Mingzhu Huang

Mercury (Hg), a persistent, bioaccumulative, and highly toxic global pollutant, poses a severe threat to aquatic ecosystems and human health. In this study, we constructed a multifunctional remediation platform based on engineered Escherichia coli that integrates real-time Hg²⁺ monitoring, efficient adsorption, and magnetic recovery. First, a tandem mercury-binding peptide (CAACAACAAC) was anchored on the bacterial surface via cell surface display technology, which significantly enhanced the Hg²⁺ adsorption capacity to nearly twice that of the control strain. Second, a highly sensitive mercury biosensor was developed using a T7 RNA polymerase-based signal amplification cascade; the introduction of degradation tags enabled post-translational regulation of the fluorescent protein, T7 RNA polymerase, and MerR, allowing real‑time tracking of dynamic changes in mercury concentration. Co-expression of the adsorption and detection modules enabled the strain to perform simultaneous mercury adsorption and monitoring. Furthermore, amine-modified magnetic nanoparticles were crosslinked with the engineered bacteria to construct a magnetic complex (HG-GFP@MNP), achieving approximately 90% mercury removal and over 90% cell recovery in natural water bodies. Finally, ecological safety was assessed using the Pseudorasbora parva. After two rounds of treatment, mercury accumulation in various fish tissues was significantly reduced, and hepatic oxidative stress markers—including superoxide dismutase, catalase, glutathione reductase, glutathione S-transferase activities, and malondialdehyde content—returned to normal levels. This study provides a transferable technical strategy for the bioremediation of heavy metal pollution.

The majority of Aeromonas strains are opportunistic pathogens for both humans and animals, causing a variety of diseases and posing a considerable risk to their health. In the current study, triploid cyprinid fish (TCF) were infected with a novel pathogenic Aeromonas sp. AS1-4 for pathological analysis. TCFs receiving Aeromonas sp. AS1-4 challenge exhibited oxidative damage in the liver and spleen, along with significant changes in immune-related gene expressions. Metabolomics assay indicated that strain AS1-4 challenge may exhibit a significant impact on metabolic processes of amino acids, with methylsuccinic acid (MSA) identified as vital biomarker. Following that, three potential probiotics designated Enterobacter strains fkY27-2, fkY84-1 and fkY84-4 were isolated from the intestine of TCFs, displaying excellent safety characteristics. In addition, intestinal Enterobacter strains exhibited multiple probiotic traits, including high degrees of hydrophobic activity, aggregation performance, biofilm-forming activity (BFA) and nutrient decomposing ability. Moreover, these probiotic isolates markedly coaggregated with Aeromonas sp. AS1-4 and Edwardsiella tarda 1l-4 and then suppressed their pathogenic biofilm-forming abilities, along with possessing robust antioxidant potential against various free radicals. These findings may provide valuable insights into metabolic response in fish post infection and health management in aquaculture.

Heavy metal resistance mechanisms and heavy metal response genes are crucial for microbial utilization in heavy metal remediation. Here, Corynebacterium crenatum was proven to possess good tolerance in resistance to copper. Then, the transcriptomic responses to copper stress were investigated, and the vital pathways and genes involved in copper resistance of C. crenatum were determined. Based on transcriptome analysis results, a total of nine significantly upregulated DEGs related to metal ion transport were selected for further study. Among them, GY20_RS0100790 and GY20_RS0110535 belong to transcription factors, and GY20_RS0110270, GY20_RS0100790, and GY20_RS0110545 belong to copper-binding peptides. The two transcription factors were studied for the function of regulatory gene expression. The three copper-binding peptides were displayed on the C. crenatum surface for a copper adsorption test. Furthermore, the nine related metal ion transport genes were deleted to investigate the effect on growth in copper stress. This investigation provided the basis for utilizing C. crenatum in copper bioremediation.

Enzyme-linked immunosorbent assay (ELISA) is widely used in the routine screening of mycotoxin contamination in various agricultural and food products. Herein, a cascade-amplifying system was introduced to dramatically promote the sensitivity of an immunoassay for ochratoxin A (OTA) detection. Specifically, a biotinylated M13 bacteriophage was introduced as a biofunctional competing antigen, in which a seven-peptide OTA mimotope fused on the p3 protein of M13 was used to specifically recognize an anti-OTA monoclonal antibody, and the biotin molecules modified on capsid p8 proteins were used in loading numerous streptavidin-labeled polymeric horseradish peroxidases (HRPs). Owing to the abundance of biotinylated p8 proteins in M13 and the high molar ratio between HRP and streptavidin in streptavidin-polyHRP, the loading amount of HRP enzymes on the M13 bacteriophage were greatly boosted. Hence, the proposed method exhibited high sensitivity, with a limit of detection of 2.0 pg/mL for OTA detection, which was 250-fold lower than that of conventional ELISA. In addition, the proposed method showed a slight cross-reaction of 2.3% to OTB, a negligible cross-reaction for other common mycotoxins, and an acceptable accuracy for OTA quantitative detection in real corn samples. The practicability of the method was further confirmed with a traditional HRP-based ELISA method. In conclusion, the biotinylated bacteriophage and polyHRP structure showed potential as a cascade-amplifying enzyme loading system for ultra-trace OTA detemination, and its application can be extended to the detection of other analytes by altering specific mimic peptide sequences.

Objective: High variabilities in tacrolimus (TAC) exposure are still problems that confuse physicians. TAC trough levels (TAC C_min) fluctuated considerably after endoscopic retrograde cholangiopancreatography (ERCP) treatment in several liver transplant (LT) patients. We aimed to investigate the variation regularity of TAC C_min post-ERCP and related factors. Methods: This study was a retrospective, observational study conducted at the First Affiliated Hospital of Zhejiang University in China. From October 2017 to January 2019, 26 LT patients that received ERCP were included (73 TAC C_min measures). The absolute difference and the variation extent in TAC C_min pre- and post-ERCP were analyzed. Patients were divided into mild and obvious variation groups, and the differences were compared. Results: The TAC C_min in LT patients significantly increased in the first three days post-ERCP (p0.05). The daily TAC dose and total bile acid (TBA) level were significantly higher (pmin. The differences in other demographics, clinical characteristics, variation in laboratory data, and serum amylase levels between the two groups were not significant. Conclusion: The TAC C_min significantly increased in LT patients during the first three days after ERCP, and the level returned to baseline within a week. The daily TAC dose and TBA levels may be related to this increase. Frequent drug concentration monitoring should be executed in the early phase post-ERCP, especially in patients with related factors.