To Örebro University

Biocides are crucial in industrial applications to minimize microbial growth and prevent product spoilage. Water-based construction coatings are susceptible to microbial contamination during manufacturing and storage and this adversely impacts product properties, reduces shelf-life and leads to substantial commercial losses. The future trend to lower the biocide concentrations in water-based coatings raises concerns about the emergence of biocide-resistant microbes. This study aims to identify and characterize the biocide-resistant microbe isolated from construction water-based coating materials to better understand its mechanisms of resistance. A total of 63 samples were collected from spoiled products, raw materials, and water from a manufacturing facility, and Pseudomonas oleovorans P4A were identified in all biocides-treated samples. A comparison between a P. oleovorans reference strain, 1045, and the P4A isolate revealed distinct colony morphology, growth rate and sensitivity to biocides and antibiotics. The P4A isolate was 3-fold more resistant to 5-chloro-2-methyl-isothiazolin-3-one (CMIT) and 1.5-fold more resistant to benzothiazolinone (BIT) compared to the reference strain. Conversely, it was 1.4-fold more sensitive to methylisothiazolinone (MIT) compared to the reference strain. No cross-resistance to antibiotics was observed. Metabolomic analysis using liquid chromatography combined with high-resolution mass spectrometry of lipids and polar metabolites showed that P4A had a relatively higher amount of lipids, while 1045 had a relatively higher amount of polar metabolites identified. A significant difference in lipid composition, specifically in diacylglycerol, phosphatidic acid, phosphatidylcholine, and phosphatidylserine was observed between P. oleovorans strains 1045 and P4A. These distinctions highlight increased lipid metabolism in P. oleovorans P4A and this may contribute to its adaptation to biocides. Microbial resistance can directly affect the effectiveness of these products, leading to an increased need for frequent maintenance and replacement, safety concerns, and environmental implications.

Phytoremediation technologies have the potential to be cost-effective solutions for managing per- and polyfluoroalkyl substances (PFAS). In this greenhouse study, we assessed the uptake of PFAS using two plant species commonly used for phytoremediation, Salix miyabeana (willow) and Populus trichocarpa (poplar). We also assessed the impact of a commercially available growth phytohormone (naphthalene acetic acid (NAA)) and a microbial amendment on plant growth and PFAS uptake. Overall, uptake was observed, depending on perfluorocarbon chain length and functional group. After 90 days, the uptake of individual PFAS in plants grown in PFAS contaminated soil ranged from 0.02 % to 35 % dry weight (dw) for willow and 0.4–29 % for poplar. Within plants, short chain PFAS (i.e., C4–7 perfluoroalkyl carboxylates (PFCA) and C4 perfluoroalkyl sulfonates (PFSA)) primarily accumulated in aboveground biomass, whereas longer chained homologues (C8–14 PFCA, C6–8 PFSA) primarily accumulated in the roots. For hormone and microbial amendments, there were no statistically significant trends for both willow and poplar (p > 0.05). Interestingly, the microbial community composition did not shift based on PFAS exposure but did shift based on plant-species. The PFAS mass balance for willow and poplar after 90 days approached 100 % (p > 0.05) for all PFAS except PFBA, PFPeA, PFOS, and FOSA. These results suggest that while willow and poplar have the potential to extract short chain PFAS from soil, phytoremediation may be more effective at stabilizing PFAS within a given area (i.e., providing hydraulic control) than extracting. 

Per-and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants, yet their impact on soil microbial diversity, function, and plant-microbe interactions remain poorly understood. This study investigates the effects of short-term (3 months, high concentration) and long-term (>30 years, low concentration) PFAS exposure on rhizosphere bacterial communities, incorporating plant interactions and functional gene profiling. Using 16S rRNA amplicon sequencing, selective microbial shifts were observed, where Firmicutes, Bacteroidetes and Gemmatimonadetes were enriched, while Actinobacteria and Acidobacteria declined in PFAS-contaminated soils. LEfSe biomarker analysis identified 33 genera including Nitrosospira, Nakamurella, Gemmatimonas, Nitrosomonas, Nordella and Pseudonocardia present in long-term exposed soils but were absent in short-term exposure, highlighting adaptive microbial responses over time. Functional predictions revealed enrichment of genes associated with xenobiotic degradation, lipid metabolism, and redox processes, inferring possible microbial metabolic adaptations to PFAS. Plant-specific effects further shaped microbial communities, with willow promoting Bacteroidetes and poplar reducing Actinobacteria, emphasizing their potential role in phytoremediation strategies. Overall, this study provides insight into potential microbial biomarkers and functional redundancy associated with PFAS exposure and features the long-term impact of PFAS on rhizoshpere microbial ecosystems, informing strategies for bioremediation and ecosystem recovery.

