Modeling microbial impact on macrophyte debris decomposition in macrophyte-dominated eutrophic lakes.

The decomposition of macrophytes plays a crucial role in the nutrient cycles of macrophyte-dominated eutrophication lakes. While research on plant decomposition mechanisms and microbial influences has rapid developed, it is curious that plant decomposition models have remained stagnant at the single-stage model from 50 years ago, without endeavor to consider any important factors. Our research conducted in-situ experiments and identified the optimal metrics for decomposition-related microbes, thereby establishing models for microbial impacts on decomposition rates (k_RDR). Using backward elimination in stepwise regression, we found that the optimal subset of independent variables-specifically Gammaproteobacteria-Q-L, Actinobacteriota-Q-L, and Ascomycota-Q-L-increased the adjusted R-squared (Ra2) to 0.93, providing the best modeling for decomposition rate (p = 0.002). Additionally, k_RDR can be modeled by synergic parameters of ACHB-Q-L, LDB-Q-L, and AB-Q-L for bacteria, and SFQ for fungi, albeit with a slightly lower Ra2 of 0.7-0.9 (p < 0.01). The primary contribution of our research lies in two key aspects. Firstly, we introduced optimal metrics for modeling microbes, opting for debris surface microbes over sediment microbes, and prioritizing absolute abundance over relative abundance. Secondly, our model represents a noteworthy advancement in debris modeling. Alongside elucidating the focus and innovative aspects of our work, we also addressed existing limitations and proposed directions for future research. SYNOPSIS: This study explores optimum metrics for decomposition-related microbes, offering precise microbial models for enhanced lake nutrient cycle simulation.

One stone, two birds: An eco-friendly aerogel based on waste pomelo peel cellulose for the efficient adsorption of dyes and heavy metal ions.

To achieve the objective of "waste control by waste", in this study, a green aerogel adsorbent comprised of pomelo-peel cellulose and sodium alginate (PCC/SA) was prepared through dual-network crosslinking. The resulting 3D hierarchical porous structured PCC/SA aerogel exhibited good structural stability, and kept the morphological integrity during 10 days in a wide pH range (2-10), suggesting its potential for recycling in diverse complex environments. Besides, the superior adsorption capacities for methylene blue (MB) and Cu(II) were observed, with the qm values and adsorption equilibrium times were recorded to be 1299.59 mg/g (300 min) and 287.55 mg/g (120 min), correspondingly. Furthermore, the favorable reusability of the PCC/SA aerogel was also demonstrated, with the removal efficiency for MB remaining almost unchanged (about 94 %) after 10 adsorption-desorption cycles, while there was a slight reduction for Cu(II) from 85.28 % to 72.47 %. XPS and FTIR analysis revealed that electrostatic attraction, hydrogen bonding, cation exchange and coordination were the major adsorption mechanisms. Importantly, the PCC/SA aerogel can be naturally degraded in soil within 10 weeks. Therefore, the as-prepared aerogel bead derived from pomelo peel shows great promise as an adsorbent for wastewater treatment containing dye and heavy metal ions.

A multicentre, randomised, double-blind, double-dummy, parallel-controlled, phase 3 clinical trial assessing the efficacy and safety of intravenous nemonoxacin malate vs. levofloxacin for community-acquired pneumonia in adult patients.

BACKGROUND: Nemonoxacin malate is a novel non-fluorinated quinolone for oral and intravenous (IV) administration. This phase 3, multicentre, randomised, double-blind, double-dummy, parallel-controlled clinical trial (NCT02205112) evaluated the efficacy and safety of IV nemonoxacin vs. levofloxacin for the treatment of community-acquired pneumonia (CAP) in adult patients. METHODS: Eligible patients were randomised to receive 500 mg nemonoxacin or levofloxacin via IV infusion, once daily for 7-14 days. The primary endpoint was the clinical cure rate at the test-of-cure (TOC) visit in the modified intent-to-treat (mITT) population. Secondary efficacy and safety were also compared between nemonoxacin and levofloxacin. RESULTS: Overall, 525 patients were randomised and treated with nemonoxacin (n = 349) or levofloxacin (n = 176). The clinical cure rate was 91.8% (279/304) for nemonoxacin and 85.7% (138/161) for levofloxacin in the mITT population (P > 0.05). The clinical efficacy of nemonoxacin was non-inferior to levofloxacin for treatment of CAP. Microbiological success rate with nemonoxacin was 88.8% (95/107) and with levofloxacin was 87.8% (43/49) (P > 0.05) at the TOC visit in the bacteriological mITT population. The incidence of drug-related adverse events (AEs) was 37.1% in the nemonoxacin group and 22.2% in the levofloxacin group. These AEs were mostly local reactions at the infusion site, nausea, elevated alanine aminotransferase/aspartate aminotransferase (ALT/AST), and QT interval prolongation. The nemonoxacin-related AEs were mostly mild and resolved after discontinuation of nemonoxacin. CONCLUSIONS: Nemonoxacin 500 mg IV once daily for 7-14 days is effective and safe and non-inferior to levofloxacin for treating CAP in adult patients.

