Antibiotics are extensively used in human medicine and animal breeding. The use of antibiotics has posed significant risks and challenges to the natural water environment. On a global scale, ...antibiotics have been frequently detected in the environment, azithromycin (254–529 ng·L−1), ciprofloxacin (245–1149 ng·L−1), ofloxacin (518–1998 ng·L−1), sulfamethoxazole (1325–5053 ng·L−1), and tetracycline (31.4–561 ng·L−1) are the most detected antibiotics in wastewater and surface water. Abuses of antibiotics has caused a significant threat to water resources and has seriously threatened the survival of human beings. Therefore, there is an urgent need to reduce antibiotic pollution and improve the environment. Researchers have been trying to develop effective methods and technologies for antibiotic degradation in water. Finding efficient and energy-saving methods for treating water pollutants has become an important global topic. Photocatalytic technology can effectively remove highly toxic, low-concentration, and difficult-to-treat pollutants, and tungsten trioxide (WO3) is an extremely potential alternative catalyst. Pt/WO3 photocatalytic degradation efficiency of tetracycline was 72.82%, While Cu-WO3 photocatalytic degradation efficiency of tetracycline was 96.8%; WO3/g-C3N4 photocatalytic degradation efficiency of ceftiofur was 70%, WO3/W photocatalytic degradation efficiency of florfenicol was 99.7%; WO3/CdWO4 photocatalytic degradation efficiency of ciprofloxacin was 93.4%; WO3/Ag photocatalytic degradation efficiency of sulfanilamide was 96.2%. Compared to other water purification methods, photocatalytic technology is non-toxic and ensures complete degradation through a stable reaction process, making it an ideal water treatment method. Here, we summarize the performance and corresponding principles of tungsten trioxide-based materials as a photocatalytic catalyst and provide substantial insight for further improving the photocatalytic potential of WO3-based materials.
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•Massive use of antibiotics has brought great risks and challenges to the water environment of natural water bodies.•Pollutants with highly toxicity, low concentration and low degradability could be effectively removed via photocatalytic technology using WO3.•Tungsten trioxide has broad application prospects in the fields of photolysis due to its environmentally friendly and excellent photostability.•We summarized the performance and corresponding principle of tungsten trioxide as a photocatalytic catalyst.•We provided a substantial insight for further improving the photocatalytic potential of tungsten trioxide-based materials.
•Hydrothermal pretreatment was applied to enhance VFAs production from food waste.•Food waste fermentation was inhibited at high hydrothermal temperature.•160°C was found to be the optimal ...hydrothermal temperature for VFAs production.•High VFAs recovery was achieved by a liquid–liquid extraction method.
Food waste (FW) was pretreated by a hydrothermal method and then fermented for volatile fatty acid (VFAs) production. The soluble substance in FW increased after hydrothermal pretreatment (⩽200°C). Higher hydrothermal temperature would lead to mineralization of the organic compounds. The optimal temperature for organic dissolution was 180°C, at which FW dissolved 42.5% more soluble chemical oxygen demand than the control. VFA production from pretreated FW fermentation was significantly enhanced compared with the control. The optimal hydrothermal temperature was 160°C with a VFA yield of 0.908g/g VSremoval. Butyrate and acetate were the prevalent VFAs followed by propionate and valerate. FW fermentation was inhibited after 200°C pretreatment. The VFAs were extracted from the fermentation broth by liquid–liquid extraction. The VFA recovery was 50–70%. Thus, 0.294–0.411g VFAs could be obtained per gram of hydrothermally pretreated FW (in dry weight) by this method.
Significance Cooperation is subject to social cheating. Cheats benefit from the activity of cooperators and gain a fitness advantage. One way higher organisms prevent infiltration by cheats is ...policing: Cooperators penalize cheats at some cost to themselves. Cooperating groups of bacteria are susceptible to social cheating, but little is known about bacterial policing. We have built on an understanding a quorum-sensing regulated cooperative activity in Pseudomonas aeruginosa to show that quorum sensing control of and resistance to cyanide production serves as a cheater policing mechanism. Understanding how bacteria cooperate and how they control social cheats has evolutionary implications, provides important insights about ways to control bacterial populations, and has ramifications with respect to synthetic system design.
The bacterium Pseudomonas aeruginosa is an opportunistic human pathogen that uses a quorum sensing signal cascade to activate expression of dozens of genes when sufficient population densities have been reached. Quorum sensing controls production of several key virulence factors, including secreted proteases such as elastase. Cooperating groups of bacteria growing on protein are susceptible to social cheating by quorum-sensing defective mutants. A possible way to restrict cheater emergence is by policing where cooperators produce costly goods to sanction or punish cheats. The P. aeruginosa LasR-LasI quorum sensing system controls genes including those encoding proteases and also those encoding a second quorum-sensing system, the RhlR-RhlI system, which controls numerous genes including those for cyanide production. By using RhlR quorum sensing mutants and cyanide synthesis mutants, we show that cyanide production is costly and cyanide-producing cooperators use cyanide to punish LasR-null social cheaters. Cooperators are less susceptible to cyanide than are LasR mutants. These experiments demonstrate policing in P. aeruginosa , provide a mechanistic understanding of policing, and show policing involves the cascade organization of the two quorum sensing systems in this bacterium.
