Synergistic impacts of antibiotics and heavy metals on Hermetia illucens: Unveiling dynamics in larval gut bacterial communities and microbial metabolites.

Hermetia illucens larvae showcases remarkable bioremediation capabilities for both antibiotics and heavy metal contaminants. However, the distinctions in larval intestinal microbiota arising from the single and combined effects of antibiotics and heavy metals remain poorly elucidated. In this study, we delved into the details of larval intestinal bacterial communities and microbial metabolites when exposed to single and combined contaminants of oxytetracycline (OTC) and hexavalent chromium (Cr(VI)). After conversion, single contaminant-spiked substrate showed 75.5% of OTC degradation and 95.2% of Cr(VI) reductiuon, while combined contaminant-spiked substrate exhibited 71.3% of OTC degradation and 93.4% of Cr(VI) reductiuon. Single and combined effects led to differences in intestinal bacterial communities, mainly reflected in the genera of Enterococcus, Pseudogracilibacillus, Gracilibacillus, Wohlfahrtiimonas, Sporosarcina, Lysinibacillus, and Myroide. Moreover, these effects also induced differences across various categories of microbial metabolites, which categorized into amino acid and its metabolites, benzene and substituted derivatives, carbohydrates and its metabolites, heterocyclic compounds, hormones and hormone-related compounds, nucleotide and its metabolites, and organic acid and its derivatives. In particular, the differences induced OTC was greater than that of Cr(VI), and combined effects increased the complexity of microbial metabolism compared to that of single contaminant. Correlation analysis indicated that the bacterial genera, Preudogracilibacillus, Enterococcus, Sporosarcina, Lysinibacillus, Wohlfahrtiimonas, Ignatzschineria, and Fusobacterium exhibited significant correlation with significant differential metabolites, these might be used as indicators for the resistance and bioremediation of OTC and Cr(VI) contaminants. These findings are conducive to further understanding that the metabolism of intestinal microbiota determines the resistance of Hermetia illucens to antibiotics and heavy metals.

Chirality Interplay between the Interior and Exterior of Metal-Organic Cages.

A series of metal-organic cages featuring two stereogenic elements, in terms of the twisting of amide moieties within the ligand backbones and the rotation of diazaanthracene segments along the ligand ridges, were exploited. These two chiral components are correlative and serve as relays for transmitting chirality information between the internal and external cages. The chirality information induced by a chiral guest inside the cage cavity can pass through the cage framework and influence the orientation of the diazaanthracene segments on the periphery of the cage. In turn, the chirality of a stereogenic center within the diazaanthracene segments can transfer back into the cavity, enabling discrimination of enantiomeric guests.

The enhanced degradation behavior of oxytetracycline by black soldier fly larvae with tetracycline resistance genes in the larval gut: Kinetic process and mechanism.

Black soldier fly larvae (larvae) can digest organic wastes and degrade contaminants such as oxytetracycline (OTC). However, compared to the kinetic processes and enhanced mechanisms used in the traditional microbial degradation of OTC, those employed by larvae are largely uncharacterized. To obtain further details, a combined analysis of larval development, larval nutritional values (crude protein, crude fat and the composition of fatty acids) and the expression of tetracycline resistance genes (TRGs) in the larval gut was performed for the degradation of OTC added to substrates and for oxytetracycline bacterial residue (OBR). When the larvae were exposed to the substrates, the degradation processes were enhanced significantly (P < 0.01), with a 4.74-7.86-fold decrease in the degradation half-life (day-1) and a 3.34-5.74-fold increase in the final degradation efficiencies. This result was attributed to the abundant TRGs (with a detection rate of 35.90%∼52.14%) in the larval gut. The TRGs presented the resistance mechanisms of cellular protection and efflux pumps, which ensured that the larvae could tolerate elevated OTC concentrations. Investigation of the TRGs indicated that enzymatic inactivation enhanced OTC degradation by larvae. These findings demonstrate that the larval degradation of antibiotic contaminants is an efficient method based on abundant TRGs in the larval gut, even though OTC degradation results in OBR. In addition, a more optimized system for higher reductions in antibiotic levels and the expansion of larval bioremediation to other fields is necessary.

The underlying mechanisms of oxytetracycline degradation mediated by gut microbial proteins and metabolites in Hermetia illucens.

Hermetia illucens larvae can enhance the degradation of oxytetracycline (OTC) through its biotransformation. However, the underlying mechanisms mediated by gut metabolites and proteins are unclear. To gain further insights, the kinetics of OTC degradation, the functional structures of gut bacterial communities, proteins, and metabolites were investigated. An availability-adjusted first-order model effectively evaluated OTC degradation kinetics, with degradation half-lives of 4.18 and 21.71 days for OTC degradation with and without larval biotransformation, respectively. Dominant bacteria in the larval guts were Enterococcus, Psychrobacter, Providencia, Myroides, Enterobacteriaceae, and Lactobacillales. OTC exposure led to significant differential expression of proteins, with functional classification revealing involvement in digestion, transformation, and adaptability to environmental stress. Upregulated proteins, such as aromatic ring hydroxylase, acted as oxidoreductases modifying the chemical structure of OTC. Unique metabolites, aclarubicin and sancycline identified were possible OTC metabolic intermediates. Correlation analysis revealed significant interdependence between gut bacteria, metabolites, and proteins. These findings reveal a synergistic mechanism involving gut microbial metabolism and enzyme structure that drives the rapid degradation of OTC and facilitates the engineering applications of bioremediation.

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.

Zinc, sulfur and nitrogen co-doped carbon from sodium chloride/zinc chloride-assisted pyrolysis of thiourea/sucrose for highly efficient oxygen reduction reaction in both acidic and alkaline media.

Zn and N co-doped carbon (Zn-N-C) shows encouraging catalytic stability for oxygen reduction reaction (ORR) because of the fulfilled d orbital of Zn, but its catalytic activity is not satisfactory. Herein, hierarchically porous Zn, S and N co-doped carbon (Zn-S-N-C) with large specific surface area (2433 m2 g-1) and pore volume (3.007 cm3 g-1) is synthesized by using NaCl/ZnCl2-assisted pyrolysis of sucrose and thiourea. The Zn-S-N-C catalyst exhibits superior ORR activity with half-wave potentials (E1/2) up to 0.774 V in 0.1 M HClO4 and 0.894 V in 0.1 M KOH, good ORR stability with 19- and 4-mV loss in E1/2 values after 10,000 potential cycles in 0.1 M HClO4 and 0.1 M KOH, respectively, and excellent methanol tolerance. The good ORR performance of Zn-S-N-C can be attributed to its enhanced intrinsic ORR activity resulting from the formation of S, N doped carbon and ZnS in Zn-S-N-C, its hierarchically porous structure resulting from the pore-forming roles played by ZnCl2, NaCl and thiourea, and its improved graphitization degree resulting from the added ZnCl2 during Zn-S-N-C synthesis. This work will provide a novel strategy for the synthesis of hierarchically porous Zn, S and N co-doped carbon materials for ORR.

A ZIF-derived hierarchically porous Fe-Zn-N-C catalyst synthesized via a two-stage pyrolysis for the highly efficient oxygen reduction reaction in both acidic and alkaline media.

A ZIF-derived Fe-Zn-N-C catalyst with sufficient exposure of bimetallic active sites and well-balanced micro/mesopores is synthesized by a two-stage pyrolysis process and exhibits superior oxygen reduction activity with high half-wave potentials of up to 0.819 V in 0.1 M HClO4 and 0.918 V in 0.1 M KOH.