Assessment of pathogenic bacteria in water and sediment from a water reservoir under tropical conditions (Lake Ma Vallée), Kinshasa Democratic Republic of Congo

This study was conducted to assess potential human health risks presented by pathogenic bacteria in a protected multi-use lake-reservoir (Lake Ma Vallée) located in west of Kinshasa, Democratic Republic of Congo (DRC). Water and surface sediments from several points of the Lake were collected during summer. Microbial analysis was performed for Escherichia coli, Enterococcus (ENT), Pseudomonas species and heterotrophic plate counts. PCR amplification was performed for the confirmation of E. coli, ENT, Pseudomonas spp. and Pseudomonas aeruginosa isolated from samples. The results reveal low concentration of bacteria in water column of the lake, the bacterial quantification results observed in this study for the water column were below the recommended limits, according to WHO and the European Directive 2006/7/CE, for bathing water. However, high concentration of bacteria was observed in the sediment samples; the values of 2.65 × 103, 6.35 × 103, 3.27 × 103 and 3.60 × 108 CFU g−1 of dry sediment for E. coli, ENT, Pseudomonas spp. and heterotrophic plate counts, respectively. The results of this study indicate that sediments of the Lake Ma Vallée can constitute a reservoir of pathogenic microorganisms which can persist in the lake. Possible resuspension of faecal indicator bacteria and pathogens would affect water quality and may increase health risks to the population during recreational activities. Our results indicate that the microbial sediment analysis provides complementary and important information for assessing sanitary quality of surface water under tropical conditions

Evidence for the efficacy of pre-harvest agricultural practices in mitigating food-safety risks to fresh produce in North America

Consumption of contaminated produce remains a leading cause of foodborne illness. Increasingly, growers are altering agricultural practices and farm environments to manage food-safety hazards, but these changes often result in substantial economic, social, and environmental costs. Here, we present a comprehensive evidence synthesis evaluating the efficacy of soil, non-crop vegetation, animal, landscape, and irrigation water management strategies aimed at reducing produce-safety risk in North America. We systematically summarized findings from 78 peer-reviewed papers on the effect of 21 management practices on the prevalence, abundance, or survival of four foodborne pathogens (i.e., E. coli, Salmonella spp., Listeria spp., and Campylobacter spp.), resulting in 113 summaries. We then organized a 30-member expert panel, who used these summaries to evaluate the impact of each practice on food-safety outcomes. While more than half of the practices were too understudied to confidently evaluate their impact on food safety, the panel did identify several practices that were associated with reduced preharvest food-safety risks, including not using raw manure, separating crop and livestock production, and choosing low-risk irrigation sources. The panel also identified practices that appear ineffective at reducing food-safety risks, such as the removal of non-crop vegetation. Overall, these findings provide insights into the food-safety impacts of agricultural and land management practices that growers, auditors, and extension personnel can use to co-manage produce preharvest environments for food safety and other aimsFunding for this research was made possible by the Center for Produce Safety (Grant# 2019CPS03), by the U.S. Department of Agriculture's (USDA) Agricultural Marketing Service through grant USDA-AMS-TM-SCBG-G-18-003, and by USDA, Agricultural Research Service, National Program 104: Food Safety (animal and plant products)Peer reviewe

Exploring research frontiers in aquatic ecosystems: role of hospital and urban effluents in the dissemination of antibiotic resistance and metals to fresh water ecosystems

Since the middle of the 20th century, pollution of freshwater resources by anthropogenic activities constitutes major sources of aquatic environment contamination. In the recent past research is documenting on the prevalence of emerging contaminants in the aquatic ecosystems. In this study we assess the emerging contaminants as well as the prevalence of antibiotic resistant Pseudomonas spp. in the sediments receiving partially/untreated wastewaters and the effects of contamination on the composition and the diversity of bacterial communities in the sediments were explored. Results of the present study highlight the release of emerging contaminants from urban, hospital and WWTP wastewaters. Consequently, sediment receiving systems can act as reservoir for metals, microbes and antibiotic resistance genes which could potentially be transferred to susceptible bacterial pathogens. The remobilization of these contaminants can place the ecosystem and humans at risk. Reduction of contaminants from the sources is recommended for further improvement of water quality

Metal Distribution and Characterization of Cultivable Lead-Resistant Bacteria in Shooting Range Soils

