Glyphosate Biodegradation by Airborne Plant Growth-Promoting Bacteria: Influence on Soil Microbiome Dynamics

Due to its persistence, glyphosate contamination in soil poses environmental and health risks. Plant growth-promoting bacteria (PGPB) offer a potential solution for mitigating glyphosate pollution. This study assessed the glyphosate degradation capacity of three airborne PGPB isolates (Exiguobacterium indicum AS03, Kocuria sediminis AS04, and Rhodococcus rhodochrous AS33) individually and in a consortium (CS) compared to natural attenuation in microcosms as the control (CTL), where soil autochthonous microorganisms (MS) were present. AS03 exhibited the highest glyphosate degradation (86.3%), followed by AS04 and AS33 at 14 days (61.6% and 64.7%). The consortium accelerated glyphosate removal, reaching 99.7%, while the control treatment removal was 94% at 60 days. Aminomethylphosphonic acid (AMPA) is the main metabolite in glyphosate degradation, and it had a maximum peak in concentration at 28 days in the CS + MS (1072 mg kg−1) and CTL (990 mg kg−1) treatments. Subsequently, a decrease in AMPA concentration was observed at 60 days up to 349 mg kg−1 and 390 mg kg−1, respectively. These results suggested that soil autochthonous microorganisms and their interactions with a consortium have similar biotransformation of glyphosate, but the AMPA conversion to other intermedium metabolites through degradation was slow. A minimum AMPA concentration of 15–45 mg kg−1 over time was detected with the consortium. The microbiome analysis revealed shifts in microbial composition, with an increase in glyphosate-degrading genera like Psychrobacter and Lyzobacter. These changes enhance soil resilience and fertility, demonstrating the potential of airborne PGPB for bioremediation and environmental sustainability.