spring in Tangchi, Lujiang, Anhui,and identified by molecular biological methods to study its morphological, physiological and growth characteristics,and the conditions of cellulase production were optimized. This study can provide reference for its biological science research and industrial application in the future. [Methods] Another thermophilic bacterium was isolated by high temperature culture, and its 16S rDNA gene sequence was determined. Its taxonomic status was determined by sequence alignment, phylogenetic tree construction and observation of cell and colony morphology. And its growth characteristics were studied. Through study of the effects of inoculum age, initial pH of fermentation medium, inoculum amount, fermentation temperature, rotation speed and fermentation time on cellulase production the cellulase production conditions were preliminarily optimized. [Results] Another thermophilic bacterium was isolated from the hot spring in Tangchi, Lujiang for the first time, which was named LJTC-2. The bacterium was Gram-positive and rod-shaped, belonging to Geobacillus. Its highest tolerance temperature was 73 °C and its optimum growth pH was about 7.0. The optimal fermentation conditions of LJTC-2 for cellulase production were determined as follows: inoculation age of 36 h, initial pH of fermentation medium of 6, inoculation amount of 2%, fermentation temperature of 60 °C, rotation speed of 180 r.min^-1, fermentation time of 60 h. Under these conditions, the enzyme activity was 183 mU.mL^-1, which was 17% higher than that before optimization. [Conclusion] The strain LJTC-2 was Geobacillus, and could tolerate high temperature of 73 °C. The results showed that LJTC-2 had the highest cellulase activity under the conditions of inoculation age of 36 h, initial pH of fermentation medium of 6, inoculation amount of 2%, 60°C , 180 .min^-1 and fermentation time of 60 h.

Key words: hot spring in Tangchi, thermophilic bacteria, geobacillus, separation and identification, cellulase production characteristics