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Prophage induction by liver microsomal metabolites of aflatoxin B1 in lysogenic Pseudomonas aeruginosa
Abstract:
Microsomal metabolites of aflatoxin B1 (AFB1) causing induction of prophage in lysogenic strain of Pseudomonas aeruginosa SM was studied. Reduction of culture turbidity was determined at various concentrations of toxin. The effect of the toxin was also studied on deoxyribonucleic acid (DNA), ribonucleic acid (RNA) and protein synthesis. AFB1 at the concentration of 50 micrograms/ml reduced initial turbidity to approximately 90% in 4 h. DNA synthesis stopped completely in the first hour but reappeared due to induction of the temperate phage. Soon after induction both RNA and protein synthesis continued but later little or no net synthesis of these macromolecules occurred. Plaque forming units (pfu) were increased approximately 90 times at 2 h as compared to the control. Testing of the effect of AFB1 on the non-lysogenic, sensitive strain demonstrated that although there was no significant decrease in culture turbidity at 50 micrograms/ml concentration of AFB1, DNA synthesis stopped completely within 1 h, while RNA and protein synthesis were increasing throughout the test interval. It has been concluded that the liver microsomal fraction of AFB1 caused induction of prophage in lysogenic cells and inhibited DNA synthesis significantly in non-lysogenic cells.
Insights
Microsomal aflatoxin B1 (AFB1) metabolites induced prophage in Pseudomonas aeruginosa. AFB1 also significantly inhibited DNA synthesis in non-lysogenic bacteria.
Area of Science:
- Microbiology
- Toxicology
- Molecular Biology
Background:
- Aflatoxin B1 (AFB1) is a potent mycotoxin known for its carcinogenic properties.
- Lysogenic bacteria harbor temperate phages, which can be induced to replicate under certain conditions.
- Understanding AFB1's effects on bacterial systems is crucial for public health and food safety.
Purpose of the Study:
- To investigate the effects of microsomal metabolites of AFB1 on a lysogenic strain of Pseudomonas aeruginosa.
- To determine the impact of AFB1 on bacterial growth, DNA, RNA, and protein synthesis.
- To compare AFB1's effects on lysogenic versus non-lysogenic bacterial strains.
Main Methods:
- Exposure of lysogenic Pseudomonas aeruginosa SM to varying concentrations of AFB1.
- Measurement of culture turbidity to assess growth inhibition.
- Quantification of DNA, RNA, and protein synthesis.
- Determination of plaque-forming units (pfu) to quantify phage induction.
- Comparative analysis using a non-lysogenic, sensitive bacterial strain.
Main Results:
- AFB1 at 50 µg/ml reduced bacterial turbidity by approximately 90% within 4 hours.
- DNA synthesis was completely inhibited in the initial hour, followed by reappearance due to phage induction.
- RNA and protein synthesis initially continued post-induction but ceased later.
- Plaque-forming units increased significantly (approx. 90-fold) in the lysogenic strain.
- In non-lysogenic strains, AFB1 inhibited DNA synthesis but allowed RNA and protein synthesis to increase.
Conclusions:
- Liver microsomal metabolites of AFB1 effectively induce prophage in lysogenic Pseudomonas aeruginosa.
- AFB1 significantly inhibits DNA synthesis in both lysogenic and non-lysogenic bacterial cells.
- The differential effects on macromolecule synthesis highlight AFB1's complex interactions with bacterial genetic material and replication.