Enhanced biodegradation of microplastic and phthalic acid ester plasticizer: The role of gut microorganisms in black soldier fly larvae

Hermetia illucens larvae are recognized for their ability to mitigate or eliminate contaminants by biodegradation. However, the biodegradation characteristics of microplastics and phthalic acid esters plasticizers, as well as the role of larval gut microorganisms, have remained largely unrevealed. Here, the degradation kinetics of plasticizers, and biodegradation characteristics of microplastics were examined. The role of larval gut microorganisms was investigated. For larval development, microplastics slowed larval growth significantly (P < 0.01), but the effect of plasticizer was not significant. The degradation kinetics of plasticizers were enhanced, resulting in an 8.11 to 20.41-fold decrease in degradation half-life and a 3.34 to 3.82-fold increase in final degradation efficiencies, compared to degradation without larval participation. The depolymerization and biodeterioration of microplastics were conspicuously evident, primarily through a weight loss of 17.63 %-25.52 %, variation of chemical composition and structure, bio-oxidation and bioerosion of microplastic surface. The synergistic effect driven by larval gut microorganisms, each with various functions, facilitated the biodegradation. Specifically, Ignatzschineria, Paenalcaligenes, Moheibacter, Morganella, Dysgonomonas, Stenotrophomonas, Bacteroides, Sphingobacterium, etc., appeared to be the key contributors, owing to their xenobiotic biodegradation and metabolism functions. These findings offered a new perspective on the potential for microplastics and plasticizers biodegradation, assisted by larval gut microbiota.