The environmentally responsible behaviors of residents and tourists are great significance to the protection of natural resources and sustainable development of ecotourism. This paper takes China's ...Qilian Mountains National Park as the case place. By constructing a theoretical model of perceived value on environmentally responsible behavior and studying the relationship between residents' and tourists' perceived value, satisfaction and environmentally responsible behavior from both subject and object perspectives, the study shows that. Educational level and occupational distribution have significant effects on residents' and tourists' perceptions of ecotourism environmentally responsible behaviors, but age only has a significant effect on residents' perceptions of ecotourism environmentally responsible behaviors. Gender differences do not affect residents' and tourists' perceptions of ecotourism environmentally responsible behaviors. The theoretical model between residents' perceptions of environmentally responsible behaviors, environmentally responsible behaviors, and satisfaction was basically confirmed. Perceived environmentally responsible behaviors of tourists does not affect satisfaction. Satisfaction has a positive effect on tourists' environmentally responsible behaviors. Perceived environmental responsibility of tourists has a significant positive effect on tourists' environmentally responsible behaviors. The overall level of residents' perception of environmentally responsible behaviors in ecotourism is higher than tourists' perception. Residents and tourists have a poor perception of ecological and environmental protection policies. This paper expects to strengthen residents' and tourists' perceptions of ecologically responsible behaviors. Establishing the sentiment of satisfaction and commitment to environmental protection motivates residents and tourists to implement environmentally responsible behaviors and contribute to the sustainable development of ecotourism.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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•FFVW reduced the relative abundance of HBPs in soils.•FFVW inhibited the co-occurrence relationship between HBPs, VFGs and ARGs.•FFVW mitigated conjugative transfer of ARGs to ...prevent the diffusion of ARGs.•The declining risk of HBPs by FFVW was attributed to inhibition of quorum sensing.•The study offered an approach to control soil HBP risk caused by organic fertilizer application.
Fermentation broth from fruit and vegetable waste (FFVW) has demonstrated remarkable ability as a soil amendment and in reducing antibiotic resistance genes (ARGs) pollution. However, the potential of FFVW to mitigate other microbial contamination such as human bacterial pathogens (HBPs) and virulence factor genes (VFGs), which are closely associated with human health, remains unknown. In this study, metagenomic analysis revealed that FFVW reduced the HBPs with high-risk of ARGs and VFGs including Klebsiella pneumoniae (reduced by 40.4 %), Mycobacterium tuberculosis (reduced by 21.4 %) and Streptococcus pneumoniae (reduced by 38.7 %). Correspondingly, VFG abundance in soil decreased from 3.40 copies/cell to 2.99 copies/cell. Further analysis illustrated that these was mainly attributed to the inhibition of quorum sensing (QS). FFVW reduced the abundance of QS signals, QS synthesis genes such as rpaI and luxS, as well as receptor genes such as rpfC and fusK, resulting in a decreased in risk of ARGs and VFGs. The pure culture experiment revealed that the expression of genes related to QS, VFGs, ARGs and mobile genetic elements (MGEs) were downregulated in Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli and K. pneumoniae treated by FFVW, consistent with the result of metagenomic analysis. This study suggested an environmentally friendly approach for controlling soil VFGs/ARGs-carrying HBPs, which is crucial for both soil and human health under the framework of “One Health”.
Quorum sensing is a concentration-sensing mechanism that plays a vital role in sludge granulation. In this study, the regularities of distribution of different signal molecules, including intra- and ...interspecific signal molecules (diffusible signal factor, DSF), interspecific signal molecules (autoinducter-2, AI-2) and intraspecific signal molecules (acyl-homoserine lactones, AHLs), from three types of anaerobic granular sludge were investigated. The results showed that 70–90% of DSF was distributed in sludge, while AI-2 in the Water phase accounted for over 80% of the total content. Interestingly, there was a positive correlation between DSF and AI-2, which played opposite roles in granulation. Moreover, more than 55% of short and medium acyl chain AHLs tended to spread in aqueous water, while the long acyl chain AHLs were closer to granular sludge than the short and medium acyl chain AHLs. With the exception of one type of sludge, the percentage of long acyl chain AHLs in the sludge phase was greater than 70%. The different distributions of signal molecules were primarily determined based on their physicochemical properties, including molecular weight and solubility in water or organic solutions. In addition, the basic properties of sludge, such as the granular level or the production of EPS, were closely related to the diversity, distribution and concentration of signal molecules. As a medium in granulation, extracellular polymeric substances production was regulated by different signal molecules from different parts of anaerobic granular sludge. This study provides a foundation for investigation of quorum sensing in the system of anaerobic granular sludge.
