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, Bacillus, Enterobacter, Kosakonia, Rhizobium, and Pseudomonas, were exposed to BIO microplastics to examine strain-specific responses. This study revealed that while most bacteria experienced growth inhibition, Kosakonia 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.

Rising global temperatures are increasingly affecting plant performance, leading to reduced growth, altered metabolism, and compromised membrane integrity. Although plant growth-promoting bacteria (PGPB) show promise in enhancing thermotolerance, the underlying mechanisms remain insufficiently explored. Therefore, this study investigated the effects of PGPB inoculation on Zea mays under control (26 °C) and heat stress (36 °C) conditions. Maize plants were inoculated with two thermotolerant bacterial strains and their effects were compared to non-inoculated plants through morphometric, biochemical, and lipidomic analyses. Heat stress negatively affected germination (−35.9%), increased oxidative stress (+46% for LPO, +57% for SOD, +68% for GPx), and altered leaf lipid composition, particularly fatty acids, glycerolipids, and sphingolipids. Inoculation with Pantoea sp. improved germination by 15% for seeds exposed to heat stress, increased growth (+28% shoot and +17% root), enhanced antioxidant defenses (+35% for CAT and +38% for APx), and reduced membrane damage by 65% compared with the control. Lipidomic profiling revealed that inoculation mitigated temperature-induced lipid alterations by reducing triacylglycerol accumulation and preserving the levels of polyunsaturated galactolipids and hexosylceramides. Notably, Pantoea sp.-inoculated plants under heat stress exhibited lipid profiles that were more similar to those of control plants, suggesting enhanced heat resilience. These results underscore the importance of specific plant–microbe interactions in mitigating heat stress and highlight PGPB inoculation as a promising strategy to enhance crop performance and resilience under projected climate warming scenarios.