Biodegradable Microplastics from Agricultural Mulch Films: Implications for Plant Growth-Promoting Bacteria and Plant’s Oxidative Stress

This study explores the interactions between biodegradable (BIO) microplastics and plant growth-promoting bacteria (PGPB), assessing their effects on soil health and crop productivity. Five bacterial strains, <i>Bacillus</i>, <i>Enterobacter</i>, <i>Kosakonia</i>, <i>Rhizobium</i>, and <i>Pseudomonas</i>, were exposed to BIO microplastics to examine strain-specific responses. This study revealed that while most bacteria experienced growth inhibition, <i>Kosakonia</i> sp. O21 was poorly affected by BIO microplastics, indicating a potential for microplastic degradation. This study further investigated the effect of these microplastics on plant growth and biochemistry. Results showed that exposure to BIO microplastics significatively reduced plant growth and caused oxidative stress, affecting membranes and proteins and inducing the activity of glutathione S-transferases (GSTs), catalase (CAT), and superoxide dismutase (SOD) as antioxidant responses. Bacterial inoculation alleviated plant oxidative stress, especially at lower concentrations of microplastics. These findings emphasize the critical role of oxidative stress in mediating the negative effects of BIO microplastics on plants and the relevance of bacterial strains that can tolerate BIO microplastics to protect plants from BIO microplastics' effects. Results also highlight the importance of extending research to assess the long-term implications of biodegradable microplastics for soil PGPBs and plant health and crop productivity. This study contributes to sustainable agricultural practices by offering insights into mitigating the risks of microplastic pollution through microbial-based interventions.