Soil-dwelling grub larvae of Protaetia brevitarsis biodegrade polystyrene: Responses of gut microbiome and host metabolism.

Plastic pollution poses a significant threat to terrestrial ecosystems, yet the potential for soil fauna to contribute to plastic biodegradation remains largely unexplored. In this study, we reveal that soil-dwelling grubs, Protaetia brevitarsis larvae, can effectively biodegrade polystyrene (PS) plastics. Over a period of 4 weeks, these grubs achieved a remarkable 61.5 % reduction in PS foam mass. This biodegradation was confirmed by the depolymerization of ingested PS, formation of oxidative functional groups, noticeable chemical modifications, and an increase of δ13C of residual PS in frass. Additionally, antibiotic treatment to suppress gut microbes led to variations in the biodegradation process. PS ingestion induced a significant shift in the gut microbiome, promoting the growth of degradation-related bacteria such as Promicromonosporaceae, Bacillaceae, and Paenibacillaceae. Furthermore, the digestion of plastic triggered extensive metabolomic reprogramming of grubs' intestines, enhancing redox capabilities and facilitating PS biodegradation. These results indicate that responsive adaptation of both the gut microbiome and the host's intestinal metabolism contributes to PS degradation. Collectively, these findings demonstrate P. brevitarsis larvae's capability to alleviate soil plastic pollution, and highlight the potential of researching soil fauna further for sustainable plastic waste management solutions.

Emerging infectious diseases and new pandemics: dancing with a ghost! Lessons in inter- and transdisciplinary research in French Guiana, South America.

In light of current international public health challenges, calls for inter- and transdisciplinary research are increasing, particularly in response to complex and intersecting issues. Although widely used under the One Health flag, it is still unclear how inter- and transdisciplinary science should be applied to infectious disease research, public health, and the different stakeholders. Here, we present and discuss our common scientific and biomedical experience in French Guiana, South America to conduct and enrich research in vector-borne and zoonotic infectious diseases, with the aim to translate findings to public health and political stakeholders. We highlight the successful progressive dissolution of disciplinary boundaries that go beyond One Health positive-driven assumptions and argue that specific local conditions, as well as strong support from research and medical institutions, have facilitated an emulsion toward inter- and transdisciplinary science. This argument is intended to improve responses to public health concerns in French Guiana and other countries and regions of the world.

Linking the Mycobacterium ulcerans environment to Buruli ulcer disease: Progress and challenges.

Buruli ulcer (BU), the second most common mycobacterial disease in West Africa, is a necrotizing skin disease that can lead to high morbidity in affected patients. The disease is caused by Mycobacterium ulcerans (MU), whose major virulence factor is mycolactone. Although early infection can be treated with antibiotics, an effective preventative strategy is challenging due to unknown reservoir(s) and unresolved mode(s) of transmission. Further, disease occurrence in remote locations with limited access to health facilities further complicates disease burden and associated costs. We discuss here MU transmission hypotheses and investigations into environmental reservoirs and discuss successes and challenges of studying MU and Buruli ulcer across human, animal, and environmental interfaces. We argue that a One Health approach is needed to advance the understanding of MU transmission and designing management scenarios that prevent and respond to epidemics. Although previous work has provided significant insights into risk factors, epidemiology and clinical perspectives of disease, understanding the bacterial ecology, environmental niches and role of mycolactone in natural environments and during infection of the human host remains equally important to better understanding and preventing this mysterious disease.

Cold Case Experiment Demonstrates the Potential Utility of Aquatic Microbial Community Assembly in Estimating a Postmortem Submersion Interval.

Microbial community assembly (MCA) of both human and nonhuman animal carcasses provides indicators useful for estimating the postmortem interval (PMI) in terrestrial settings. However, there are fewer studies estimating postmortem submersion intervals (PMSIs) in aquatic habitats. No aquatic studies to date assessed MCA in the context of a death investigation, with all previous studies focusing on important basic ecological questions. Within the context of a cold case investigation, we performed an experiment using replicate adult swine carcasses to describe postmortem MCA variability within a nonflowing aquatic habitat. Using high-throughput sequencing of carcass postmortem microbiomes, we described MCA variability and identified key taxa associated with decomposition in an aquatic habitat similar to the cold case body recovery site. We also modeled key taxa for estimating PMSIs, modeling within ±3 days (mean square error) postmortem using random forest regression. Our findings show significant changes in microbial communities as decomposition progressed, and several taxa were identified as important indicator taxa which may be useful for future estimates of PMSI. While descriptive, this study provides initial findings quantifying MCA variability within a nonflowing aquatic habitat. Within the context of the cold case investigation, we discuss how postmortem microbial samples collected at the time of body recovery could have been an important piece of evidence for understanding the PMSI of recovered remains. Additional experimental studies are needed to explicitly test and identify mechanisms associated with postmortem MCA variability in other habitats and under different temperature (e.g., seasons) conditions.

