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Solid food waste is a significant threat to the environment. Thermodynamic calculations allow determining theoretically possible metabolic pathways for degradation of organic compounds by microorganisms, and to select the optimal one to increase efficiency of food waste recycling. The purpose of our work was application of thermodynamic calculations to find out suitable fermentation parameters for regulation of microbial metabolism Environmental Research, Engineering and Management 2018/74/4 32 to ensure a high rate of waste decomposition and formation of valuable products. The following methods were used: colorimetric and potentiometric for pH and oxidation-reduction potential (ORP) measurement, volumetric and chromatographic for the study of volume and composition of synthesised gas, and mathematical for fermentation parameters calculation. Fermentation of multicomponent kitchen food waste under theoretically calculated optimal parameters pH = 7.0 and Eh in the range form-250 to-350 mV provided extremely high metabolic activity of a hydrogen-producing microbial community, which resulted in a decrease in duration of batch fermentation to three days and an increase in hydrogen yield from 16 to 80-115 L/kg of dry waste. The coefficient of waste destruction (Kd), i.e., the ratio of initial and final weight of waste, reached 91. Obtained after fermentation, an unfermented lignocellulosic substrate was shown to be applied as plant probiotics and to supply mineral nitrogen for plant nutrition in an arid condition. Thus, high efficiency of application of a thermodynamic prognosis method of microbial interaction with organic compounds was shown to become the base for biotechnology of destruction of environmentally hazardous solid food waste with simultaneous obtainment of valuable products: environmentally friendly energy carrier-molecular hydrogen, as well as a lignocellulosic substrate to increase crop yields.

Microbial communities o f the Ecuadorian Andes and volcano Tungurahua were shown to be super resistant to representative toxic metals. Maximum permissible concentrations o f toxic metals were 100 ppm o f Hg2+ , 500 ppm o f Co2+ and Ni2+ , 1000 and 1500 ppm o f Cr(VI), 10000 and 20000 ppm o f Cu2+. The effect o f metal concentration increasing on the biomass growth, CO2 and H2 synthesis was investigated. Two types o f response o f microbial communities on the increasing o f toxic metals concentrations were discovered. The first type o f response is the catastrophic inhibition o f microbial growth. The second type o f response is the absence o f microbial growth inhibition at certain metal concentration gradient. The succession o f qualitative structure o f Ecuadorian mi crobial communities was shown fo r the first time. Bacteria, yeasts and finally fungi consistently dominate in the microbial community at the Cu2+ concentration raising. Microorganisms resistant to ultra-high concentrations o f toxic metals (e.g., 3000 ... 20000 ppm o f Cu2+) were isolated from Ecuadorian ecosystems. These microorganisms are able to accumulate toxic metals.

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The diets and resource partitioning of six co‐occurring gobiids (Caucasian dwarf goby Knipowitschia caucasica; monkey goby, Neogobius fluviatilis; racer goby, Babka gymnotrachelus; round goby, Neogobius melanostomus; bighead goby, Ponticola kessleri; and western tubenose goby, Proterorhinus semilunaris) have been investigated in freshwater of the Dnieper River basin. The studied gobies were characterised by relatively similar generalised feeding strategies with the dominance of chironomid larvae in their diets, except Caucasian dwarf goby, the diet of which was dominated by copepods and cladocerans. The ontogenetic diet shift was clearly observed in all studied gobiids, except Caucasian dwarf gobies, adults of which had almost the same food spectrum as their juveniles. The highest diet overlaps were observed between monkey and racer gobies, and between monkey and round gobies. The lowest values of the diet overlap indices were recorded between Caucasian dwarf and round gobies, and between Caucasian dwarf and bighead gobies. Each studied goby species can be characterised by a unique set of features resulting in dietary partitioning such as consuming prey organisms inhabiting different microhabitats, different sizes, different spawning periods and ontogenetic diet shifts.