The complex interactions between novel DEHP-metabolising bacteria and the microbes in agricultural soils

The indigenous microorganisms with the ability of metabolising di-(2-ethylhexyl) phthalate (DEHP) in agricultural soils and their interactions with non-degrading microbes were revealed by DNA-based stable isotope probing coupled with molecular ecological network. Aside from the previously reported DEHP degraders (family Planococcaceae and genus Sphingobacterium), five OTUs representing bacteria affiliated with genus Brevundimona, class Spartobacteria, genus Singulisphaera, genus Dyella and class Ktedonobacteria were linked with DEHP biodegradation. The analysis of the constructed ecological network based on soil microbial communities demonstrated the negative relationships between DEHP degraders and the dominant family Oxalobacteraceae in soils. Additionally, two cultivable bacteria isolated from the same soils, Rhizobium-1 and Ensifer-1, had strong capabilities in degrading DEHP but their involvement in in situ DEHP degradation was questioned, as their DNA was not labelled with ¹³C from DEHP. These findings provide deeper understanding on the indigenous DEHP-degrading communities and will benefit the remediation of phthalate esters contaminated soils.