Biodegradation of Polystyrene by Dark ( Tenebrio obscurus) and Yellow ( Tenebrio molitor) Mealworms (Coleoptera: Tenebrionidae).

Yellow mealworms (larvae of Tenebrio molitor, Coleoptera: Tenebrionidae) have been proven to be capable of biodegrading polystyrene (PS) products. Using four geographic sources, we found that dark mealworms (larvae of Tenebrio obscurus) ate PS as well. We subsequently tested T. obscurus from Shandong, China for PS degradation capability. Our results demonstrated the ability for PS degradation within the gut of T. obscurus at greater rates than T. molitor. With expanded PS foam as the sole diet, the specific PS consumption rates for T. obscurus and T. molitor at similar sizes (2.0 cm, 62-64 mg per larva) were 32.44 ± 0.51 and 24.30 ± 1.34 mg 100 larvae-1 d-1, respectively. After 31 days, the molecular weight ( Mn) of residual PS in frass (excrement) of T. obscurus decreased by 26.03%, remarkably higher than that of T. molitor (11.67%). Fourier transform infrared spectroscopy (FTIR) indicated formation of functional groups of intermediates and chemical modification. Thermo gravimetric analysis (TGA) suggested that T. obscurus larvae degraded PS effectively based on the proportion of PS residue. Co-fed corn flour to T. obscurus and wheat bran to T. molitor increased total PS consumption by 11.6% and 15.2%, respectively. Antibiotic gentamicin almost completely inhibited PS depolymerization. High-throughput sequencing revealed significant shifts in the gut microbial community in both Tenebrio species that were associated with the PS diet and PS biodegradation, with changes in three predominant families (Enterobacteriaceae, Spiroplasmataceae, and Enterococcaceae). The results indicate that PS biodegradability may be ubiquitous within the Tenebrio genus which could provide a bioresource for plastic waste biodegradation.

Ubiquity of polystyrene digestion and biodegradation within yellow mealworms, larvae of Tenebrio molitor Linnaeus (Coleoptera: Tenebrionidae).

Academics researchers and "citizen scientists" from 22 countries confirmed that yellow mealworms, the larvae of Tenebrio molitor Linnaeus, can survive by eating polystyrene (PS) foam. More detailed assessments of this capability for mealworms were carried out by12 sources: five from the USA, six from China, and one from Northern Ireland. All of these mealworms digested PS foam. PS mass decreased and depolymerization was observed, with appearance of lower molecular weight residuals and functional groups indicative of oxidative transformations in extracts from the frass (insect excrement). An addition of gentamycin (30 mg g-1), a bactericidal antibiotic, inhibited depolymerization, implicating the gut microbiome in the biodegradation process. Microbial community analyses demonstrated significant taxonomic shifts for mealworms fed diets of PS plus bran and PS alone. The results indicate that mealworms from diverse locations eat and metabolize PS and support the hypothesis that this capacity is independent of the geographic origin of the mealworms, and is likely ubiquitous to members of this species.

Microbial Biofilm Community Variation in Flowing Habitats: Potential Utility as Bioindicators of Postmortem Submersion Intervals.

Biofilms are a ubiquitous formation of microbial communities found on surfaces in aqueous environments. These structures have been investigated as biomonitoring indicators for stream heath, and here were used for the potential use in forensic sciences. Biofilm successional development has been proposed as a method to determine the postmortem submersion interval (PMSI) of remains because there are no standard methods for estimating the PMSI and biofilms are ubiquitous in aquatic habitats. We sought to compare the development of epinecrotic (biofilms on Sus scrofa domesticus carcasses) and epilithic (biofilms on unglazed ceramic tiles) communities in two small streams using bacterial automated ribosomal intergenic spacer analysis. Epinecrotic communities were significantly different from epilithic communities even though environmental factors associated with each stream location also had a significant influence on biofilm structure. All communities at both locations exhibited significant succession suggesting that changing communities throughout time is a general characteristic of stream biofilm communities. The implications resulting from this work are that epinecrotic communities have distinctive shifts at the first and second weeks, and therefore the potential to be used in forensic applications by associating successional changes with submersion time to estimate a PMSI. The influence of environmental factors, however, indicates the lack of a successional pattern with the same organisms and a focus on functional diversity may be more applicable in a forensic context.

Larval development rates of Chrysomya rufifacies Macquart, 1842 (Diptera: Calliphoridae) within its native range in South-East Asia.

