A range of novel substrates for the detection of bacterial hydrolyases have been examined in both liquid and solid media. The potential inhibitory effect of these substrates on both Gram-positive and Gram-negative organisms has been evaluated. In addition a range of alternative substrates possessing an appropriate chemical configuration have also been evaluated as substrates in this thesis. It has been demonstrated that substrates based on 4-aminophenol, particularly the dichloro derivative produce intensely coloured reaction products upon hydrolysis and subsequent coupling with 1-naphthol. A derivative of 1-naphthol, 3,5-dihydroxy-2-naphthoic acid, was shown to react favourably with a number of released core compounds, producing a wide variety of coloured complexes. In comparison with o-nitropheny1-13-D-galactoside (ONPG), the novel substrates for the detection of P-galactosidase activity showed wide differences in K. and V. values. Overall these substrates performed well in liquid media, especially the dichloro derivatives for detection of a range of bacterial hydrolyases. The substrates have also been evaluated in solid media and have been shown to produce intensely coloured reaction products. The fact that these substrates offer themselves to the production of novel dual substrate systems indicates their potential diagnostic applications. Use of L-alanyl-DEPPD in combination with 1-naphthyl-J3-D-galactoside has been shown to be of diagnostic potential for the detection of 13-galactosidase activity in Gram-negative organisms. In addition, a combination of substrates, L-prolyl-4-amino-2,6-dichlorophenol and 1-naphthyl-O-D¬glucoside has also been shown to have potential for the production of a medium specifically for the isolation of Serratia sp. This dual substrate system also has applications for the production of media for the specific isolation and detection of numerous clinically important pathogens e.g Enterococcus sp, C.perfringens and Yersinia enterocolitica.
|Publication status||Accepted/In press - 28 Apr 2004|