ABSTRACT
Assessment of amino acid decarboxylase activity can be conducted using tubed broth or plated agar. In this study, the test was carried out in microtitre plates containing lysine, ornithine, arginine, tyrosine, tryptophan, phenylalanine or histidine as biogenic amine precursors. Møller decarboxylase base broth (MDB) with or without 1% of a known amino acid were added to wells of a 96 well-microtitre plate. The wells were inoculated with Escherichia coli, Klebsiella pneumoniae, Acinetobacter anitratus or Staphylococcus aureus to the final concentration of 6.0 x 10(7) cfu/ml and incubated at 35ºC. The absorbance of the culture broth was read at 570 nm at 0, 1.0, 2.0, 3.0, 4.0, 5.5, 6.5 and 7.5 hour. Comparison of means of A'(570) between 0 hour and a specified incubation time was determined statistically. Positive decarboxylase activities were detected in the media inoculated with E. coli and K. pneumoniae in less than 6 hours. The current method is suitable for immediate producers of amino acid decarboxylase enzymes. It costs less as it uses less amino acid and it has the potential to be used for screening aliquots of food materials for amino acid decarboxylase activities.
Subject(s)
Amino Acids/metabolism , Bacteria/enzymology , Bacteria/isolation & purification , Bacteriological Techniques/methods , Carboxy-Lyases/metabolism , Bacteriological Techniques/economics , Colorimetry/economics , Colorimetry/methods , Food Microbiology , Foodborne Diseases/microbiology , Humans , Time FactorsABSTRACT
Assessment of amino acid decarboxylase activity can be conducted using tubed broth or plated agar. In this study, the test was carried out in microtitre plates containing lysine, ornithine, arginine, tyrosine, tryptophan, phenylalanine or histidine as biogenic amine precursors. Møller decarboxylase base broth (MDB) with or without 1% of a known amino acid were added to wells of a 96 well-microtitre plate. The wells were inoculated with Escherichia coli, Klebsiella pneumoniae, Acinetobacter anitratus or Staphylococcus aureus to the final concentration of 6.0 x 107 cfu/ml and incubated at 35oC. The absorbance of the culture broth was read at 570 nm at 0, 1.0, 2.0, 3.0, 4.0, 5.5, 6.5 and 7.5 hour. Comparison of means of A’570 between 0 hour and a specified incubation time was determined statistically. Positive decarboxylase activities were detected in the media inoculated with E. coli and K. pneumoniae in less than 6 hours. The current method is suitable for immediate producers of amino acid decarboxylase enzymes. It costs less as it uses less amino acid and it has the potential to be used for screening aliquots of food materials for amino acid decarboxylase activities.
ABSTRACT
Three popular medicinal plants regarded as improving human sexual function in some parts of Southeast Asia were analysed for their mutagenic properties using modified Ames test (fluctuation test). Extract of one of the plants, Tacca integrifolia Ker-Gawl., was found to be mutagenic using Salmonella typhimurium strains TA98 and TA100. Extract of T. integrifolia, Eurycoma longifolia Jack and Helmintostachys zeylanica (L.) Hook were cytotoxic to human cell lines, Hep2 and HFL1, with IC50 ranging from 11 mug/ml to 55 mug/ml. Extract of E. longifolia was the most cytotoxic with IC50 of 11 mug/ml and 13 mug/ml on Hep2 and HFL1 cell lines respectively. Combined extract of T. integrifolia and H. zeylanica was more cytotoxic than single extract on both Hep2 and HFL1 cell lines while combined extract of E. longifolia and H. zeylanica was more cytotoxic than single extract on Hep2 cell lines. Under the conditions of this study it can be concluded that T. integrifolia is mutagenic and the combined extracts of the medicinal plants was highly cytotoxic.
