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M S Kalra

Publications and source records attributed to M S Kalra.

6 recordsLinked to original sources

Pleiotropic changes in the activities of extracellular toxins of Pseudomonas aeruginosa protease-deficient mutants.

Protease-deficient mutants of Pseudomonas aeruginosa obtained by ethyl methane sulphonate treatment were found to show pleiotropic effect on various extracellular toxin activities. Of eight mutants five were completely deficient in lecithinase and four in collagenase activity. The decreased hemolytic activity was obtained in five mutants and enterotoxin activity in seven mutants as compared to parent strain.

Complement Hemolytic Activity Assay

Studies on Streptococcus faecalis enterotoxin.

Streptococcus faecalis has been reported to cause food poisoning. Six strains of S. faecalis were tested for Sherman's criteria. These strains were non-hemolytic, DNase+ and Ent+. The enterotoxin was purified on Sephadex G-200 column and maximum activity was observed at 37 C and pH 7.0. Enterotoxin treated with trypsin and papain elicited very poor response to fluid accumulation. The sensitivity of all the strains against different antibiotics was determined. Strain 53 M was treated with acridine orange and ethidium bromide and a total of 44 Amps Strr and 3 Amps Strs mutants were tested for toxin production. Out of these only 4 were toxin negative, amongst which 3 were also DNase negative and 1 showed partial DNase activity.

Acridine Orange

Aflatoxin B1 effect on beta-D-galactosidase in some starter cultures.

Six starter cultures were examined for their ability to induce beta-D-Galactosidase activity. The maximum (713 x 10(-4) units/ml) and minimum (140 x 10(-4) units/ml) enzyme activity was shown by Lactobacillus bulgaricus and Streptomyces thermophilus, respectively. The maximum inhibition by aflatoxin B1 of induction and activity of enzyme in vitro was observed at 60 micrograms/ml in all cultures. However, low levels of the toxin stimulated induction of the enzyme in Streptococcus lactis and S. thermophilus.

Aflatoxins