Shooting ranges represent about 10% of polluted sites in Switzerland. This pollution, mainly consisting of lead (Pb) and antimony (Sb), can spread into the local groundwater, wildlife, and plants. In this study, shooting range stop butt soils (elevated soil mount behind the target) of 3 sites (Versoix, Cartigny and Nyon, Western Switzerland) were investigated for metal contamination and culturable lead-resistant bacteria in contaminated soils. The ICP-MS analysis of surface stop butt soils (0-5 cm) indicated high metal concentrations especially for Pb and Sb; e.g. the Pb concentration ranging from [61,135 to 395,651], [23,821 to 201,268] and [120 to 27,517] mg kg-1 in the soil from the sites of Versoix, Cartigny and Nyon, respectively. Molecular analysis of 16S rRNA gene demonstrates the presence of bacteria from diverse classes: Flavobacteriia, α-Proteobacteria, γ-Proteobacteria, Actinobacteria and Bacilli that exhibited high Pb MIC value from 1,036 to 2,694 mg kg-1. The isolated strains could be the subject of further studies to evaluate their role in bioremediation of lead contaminated soil

Multiwall Carbon Nanotubes Induce More Pronounced Transcriptomic Responses in Pseudomonas aeruginosa PG201 than Graphene, Exfoliated Boron Nitride, or Carbon Black.

Carbonaceous and boron nitride (BN) nanomaterials have similar applications and hydrophobic properties suggesting common release pathways and exposure to bacteria. While high nanomaterial concentrations can be bactericidal or growth-inhibitory, little is known regarding bacterial transcriptional responses to non-growth-inhibitory nanomaterial concentrations. Here, using one strain of Pseudomonas aeruginosa-a clinically and environmentally important bacterial taxon-we analyzed the comparative transcriptomic response to carbonaceous or BN nanomaterials. We show that, at non-growth-inhibitory, equal mass concentrations (10 mg/L), multiwall carbon nanotubes (MWCNTs) induced differential regulation of 111 genes in P. aeruginosa, while graphene, BN, and carbon black caused differential regulation of 44, 26, and 25 genes, respectively. MWCNTs caused the upregulation of genes encoding general stress response (9 genes), sulfur metabolism (15), and transport of small molecules (7) and downregulation of genes encoding flagellar basal-body rod proteins and other virulence-related factors (6), nitrogen metabolism (7), and membrane proteins (12), including a two-component regulatory system CzcS/R. Because two-component systems are associated with antibiotic resistance, the antibiotic susceptibility of P. aeruginosa was tested following MWCNT exposure. In MWCNT-treated cultures, the minimal inhibitory concentrations (MICs) of meropenem and imipenem decreased from 0.06 to 0.03 μg/mL and from 0.25 to 0.125 μg/mL, respectively. Taken together, whole genome analysis indicated that, in the absence of growth inhibition, nanomaterials can alter bacterial physiology and metabolism. For MWCNTs, such alterations may include downregulation of antibiotic resistance pathways, suggesting that pre-exposure to MWCNTs could potentially render bacteria more susceptible to carbapenems which are often the last resort for the globally concerning, highly antibiotic resistant P. aeruginosa

Multiwall Carbon Nanotubes Induce More Pronounced Transcriptomic Responses in Pseudomonas aeruginosa PG201 than Graphene, Exfoliated Boron Nitride, or Carbon Black.

Carbonaceous and boron nitride (BN) nanomaterials have similar applications and hydrophobic properties suggesting common release pathways and exposure to bacteria. While high nanomaterial concentrations can be bactericidal or growth-inhibitory, little is known regarding bacterial transcriptional responses to non-growth-inhibitory nanomaterial concentrations. Here, using one strain of Pseudomonas aeruginosa-a clinically and environmentally important bacterial taxon-we analyzed the comparative transcriptomic response to carbonaceous or BN nanomaterials. We show that, at non-growth-inhibitory, equal mass concentrations (10 mg/L), multiwall carbon nanotubes (MWCNTs) induced differential regulation of 111 genes in P. aeruginosa, while graphene, BN, and carbon black caused differential regulation of 44, 26, and 25 genes, respectively. MWCNTs caused the upregulation of genes encoding general stress response (9 genes), sulfur metabolism (15), and transport of small molecules (7) and downregulation of genes encoding flagellar basal-body rod proteins and other virulence-related factors (6), nitrogen metabolism (7), and membrane proteins (12), including a two-component regulatory system CzcS/R. Because two-component systems are associated with antibiotic resistance, the antibiotic susceptibility of P. aeruginosa was tested following MWCNT exposure. In MWCNT-treated cultures, the minimal inhibitory concentrations (MICs) of meropenem and imipenem decreased from 0.06 to 0.03 μg/mL and from 0.25 to 0.125 μg/mL, respectively. Taken together, whole genome analysis indicated that, in the absence of growth inhibition, nanomaterials can alter bacterial physiology and metabolism. For MWCNTs, such alterations may include downregulation of antibiotic resistance pathways, suggesting that pre-exposure to MWCNTs could potentially render bacteria more susceptible to carbapenems which are often the last resort for the globally concerning, highly antibiotic resistant P. aeruginosa

