Abstract: [Objective] To isolate the heat-resistant Bacillus strain from the fermentation liquid of microorganisms, and to evaluate the disinfective effect of several commonly used disinfection techniques on Bacillus circulans. [Method] The heat-resistant strain was screened from the fermentation liquid of microorganisms by heat treatment at 100 ℃for 30 minutes. The obtained heat-resistant strain was identified via colony morphology, cultural characteristics, Gram staining, biochemical confirmation and molecular biological identification. A phylogenetic tree was constructed for gene sequence alignment analysis. The disinfective effect of hot air treatment, ultraviolet irradiation and peracetic acid disinfection techniques on the isolated strain was assessed. [Result] One heat-resistant bacterial strain was isolated from the fermentation liquid of microorganisms, and it was identified as Bacillus circulans. By comparing the disinfective effect of different disinfection technologies on Bacillus circulans in micro-ecological preparations, it was found that when the bacterial solution was treated at 120 ℃ for 60 minutes under the dry heat condition and treated at 120 ℃ for 10 minutes under the humid heat condition, and when the ultraviolet irradiation time exceeded 140 minutes （radiation intensity reached 110 μW/cm²） and the volume fraction of peroxyacetic acid was higher than 2.75%, the growth of Bacillus circulans was effectively inhibited. [Conclusion] The Bacillus circulans strain was successfully isolated from the fermentation liquid of microorganisms, and the disinfection effective test provided references for the subsequent safe production of micro-ecological preparations and optimization of the fermentation conditions of the bacteria.

Key words: Bacillus circulans, micro-ecological preparations, bacterial isolation and identification, disinfection techniques