Isolation and identification of Burkholderia gladiolus in wet rice-products and the environment,detection of toxin-producing genes and analysis of bongkrekic acid production
Objective The pathogenic characteristics,virulence gene sequencing and evolutionary tree construction of Burkholderia gladiolus isolated from wet rice-products and environmental samples were carried out to explore the detection and toxin production mechanism of the bacteria.Methods From July 2021 to June 2022,222 wet rice-products and related environmental samples were collected for isolation and identification of Burkholderia gladiolus in accordance with the national standard GB4789.29-2020;time-of-flight mass spectrometer and PCR analyses were used for auxiliary identification.The positive strains were subjected to whole genome second-generation sequencing and bongkrekic acid detection.Results A total of 7 strains of Burkholderia gladiolus were isolated in this study.Among them,bon virulence genes were detected in 3 strains(DGTCP03,DGTCP04,and DGTCP05);after toxigenic culture,the concentrations of bongkrekic acid detected were 17.3,12.1,and 16 480 μg/L,respectively.The remaining 4 strains were negative for bon virulence genes and did not produce bongkrekic acid after toxigenic culture.After whole genome second-generation sequencing of the 7 strains,the bon virulence gene clusters were analyzed.All 3 isolates carried relatively complete bon virulence gene clusters,and most of the fragment similarities reached more than 90％.The remaining four isolates only carried bonG and bonH,with similarities ranging from 40％to 75％.In the phylogenetic tree homology analysis,the seven strains isolated were all in the second largest evolutionary branch,among which DGTCP01 and DGTCP02 were closely related.Conclusions With the increase of bonA gene similarity in Burkholderia gladioli,the amount of bongkrekic acid produced also increased significantly.Most of the seven strains were highly related to clinical isolates from the United States,providing relevant evidence for subsequent epidemiological investigations and market supervision.
Burkholderia gladiolibon virulence geneBongkrekic acidPhylogenetic tree
NETL
NSTL
万方数据
