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[Detection of some toxin genes related to pathogenicity in Bacillus cereus group strains]

Xiao-min Hu1, Ya-jun Cai, Guo-ping Zhou

  • 1Wuhan Institute of Virology, C4S, Wuhan 430071, China. xiaomin.hu@gmail.com

Wei Sheng Wu Xue Bao = Acta Microbiologica Sinica
|August 4, 2007
PubMed

Insights

Many Bacillus thuringiensis strains, including commercial ones, possess enterotoxin genes. However, one B. cereus strain lacks these genes, making it a candidate for safer insecticidal engineering.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Bacterial Pathogenesis

Background:

  • Bacillus thuringiensis (Bt) and Bacillus cereus (Bc) are closely related within the B. cereus group.
  • Bt produces insecticidal crystal proteins via plasmids, while sharing high chromosomal similarity with Bc.
  • Pathogenicity in B. cereus group bacteria is often linked to enterotoxin genes and virulence factors like plcR.

Purpose of the Study:

  • To investigate the prevalence of enterotoxin genes (hbl, nhe) and the plcR gene in B. cereus group strains.
  • To identify potential candidate strains for developing safer insecticidal Bt strains by assessing their enterotoxigenic potential.

Main Methods:

  • Polymerase Chain Reaction (PCR) was used to detect specific toxin genes.
  • Twenty-six strains from the B. cereus group, including B. thuringiensis, were analyzed.
  • Presence or absence of hbl genes, nhe genes, and plcR was determined for each strain.

Main Results:

  • The pleiotropic virulence regulator plcR was found in 17 of the 26 surveyed strains.
  • Approximately 73% of B. cereus group strains and 83% of B. thuringiensis strains harbored at least one hbl and one nhe gene.
  • Bacillus cereus DBt248 was identified as negative for all tested hbl, nhe, and plcR genes.

Conclusions:

  • Many B. thuringiensis strains, including those used commercially, carry enterotoxin genes.
  • Bacillus cereus DBt248 presents a promising candidate for developing genetically engineered insecticidal strains due to its lack of enterotoxin genes.
  • This finding supports the potential for creating safer biocontrol agents by utilizing enterotoxin-negative host strains.

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