Study On Degradation Of Plastics Polymers By Intestinal Microbes Of Zophobas Morio And Tenebrio Molitor

Polyolefin is a type of plastic that is widely used in daily life.Polyolefin is difficult to be degraded due to its stable structure.At present,the main degradation methods are thermal degradation,photodegradation in natural environment and biological degradation.Due to the high cost and long time spent on thermal degradation and photodegradation.Therefore,the study of biodegradable polyolefin is of great significance.Studies have confirmed that yellow mealworms(Tenebrio molitor)and insect-super mealworms(Zophobas morio)have a certain depolymerization ability to some plastic polymers.Polystyrene(PS)and polyethylene(PE)are the two most widely used plastics in polyolefin plastics.In this study,PS and PE were used as experimental materials to explore the ability of T.molitor and Z.morio to depolymerize and biodegrade polyolefin plastics,and to analyze the changes of PS and PE after passing through the intestinal tract of T.molitor and Z.morio through various chemical analysis methods.Illumina Mi Seq high-throughput sequencing analysis of the role of gut microbes in the degradation process of T.molitor and Z.morio.The main contents and conclusions are as follows:(1)By setting different feeding conditions,the survival rates of T.molitor and Z.morio during the experiment were determined.The T.molitor consumed both PS and PE over a 60 day.The Z.morio consumed PS over a 50 day but not eat PE at all.(2)Fourier transform infrared spectroscopy and thermogravimetric analyses of frass confirmed the formation of new oxygen-containing functional groups,and the change in physical property and chemical modification,indicating that biodegradation of PS and PE occurred.Hydrogen spectroscopy(1H-NMR)confirmed that the structure of PS changed after passing through the intestines of Z.morio.Gel permeationchromatography analysis confirmed broad depolymerization of PS and PE-1 i.e.decrease in both Mw and Mn but revealed limited-depolymerization of PE-2 i.e.increase in Mn and decrease in Mw.This indicates that Z.morio and T.molitor are extensively biodegradable to PS,while T.molitor is selective to degrade PE.(3)Illumina Mi Seq high-throughput sequencing analysis of intestinal microbial community structure of T.molitor and Z.morio.The study found that the intestinal flora of T.molitor and Z.morio showed significant differences under different feeding conditions.Using PS as the sole carbon source,a 90-day in vitro culture experiment was carried out on Z.morio intestinal microorganisms.Illumina Mi Seq high-throughput sequencing showed that the intestinal flora with PS degradation function was found to be significantly enriched.(4)Using PS and PE as the sole carbon source,8 strains of intestinal degrading bacteria with PS or PE as the sole carbon source were initially isolated from the intestinal tract of T.molitor.In summary,both Z.morio and T.molitor can degrade PS,and Z.morio have a stronger ability to bite PS.This study not only proved that intestinal bacteria played an essential role in the degradation of PS and PE by Z.morio and T.molitor but also provided new theoretical basis and application ideas for the biodegradation of PS.