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•Signal molecules distribution differed at different positions on AnGS.•Signal molecules distribution was affected by their physicochemical properties.•QS will dominate the granulation of anaerobic sludge by regulating EPS production.•The relationship between the size of granular sludge and QS was discussed.
In this paper, a TiO2 thin film-modified stainless steel mesh (SSM/TiO2-H) was prepared by an electrochemical method and applied as an anode in microbial fuel cells (MFCs) to enhance their power ...output. A maximum projected current density of 69.5±1.2A/m2 was obtained from our SSM/TiO2-H electrode. This high current was attributed to the favorable biocompatibility of the electrode. We measured a total protein density of 2431±224μgprot/cm2 on the SSM/TiO2-H electrode after 20-days of cultivation, which was approximately 12 times greater than that of the untreated SSM. In addition, electrochemical impedance spectroscopy showed that the charge transfer resistance between the biofilm and electrode was only 3.55Ω and a thick and dense biofilm was measured on the surface of SSM/TiO2-H (28.3±0.5μm). All peaks occurred at −0.30±0.05V in differential pulse voltammetry curves, indicating that the high current showed no contributions from changes of the exocellular electron transfer components. These results should guide future studies of stainless steel mesh for applications in MFCs. Our method represents a new approach to achieve high energy output anode through modifying the properties of titanium dioxide thin films.
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•Sub-lethal concentrations of ampicillin could induce the rapid evolution of antibiotic resistance of Pseudomonas aeruginosa.•Quorum sensing participated in resistance revolution ...induced by sub-lethal ampicillin in Pseudomonas aeruginosa.•The RhlI/R but not the LasI/R circuit is involved in resistance evolution under sub-lethal ampicillin conditions.
The rapid increase of antibiotic resistance is a serious challenge around the world. Antibiotics are present in various environments at sub-lethal concentrations, but how resistance emerges under sub-lethal conditions is not fully clear. In this study, we evolved Pseudomonas aeruginosa PAO1 under sub-lethal conditions, in the presence of either 15–30 μg/mL or 150–300 μg/mL of ampicillin. We found a ~ 5–6 fold increase in the minimum inhibitory concentration (MIC) among evolved isolates exposed to 15–30 μg/mL of ampicillin, and more than a 19-fold of increase in 150–300 μg/mL of ampicillin exposure. DNA sequencing revealed that mpl and ampD were frequently mutated in these resistant strains. We performed a transcriptome analysis of deletion mutations of mpl or ampD, compared to PAO1. Both showed a two-fold increase in expression of quorum sensing (QS) genes including lasR and rhlI/R; the heightened expression was positively correlated with the expression of the ampicillin resistance gene ampC. We queried if quorum sensing contributes to the increase in the ampicillin MIC. After adding the quorum quencher acylase I, the growth yield both decreased by roughly 50% for Δmpl in 2000 μg/mL of ampicillin and ΔampD in 4000 μg/mL of ampicillin. Addition of the QS signals into synthase mutants restored the higher MIC, but only for the rhlI/R circuit. This study highlights the involvement of QS in antibiotic resistance evolution, and shows the multifactorial contributors to the observed phenotypes.
Chitin biomass, a rich renewable resource, is the second most abundant natural polysaccharide after cellulose. Conversion of chitin biomass to high value-added chemicals can play a significant role ...in alleviating the global energy crisis and environmental pollution. In this review, the recent achievements in converting chitin biomass to high-value chemicals, such as 5-hydroxymethylfurfural (HMF), under different conditions using chitin, chitosan, glucosamine, and
-acetylglucosamine as raw materials are summarized. Related research on pretreatment technology of chitin biomass is also discussed. New approaches for transformation of chitin biomass to HMF are also proposed. This review promotes the development of industrial technologies for degradation of chitin biomass and preparation of HMF. It also provides insight into a sustainable future in terms of renewable resources.
Effective video monitoring systems require optimization of camera and road network coverage, to exploit fully the hardware and software solutions in smart city traffic applications. Monitoring ...requirements have grown increasingly diverse as scenes are becoming increasingly complex, thereby transforming the camera and road network coverage optimization issue into a nonlinear, high-dimension, and multi-objective problem. Previous research on this topic however, has focused on a single, specific optimization objective, which may result in invalid optimization results in actual applications. To extend this research, we propose a multi-objective scheduling optimization algorithm for a camera network that addresses the problem of directional road network coverage. In this solution, we incorporate an expanding parameter of main optical axes into particle swarm optimization algorithm. Our new strategy divides the range of main optical axes of all the cameras to control the scheduling number, achieving collaborative optimization of multiple objectives. In a simulated camera and road network, an experiment was designed for evaluating the effectiveness of the proposed method, comparing the distribution of optimization results with the global and local optimal solutions of the true value. A second experiment compared the distribution, performance and running time of the optimization results with different values of expanding parameter of main optical axes. A third experiment compared the performance of the optimization solutions with different values of camera parameters. The results showed that the proposed method can adapt to user application preference, and is effective and robust to schedule and allocate monitoring resources in different scenarios.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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