Bacillus wiedmannii biovar thuringiensis: a specialized mosquitocidal pathogen with plasmids from diverse origins

Abstract

Bacillus cereus sensu lato also known as B. cereus group is composed of an ecologically diverse bacterial group with an increasing number of related species, some of which are medically or agriculturally important. Numerous efforts have been undertaken to allow presumptive differentiation of B. cereus group species from one another. FCC41 is a Bacillus sp. strain toxic against mosquito species like Aedes aegypti, Aedes (Ochlerotatus) albifasciatus, Culex pipiens, Culex quinquefasciatus, and Culex apicinus, some of them responsible for the transmission of vector-borne diseases. Here, we report the complete genome sequence of FCC41 strain, which consists of one circular chromosome and eight circular plasmids ranging in size from 8 to 490 kb. This strain harbors six crystal protein genes, including cry24Ca, two cry4-like and two cry52-like, a cry41-like parasporin gene and multiple virulence factors. The phylogenetic analysis of the whole-genome sequence of this strain with molecular approaches places this strain into the Bacillus wiedmannii cluster. However, according with phenotypical characteristics such as the mosquitocidal activity due to the presence of Cry proteins found in the parasporal body and cry genes encoded in plasmids of different sizes, indicate that this strain could be renamed as B. wiedmannii biovar thuringiensis strain FCC41.

Proposal of a Taxonomic Nomenclature for the Bacillus cereus Group Which Reconciles Genomic Definitions of Bacterial Species with Clinical and Industrial Phenotypes

“…3A and D). These results are consistent with previous findings, as Bt toxin production has been attributed to numerous lineages (29,51,52).…”

“…An ideal taxonomy should be interpretable, without sacrificing the resolution provided by contemporary technologies. Several publications have appended the term "biovar" to species names to denote isolates which exhibit interesting phenotypes (e.g., anthrax-causing "B. cereus" as B. cereus biovar anthracis and Cry-producing B. wiedmannii as B. wiedmannii biovar thuringiensis) (41,52). We therefore propose a taxonomic framework consisting of (i) an amended collection of genomospecies, corresponding to resolvable genomospecies obtained at Ϸ92.5 ANI; (ii) a formal collection of subspecies, which account for established lineages of medical importance; and (iii) a formalized and extended collection of biovars, which account for phenotypic heterogeneity (Fig.…”

Culex quinquefasciatus carrying Wolbachia is less susceptible to entomopathogenic bacteria

“…The variability in the response of mosquitoes carrying the native Wolbachia strain and Wolbachia -free isoline to the different entomopathogenic bacteria, used in this work, could be explained by the differential production of putative virulence factors and extracellular degradative enzymes, such as bacteriocins, phospholipases C, enterotoxins, hemolysins, and some antibacterial proteins 27 , 33 , 34 ; all this might cause modifications or imbalances in the intestinal microflora of insects that, in some way, could participate in the pathogenic activity (Table 1 ). Moreover, the mosquitocidal bacterial strains Bti H14 and Ls 2362 showed significant differences in the mortality of Cx.…”

No Assembly Required: Using BTyper3 to Assess the Congruency of a Proposed Taxonomic Framework for the Bacillus cereus Group With Historical Typing Methods

“…isolates to genomospecies using species type strain genomes and historical species thresholds (i.e., 94–96 ANI) has been important for whole-genome characterization for B. cereus s.l. strains, including those responsible for illnesses and/or outbreaks ( Lazarte et al, 2018 ; Bukharin et al, 2019 ; Carroll et al, 2019 ). Here, we show that all 18 published B. cereus s.l.…”