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Characterization and Pathogenicity of Two Bacteria Isolated from A Local Chinese Hospital

Liang Chen, Shuang Lu, Weiping Cao, Peng Lü, Chunxia Zhang, Hongzheng Gu and Keping Chen

Contamination and antimicrobial resistance levels in hospitals raise increasing concern not only in the fields of medicine and healthcare, but also in environment protection. In this experiment, two strains of bacteria were isolated from a Chinese local hospital, and their physiological and biochemical characteristics and drug resistance were investigated. We identified these two strains of bacteria as Bacillus subtilis and Bacillus cerecus using 16S rRNA sequence and phylogenetic analysis as well as proteomic tandem mass spectrometry. The pathogenicity of the two strains was studied using silkworms, and we found that B. cereus had a strong pathogenicity, with half of the lethal dose being 4 × 10⁴ cfu/ml. Moreover, the supernatant of B. cereus also had a strong lethality to silkworm, possibly due to the presence of flagella protein and metal proteases. These two proteins may play an important role in the pathogenicity of B. cereus.