Mercury (Hg)-contaminated soil poses a significant threat to the environment and human health. Hg-resistant microorganisms have the ability to survive under the stress of inorganic and organic Hg and effectively reduce Hg levels and toxicity. Compared to physical and chemical remediation methods, microbial remediation technologies have garnered increasing attention in recent years due to their lower cost, remarkable efficacy, and minimal environmental impact. This paper systematically elucidates the molecular mechanisms of Hg resistance in microbes, with a focus on their potential applications in phytoremediation of Hg-contaminated soils through plant-microbe interactions. Furthermore, it highlights the critical role of microbes in enhancing the effectiveness of transgenic plants for Hg remediation, aiming to provide a theoretical foundation and scientific basis for the bioremediation of Hg-contaminated soils.
Mercury/toxicity* ; Biodegradation, Environmental ; Soil Pollutants/isolation & purification* ; Soil Microbiology ; Plants, Genetically Modified/metabolism* ; Bacteria/genetics*

Protein tyrosine phosphatases (PTPs, EC 3.1.3.48) are key regulators of cellular processes, with the catalytic activity attributed to the conserved motif (H/V)CX₅R(S/T), where cysteine and arginine residues are critical. Previous studies revealed that alternative splicing of extracellular phosphatase mRNA precursors in Metarhizium anisopliae generated two distinct transcripts, with the longer sequence containing a novel HCPTPMLS motif resembling PTP signatures but lacking the arginine residue. To identify the novel signature motif and characterize its enzymatic properties, we heterologously expressed and purified both proteins in Pichia pastoris and comprehensively characterized their enzymatic properties. The protein containing the HCPTPMLS motif (designated as L-protein) exhibited the highest activity at pH 5.5 and a strong preference for pTyr substrates. Its phosphatase activity was inhibited by Ag⁺, Zn²⁺, Cu²⁺, molybdate, and tungstate, but enhanced by Ca²⁺ and EDTA. AcP101 (lacking HCPTPMLS) showed the maximal activity at pH 6.5 and a strong preference toward pNPP (P < 0.05), with the activity inhibited by NaF and tartrate, but enhanced by Mg²⁺ and Mn²⁺. Functional analysis confirmed that the L-protein retained the PTP activity despite the absence of arginine in its signature motif, while AcP101 functioned as an acid phosphatase. This study provides the first functional validation of an arginine-deficient PTP motif, expanding the definition of PTP signature motifs and offering new insights for phosphatase classification.
Metarhizium/genetics* ; Protein Tyrosine Phosphatases/chemistry* ; Amino Acid Motifs ; Recombinant Proteins/biosynthesis* ; Amino Acid Sequence ; Pichia/metabolism* ; Fungal Proteins/chemistry* ; Substrate Specificity ; Saccharomycetales

The wide use of ZnO and CuO nanoparticles in research, medicine, industry, and other fields has raised concerns about their biosafety. It is therefore unavoidable to be discharged into the sewage treatment system. Due to the unique physical and chemical properties of ZnO NPs and CuO NPs, it may be toxic to the members of the microbial community and their growth and metabolism, which in turn affects the stable operation of sewage nitrogen removal. This study summarizes the toxicity mechanism of two typical metal oxide nanoparticles (ZnO NPs and CuO NPs) to nitrogen removal microorganisms in sewage treatment systems. Furthermore, the factors affecting the cytotoxicity of metal oxide nanoparticles (MONPs) are summarized. This review aims to provide a theoretical basis and support for the future mitigating and emergent treatment of the adverse effects of nanoparticles on sewage treatment systems.
Wastewater/toxicity* ; Sewage/chemistry* ; Zinc Oxide/chemistry* ; Waste Disposal, Fluid ; Nanoparticles/chemistry* ; Metal Nanoparticles/chemistry* ; Nitrogen/metabolism* ; Water Purification

