Endosulfan induced biochemical changes in nitrogen-fixing cyanobacteria

Area of Science:

• Environmental Science
• Biotechnology
• Microbiology

Background:

• Pesticide contamination in aquatic ecosystems, including paddy fields, poses a global environmental threat.
• Cyanobacteria, as non-target organisms, are significantly impacted by pesticides.
• Selecting pesticide-tolerant cyanobacterial strains is essential for their effective use as biofertilizers.

Purpose of the Study:

• To investigate the stress responses of three cyanobacterial strains (Aulosira fertilissima, Anabaena variabilis, Nostoc muscorum) to the organochlorine pesticide endosulfan.
• To elucidate the role of oxidative stress, proline, and antioxidant enzymes in detoxifying endosulfan-induced free radicals.
• To determine the tolerance levels of different cyanobacterial strains to endosulfan.

Main Methods:

• Exposure of cyanobacterial cultures to varying concentrations of endosulfan.
• Measurement of growth parameters, photosynthetic pigments, carbohydrates, and total protein.
• Assay of oxidative stress markers such as malondialdehyde (MDA) and antioxidant enzymes including superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase (CAT).

Main Results:

• Endosulfan exposure led to reduced growth, photosynthetic pigments, and carbohydrates at higher concentrations, alongside increased total protein.
• Elevated levels of MDA indicated free radical formation, while increased SOD, APX, CAT, and proline suggested their involvement in the detoxification process.
• Lower endosulfan concentrations resulted in enhanced photosynthetic pigments. The tolerance order was determined as Nostoc muscorum > Anabaena variabilis > Aulosira fertilissima.

Conclusions:

• Cyanobacteria exhibit distinct responses to endosulfan, involving oxidative stress and a complex antioxidant defense system.
• Proline and key antioxidant enzymes (SOD, APX, CAT) play crucial roles in mitigating endosulfan-induced oxidative damage.
• Nostoc muscorum demonstrates the highest tolerance to endosulfan, making it a promising candidate for biofertilizer applications in contaminated environments.