Natural isolates of Bacillus thuringiensis display genetic and psychrotrophic properties characteristic of Bacillus weihenstephanensis.
OBJECTIVE
To determine the potential of Bacillus thuringiensis, known primarily for its entomopathogenicity, to be a psychrotolerant contaminant of stored products.


RESULTS
We determined the genetic properties and diversity of cold-adapted isolates of B. thuringiensis based on (i) the presence of cspA, a genetic determinant that confers psychrotolerance in Bacillus weihenstephanensis, (ii) 16S rRNA genes, and (iii) pulse-field gel electrophoretic (PFGE) genome profiles. We assessed the pathogenic potential of these isolates based on whether they harboured various combinations of known toxigenic-associated determinants (nheA, hblA, cytK). Of 36 nonclonal B. thuringiensis cultured from soil and milk, 21 harboured cspA, and of these, 16 (76%) were psychrotolerant and possessed genetic signatures typical of psychrotrophic Bacillus species. The majority of psychrotolerant isolates contained various combinations of nheA, hblA, and cytK.


CONCLUSIONS
Our results show that natural isolates of psychrotolerant B. thuringiensis occur in soil and milk, and suggest that psychrotolerance is determined by cspA.


CONCLUSIONS
The presence of cspA in combination with nheA, hblA, and cytK could be of concern if commercial products are contaminated with strains that harbour these determinants.
Bartoszewicz
M
M
Department of Microbiology, Institute of Biology, University of Bialystok, Bialystok, Poland.
Bideshi
D K
DK
Kraszewska
A
A
Modzelewska
E
E
Swiecicka
I
I
D000818:Animals; D001407:Bacillus / Q000145:classification / Q000235:genetics* / Q000254:growth & development; D001413:Bacillus thuringiensis / Q000235:genetics* / Q000254:growth & development / Q000302:isolation & purification*; D001426:Bacterial Proteins / Q000235:genetics; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000032:analysis / Q000235:genetics; D004275:DNA, Ribosomal / Q000032:analysis / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D004768:Enterotoxins / Q000235:genetics; D006360:Heat-Shock Proteins / Q000235:genetics; D008892:Milk / Q000382:microbiology*; D010572:Pest Control, Biological; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D016601:RNA-Binding Proteins / Q000235:genetics; D012988:Soil Microbiology; D013696:Temperature
D001426:Bacterial Proteins; C099484:CspA protein, Bacillus; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D004768:Enterotoxins; D006360:Heat-Shock Proteins; D012336:RNA, Ribosomal, 16S; D016601:RNA-Binding Proteins