Bacterial amylolytic activity enhances beta-glucuronidase expression of amylase-negative Escherichia coli strain in starch-medium

The possibility of associating starch degradation with bacterial beta -gluc uronidase expression was examined. We proved that starving, in starch mediu m, amylase-negative Escherichia coil (M94) which has constitutive beta -glu curonidase greatly reduces (p < 0.01) its background activity, but the addi tion of both cell-free supernatants or cells of Bacillus subtilis (B10) pro ducing amylase greatly increases (p < 0.01) the E. coli beta -glucuronidase activity. Increases in activity were maximal when amylase in the medium ra nged from 0.3 to 0.8 U ml(-1) and pH from 6.8 to 6.3, whereas higher amylas e activity interacted with E. coli viability and the effect on beta -glucur onidase was less evident. The impact of B. subtilis amylase on E. coli beta -glucuronidase induction, observed when the organisms were cocultured, ind irectly supports the hypothesis that amylolytic activity of hindgut bacteri a may be effective on beta -glucuronidase induction of the climax microflor a. This last finding is important in the health field, considering the impl ication between the deconjugating role of this enzyme and consequent activa tion of toxic and carcinogenic compounds.