Relative to a common phthalate, citrate-based plasticizers exert minimal impact on soil bacterial community composition Raw sequence reads

Citrate-based plasticizers are often regarded as being less environmentally harmful alternatives to phthalate-based plasticizers like dibutyl phthalate (DBP). Here, we tested these assertions by investigating the impacts of acetyl tributyl citrate (ATBC) and triethyl citrate (TEC) relative to DBP on soil bacterial and fungal communities - which were used as indicators of environmental health due to their critical roles in ecosystem function. Biopolymer pieces with and without plasticizers were incubated (i.e., buried) in soil, and after 14 weeks, the bacterial and fungal biomass and community diversity on the biopolymer, attached soil and bulk soil was characterized using metabarcoding and quantitative PCR. Differences between incubated and non-incubated biopolymer samples were also analyzed using X-ray micro-computed tomography, gel permeation chromatography and 1H-nuclear magnetic resonance spectroscopy to assess biopolymer degradation and plasticizer migration. Surface degradation and plasticizer migration were observed for all treatments, with minor impacts of plasticizers on microbial biomass and diversity. Critically, however, biopolymer-associated bacterial communities formed two groups that were compositionally distinct. One group comprised the DBP samples while the other comprised the control, ATBC and TEC samples. This indicated that DBP impacts soil bacterial community composition, with potential consequences for ecosystem function, while the effects of the citrate-based plasticizers were negligible, supporting their use as less environmentally impactful alternatives to phthalates.