Per- and polyfluoroalkyl substances (PFAS), also known as 'forever chemicals', are of high concern for human and ecosystem health. PFAS were first synthesised and developed in the late 1930s, and are now commonplace in many everyday objects, such as frying pans, food packaging and cleaning products. Due to their long half-life, these chemicals remain at high concentrations in both the environment and within exposed organisms, where they have toxic effects. Several model and animal models have been developed to help determine the deleterious effects of PFAS, which has led to the identification of multiple pathways and mechanisms that are affected or presumed to be affected. In this Review, we present an overview of PFAS and discuss possible effects on humans and wildlife. We discuss the pros and cons of various vertebrate and invertebrate model systems that have been used to study PFAS. Finally, to further address these chemicals in the future, we discuss different approaches to removing PFAS from the environment.

Metal contamination of aquatic environments remains a major concern due to their persistence. The water flea Daphnia magna is an important model species for metal toxicity studies and water quality assessment. However, most research has focused on physiological endpoints such as mortality, growth, and reproduction in laboratory settings, as well as neglected toxicogenomic responses. Copper (Cu) and zinc (Zn) are essential trace elements that play crucial roles in many biological processes, including iron metabolism, connective tissue formation, neurotransmitter synthesis, DNA synthesis, and immune function. Excess amounts of these metals result in deviations from homeostasis and may induce toxic responses. In this study, we analyzed Daphnia magna transcriptomic responses to IC5 levels of Cu (120 µg/L) and Zn (300 µg/L) in environmental water obtained from a pristine lake with adjusted water hardness (150 mg/L CaCO3). The study was carried out to gain insights into the Cu and Zn regulated stress response mechanisms in Daphnia magna at transcriptome level. A total of 2,688 and 3,080 genes were found to be differentially expressed (DEG) between the control and Cu and the control and Zn, respectively. There were 1,793 differentially expressed genes in common for both Cu and Zn, whereas the number of unique DEGs for Cu and Zn were 895 and 1,287, respectively. Gene ontology and KEGG pathways enrichment were carried out to identify the molecular functions and biological processes affected by metal exposures. In addition to well-known biomarkers, novel targets for metal toxicity screening at the genomic level were identified.

Biocide resistance poses a significant challenge in industrial processes, with bacteria like Pseudomonas oleovorans exhibiting intrinsic resistance to traditional antimicrobial agents. In this study, the impact of biocide exposure on the metabolome of two P. oleovorans strains, namely, P. oleovorans P4A, isolated from contaminated coating material, and P. oleovorans 1045 reference strain, were investigated. The strains were exposed to 2-Methylisothiazol-3(2H)-one (MI) MIT, 1,2-Benzisothiazol-3(2H)-one (BIT), and 5-chloro-2-methyl-isothiazol-3-one (CMIT) at two different sub-inhibitory concentrations and the lipids and polar and semipolar metabolites were analyzed by ultra-high performance liquid chromatography quadrupole time-of-flight mass spectrometry UPLC-Q-TOF/MS. Exposure to the BIT biocide induced significant metabolic modifications in P. oleovorans. Notable changes were observed in lipid and metabolite profiles, particularly in phospholipids, amino acid metabolism, and pathways related to stress response and adaptation. The 1045 strain showed more pronounced metabolic alterations than the P4A strain, suggesting potential implications for lipid, amino acid metabolism, energy metabolism, and stress adaptation. Improving our understanding of how different substances interact with bacteria is crucial for making antimicrobial chemicals more effective and addressing the challenges of resistance. We observed that different biocides trigged significantly different metabolic responses in these strains. Our study shows that metabolomics can be used as a tool for the investigation of metabolic mechanisms underlying biocide resistance, and thus in the development of targeted biocides. This in turn can have implications in combating biocide resistance in bacteria such as P. oleovorans.

Environmental DNA (eDNA) analysis is a powerful tool for quantifying and assessing the diversity of organisms in the environment. Unfortunately, isolating eDNA from aquatic environments is challenging due to the difficulties associated with water collection, preservation of samples during transportation, and onsite filtration. These processes are expensive and time-consuming and can lead to eDNA degradation. These difficulties can be addressed by preserving eDNA in the collected water. In this study, we assessed the effect of short- and long-term water storage using three different cationic surfactants on the half-life of zebrafish (Danio rerio) mitochondrial DNA (mtDNA) in mesocosm water. The surfactants used were benzalkonium chloride (BAC), cetylpyridinium chloride (CPC), and cetyltrimethylammonium bromide (CTAB). We observed that CPC and CTAB treatment extended the half-life of mtDNA by 3-5 times. Analysis by quantitative polymerase chain reaction (qPCR) demonstrated a mtDNA retention rate of 17.6%, 26.3%, and 2.2% for CPC, CTAB, and BAC, respectively, compared to 0.1% in untreated water after 30 days. The preservation of mtDNA by cationic surfactants was attributed to their bactericidal and cytotoxic properties as well as their electrostatic interaction with DNA molecules, as observed by spectrofluorometric analysis and subsequent precipitation. Our results demonstrated an inexpensive and convenient method to protect eDNA in water and improve its extraction.

