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Four novel Pseudomonas strains with record resistance to copper (Cu2+) previously isolated from ecologically diverse samples (P. lactis UKR1, P. panacis UKR2, P. veronii UKR3, and P. veronii UKR4) were tested against sonochemically synthesised copper-oxide (I) (Cu2O) and copper-oxide (II) (CuO) nanoparticles (NPs). Nanomaterials characterisation by X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and High-Resolution Transmission Electron Microscopy (HRTEM) confirmed the synthesis of CuO and Cu2O NPs. CuO NPs exhibited better performance in inhibiting bacterial growth due to their heightened capacity to induce oxidative stress. The greater stability and geometrical shape of CuO NPs were disclosed as important features associated with bacterial cell toxicity. SEM and TEM images confirmed that both NPs caused membrane disruption, altered cell morphology, and pronounced membrane vesiculation, a distinctive feature of bacteria dealing with stressor factors. Finally, Cu2O and CuO NPs effectively decreased the biofilm-forming ability of the Cu2+-resistant UKR strains as well as degraded pre-established biofilm, matching NPs’ antimicrobial performance. Despite the similarities in the mechanisms of action revealed by both NPs, distinctive behaviours were also detected for the different species of wild-type Pseudomonas analysed. In summary, these findings underscore the efficacy of nanotechnology-driven strategies for combating metal tolerance in bacteria.

Food resources are essential for the survival and growth of the population. Soil phytopathogenic nematodes cause great damage to agricultural crops, endangering food supplies and resources in general. Different methods have been used to control them. However, this issue still requires a more effective solution. Caenorhabditis elegans (CGC strain wild-type N2) was applied as a model with an Escherichia coli OP50 feeding substrate for nematodes. Our approach was based on the thermodynamically substantiated creation of growth conditions that are unfavorable for nematodes to suppress them irreversibly. The thermodynamic calculations showed that obligate anaerobic conditions, namely the absence of oxygen and a low redox potential (−100 mV and below), were potentially unacceptable for nematodes. Anaerobic conditions were created using both abiogenic (physicochemical) and biological methods. Abiogenic anaerobic conditions were achieved by preventing oxygen access and adding low-potential sodium sulfide (Eh = −250...−200 mV) to the cultivation medium. By applying biological methods, Pleurotus ostreatus Po4 and E. coli O2 was completely removed and the redox potential was decreased from +100…+200 mV to −100...−200 mV (in particular, due to the synthesis of H2S). Even the short-term exposure (1–2 days) of nematodes under anaerobic conditions led to their suppression and death. Thus, the short-term creation of anaerobic conditions in the soil may be an effective method to control, e.g., phytopathogenic aerobic nematodes. This research contributes to the development of foundations to preserve agricultural plants and increase crop yield as well as the development of an approach for the environmentally friendly control of phytopathogens.

Sugar beet (Beta vulgaris L.) is a valuable sugar-providing crop accounting for around 25% of global white sugar production. It is an integral part of the food industry. Several factors cause a decrease in the yield of this food crop. The infection of phytopathogenic fungi is one of the most hazardous. Though several methods to control Rhizoctonia solani have been developed, the problem is still not solved. Thus, the goal of this work was to investigate the effect of abiotic factors (pH, Eh, presence or absence of O2) and biotic ones (microbial community) on the fungal pathogen R. solani AG 2-2IIIB for its control and sugar beet protection. Microbiological methods were used to conduct the research. Thermodynamic calculations were applied to determine the conditions necessary for suppression of R. solani AG 2-2IIIB. As a result, a comparison of the effect of abiotic and biotic mediated factors on the efficiency of the growth of Rhizoctonia solani AG 2-2IIIB was carried out. Obtained data showed the following: mainly the abiotic factors provided via chemical buffers or removal of oxygen caused the inhibition of R. solani; the values of 5.5 ≤ pH ≤ 8.5, Eh ≤ −200 mV, and oxygen absence inhibited its growth. The maintenance of these factors via microbial communities enhanced the suppressive effect, bringing about the death of mycelium. The study of microbial strains revealed the inhibitory effect of microbial metabolites and provided more effective control of Rhizoctonia solani AG 2-2IIIB.

Environmental copper pollution causes major destruction to ecological systems, which require the development of environmentally friendly biotechnological, in particular, microbial methods for copper removal. These methods rely on the availability of microorganisms resistant to high levels of copper. Here we isolated four bacterial strains with record resistance to up to 1.0 M Cu(II). The strains were isolated from ecologically diverse soil samples, and their genomes were sequenced. A 16S rRNA sequence-based phylogenetic analysis identified that all four isolates belong to the genus Pseudomonas. Particularly, strains UKR1 and UKR2 isolated from Kyiv region in Ukraine were identified as P. lactis and P. panacis, respectively, and strains UKR3 and UKR4 isolated from Svalbard Island in the Arctic Ocean and Galindez Island in Antarctica, respectively, were identified as P. veronii. Initial in-silico screening for genes encoding copper resistance mechanisms showed that all four strains encode copper resistance proteins CopA, CopB, CopD, CopA3, CopZ, as well as two-component regulatory system CusRS, all known to be associated with metal resistance in Pseudomonas genus. Further detailed studies will aim to characterize the full genomic potential of the isolates to enable their application for copper bioremediation in contaminated soils and industrial wastewaters.

