The developing resistance of plant pathogenic fungi to commercial fungicides has become a serious problem for efficient plant disease control. The use of antifungal preparations based on living microorganisms or their metabolites represents one of the possible environmentally friendly approaches. However, since a complete rejection of chemical fungicides is impossible, the combining of biopreparations and fungicides may be considered a promising biocontrol approach. Promising strains for the development of antifungal biopreparations include Penicillium fungi producing various biologically active compounds with antimicrobial and antiviral activities. A dry biomass of the P. chrysogenum F-24-28 strain (DMP) obtained from the P. chrysogenum VKPM F-1310 strain by induced mutagenesis possessed a high antifungal efficiency. According to in vitro experiments, supplementation of agarized medium with DMP (7.5–10 g/L) resulted in a significant growth inhibition in several plant pathogenic Fusarium fungi. The combination of DMP with a commercial azoxystrobin-based fungicide resulted in a prolonged growth inhibition in F. oxysporum, F. graminearum and F. culmorum even at fungicide concentrations significantly below the recommended level (0.5–2.5 mg/L or 2.5–12.5 g/ha vs. the recommended 100–275 g/ha). These results demonstrate a possibility to develop an efficient environmentally friendly biopreparation suitable to control crop diseases caused by a wide range of plant pathogens, and to prevent a possible selection and spreading of resistant pathogen strains.

Sclerotinia sclerotiorum (Lib.) de Bary is a plant pathogen with a wide host range, which causes significant yield and storage losses of edible roots and other plant products. Due to its ability to sclerotia formation, the efficient control of this pathogen is complicated. The study of five Bacillus strains (B. subtilis VKM B-3154D, VKM B-3155D, VKM B-3505D, VKM B-2998D, and B. amyloliquefaciens VKM B-3153D) showed their ability to produce polyene antibiotics suppressing the growth and development of plant pathogenic fungi. The maximum concentration of polyene compounds was revealed for B. subtilis VKM B-2998D. A high in vitro antifungal activity of a dry mycelium biomass (DMP) of Penicillium chrysogenum VKM F-4876D, B. subtilis VKM B-2998D, and their combination has been demonstrated in relation to S. sclerotiorum. A combined application of DMP (0.3 g/L) and azoxystrobin at low dosage (2.5 mg/L) showed a high suppressing activity towards S. sclerotiorum (100% growth inhibition) including inhibition of a sclerotia formation that may be useful for the development of efficient methods of crop protection against this plant pathogen. A high performance liquid chromatography (HPLC) analysis of DMP revealed the presence of mevastatin suggesting the mechanism of the DMP antifungal activity is based on the blocking of the ergosterol (the main component of fungal cell walls) biosynthesis. The results of the study provide a prerequisite to the development of biopreparations to control S. sclerotiorum, whose use may provide a reduction of concentrations of fungicides used in agriculture and the corresponding reduction of their negative xenobiotic impact on the environment and recovery of the ecological balance in the soil.

The normal functioning of a gastrointestinal microflora in poultry and livestock is of significant importance, since its imbalance negatively influences an organism’s functions. In this study, the UV mutagenesis and selection were used to obtain two Bacillus strains possessing antagonistic activity towards Escherichia coli and Staphylococcus aureus, and their potential as a probiotic feed additive was evaluated. Compared to the parental strains, the ability of B. subtilis RBT-7/32 and B. licheniformis RBT-11/17 strains to suppress E. coli increased by 77 and 63%, respectively; the corresponding ability of these strains to suppress S. aureus increased by 80 and 79%, respectively. RBT-11/17 could not utilize microcrystalline cellulose and carboxymethyl cellulose, whereas cellulolytic activity of RBT-7/32 was doubled compared to the initial strain. The amylolytic activity of new strains was increased by 40%. Cultivation of strains on media containing soybean, pea, and corn meal did not provide any difference in the biomass production compared to the control. The heating of a water suspension of a dried biomass of the strains for 10–20 min at 80 and 100 °C or incubation in water solutions of citric, ascorbic, acetic, and formic acids (pH 3.0) for 3 and 24 h at 40 °C did not provide any negative influence on the spore survivability. Both strains were evaluated for their resistance to a number of veterinary antibiotics. Thus, RBT-7/32 and RBT-11/17 strains have good prospects for use in feed additives.

