Gut microbiome of mealworms (Tenebrio molitor Larvae) show similar responses to polystyrene and corn straw diets

Abstract

Background Some insects can degrade both natural and synthetic plastic polymers, their host and gut microbes play crucial roles in this process. However, there is still a scientific gap in understanding how the insect adapted to the polystyrene (PS) diet from natural feed. In this study, we analyzed diet consumption, gut microbiota responses, and metabolic pathways of Tenebrio molitor larvae exposed to PS and corn straw (CS). Results T. molitor larvae were incubated under controlled conditions (25 ± 1 °C, 75 ± 5% humidity) for 30 days by using PS foam with weight-, number-, and size-average molecular weight (Mw, Mn, and Mz) of 120.0, 73.2, and 150.7 kDa as a diet, respectively. The larvae exhibited lower PS consumption (32.5%) than CS (52.0%), and these diets had no adverse effects on their survival. The gut microbiota structures, metabolic pathways, and enzymatic profiles of PS- and CS-fed larvae showed similar responses. The gut microbiota of larvae analysis indicated Serratia sp., Staphylococcus sp., and Rhodococcus sp. were associated with both PS and CS diets. Metatranscriptomic analysis revealed that xenobiotics, aromatic compounds, and fatty acid degradation pathways were enriched in PS- and CS-fed groups; laccase-like multicopper oxidases, cytochrome P450, monooxygenase, superoxidase, and dehydrogenase were involved in lignin and PS degradation. Furthermore, the upregulated gene lac640 in both PS- and CS-fed groups was overexpressed in E. coli and exhibited PS and lignin degradation ability. Conclusions The high similarity of gut microbiomes adapted to biodegradation of PS and CS indicated the plastics-degrading ability of the T. molitor larvae originated through an ancient mechanism that degrades the natural lignocellulose. Graphical Abstract

Molecular-Weight-Dependent Degradation of Plastics: Deciphering Host–Microbiome Synergy Biodegradation of High-Purity Polypropylene Microplastics by Mealworms

“…This suggests that the ability of T. molitor to degrade PP can be traced back to its ability to degrade natural lignocellulosic polymers. ,, …”

“…This suggests that the ability of T. molitor to degrade PP can be traced back to its ability to degrade natural lignocellulosic polymers. 31,32,67 Functional Prediction of the Gut Microbial Communities. Functional prediction by PICRUSt analysis revealed a higher abundance of specific enzymes, i.e., alkane-1-monooxygenase, carboxylesterase, cutinase, and dehydrogenase in PP-fed larvae compared to those fed with WB (control) (Figure 3a−f).…”

“…Among these, T. molitor larvae have been extensively studied for their ability to degrade a wide range of materials, including wood residues in the environment, lignocellulosic agricultural residues, , and various plastics including polystyrene (PS), − ,− low-density polyethylene (LDPE) and high-density polyethylene (HDPE), ,,, polyvinyl chloride (PVC), polyethylene terephthalate (PET), polyurethane (PUR), polylactic acids (PLA), and even rubber and graphene oxide . Our previous study first confirmed the biodegradation of commercial PP foam by the larvae of T.…”

“…6,7 Recent researchers have identified certain macroinvertebrates capable of biodegrading major plastics, 8 such as insect larvae belonging to darkling beetles (Coleoptera: Tenebrionidae) including Tenebrio molitor (T. molitor), 9−13 Tenebrio obscurus, 14 Zophobas atratus, 15,16 Uloma sp., 17 and Plesiophthalmus davidis; 18 pyralid moths (Lepidoptera: Pyralidae) including Plodia interpunctella, 19,20 Galleria mellonella, 21−27 and Achroia grisella; 28 as well as other macroinvertebrates e.g., land snails Achatina Fulica. 29 Among these, T. molitor larvae have been extensively studied for their ability to degrade a wide range of materials, including wood residues in the environment, 30 lignocellulosic agricultural residues, 31,32 and various plastics including polystyrene (PS), 7−9,31−35 low-density polyethylene (LDPE) and high-density polyethylene (HDPE), 12,15,36,37 polyvinyl chloride (PVC), 15 polyethylene terephthalate (PET), 38 polyurethane (PUR), 39 polylactic acids (PLA), 40 and even rubber 41 and graphene oxide. 42 first confirmed the biodegradation of commercial PP foam by the larvae of T. molitor and Z. atratus.…”

Comparative Metagenomics Provide Mechanistic Insights into the Biodegradation of the Non-hydrolysable Plastic Polyvinyl Chloride in Gut Microbiota of Insect Larvae

“…While various strains of fungi (e.g., White Rot Fungi 9 and Phanerochaete chrysosporium 10 ) and bacteria (e.g., Pseudomonas citronellolis and Bacillus flexus 11,12 ) have been identified, most studies have primiarily reported the morphological and physicochemical changes of PVC plastic (e.g., weight loss and molecular weight). Notably, many studies have demonstated the ccapacity of insect gut microbiota to biodegrade plastics, including PS 13,14 , PET 15 , PVC 16,17 . However, little is known about the PVC-degrading genes and enzymes within these degrading strains or microbial communities 18 .…”