Phosphorus accumulation during the ice-on season in macrophyte-dominated eutrophic lakes and its implications.

Macrophyte overgrowth in eutrophic lakes can hasten the decline of shallow water bodies, yet the impact of macrophyte deposition on sediment phosphorus (P) accumulation in the ice-on season remains unclear. Comparative analyses of P variations among 13 semi-connected sub-lakes in Wuliangsu Lake in China, a typical MDE lake, considered external flow and macrophyte decomposition as driving forces. Sediment P fractions and water total phosphorus (TP) were analyzed at 35 sampling points across three ice-on season stages, along with macrophyte TP content to assess debris contributions. Our findings reveal that phosphorus accumulation occurs during the ice-on season in the MDE lake, with an average TP content increase of 16 mg/kg. However, we observed a surprisingly small sediment nutrient accumulation ratio (ΔTP/ΔTN=0.006) compared to macrophyte nutrient levels before decomposition. Further analysis of the dominant species, Potamogeton pectinatus, indicates that a significant portion (55%) of macrophyte phosphorus is released before the ice-on season. This highlights the critical importance of timing macrophyte harvesting to precede the phosphorus leaching process, which has implications for lake management and ecosystem restoration efforts. Additionally, our research demonstrates similar transformations among different sediment fractions as previously reported. Macrophyte debris decomposition likely serves as the primary source of Residual P (Res-P) or TP accumulation. In addition, Ca-bound P (Ca-P) generally showed a decrease, which mainly caused by its transformation to Fe/Al-bound P (Fe/Al-P), Exchange-P (Ex-P), and sometimes to Res-P. However, we emphasize the significant impacts of flow dynamics on Ca-P transport and transformations. Its hydrodynamic action increases water dissolved oxygen, which accelerates the transformation of Ca-P to more easily released Fe/Al-P and Ex-P. Furthermore, hydrodynamic transport also leads to upstream Ca-P transport to downstream. This underscores the necessity of considering flow dynamics when estimating phosphorus variations and formulating phosphorus restoration strategies.

Deciphering the removal of antibiotics and the antibiotic resistome from typical hospital wastewater treatment systems.

Hospital wastewater treatment systems (HWTSs) are a significant source and reservoir of antibiotic resistance genes (ARGs) and a crucial hub for transmitting ARGs from clinical to natural environments. However, there is a lack of research on the antibiotic resistome of clinical wastewater in HWTSs. In this study, we used metagenomics to analyze the prevalence and abundance of ARGs in five typical HWTSs. A total of 17 antibiotics from six categories were detected in the five HWTSs; ß-lactam antibiotics were found at the highest concentrations, with up to 4074.08 ng·L-1. We further found a total of 21 ARG types and 1106 subtypes of ARGs with the highest percentage of multi-drug resistance genes (evgS, msbA, arlS, and baeS). The most abundant last-resort ARGs were mcr, which were detected in 100 % of the samples. HWTSs effluent is a major pathway for the transmission of last-resort ARGs into urban wastewater networks. The removal of antibiotics, antibiotic-resistant bacteria, and ARGs from HWTSs was mainly achieved by tertiary treatment, i.e., chlorine disinfection, but antibiotics and ARGs were still present in the HWTSs effluent or even increased after treatment. Moreover, antibiotics and heavy metals (especially mercury) in hospital effluents can exert selective pressure for antibiotic resistance, even at low concentrations. Qualitative analyses based on metagenome-assembled genome analysis revealed that the putative hosts of the identified ARGs are widely distributed among Pseudomonas, Acidovorax, Flavobacterium, Polaromonas, and Arcobacter. Moreover, we further assessed the clinical availability of ARGs and found that multidrug ARGs had the highest clinical relevance values. This study provides new impulses for monitoring and removing antibiotics and ARGs in the hospital sewage treatment process.

An analytical overview of the composition and characteristics of China's food safety standards.

This paper discusses the framework of China's food safety standards and provides a brief overview of the problems and developmental characteristics of food safety in China. The composition and characteristics of China's food safety standards are revealed by an analysis of the changes in China's general food standards, an overview of the characteristics of the hygiene requirements in the production and operation process, and an introduction to food product and test method standards. In conclusion, Chinese food safety standards are still being improved, but they must also be effectively implemented and followed up in real time in order to continuously improve the quality of food and reduce food safety incidents. © 2024 Society of Chemical Industry.