Resource utilization is an effective way to cope with the rapid increase of kitchen waste and excess sludge, and volatile fatty acids produced by anaerobic fermentation is an important way of recycling organic waste. However, the single substrate limits the efficient production of volatile fatty acids. In recent years, volatile fatty acids produced by anaerobic co-fermentation using different substrates has been widely studied and applied. In this paper, we analyze the characteristics of fermentation to produce acid using kitchen waste and excess sludge alone or mixture. Influences of environmental factors and microbial community structure on the type and yield of volatile fatty acids in the anaerobic fermentation system are discussed in detail. Moreover, we propose future research directions, to provide a reference for recycling kitchen waste and excess sludge.
Anaerobiosis ; Bioreactors ; Fatty Acids, Volatile ; Fermentation ; Hydrogen-Ion Concentration ; Microbiota ; Organic Chemicals ; Sewage

Nitrite is a by-product of the nitrogen cycle. The excessive nitrite not only constrains growth and metabolism of bacteria, but also impairs health of humans and aquatic organisms. On the other hand, the continuous maintaining of nitrite accumulation could achieve the shortcut nitrification process, and reduce energy consumption of biological nitrogen removal to save cost. This article reviews the biological processes and causes of nitrite accumulation in the water environment, and summarizes the factors that affect the accumulation of nitrite, to provide reference for wastewater treatments, including improving the nitrogen removal efficiency, reducing operating costs, decreasing discharge of sewage and nitrite nitrogen in natural water.

Phosphatases play a key role not only in cell physiological functions of an organism, but also in host-pathogen interactions. Many studies demonstrated that some Gram-negative pathogenic bacteria could evade host immunity and promote pathogenicity by injecting phosphatases into host cells through type III secretion system. However, there were few reports about pathogenic fungi evading the immunity of hosts. Our researches indicated that the entomogenic fungus Metarhizium anisopliae could dephosphorylate the signal transduction substance of locust humoral immunity specifically in vitro by secreting extracellular protein tyrosine phosphatase, which implied that the fungus might interfere with the immune defense of locust. To provide reference for further studies of the functions of phosphatases, we reviewed the types of phosphatases and their roles in pathogen infection.
Animals ; Fungal Proteins ; metabolism ; Fungi ; enzymology ; physiology ; Gram-Negative Bacteria ; enzymology ; physiology ; Grasshoppers ; immunology ; microbiology ; Host-Pathogen Interactions ; Metarhizium ; enzymology ; Phosphoric Monoester Hydrolases ; classification ; physiology ; secretion

Aim To investigate the effect of puerarin(Pue)on the experimental insulin resistance(IR)and the mechanism of Pue-treated metabolic syndrome(MS).Methods IR rat model was induced by i.v.small dosage streptozotocin(STZ)and high fatty diet.The effect of Pue on insulin sensitivity was studied by reformed hyperinsulinism euglycemia clamp technique(HEPC)on IR rats.Results The basic blood glucose(BBG),basic blood plasma insulin(BINS)and stable basic blood plasma insulin(SINS)of IR rats induced by high-fat feed were higher than those of control group,and those of the group treated by Pue were observably lower than those of IR model group.In HECT text,the average rate of glucose injection of IR model group was lower than that of control group from 60 min to 120 min,but the rate of high dose and middle dose of Pue group was significantly higher than that of IR model group.Conclusion The results suggest that Pue can improve the insulin sensitivity,and reduce basic blood glucose and blood plasma insulin of the experimental insulin resistance rats.

Object To investigate the effect of puerarin (Pue) on renal protein kinase C (PKC) activity, kidney structure and function in diabetic rats. Methods STZ-induced diabetic rats were randomly divided into five groups: Diabetic rats model group (DM), Pue (500, 250, 125 mg/kg) treatment group, and VitE group, in addition, normal rats for control group. All rats were given by ig for 12 weeks. Kidney function and kidney index were determined; The PKC activity was measured by ELISA. The excretion of microalbuminuria (MAU) was measured by radio-immunoassay, and kidney tissue was observed by light-microscope and transmission electron microscope. Results The excretion of MAU, kidney index (kidney weight/body weight) and PKC activity in diabetic rats were significantly increased. The excretion of MAU, and PKC activity were markedly decreased in Pue treatment group, and kidney pathologic changes of diabetic rats in Pue treatment group were improved. Conclusion Pue can ameliorate early kidney hy-perdynamic abnormality in diabetic rats, possess protective effect on kidney of diabetic rats, whose mechanism may be associated partly with a down-regulation of PKC activity.