Carbaryl stress induced cellular changes in Calothrix brevissima.

Area of Science:

• Agricultural Science
• Environmental Science
• Biochemistry

Background:

• Cyanobacterial biofertilizers are vital for sustainable agriculture but are susceptible to pesticides.
• Carbaryl, a common carbamate pesticide, poses a threat to non-target organisms in paddy fields.
• Understanding the biochemical impacts of carbaryl on cyanobacteria is crucial for mitigating agricultural risks.

Purpose of the Study:

• To investigate the cellular and biochemical effects of carbaryl exposure on the cyanobacterial biofertilizer Calothrix brevissima.
• To analyze changes in fatty acids, electrolyte leakage, sulfur metabolism, and osmolytes in response to carbaryl.
• To elucidate the protective mechanisms employed by C. brevissima against carbaryl-induced stress.

Main Methods:

• Exposure of Calothrix brevissima to varying concentrations of carbaryl (0-40 mg L(-1)).
• Biochemical analyses to quantify changes in fatty acids, electrolyte leakage, sulfur-containing metabolites, antioxidants, and osmolytes.
• Assessment of lipid peroxidation and free radical scavenging activity.

Main Results:

• Carbaryl exposure, particularly at 40 mg L(-1), reduced polyunsaturated fatty acids by 32% and increased membrane leakage by 27%, indicating lipid peroxidation.
• Significant increases were observed in sulfur-containing metabolites (cysteine, cystine, methionine) and antioxidants (glutathione S-transferase, glutathione reductase, reduced/oxidized glutathione).
• Osmolytes like mannitol, trehalose, and glycogen increased substantially, demonstrating their protective role against carbaryl-induced stress.

Conclusions:

• Carbaryl significantly impacts the cellular integrity and biochemical pathways of Calothrix brevissima.
• Cyanobacteria exhibit robust antioxidant and osmolyte defense systems to mitigate pesticide-induced oxidative stress.
• These findings highlight the vulnerability of cyanobacterial biofertilizers to pesticides and the importance of their biochemical resilience.