Ecological consequences of ingestion of Bacillus cereus on Bacillus thuringiensis infections and on the gut flora of a lepidopteran host

Raymond, Ben; Lijek, Rebecca S.; Griffiths, Robert I.; Bonsall, Michael B.. 2008 Ecological consequences of ingestion of Bacillus cereus on Bacillus thuringiensis infections and on the gut flora of a lepidopteran host. Journal of Invertebrate Pathology, 99 (1). 103-111.

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The Bacillus cereus group comprises a diverse array of non-pathogenic bacteria as well as pathogens such as Bacillus thuringiensis. Their spores are found together in soil and leaves and are therefore likely to commonly interact within hosts. Mixed infections of pathogenic B. thuringiensis and non-pathogenic strains have been little studied, despite their potential impact on biological control and the evolutionary ecology of virulence. Antibiotic secreting strains of B. cereus have been shown to be able to synergize B. thuringiensis (Bt) infections. We explored the ecology of these mixed infections more broadly in the diamondback moth (DBM). We tested whether antibiotic-expressing B. cereus can synergize Bt infections initiated with spores, investigated whether ingestion of antibiotic-expressing B. cereus had any consequences for the larval gut flora and whether synergistic interactions with B. cereus increase Bt reproduction. Ingestion of high-antibiotic secreting B. cereus synergized infections of B. thuringiensis in diamondback moth larvae, but at a lower level than previously reported. Coinfection also increased slightly the number of Bt spores found in cadavers. Culture independent analysis of gut homogenates indicated that ingestion of an antibiotic-expressing strain of B. cereus reduced the abundance of the gut flora and led to gut communities being dominated bacteria with DGGE profiles very similar to pure B. cereus cultures. Ingestion of B. cereus, regardless of genotype, reduced densities of an enteric isolate of Enterobacter sp. These findings support the hypothesis that antibiotic secretion in the gut synergizes B. thuringiensis infections by reducing the abundance of the commensal gut flora and facilitating invasion by bacteria in the B. cereus group.

Item Type: Publication - Article
Digital Object Identifier (DOI):
Programmes: CEH Programmes pre-2009 publications > Biodiversity > BD03 The Genetic Basis of Ecological Function > BD03.1 Molecular ecology
UKCEH and CEH Sections/Science Areas: Hails
ISSN: 0022-2011
Additional Keywords: Antagonism, Bt, Competition, Microbial diversity, Mixed infection, Population density, Synergistic interaction
NORA Subject Terms: Biology and Microbiology
Date made live: 30 Mar 2009 11:39 +0 (UTC)

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