The weed Solidago canadensis L. poses a global threat to the environment as it spreads uncontrollably on roadsides, in forests, fields, meadows, and farmland. Goldenrod emits toxic substances that suppress other plants on the site, displacing wild ones. Thus, goldenrod conquers huge areas very quickly. The use of herbicides and mechanical methods does not solve the problem of the spontaneous spread of goldenrod. On the other hand, many scientists consider goldenrod as a valuable source of biologically active substances: flavonoids, phenolic compounds, vitamins, etc. In this study, we consider Solidago plants as a promising, free (cheap), and renewable substrate for the production of methane gas. The goal of the study was to identify the main patterns of degradation of the Solidago canadensis L. plant by methane-producing and sulfate-reducing bacteria with methane gas production and simultaneous detoxification of toxic copper. The composition of the gas phase was monitored by gas chromatography. The pH and redox potential parameters were determined potentiometrically; metal concentrations were measured by photometry. The concentration of flavonoids, sugars and phenolic compounds in plant biomass was determined according to well-known protocols. As a result of the study, high efficiencies of methane degradation in the Solidago plant and copper detoxification were obtained. Methane yield has reached the value of 68.2 L kg−1 TS of Solidago canadensis L. biomass. The degradation coefficient (Kd) was also high at 21.4. The Cu(II) was effectively immobilized by methanogens and sulfate reducers during the goldenrod degradation at the initial concentrations of 500 mg L−1. Thus, a new method of beneficial application of invasive plants was presented. The result confirms the possibility of using methanogenic microorganisms to produce methane gas from invasive weeds and detoxification of toxic metals.

The use of fossil fuels (methane, oil, etc.) is undergoing an unprecedented crisis now. There is the urgent need to search for alternative energy sources. A wide range of degraded organic materials can be effectively used to provide energy together with environmental protection. Soapstock is a hazardous waste containing a high concentration of toxic organic compounds of man-made origin (fatty acids, surfactants, dyes, etc.). To prevent environmental contamination such substances require an effective treatment approach. The goal of the study was to isolate the adapted-to-fatty-acids methanogenic microbiome and investigate the patterns of sodium acetate and soapstock degradation with simultaneous biomethane synthesis. The effectiveness of the degradation of sodium acetate and soapstock by non-adapted and adapted microbiomes was evaluated by decreasing the concentration of dissolved organic compounds. The effectiveness of the fermentation process was determined by the biogas (mixture of CH4 and CO2) yield. The most effective degradation occurred in the variant with sodium acetate and adapted methanogens and amounted to 77.9%. In other variants, the patterns and the efficiency of purification were similar ranging from 60.6 to 68.0%. The biomethane was mostly synthesized by adapted methanogens on the soapstock and sodium acetate as substrates. Thus, the CH4 yield was 368.4 L/kg of dissolved organic compounds or 127.5 L/kg of soapstock. The results of this study demonstrated the potential of methanogenic microorganisms in the biodegradation of soapstock with simultaneous biogas synthesis. The results can serve as a basis to reduce the reliance on fossil fuels by generating biomethane via the fermentation of toxic organics.

Environmental pollution by toxic metals is a common ecological problem. Chromium and copper compounds released into the environment as a result of human-made stress pose a serious threat to living organisms. Phytoremediation is a promising method of toxic metals removal from contaminated sites. The concentration of metals in grass biomass—in the roots and aerial parts—was determined by X-ray fluorescence analysis. The estimation of numbers of microorganisms was conducted by a tenfold dilution and spread-plating method. It was shown that lawn grass accumulated from 69.1 ± 13.2 to 497.7 ± 74.1 mg/kg Cu and Cr during the growth in the contaminated soil with 50, 100, and 200 mg/kg of metals. In general, there was a pattern of accumulation of copper in the aerial part of the grass and chromium in the roots. Thus, the total copper concentration in the aerial part ranged from 105.2 ± 23.8 to 497.7 ± 74.1 mg/kg of plant biomass. The total chromium concentration in the roots ranged from 156.4 ± 47.9 to 426.8 ± 62.5 mg/kg. The viability of the soil microbiome was not inhibited at such metal concentrations. The obtained data allow lawn grass to be considered as promising for the phytoremediation of contaminated areas.

