ABSTRACT
The activities of various concentrations of 4 acidity regulators (anhydrous citric acid, phosphoric acid, malic acid and lactic acid) used in food industries in Iraq was assayed using the Salmonella/microsome mutagenicity assay. None of the samples was mutagenic in the absence or in the presence of S9 to any of the tester strains of Salmonella typhimurium.
Subject(s)
Citrates/pharmacology , Food Additives/pharmacology , Lactates/pharmacology , Malates/pharmacology , Phosphoric Acids/pharmacology , Salmonella typhimurium/drug effects , Animals , Biotransformation , Citric Acid , Hydrogen-Ion Concentration , Lactic Acid , Male , Microsomes, Liver/metabolism , Mutagenicity Tests , RatsABSTRACT
Pure pyocyanin was prepared from 120 strains of Pseudomonas aeruginosa isolated from different clinical specimens. The modified method used increased the purification 425-fold. The spectra of pyocyanin of all strains were found to be identical with a single major peak at 363 nm. The only difference between these spectra appeared to be the level value absorbance. Strains recovered from different clinical specimens differ in their ability for pigment production. The strains isolated from urine produced higher amounts of pyocyanin than other isolates.
Subject(s)
Phenazines/isolation & purification , Pseudomonas aeruginosa/metabolism , Pyocyanine/isolation & purification , Humans , Pyocyanine/biosynthesis , Spectrophotometry, UltravioletABSTRACT
Fifty-six selected strains of Pseudomonas aeruginosa belonging to 8 different pyocin types (H, I, 15, 6, PTI-1, PTI-2, PTI-3, PTI-4) were treated with subinhibitory concentrations (MIC/2) of either gentamicin or carbenicillin. Both treatments induced changes in pyocin patterns for all types but at different levels. The percentage of strains that retained their pyocin pattern were more or less equal in both treatments. In treated and untreated producers, the growth inhibition ability for 5 different strains of Enterobacteriaceae (Escherichia coli K12, E. coli EB, Proteus vulgaris, Salmonella typhi, Shigella flexneri) was also investigated. In all pyocin patterns the number of producers that inhibit the growth of these strains was lower after treatment with gentamicin or with carbenicillin, a smaller decrease was detected in the latter treatment. It appeared that the subinhibitory concentrations of these antibiotics are capable of protecting the Enterobacteriaceae strains from the action of the pyocins.
Subject(s)
Bacteriocins/biosynthesis , Carbenicillin/pharmacology , Gentamicins/pharmacology , Pseudomonas aeruginosa/drug effects , Pyocins/biosynthesis , Enterobacteriaceae/drug effects , Enterobacteriaceae/growth & development , Proteus vulgaris/drug effects , Proteus vulgaris/growth & development , Pseudomonas aeruginosa/growth & development , Pseudomonas aeruginosa/metabolism , Pyocins/pharmacology , Salmonella typhi/drug effects , Salmonella typhi/growth & development , Shigella flexneri/drug effects , Shigella flexneri/growth & developmentABSTRACT
Investigations of the phenomenon of transformation in Rhizobium were carried out. Streptomycin resistance (str) was the genetic marker used in all experiments, with the exception of auxotrophic strains. Twenty-one experiments were performed on nine different Rhizobium strains. Some of these strains were previously reported to be transformed, while others had no prior history of transformation. Different conditions which are thought to affect the development of competence were used. In these experiments no positive results were obtained. The possibility that the experiments failed, due to inactivation of donor DNA during its preparation, was ruled out by comparison with results obtained with strains of Bacillus subtilis.