Quantification and characterization of mercury resistant bacteria in sediments contaminated by artisanal small-scale gold mining activities, Kedougou region, Senegal

This study describes Hg-resistant bacterial present in the aquatic sediments artisanal small-scale gold mining ASGM activities along Gambia River Kedougou, Senegal. Mercury (Hg) is used for gold amalgamation in artisanal small-scale gold mining (ASGM) activities. The level of total Hg in sediment samples was determined by automatic mercury analyser. Bacterial (colony-forming units) susceptibility to Hg was evaluated by minimal inhibitory concentrations. The phylogenetic diversity analysis of the Hg-resistant bacteria was performed by PCR amplification of 16S rDNA on isolated bacterial strains, followed by restriction fragment length polymorphism, cloning and sequencing. The results documente high concentrations of Hg in ASGM activity areas, ranging between 2.4 to 6.2 mg kg-1. Population densities of heterotrophic bacteria in wet sediment ranging from 3.7x106 to 4.6x108 CFU g-1. The isolated bacterial strains from highly Hg-contaminated sites can grow to medium containing up to 17 mg L-1 of Hg2+. In this study, bacterial strains resistant to Hg are Stenotrophomonas maltophilia, Dyella ginsengisoli, Arthobacter defluvi, Arthobacter pascens, Bacillus firmus and Pseudomonas moraviensis. Our results demonstrate the occurrence the presence of diverse groups of bacterial strains resistant to metal (Hg) under tropical conditions. The isolated strains are particularly interesting for further studies to evaluate their role in bioremediation of Hg in contaminated aquatic ecosystems

Influence of diglyme and cumene additives upon emission and combustion behaviour of diverse biodiesel fuelled diesel engine

The growing need for sustainable and eco-friendly fuels aligns with global efforts to achieve the United Nations Sustainable Development Goals (SDGs), particularly SDG 7 (Affordable and Clean Energy), SDG 13 (Climate Action), and SDG 12 (Responsible Consumption and Production). This study addresses these goals by investigating the potential of biodiesel blends supplemented with innovative fuel additives to improve engine performance and reduce environmental impact. Specifically, the effects of diglyme (DG) and cumene (CU) as fuel additives on the combustion, performance, and emission characteristics of diesel engines fueled with jojoba methyl ester (JME), polanga oil methyl ester (PME), and their blended variant mixed methyl ester (MME) were evaluated. Experiments were conducted on a single-cylinder, 4-stroke, water-cooled, direct injection diesel engine operating at a constant speed of 1500 rpm and injection timing of 21ºbTDC under varying load conditions (0–5.02 kW). DG (5 % vol./vol.) was used as a cetane improver, while CU (5 % vol./vol.) functioned as an antioxidant. The results demonstrated that the blends MME15+CU5 and MME15+DG5 exhibited superior thermo-chemical properties and engine performance. MME15+CU5 achieved an 8.77 % increase in brake thermal efficiency (BTE), along with reductions in brake-specific energy consumption (BSEC) (5.64 %) and exhaust gas temperature (EGT) (12.02 %) at peak load. Similarly, MME15+DG5 delivered a 15.78 % improvement in BTE, with reductions in BSEC (17.11 %) and EGT (5.48 %). Emission analysis revealed significant reductions in CO (53.52 %), HC (81.25 %), NOx (26.11 %), and smoke opacity (25.79 %) for MME15+DG5 compared to diesel. These findings underscore the potential of (diglyme and cumene) additives enhanced biodiesel blends as sustainable, efficient alternatives to conventional diesel, contributing to the reduction of greenhouse gas emissions (SDG 13) and fostering responsible energy production and consumption (SDG 12), while promoting access to clean energy solutions (SDG 7)