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Bacterial amylolytic activity enhances β ‐glucuronidase expression of amylase‐negative Escherichia coli strain in starch‐medium
Author(s) -
Cenci Giovanni,
Caldini Giovanna,
Trotta Francesca
Publication year - 2000
Publication title -
journal of basic microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.58
H-Index - 54
eISSN - 1521-4028
pISSN - 0233-111X
DOI - 10.1002/1521-4028(200012)40:5/6<311::aid-jobm311>3.0.co;2-5
Subject(s) - amylase , strain (injury) , starch , chemistry , food science , glucuronidase , microbiology and biotechnology , enzyme , biochemistry , biology , anatomy
The possibility of associating starch degradation with bacterial β ‐glucuronidase expression was examined. We proved that starving, in starch medium, amylase‐negative Escherichia coli (M94) which has constitutive β ‐glucuronidase greatly reduces ( p < 0.01) its background activity, but the addition of both cell‐free supernatants or cells of Bacillus subtilis (B10) producing amylase greatly increases ( p < 0.01) the E. coli β ‐glucuronidase activity. Increases in activity were maximal when amylase in the medium ranged from 0.3 to 0.8 U ml —1 and pH from 6.8 to 6.3, whereas higher amylase activity interacted with E. coli viability and the effect on β ‐glucuronidase was less evident. The impact of B. subtilis amylase on E. coli β ‐glucuronidase induction, observed when the organisms were cocultured, indirectly supports the hypothesis that amylolytic activity of hindgut bacteria may be effective on β ‐glucuronidase induction of the climax microflora. This last finding is important in the health field, considering the implication between the deconjugating role of this enzyme and consequent activation of toxic and carcinogenic compounds.