A huge amount of organic waste is generated annually around the globe. The main sources of solid and liquid organic waste are municipalities and canning and food industries. Most of it is disposed of in an environmentally unfriendly way since none of the modern recycling technologies can cope with such immense volumes of waste. Microbiological and biotechnological approaches are extremely promising for solving this environmental problem. Moreover, organic waste can serve as the substrate to obtain alternative energy, such as biohydrogen (H2) and biomethane (CH4). This work aimed to design and test new technology for the degradation of food waste, coupled with biohydrogen and biomethane production, as well as liquid organic leachate purification. The effective treatment of waste was achieved due to the application of the specific granular microbial preparation. Microbiological and physicochemical methods were used to measure the fermentation parameters. As a result, a four-module direct flow installation efficiently couples spatial succession of anaerobic and aerobic bacteria with other micro- and macroorganisms to simultaneously recycle organic waste, remediate the resulting leachate, and generate biogas.

The aquatic plant Pistia stratiotes L. is environmentally hazardous and requires effective methods for its utilization. The harmfulness of these plants is determined by their excessive growth in water bodies and degradation of local aquatic ecosystems. Mechanical removal of these plants is widespread but requires fairly resource-intensive technology. However, these aquatic plants are polymer-containing substrates and have a great potential for conversion into bioenergy. The aim of the work was to determine the main patterns of Pistia stratiotes L. degradation via granular microbial preparation (GMP) to obtain biomethane gas while simultaneously detoxifying toxic copper compounds. The composition of the gas phase was determined via gas chromatography. The pH and redox potential parameters were determined potentiometrically, and Cu(II) concentration photocolorimetrically. Applying the preparation, high efficiency of biomethane fermentation of aquatic plants and Cu(II) detoxification were achieved. Biomethane yield reached 68.0 ± 11.1 L/kg VS of Pistia stratiotes L. biomass. The plants’ weight was decreased by 9 times. The Cu(II) was completely removed after 3 and 10 days of fermentation from initial concentrations of 100 ppm and 200 ppm, respectively. The result confirms the possibility of using the GMP to obtain biomethane from environmentally hazardous substrates and detoxify copper-contaminated fluids.

The constant increase in the amount of food waste accumulating in landfills and discharged into the water reservoirs causes environment pollution and threatens human health. Solid and liquid food wastes include fruit, vegetable, and meat residues, alcohol bard, and sewage from various food enterprises. These products contain high concentrations of biodegradable organic compounds and represent an inexpensive and renewable substrate for the hydrogen fermentation. The goal of the work was to study the efficiency of hydrogen obtaining and decomposition of solid and liquid food waste via fermentation by granular microbial preparation (GMP). The application of GMP improved the efficiency of the dark fermentation of food waste. Hydrogen yields reached 102 L/kg of solid waste and 2.3 L/L of liquid waste. The fermentation resulted in the 91-fold reduction in the weight of the solid waste, while the concentration of organics in the liquid waste decreased 3-fold. Our results demonstrated the potential of granular microbial preparations in the production of hydrogen via dark fermentation. Further development of this technology may help to clean up the environment and reduce the reliance on fossil fuels by generating green hydrogen via recycling of household and industrial organic wastes.

The new modification of potentiometric pH and Eh measuring was developed. The essence of the method is to measure pH and Eh in compact hermetic redox cell. This modification provides reliable and fast pH and Eh measuring with minimum expense of culture liquid (1 cm3 for each measuring). The application of the developed modification in microbiology was shown on the example of bacterial culture Kocuria carniphila isolated from Negev desert soil (Israel). Dynamics of the Eh changing in the growing culture allows establishing the influence of the carbon and energy sources concentration on the microbial growth, the rate of oxygen consumption and character of microbial interaction with toxic compounds. Copiotriphic conditions (800 mg/l C) were shown to be optimal for K. carniphila. It was shown that K. carniphila was resistant to 200 ppm of Cu2+, nevertheless it did not extract Cu2+ out of liquid medium.

An effective express method of determining organic compound concentration in biological systems (soil water extracts, culture liquid etc.) is developed. The method is based on the permanganate redox titration of carbon-containing sample in an acidic medium (pH ≈ 0) at temperature of 100°C. On the example of basic microbial metabolism of monosaccharides, alcohols, organic acids, the suitability of the method for quantitative determination of total organic carbons is shown. The method measures the rate of glucose consumption by Escherichia coli 926 (ATCC 8789) in M9 medium. We created the average calibration curve for determining carbon concentration in multi-component biological samples. The permanganate method provides high accuracy results which are comparable with the widely used phenol-sulfuric acid method. The sensitivity of the method to carbon concentration is 25 mg/l.

The method of sterile anaerobic centrifugation was developed. The essence of the method is centrifuging the suspensions of bacteria or insoluble metal compounds in sealed flasks immersed in a water layer. Dipping flasks in water prevents destruction of the flasks under the centrifugal force. The method provides the possibility to centrifuge in anaerobic (inert gas) atmosphere. Thus, the method allows obtaining biomass of both aerobic and anaerobic microorganisms in a sterile conditions and preparing sterile insoluble metal compounds.