Pathogenicity and Genomic Characterization of a Novel Genospecies, Bacillus shihchuchen, of the Bacillus cereus Group Isolated from Chinese Softshell Turtle (Pelodiscus sinensis)

Abstract

The Chinese softshell turtle (CST; Pelodiscus sinensis) is a freshwater aquaculture species of substantial economic importance that is commercially farmed across Asia, particularly in Taiwan. Although diseases caused by the Bacillus cereus group (Bcg) pose a major threat to commercial CST farming systems, information regarding its pathogenicity and genome remains limited. Here, we investigated the pathogenicity of Bcg strains isolated in a previous study and performed whole-genome sequencing. Pathogenicity analysis indicated that QF108-045 isolated from CSTs caused the highest mortality rate, and whole-genome sequencing revealed that it was an independent group distinct from other known Bcg genospecies. The average nucleotide identity compared to other known Bcg genospecies was below 95%, suggesting that QF108-045 belongs to a new genospecies, which we named Bacillus shihchuchen. Furthermore, genes annotation revealed the presence of anthrax toxins, such as edema factor and protective antigen, in QF108-045. Therefore, the biovar anthracis was assigned, and the full name of QF108-045 was Bacillus shihchuchen biovar anthracis. In addition to possessing multiple drug-resistant genes, QF108-045 demonstrated resistance to various types of antibiotics, including penicillins (amoxicillin and ampicillin), cephalosporins (ceftifour, cephalexin, and cephazolin), and polypeptides, such as vancomycin.

Comparative pathogenicity and histopathological analysis of Edwardsiella anguillarum intraperitoneal infection in milkfish (Chanos chanos), Nile tilapia (Oreochromis niloticus) and Asian seabass (Lates calcarifer)

“…Throughout the 14-day experimental period, PCR assays were performed on tissue DNA samples (spleen and head kidney) from each fish to confirm the presence of E. anguillarum. Genomic DNA was extracted from fish tissue (spleen and head kidney) samples following the method described by Cheng et al (2023), with slight modifications. Briefly, the extraction process utilized the reagent Genomaker® (Bio-East Technology, Taiwan) following the manufacturer's protocol.…”

Nocardiosis and other common diseases of cultured golden pompano (Trachinotus blochii) in Taiwan

“…Besides the already-isolated bacteria in TSN and LJ medium, tissues of which presented observable gross lesions were kept for PCR. DNA extraction from isolated bacteria and organ tissues was performed using Genomaker reagent (Bio-East Technology) as previously described (Cheng et al, 2023), while RNA extraction utilized TRIzol reagent (Zymeset Biotechnology). For RNA extraction, 1 μg of total RNA was reverse-transcribed in accordance with the manufacturer's instructions.…”