An Investigation of Bacillus thuringiensis in Rectal-Collected Fecal Samples of Cows
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In order to better understand the range and role of Bacillus thuringiensis (Bt) and its toxins in nature, we have undertaken a study of Bt taken directly from the rectum of 117 cows from 37 farms on the Caribbean island of Trinidad. Thirty-seven fecal samples (32%) were found to contain at least one Bt. Generally only one or two isolates with a particular crystal morphology were isolated from any one sample, however, a few samples contained more, up to 11 isolates, suggesting post-ingestion amplification. Bioassays using larvae of Musca domestica, Caenorhabditis elegans and Tetrahymena pyriformis showed no observable toxicity in gross bioassays. Very small dot-like parasporal bodies, not generally characteristic of Bt, were isolated from 44% of the samples, which in many instances appeared unstable and whose relation to Bt Cry protein-containing parasporal bodies is unknown. In conclusion, we find little evidence for a host adapted strain of Bt in the cows examined, nor toxicity to organisms that might logically be associated with either the cow or its feces. The presence of a large number of isolates containing small dot-like parasporal bodies, possibly either poly-β-hydroxybutyrate storage bodies or Cry proteins, was unexpected and merits further investigation.
JNR thanks the Faculty Research Council at the University of Texas-Pan American for financial support of work described in this Report and Welch Foundation Grant BG-0017.
- 2.Soberón M, Gill SS, Bravo A (2009) Signaling versus punching hole: how do Bacillus thuringiensis toxins kill insect midgut cells? Cell Mol Life Sci Jan 13 (online publication)Google Scholar
- 14.Rampersad J. (2006) A study on the isolation of Bacillus thuringiensis from the environment: a critical look at library construction. PhD thesis, The University of the West Indies, Trinidad and TobagoGoogle Scholar
- 21.Nickerson KW, Zarnick WJ, Kramer VC (1981) Poly-β-hydroxybutyrate parasporal bodies in Bacillus thuringiensis. FEMS Microbiol Lett 12:327–331Google Scholar