The biological control of fungal crop diseases based on the use of micro-organisms or their metabolites is a promising environmentally friendly alternative to common fungicide-based technologies. Penicillium fungi which synthesize various biologically active compounds with a wide range of antimicrobial activity are of special interest as potential producers of antifungal biopreparations. The purpose of this study was the evaluation of the antifungal activity of a dry biomass of the Penicillium chrysogenum VKPM F-4876D strain (DMP), both individually and combined with commercial azoxystrobin-, fludioxonil-, difenoconazole-, and tebuconazole-based fungicides commonly used to control early blight, towards Alternaria solani, an infectious agent of this potato disease. The study was performed under in vitro (cultivation on solid and liquid media) and in vivo (detached potato leaves) conditions. The cultivation of A. solani on agarized medium supplemented with 5 g/L of DMP caused significant morphological changes in pathogen colonies, whereas 7.5 g/L of DMP resulted in complete suppression of pathogen development. DMP addition to the liquid culture of A. solani significantly increased electrolyte release, i.e., impaired the cell membrane integrity in the pathogen. Combining DMP (1–2 g/L) with fungicides at a dose range of 0.01–10 mg/L resulted in significant in vitro growth inhibition of A. solani. The best result was obtained for the combination of DMP (1 g/L) with fludioxonil (1–5 mg/L) or tebuconazole (10 mg/L): a significant and prolonged antifungal effect (96–97% growth inhibition) was observed during the whole 14-day period of observation. The treatment of detached potato leaves with 1 g/L of DMP prior to artificial infection with A. solani resulted in a four-fold increase in the number of uninfected leaves and a two-fold reduction in the number of severely infected leaves compared to the control. These results demonstrate the possibility to develop an efficient environmentally friendly approach to manage potato early blight and provide prerequisites for the reduction in pesticide load on agrobiocoenoses, thus contributing to the restoration of ecological balance and the prevention of the emergence and spread of resistant pathogen strains.

Carotenoids represent a group of isoprenoid pigments whose high biological activity is not limited to their provitamin properties. Due to their ability to participate in redox reactions, carotenes are increasingly considered as promising compounds in the prevention and correction of cardiovascular and neurodegenerative disorders, as well as in oncology and the treatment of various other diseases. Carotenoids are widely used in the manufacture of food additives and dyes, feed for aquaculture, farm animals and poultry, as well as in so-called nutraceuticals and cosmetics. When formulating optimal feeding rations, vitamin A nutrition is often considered separately due to its vital role in normal growth, development, maintenance and reproduction. The main precursor of vitamin A is β-carotene, which naturally enters the body exclusively via vegetable-based provender. However, since the carotene contained in plant raw materials is an unstable compound, the use of feed additives containing β-carotene becomes relevant. In industry, carotenoids can be produced either by chemical or biological synthesis. However, the majority of carotenoids – 80–90% – are obtained by chemical synthesis. At the same time, public demand for sustainable production dictates the need to find alternative approaches for obtaining this valuable commodity. The article provides an overview of the main biotechnological methods for the production of carotenes using various microorganisms, including microalgae, bacteria and fungi, as well as analysing the effect of culture conditions on the yield of target pigments.

A continuing interest of scientists regarding the development of new β-carotene production technologies is due to the high biological activity of this compound and its wide application range. Bacteria are considered among the possible β-carotene producers convenient for industrial use. The purpose of this study was to develop a Mycolicibacterium neoaurum strain with an enhanced ability for β-carotene production and to optimize the fermentation conditions to improve the final yield of the target compound. Using chemical mutagenesis with N-nitroso-N-methylurea along with further strain selection, a M. neoaurum strain Ac-501/22, whose productivity was 2.7-fold higher than that of the parental strain Ac-501, was developed. The effect of nitrogen and carbon sources as well as cultivation conditions on the growth of M. neoaurum Ac-501/22 and β-carotene production were studied to select the optimal fermentation regime. Due to an increase in the temperature of cultivation from 30 to 35 °C, replacement of glucose with glycerin (20.0 g/L) and degreased soybean flour with powdered milk (10.0 g/L), and increase in the urea content from 0.5 to 1.0 g/L, the level of β-carotene production was improved to 183.0 mg/kg that was 35% higher than in the control. Further strain fermentation in a 3 L bioreactor using an optimized medium with the pH level maintained at 7.0–7.2 and 50% pO₂ provided the maximum output of the target compound (262.4 mg/kg of dry biomass) that confirmed the prospects of the developed strain as an industrial β-carotene producer.