The conducted experiments showed that fish grown using feed containing probiotics with different mechanisms of action — enzymatic and antioxidant — showed gains and fatness coefficient exceeding the control values by more than 7 % and 5–13 %, respectively, with a decrease in feed costs of 6.7 %. Analysis of weight distribution among the studied fish groups revealed that in the experiments the percentage of individuals with higher body weight was higher by 9.65 and 14.75 %, amounting to 58.16 and 63.26 %, respectively. In the open field test, the juvenile sterlet from the 2nd experimental group recorded orientation activity, which was lower than in the 1st experimental and control groups by 3.79 % and 1.61 %, respectively, amounting to 34.8 units/min. However, the background motor activity in this group was the highest — 36.78 units/min. In the 1st experimental and control groups, on the contrary, a decrease in this indicator was observed. It was found that in individuals of the experimental groups, an increase in the reaction to the primary stimulus (vibroacoustic stimulus) was observed, followed by a sharp decrease in activity when exposed to the second stimulus. This indicates the manifestation of a defensive reaction (freezing), characteristic of sturgeon fish. In the control group, the reaction to the primary stimulus also increases, but to a lesser extent, and then remains almost unchanged. After exposure to the third stimulus, the activity of individuals of the control group does not return to the original level, exceeding it by 13.35%. At the same time, in individuals of the experimental groups, the activity approaches the background level. The ratio of orienting activity to background activity (activation level) in fish of the second experimental group was 13.9% lower than in the first experimental and control groups. This indicates that fish from the first experimental and control groups exhibit higher activity when entering a new environment. At the same time, individuals from the second experimental group demonstrate more restrained motor behavior. The reactivity indices in the experimental groups under the influence of low-frequency sound are 1,46–10,54 % higher, under short-term light stimulus and constant light exposure they are lower by 12.09–27.47 % and by 9.72–14.88 % in the 2nd and 1st groups, respectively, compared to the control group. Fish fed with feeds with experimental probiotic additives demonstrated increased resistance to high temperature and salinity. The highest heat resistance and salt tolerance were shown by fish from the first experimental group. Probiotic preparations with targeted action stimulate growth and stabilize the physiological state of fish in extreme conditions.

Aim of the Study: To evaluate the effects of feed supplementation of Bacillus subtilis KATMIRA1933 (0.1%), B. subtilis KB41 (0.1%), and Bacillus amyloliquefaciens KB54 (0.1%) probiotics on growth performance, biochemical blood parameters, intestinal morphology, and the immune system of Ross 308 broilers housed on deep litter. Methods and Results: A total of 160 newly hatched Ross 308 broilers were involved in the 42-day-long study with evaluation of growth performance at 7, 14, 21, 28, 35, and 42 d and biochemical blood analysis, histological investigation of jejunum tissues, and analysis of IL-6 and IL-10 gene expression of broilers at 42 d. As a result, probiotic KB41 significantly improved growth performance on the 42nd day of the experiment (P < 0.01), increased the number of Lactobacillus bacteria in the ceca (P = 0.03), and promoted IL-6 and IL-10 genes expression in the spleen of the chickens (P < 0.01). The results of this study generally correspond to our previous study, which included an evaluation of Bacillus-based KB41 and KB54 probiotics on production performance and the immune system of broilers housed in cages, although the effects are less prominent. Conclusions: Less prominent effects are probably linked to the colonization of the broilers' gastrointestinal tract with unknown bacilli of apparent environmental origin, as the broilers were housed in standard conditions. Significance and Impact of Study: This study provides more evidence of B. subtilis KB41 and B. amyloliquefaciens KB54 effectiveness in poultry.

The share of microorganisms cultivated in laboratory conditions from the total diversity of prokaryotes is no more than 0.1%. At the same time, with the help of metagenomic and metatranscriptomic analysis methods, it is annually possible to identify new taxonomic groups of microorganisms that do not have cultivated representatives. One of the most important parameters affecting the cultivability of microorganisms is the composition of atmospheric gases in the environment. The study analyzed the cultivated part of the soil microbial community under conditions of high CO2 content, namely 5% of the composition of the gas mixture, in oligotrophic media.

