Affiliation:
1. Wageningen Centre for Food Sciences
2. Agrotechnology and Food Innovations
3. Laboratory of Food Microbiology, Wageningen University, Wageningen, The Netherlands
Abstract
ABSTRACT
Bacillus cereus
endospores germinate in response to particular nutrients. Spores are able to sense these nutrients in the environment by receptors encoded by the
gerA
family of operons. Analysis of the
Bacillus cereus
ATCC 14579 genome revealed seven
gerA
family homologues. Using a transposon Tn
917
-based insertional mutagenesis approach followed by an enrichment procedure to select for
l
-alanine-induced germination mutants, we isolated a mutant with a defect in the
l
-alanine germination pathway. The transposon disrupted the last gene of a tricistronic
gerA
family operon, designated
gerR
, with the order
gerRA
,
gerRC, gerRB
. A second mutant was created by insertion of pMUTIN4 in
gerRC
. Both mutants showed the same phenotype for nutrient-induced germination. Spores of the
gerR
mutant strains were blocked in their
l
-alanine-initiated germination pathway and showed a delayed inosine-induced germination response. Apparently, germination mediated by
l
-alanine and inosine cannot be compensated for completely by the other germinant receptors, and this points towards an essential role of the
gerR
-encoded receptor in the receptor complex. In food products, spores of the mutant strains showed a reduced germination response compared to spores of the parental strain. High-pressure-initiated germination was not affected by the
gerR
mutations, as experiments with 100 and 550 MPa showed no difference with spores of the parental strain.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
70 articles.
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