Metal contamination of aquatic environments remains a major concern and has received significant attention in recent years. The present study aimed to evaluate the effects of metal mixtures of varying concentrations over time in a lake receiving runoff water from a decommissioned mine. By subjecting several organisms to this water, we aimed to identify the most susceptible species, thus enabling a comprehensive evaluation of the risk posed by different toxins to the biotic environment.

We have evaluated the effects of mixed metal exposure on survival and stress gene expression in selected invertebrate and vertebrate model species. Our observations revealed differences in sensitivity among the invertebrate models Caenorhabditis elegans, Daphnia magna, Ceriodaphnia dubia, and Heterocypris incongruens, as well as in the vertebrate model Zebrafish (Danio rerio) and two cell lines; a zebrafish liver cell line (ZFL) and a human hepatocellular carcinoma cell line (HepG2). While the sensitivity shows great variation among the tested species, the expression of metallothionein was consistent with the levels of metals found in the mixed exposure media. Despite differences in acute toxicity, the universal induction of mt1/A and mt2/B genes make them an important biomarker for assessing the environmental risk of metals.

BACKGROUND: Diarrhea is a serious health problem in children, with the highest mortality rate in sub-Saharan Africa. Diarrheagenic Escherichia coli (DEC) is among the major bacterial causes of diarrhea in children under age five. The present study aims to determine molecular epidemiology and antimicrobial resistance profiles of DEC and identify contributing factors for acquisition among children under age five in Central Ethiopia.

METHODS: A health facility-centered cross-sectional study was conducted in Addis Ababa and Debre Berhan, Ethiopia, from December 2020 to August 2021. A total of 476 specimens, 391 from diarrheic and 85 from non-diarrheic children under age five were collected. Bacterial isolation and identification, antimicrobial susceptibility, and pathotype determination using polymerase chain reaction (PCR) were done.

RESULTS: Of the 476 specimens analyzed, 89.9% (428/476) were positive for E. coli, of which 183 were positive for one or more genes coding DEC pathotypes. The overall prevalence of the DEC pathotype was 38.2% (183/476). The predominant DEC pathotype was enteroaggregative E. coli (EAEC) (41.5%, 76/183), followed by enterotoxigenic E. coli (21.3%, 39/183), enteropathogenic E. coli (15.3%, 28/183), enteroinvasive E. coli (12.6%, 23/183), hybrid strains (7.1%, 13/183), Shiga toxin-producing E. coli (1.6%, 3/183), and diffusely-adherent E. coli (0.6%, 1/183). DEC was detected in 40.7% (159/391) of diarrheic and 28.2% (24/85) in non-diarrheic children (p = 0.020). The majority of the DEC pathotypes were resistant to ampicillin (95.1%, 174/183) and tetracycline (91.3%, 167/183). A higher rate of resistance to trimethoprim-sulfamethoxazole (58%, 44/76), ciprofloxacin (22%, 17/76), ceftazidime and cefotaxime (20%, 15/76) was seen among EAEC pathotypes. Multidrug resistance (MDR) was detected in 43.2% (79/183) of the pathotypes, whereas extended spectrum ß-lactamase and carbapenemase producers were 16.4% (30/183) and 2.2% (4/183), respectively.

CONCLUSION: All six common DEC pathotypes that have the potential to cause severe diarrheal outbreaks were found in children in the study area; the dominant one being EAEC with a high rate of MDR.

Per- and polyfluoroalkyl substances (PFAS) are anthropogenic compounds threatening water quality and food safety worldwide. Phytoremediation is a nature-based, cost-effective, and scalable solution with high potential for treating PFAS-contaminated sites. However, there is a large knowledge gap regarding choice of plant species and methods to enhance performance. This study assessed the PFAS phytoextraction potential of sunflower (Helianthus annuus), mustard (Brassica juncea), and industrial hemp (Cannabis sativa) in a greenhouse experiment, using inorganic fertilizer and a microbial mixture as supplements. PFAS concentrations were measured using UPLC-MS/MS, and bioconcentration factors for different plant tissues and removal efficiency were determined. Perfluoroalkyl carboxylic acid (PFCA) accumulation was 0.4-360 times higher than that of perfluoroalkyl sulfonic acid (PFSA) homologues of similar perfluorocarbon chain length. Inorganic fertilizer significantly (p < 0.001) reduced PFAS concentration in all plant tissues, whereas the microbial mixture tested did not affect PFAS concentration. PFAS uptake ranged from 0.2 to 33% per crop cycle. Overall, the potential number of crop cycles required for removal of 90% of individual PFAS ranged from six (PFPeA) to 232 (PFOA) using sunflower, 15 (PFPeA) to 466 (PFOS) using mustard and nine (PFPeA) to 420 (PFOS) using Hemp. In this study, the percentage of PFAS removal by plants was determined, and an estimation of the time required for PFAS phytoextraction was determined for the first time. This information is important for practical phytoremediation applications.