Bioaugmentation of a Biobed Packing Material with an iprodione-degrading Bacterial Consortium Enhances the Dissipation of Iprodione and Mitigates Adverse Effects on the Microbiota

Iprodione (IPR) is a common contaminant of natural water resources. On-farm biopurification systems (BPS) like biobeds can degrade pesticides and prevent point source contamination. In cases of toxic or mobile chemicals like IPR, inoculation of biobed packing material (BPM) with specialized pesticide-degrading microorganisms can enhance BPS performance. Still, little is known about the efficiency of bioaugmentation against IPR and its effects on the BPM microbiota. We hypothesized that adding an IPR-degrading bacterial consortium (BC) in a BPS will enhance the transformation of IPR and its derivatives and alleviate their adverse impact on the BPM microbiota. We measured the transformation of IPR in BPM inoculated (BPM + IPR + BC) or not inoculated (BPM + IPR) with an IPR-degrading BC. Furthermore, the effects of IPR on the activity of key soil microbial enzymes and on the abundance of total bacteria, fungi, and specific bacterial taxa were determined in the above treatments compared with a control (BPM). BPM bioaugmentation accelerated IPR degradation in BPM + IPR + BC (t1/2: 4.3 d) compared to BPM + IPR (t1/2: 9.1 d). Accordingly, significantly lower enzymatic activities and abundances of total fungi, total bacteria, Pseudomonadota, Actimycetota, and Bacillota were evident in the first 14 days in BPM + IPR compared to BPM and BPM + IPR + BC. However, the effects were transient, and recovery was observed thereafter. Bioaugmentation of BPM with an IPR-degrading BC accelerated the dissipation of IPR and its derivatives and led to mitigation of the toxicity of IPR to the activity and abundance of the BPM microbiota.