Chrysomya rufifacies represents an important indicator species in forensic entomology that is often used to estimate the minimum postmortem interval (PMImin) in crime scene investigation. However, developmental rates differ locally, so that estimates should be based on regionally generated development data. Therefore, we determined the developmental rates of C. rufifacies within its native range in Thailand under nine constant temperature regimes: 15, 18, 21, 24, 27, 30, 33, 36 and 39°C. Developmental times from egg to adult varied among the temperatures and were longest at 15°C (618h) and shortest at 33°C (168h). No pupae emerged at 39°C. We used linear regression models to estimate the minimum development threshold temperatures for each life stage: egg stage=9.5°C, first to second instar=10.8°C, second to third instar=11.5°C, third instar to pupariation=11.4°C, pupariation to adults=5.0°C; the minimum threshold to complete all larvae stages was 11.1°C and to complete all life stages from eggs to adult was 9.5°C. We further generated isomorphen and isomegalen diagrams that can be used to quickly estimate the PMImin for forensic applications.

The Potential of High-throughput Metagenomic Sequencing of Aquatic Bacterial Communities to Estimate the Postmortem Submersion Interval.

Human remains can be discovered in freshwater or marine ecosystems, circumstances where insects and other invertebrates have infrequently been used for understanding the time of postmortem submersion. In this study, the identification and succession of epinecrotic bacterial communities on vertebrate remains were described during decomposition in a temperate headwater stream during two seasons (summer and winter). Bacterial communities were characterized with 454 pyrosequencing and analyzed at phyletic and generic taxonomic resolutions. There was a significant increase in genera richness over decomposition during both seasons. Additionally, multivariate statistical modeling revealed significant differences in bacterial communities between seasons at both taxonomic resolutions and siginificant genera differences among sampling days within each season, suggesting a succession of these communities. These data are the first to describe aquatic bacterial succession using high-throughput metagenomic sequencing on vertebrate remains submerged in a freshwater habitat, and provide initial evidence for their potential use in forensic investigations.

Fish and amphibians as potential reservoirs of Mycobacterium ulcerans, the causative agent of Buruli ulcer disease.

BACKGROUND: Buruli ulcer is a skin disease often associated with proximity to certain water bodies in Africa. Much remains unknown about the reservoir and transmission of this disease. Previous studies have suggested that fish may concentrate Mycobacterium ulcerans, the etiological agent of the disease, in their gills and intestines and serve as passive reservoirs of the bacterium. The objective of this study was to test the hypothesis that fish and amphibians serve as natural reservoirs of M. ulcerans or other closely related mycolactone-producing mycobacteria. METHODS: Polymerase chain reaction targeting the enoyl reductase (ER) domain present in mlsA, which is required for mycolactone production, was used to screen water, fish, and amphibians from water bodies in Ghana for the presence of mycolactone-producing mycobacteria, and positive specimens were subjected to variable number tandem repeat (VNTR) typing. RESULTS: The use of VNTR typing revealed the presence of Mycobacterium liflandii in a tadpole and a fish, and M. ulcerans in an adult frog. Similarity percentage analysis (SIMPER) showed that the predatory cichlid Hemichromis bimaculatus was associated with ER-positive water bodies. No amphibian species or fish-feeding guild served as a reliable indicator of the presence of mycolactone-producing mycobacteria in a water body, and there was no significant difference between fish and amphibian positivity rates (P-value=0.106). There was a significant difference between water bodies in the total number of ER-positive specimens (P-value=0.0164). CONCLUSIONS: Although IS2404-positive tadpoles and fish have been reported, this is the first VNTR confirmation of M. ulcerans or M. liflandii in wild amphibian and fish populations in West Africa. Results from this study suggest that amphibians should be carefully examined as potential reservoirs for M. ulcerans in West Africa, and that H. bimaculatus may be useful as an indicator of habitats likely to support mycolactone-producing mycobacteria.

Evaluation of VNTR typing for the identification of Mycobacterium ulcerans in environmental samples from Victoria, Australia.

Reliable molecular detection of Mycobacterium ulcerans in environmental samples is essential to study the ecology and transmission of this important human pathogen. Variable number tandem repeat (VNTR) typing is a valuable method for distinguishing M. ulcerans isolates from different geographic regions and for distinguishing M. ulcerans from other members of the Mycobacterium marinum/M. ulcerans complex, but its application to environmental samples has not yet been evaluated systematically. This study compares the sensitivity and specificity of PCR detection of 13 VNTR loci to determine the best loci for the analysis of environmental samples. This study demonstrates that VNTR typing using selected loci can be a useful addition to established molecular methods for detecting M. ulcerans in the environment and highlights some of the issues encountered when using molecular methods to detect microorganisms in environmental samples. When applied to environmental samples collected from an endemic region in Victoria, Australia, VNTR typing confirmed that the strain of M. ulcerans being detected was indistinguishable from the strain causing disease in humans in that region.