Impact of Organic Substrates on Oxidative Stress and Antioxidant Responses in Perionyx excavatus

Aim: The present study aimed to evaluate the influence of different organic substrates on oxidative stress and antioxidant defense mechanisms in the earthworm Perionyx excavatus, with particular emphasis on biochemical responses, antioxidant enzyme activities, oxidative damage biomarkers, and reactive oxygen species (ROS) balance under vermicomposting conditions. Methodology: A controlled laboratory experiment was conducted over a 28-day exposure period to assess oxidative and biochemical responses of P. excavatus under 04 substrate treatments: garden soil (control), cow dung + sugarcane bagasse (1:1), horse dung + sugarcane bagasse (1:1), and a mixed substrate of cow dung + horse dung + sugarcane bagasse (1:1:1). Biochemical parameters such as total protein content and antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) was analyzed. Detoxification enzyme glutathione-S-transferase (GST) and reduced glutathione (GSH) levels were also quantified. Oxidative damage was assessed through lipid peroxidation (MDA) and DNA damage using comet assay. Data were expressed as mean ± standard deviation (n = 5) and analyzed using one-way ANOVA followed by Tukey’s HSD test (p < 0.05). Results: Organic substrates significantly modulated biochemical and oxidative responses in P. excavatus. Treated groups exhibited elevated protein content and antioxidant enzyme activities compared to the control. The mixed substrate showed the highest SOD, CAT, GPx, GST activities and GSH levels, indicating enhanced antioxidant defense. Conversely, the horse dung + bagasse treatment exhibited increased lipid peroxidation and DNA damage, reflecting higher oxidative stress. Conclusion: Substrate composition strongly influences oxidative physiology in P. excavatus. Mixed substrates enhance antioxidant defenses and reduce oxidative damage, supporting efficient vermicomposting. The species also serves as a reliable bioindicator of substrate quality and oxidative stress.