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Gut digestion by earthworms (GDE) is a crucial step in vermicomposting, affecting the fate of antibiotic resistance genes (ARGs) in vermicompost sludge. The extracellular polymeric substance (EPS) matrix of sludge is an important space for ARG transfer. However, the effect of GDE on EPS-associated ARGs remains unclear. Therefore, this study explored the role of GDE in driving the transfer of ARGs within different EPS layers in sludge. For this, the changes in intracellular ARGs and EPS-associated ARGs in sludge were analyzed after 5 days of the GDE process. The results showed that after the GDE process, both nitrate and dissolved organic carbon significantly increased in all EPS layers of sludge, while the proteins and polysaccharides only enhanced in soluble and loosely bound EPS of sludge. In addition, a 7.0% decrease in bacterial diversity was recorded after the GDE process, with a functional bacterial community structure emerging. Moreover, the absolute abundance of total ARGs and mobile genetic elements decreased by 90.71% and 61.83%, respectively, after the GDE process. Intracellular ARGs decreased by 92.1%, while EPS-associated ARGs increased by 4.9%, indicative of intracellular ARG translocation into the EPS during the GDE process. Notably, the ARGs exhibited significant enrichment in both the soluble and loosely bound EPS, whereas they were reduced in the tightly bound EPS. The structural equation modeling revealed that the GDE process effectively mitigated the ARG dissemination risk by modulating both the EPS structure and microenvironment, with the organic structure representing a primary factor influencing ARGs in the EPS. [Display omitted] • Nitrate and DOC increased in all EPS layers of sludge after GDE process. • Extracellular free DNA increased in out layer of EPS after GDE process. • GDE reduced absolute abundance of intracellular ARGs in sludge. • ARGs and MGEs mainly enriched in SEPS and LB-EPS of earthworm castings. • EPS structure was correlated with ARGs distribution and diversity in GDE process. [ABSTRACT FROM AUTHOR]

H 2 O 2 usually develops after implanting an implant of biomedical material in human body. Our study showed that H 2 O 2 has dual effects on degradation behaviour of biomedical material depending on its concentration. As for a SLMed CoCrMo alloy, a critical concentration of H 2 O 2 exists, below which the corrosion potential shifts positively as the concentration increases, facilitating the passive film formation; and above which, the film becomes less protective due to the change in composition of the film. The corrosion resistance of XOZ plane of the alloy is better than that of XOY plane due to less grain boundaries and secondary precipitates. • A critical concentration of H 2 O 2 exists, below which the formation of passive film was facilitated with increasing concentration, and above which the change of passive film composition results in lower corrosion resistance. • The passive film formed in 9 g/L NaCl + 30 mM H 2 O 2 mainly consist of oxide/hydroxide of Co, which is less protective than Cr 2 O 3 formed in solutions without H 2 O 2. • Corrosion resistance of XOZ plane of the tested SLMed CoCrMo alloy is larger than that of XOY plane due to less grain boundaries and secondary precipitates. [ABSTRACT FROM AUTHOR]