3.2. Biochemical characterization and molecular identification of bacteria
Gram staining revealed that the SZ01 strain was red, indicating that it was a gram-negative bacterium. The specific physical and chemical characteristics of this bacterium are shown in Table 1. The physical and chemical characteristics of the SZ01 strain suggest that this bacterium was Klebsiella pneumoniae . After gene amplification, the size of the 16S rRNA fragment of the SZ01 strain was about 1500 bp, which was consistent with the expected size for 16S rRNA. The 16S rRNA gene sequence(GenBank login No.: MT192711)of the SZ01 strain was incorporated into the gene library and analyzed using the NCBI-blast program. The results showed that isolates showed the highest homology with K. pneumoniae . The 16S rRNA gene sequences of severalKlebsiella species and important aquatic pathogenic bacteria were selected to construct a development tree based on the 16S rRNA gene sequence (Figure 3). Results showed that the isolated bacteria andK. pneumoniae (GenBank login No. is KF733734.1) were clustered into the same branch(Figure 3),and had the highest homology. However, K. pneumoniae(GenBank login No. was KF733734.1) was isolated from the human oral cavity. Therefore, physical and chemical characteristics as well as gene analysis of the SZ01 strain all comprehensively suggest that the isolated SZ01 strain was K. pneumoniae.
Table1. Physiological and biochemical characteristics of the SZ01 strain