Genotype and virulence gene analyses of Bacillus cereus group clinical isolates from the Chinese softshell turtle (Pelodiscus sinensis) in Taiwan

Abstract

Chinese softshell turtles (Pelodiscus sinensis) (CST) are susceptible to infections by bacteria belonging to the Bacillus cereus group (Bcg). Bcg includes several closely related species, two of which, B. cereus and B. thuringiensis, are pathogens of aquatic animals or insects. In the present study, we collected 57 Bcg isolates obtained from diseased CST from 2016 to 2019 in Kaohsiung and Pingtung, the areas with the most CST farms in Taiwan. All isolates were divided into four genotypes with two restriction enzymes, SmaI and NotI, by pulsed-field gel electrophoresis and enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR).Representative isolates from each genotype were subjected to phylogenetic tree analysis using 16S rDNA and pyruvate carboxylase genes as phylogenetic markers, and these CST isolates appeared in different clades. PCR was performed targeting six selected virulence genes, four of which were detected in CST isolates, including cytotoxin K (1/57), hblC of the haemolysin BL complex (46/57), nheA of the nonhaemolytic enterotoxin complex (52/57) and enterotoxin FM (57/57), whereas cereulide synthetase and cereulide peptide synthase-like genes were not detected in any isolates.

Bacillus cereus, a potential pathogen of snakehead fish Ophiocephalus argus

“…The same strain (CA4) confirmed by phenotypic and molecular identification was re-isolated from the experimental diseased fish. Furthermore, blood vessel congestion and macrophage infiltration were observed in the liver of artificially and naturally infected snakehead fish (Figure 4), similar to those observed in B. cereusinfected Pelodiscus sinensis (Cheng et al, 2021). Thus, isolate CA4 was identified as snakehead fish's causative pathogen associated with hepatic hemorrhage.…”

Phenotypic and genotypic analysis of Edwardsiella isolates from Taiwan indicates wide variation with a particular reference to Edwardsiella tarda and Edwardsiella anguillarum

“…In recent study, the PFGE method have been used to identify genotype change in Edwardsiella tarda strain from Japanese eel disease A. japonica in Taiwan (Lo et al, 2014), A. japonica in Korea (Kim et al, 2014); flounder ( P. olivaceus ), oscar ( Astronotus ocellatus ) and Japanese eel ( A. japonica ) in China (Yang et al, 2013). These methods have been applied also to other bacteria such as Bacillus cereus (Cheng et al, 2021), Photobacterium damselae subsp. piscicida (Pham et al, 2020) and Streptococcus dysgalactiae (Nguyen et al, 2017; Tsai et al, 2015).…”

Genotyping and phenotyping of Lactococcus garvieae isolates from fish by pulse‐field gel electrophoresis (PFGE) and electron microscopy indicate geographical and capsular variations

“…PFGE has consistently been proven to be more selective for specific bacteria than standard serotyping, ribotyping, or MLST (Ferrario et al., 2013; Shabayek & Spellerberg, 2018). The collection of isolates through a comparative study of cost‐effective fingerprinting approaches to minimize workflow times and bias in genomic interpretation from costly techniques such as whole‐genome sequencing (Adams, 2019; Chen et al, 2012; Cheng et al., 2021; Pham et al., 2020). Although the variable copy number of the 16S rRNA is associated with evolutionary distance as observed in the NGS technique, similar discrimination based on macrorestriction fragments is also evident in PFGE analysis (Terletskiy et al 2020).…”