Related Experiment Videos
A cyanobacterial mutant resistant against a bleaching herbicide
A Vaishampayan1, R P Sinha, A K Gupta
1Department of Genetics and Plant Breeding, Banaras Hindu University, Varanasi, India.
Journal of Basic Microbiology
|September 15, 2000
Summary
The herbicide SAN 6706 harms nitrogen-fixing cyanobacteria, but this effect is reversible with glucose or ATP. A resistant mutant suggests a defect in the photosynthetic system's phosphorylation.
Area of Science:
- * Biochemistry and molecular biology of cyanobacteria.
- * Photosynthesis and nitrogen fixation mechanisms.
- * Herbicide toxicity and resistance studies.
Background:
- * The nitrogen-fixing cyanobacterium *Nostoc muscorum* exhibits sensitivity to the herbicide SAN 6706.
- * Herbicide toxicity is exacerbated in nitrogen-free media and can be mitigated by glucose or ATP supplementation.
- * This highlights the organism's reliance on specific carbon and energy sources for survival under stress.
Purpose of the Study:
- * To investigate the mechanism of SAN 6706 toxicity in *Nostoc muscorum*.
- * To isolate and characterize a mutant strain resistant to SAN 6706.
- * To elucidate the role of phosphorylation in herbicide resistance and photosynthetic function.
Main Methods:
- * Exposure of *Nostoc muscorum* to varying concentrations of SAN 6706.
- * Isolation and genetic characterization of a resistant mutant strain.
- * Assessment of nitrogenase activity and growth under different media conditions (nitrogen-free, combined nitrogen, ATP/glucose supplementation).
- * Cross-resistance studies with methylamine, a photophosphorylation inhibitor.
Main Results:
- * *Nostoc muscorum* is sensitive to SAN 6706 (30-45 microM), with increased toxicity in nitrogen-free medium.
- * Glucose or ATP reversed SAN 6706 toxicity, indicating a role for carbon/energy metabolism.
- * A resistant mutant (resistance factor >100) was isolated, capable of nitrogenase activity with exogenous ATP.
- * The mutant showed cross-resistance to methylamine, suggesting defective photophosphorylation.
Conclusions:
- * SAN 6706 toxicity in *Nostoc muscorum* is linked to energy metabolism and phosphorylation processes.
- * The isolated mutant exhibits impaired photosynthetic phosphorylation, conferring resistance to SAN 6706 and methylamine.
- * This study provides insights into cyanobacterial herbicide resistance mechanisms and the importance of photophosphorylation.