InSyB2020 Invited Speaker 9 | Genomic and Molecular Characterization of Bacillus anthracis

Genomic and molecular characterization of a unique, avirulent variant of Bacillus anthracis from hot spring
by Aparna Banerjee, Centro de Investigación de Estudios Avanzados del Maule, Vicerrectoría de Investigación y Postgrado, Universidad Católica del Maule, Talca, Chile
Abstract:
Thermophilic bacilli in both aerobic and facultative anaerobic forms have been isolated for over a hundred years from different mesophilic or thermophilic environments as they are likely source of bioactive secondary metabolites. However, the taxonomic resolution in the Bacillus genus at species/strain level is very puzzling for the inadequate divergence of the 16S rRNA genes. One such recurrent problem is among Bacillus anthracis, B. cereus and B. thuringiensis. The otherwise anthrax-causing B. anthracis strains have their typical virulence factors coded in two well-known plasmids, pXO1 (toxin genes) and pXO2 (capsule genes). Our study aimed at the complete molecular and genomic characterization of a thermophilic and environmental isolate of B. anthracis strain PFAB2. This unique strain was isolated from a hot spring named Panifala from West Bengal, India and is a good producer of thermostable dextran-type of exopolysaccharide (EPS) (Banerjee et al., 2016; Banerjee et al., 2018). We implemented comparative genomics between the PFAB2 genome and diverse other strains of B. anthracis, along with closely related B. cereus strains. The pangenome advocated that the PFAB2 genome harbour no complete prophage genes. Cluster analysis of Bray-Kurtis similarity resemblance matrix shown that gene content of PFAB2 was more closely related to the other environmental strains of B. anthracis. The secretome analysis and the in vitro and in vivo pathogenicity tests validated the unique avirulent phenotype of this strain. The most feasible justification for this novel phenotype is the apparent absence of plasmids genes for capsule biosynthesis and toxins secretion in the draft genome. Additional features of PFAB2 are good spore-forming and germinating capabilities along with rapid replication capability (Banerjee et al., 2019). The high replication rate in a wide range of temperatures and culture media, thermostable functional EPS production, the non-pathogenicity, the good spore forming capability and its genomic similarity to the Ames type strain together make PFAB2 a fascinating model strain for the study of the pathogenic evolution of B. anthracis.
This invited talk is a part of InSyB2020 (incob.apbionet...) which is organized by APBioNET (www.apbionet.o....