Genetic evolution and prevalence
In order to study the genetic characteristics of the bacterium, we carried out the whole gene sequencing analysis of the bacillus. The 16SrRNA phylogenetic tree analysis showed that the bacterium belongs toChromobacterium, which is in the same branch asChromobacterium haemolyticum , with a homology of 79% (Fig. 2A). The climatic characteristics of Guangdong Province are more suitable for the reproduction of Chromobacterium , so we expanded the detection range. The Chromobacterium haemolyticum was also detected in water sources and fecal samples in other areas with unexplained diarrhea. The bacteria were detected in the three regions of HEYUAN, MAOMING, and SHANWEI, among which the incidence was more severe in HEYUAN region (Fig.2B). These results suggest that the GDHYZ30 strain should be noteworthy to focus on in south China, since this novelChromobacterium haemolyticum could be an important agent causing diarrhea and death in piglets, and a potential infection risk factor for human beings by food chain as well.