Environmental Factors Determining the Epidemiology and Population Genetic Structure of the Bacillus cereus Group in the Field

• DOI: 10.1371/journal.ppat.1000905
• Publication Date: 2010-05-20T19:05:31Z
• Authors: Ben Raymond; Kelly L. Wyres; Samuel K. Sheppard; Richard J. Ellis; Michael B. Bonsall
• Keywords: Biopesticide; Cereus; Bacillus thuringiensis; Multilocus sequence typing

Bacillus thuringiensis (Bt) and its insecticidal toxins are widely exploited in microbial biopesticides genetically modified crops. Its population biology is, however, poorly understood. Important issues for the safe, sustainable exploitation of Bt include understanding how selection maintains expression nature, whether entomopathogenic is ecologically distinct from related human pathogens cereus group, use pesticides alters natural bacterial populations. We addressed these questions with a MLST scheme applied to field experiment which we excluded/added insect hosts factorial design. The presence insects increased density Bt/B. soil proportion strains expressing toxins. found near-epidemic structure dominated by single genotype (ST8) sprayed unsprayed enclosures. Biopesticidal ST8 proliferated after spraying but was also naturally associated leaves more than any other genotype. In an independent several isolates proved better range non-pathogenic STs at endophytic epiphytic colonization seedlings soil. This first experimental demonstration behaving as specialized pathogen field. These data provide basis both ecology influence anthropogenic factors on showed habitat associations that differed markedly previous studies less coherent B. sample collections. host-specific adaptations ST8, close association toxin plasmid high prevalence within clade analogous anthracis. suggests resistance will have been stronger classes.