Ugotavljanje indikatorskih bakterij fekalnega onesnaženja in prisotnosti vrste Escherichia coli, ki tvori encime β-laktamaze v črni vodi

The aim of this study was to identify and quantify faecal indicator bacteria in blackwater collected from a source separation unit and determine the amount of E. coli isolates resistant to antimicrobials and their potential to produce extended spectrum β-lactamases (ESβLs) and metallo-β-lactamases (MβLs), which hydrolyse the most important antibiotics used in clinical practice. Most of the isolates were resistant to amoxicillin with clavulanic acid (36.4 %), followed by ticarcillin with clavulanic acid (22.7 %) and tetracycline (18.2 %). ESβL-producing genes blaCTX-M and blaTEM were found in three (13.6 %) and four (18.2 %) E. coli strains, respectively, while MβL genes were found in two (9.1 %). By separating at source, this pilot study clearly shows that gastrointestinal bacteria of healthy people can be an important source of antibiotic resistance released into the environment through wastewaters. One way to prevent that is to treat wastewater with a combination of TiO2, UV light, or ozone, as successful methods to remove resistant bacteria and prevent their spread in the environment.V vzorcih črne vode, ki je ena od frakcij odpadne vode, smo ugotavljali prisotnost in število fekalnih indikatorskih bakterij, vključno z bakterijo Escherichia coli (E. coli). Pri osamljenih sevih E. coli smo ugotavljali njihovo odpornost proti izbranim antibiotikom in njihov potencial za tvorbo nekaterih β-laktamaz razširjenega spektra in metalo-β-laktamaz. Preizkušeni sevi so bili najpogosteje odporni proti amoksicilinu s klavulansko kislino (36,4 %), tikarcilinu s klavulansko kislino (22,7 %) in tetraciklinu (18,2 %). Nukleotidne sekvence za blaCTX-M in blaTEM smo našli pri treh (13,6 %) in štirih (18,2 %) sevih, medtem ko smo gene za izbrane metalo-β-laktamaze ugotovili pri dveh (9,1 %) sevih E. coli. Pilotna študija, z ločevanjem odpadne vode na viru nastanka, kaže, da so bakterije v prebavnem traktu zdravih ljudi lahko pomemben vir prenosa odpornosti proti antibiotikom v okolju preko odpadne vode. Eden izmed načinov za preprečevanje širjenja odpornosti proti antibiotikom je čiščenje odpadne vode z uporabo kombinacije TiO2, UV svetlobe in ozona, ki so se pokazale kot uspešne metode za odstranjevanje bakterij, odpornih proti antibiotikom

Simply applicable method for microplastics determination in environmental samples

Microplastics (MPs) have gained significant attention in the last two decades and have been widely researched in the marine environment. There are, however, less studies on their presence, routes of entry, and impacts on the biota in the soil environment. One of the main issues in the study of MPs is a lack of standardized methods for their identification in environmental samples. Currently the most commonly used techniques are thermal desorption gas chromatography–mass spectrom etry (GC–MS) methods and pyrolysis followed by GC–MS. In this study, headspace-solid phase microextraction followed by GC–MS is proposed as a simple and widely applicable method for the de termination of commonly present polymer MPs (polyethylene terephthalate, polystyrene, polyvinyl chloride, polyethylene, and polypropylene) in environmental samples, for analytical laboratories with basic equipment worldwide. The proposed method is based on the identification of compounds, which are formed during the well-controlled melting process of specific coarse (1–5 mm) and fine fraction (1 mm–100 µm) MPs. The method was upgraded for the identification of individual polymer type in blends and in complex environmental matrices (soil and algae biomass). The successful application of the method in complex matrices makes it especially suitable for widescale use

Extraction and identification of a wide range of microplastic polymers in soil and compost

Microplastic pollution is globally widespreadhowever, the presence of microplastics in soil systems is poorly understood, due to the complexity of soils and a lack of standardised extraction methods. Two commonly used extraction methods were optimised and compared for the extraction of low-density (polyethylene (PE)) and high-density microplastics (polyethylene (PET)), olive-oil-based extraction, and density separation with zinc chloride (ZnCl2). Comparable recoveries in a low-organic-matter matrix (soilmost >98%) were observed, but in a high-organic-matter matrix (compost), density separation yielded higher recoveries (98 ± 4% vs. 80 ± 11%). Density separation was further tested for the extraction of five microplastic polymers spiked at different concentrations. Recoveries were >93% for both soil and compost, with no differences between matrices and individual polymers. Reduction in levels of organic matter in compost was tested before and after extraction, as well as combined. Double oxidation (Fenton’s reagent and 1 M NaOH) exhibited the highest reduction in organic matter. Extracted microplastic polymers were further identified via headspace solid-phase microextraction–gas chromatography–mass spectrometry (HS-SPME–GC–MS). This method has shown the potential for descriptive quantification of microplastic polymers. A linear relationship between the number of particles and the signal response was demonstrated for PET, polystyrene (PS), polyvinyl chloride (PVC), and PE (R$^2$ > 0.98 in alluvial soil, and R$^2$ > 0.80 in compost). The extraction and identification methods were demonstrated on an environmental sample of municipal biowaste compost, with the recovery of 36 ± 9 microplastic particles per 10 g of compost, and the detection of PS and PP