Экспериментально изучено влияние пробиотических препаратов в составе корма на рост, развитие и поведенческие реакции молоди рыб разных видов: стерляди, гибрида белуги и стерляди, чешуйчатого карпа - в условиях установок с замкнутым водообеспечением. Корма, содержащие пробиотические добавки, способствовали интенсивному росту и высокой выживаемости рыб (до 100 %). В ходе эксперимента в группах «опыт» отмечен наибольший прирост массы по показателям абсолютного и среднесуточного прироста, что говорит об эффективности использования кормов. Кормовой коэффициент в варианте «опыт» для карпа оказался ниже по сравнению с контролем на 1.25 единицы, или на 21 %. Исследование двигательной активности молоди рыб после кормления экспериментальными кормами выявило положительные изменения в их поведении. Молодь из группы «опыт» лучше адаптировалась к новым условиям среды и проявляла более высокую устойчивость к стрессовым раздражителям. Таким образом, полученные результаты подчеркивают потенциальные преимущества использования пробиотиков в составе кормов для улучшения роста и здоровья молоди рыб.

В настоящее время происходит бурный рост и развитие отечественного кормопроизводства, появляются новые рецептуры комбинированных кормов. В связи с этим растет необходимость в качественной оценке эффективности различных добавок, входящих в состав этих кормов, и для этого необходима надежная модель для оценки состояния рыбы. Проанализировано изменение морфологических и физиологических признаков, а также состояния микробиома у стерляди, потреблявшей корма различного качества, для определения физиологических показателей, наиболее подверженных влиянию состава пищи. Стерлядь, получавшая корм ненадлежащего качества, в среднем обладала на 7 % меньшей конечной массой, кровь рыб характеризовалась значительным падением уровня триглицеридов и β-липопротеидов в конце эксперимента. Результаты анализа кишечного микробиома показали, что у стерляди, получавшей некачественный корм, в кишечнике увеличивалось количество Enterococcus и актиномицетов, а также появлялось значительное количество представителей лактозоположительных бактерий, которые отсутствовали у особей из контрольной группы. Кроме того, у рыб, получавших некачественный корм, но остававшихся в хорошем физиологическом состоянии, в кишечнике были обнаружены бактерии Bacillus , отсутствовавшие у других групп, что может говорить о потенциальной пробиотической активности бактерий рода Bacillus, выделенных из их микробиома.

This review aims to systematize data on the construction and applications of bacterial lux-biosensors in various fields ranging from investigation of gene regulation and regulatory networks to the new probiotics' search and ecotoxicological research. The typical technical solutions and devices required for diverse tasks applying lux-biosensors are reviewed. Aspects of the application of lux-biosensors in fundamental researches, such as the study of oxidative stress, heat shock, DNA-damaging, pro- and antioxidant activities, are also considered. This technology allows rapid screening of the biological activities of newly synthesized compounds, which could be applied as components for fuels, household chemicals, and drugs. Works related to the ecological state assessment on water resources are also described. The use of lux-biosensor complexes based on different organisms, including both gram-positive and gram-negative bacteria, makes toxicological investigations more comprehensive. Bacterial lux-biosensors based on Escherichia coli can be used as a model for evaluation of the effect of certain substances on the transmembrane potential in mitochondria, albeit with extrapolation to a certain extent. Another aspect that draws our interest is that biosensors are able to help predict some systemic properties of probiotics. In the future, it's quite promising to see more applications of lux-biosensors for environmental control, microbial-microbial interaction assessment, antioxidant action mechanism studies and toxicological studies in the development of new drugs.

This paper presents the results of the investigation of the effect of probiotic preparations based on Bacillus strains on Artemia salina nauplii. The use of live food is a necessary step in cultivation of many fish species, and Artemia nauplii are widely used for this purpose. It is crucial to use probiotics in aquaculture, as they can act as natural antagonists of aquatic pathogens, as well as stimulate fish growth and development. This work aims to study the immobilization of probiotic Bacillus strains on Artemia nauplii in order to develop highly effective feeds with probiotic properties for juvenile fish. Experiments on the introduction of various doses of preparations based on three probiotic strains of Bacillus into the water during the rearing of Artemia salina cysts were carried out. The number of bacteria in the water, as well as on the surface and inside the nauplii, was estimated by plating on nutrient media. It has been established that, despite the fact that brine shrimps do not feed at the orthonauplius stage, when probiotic strains are introduced into the water, bacteria are immobilized on the covers of the crustaceans; the concentration of the introduced Bacillus strains in the wipe samples taken from the nauplii surface is 1 order higher than it is for the planktonic form in the water. The introduction of bacilli at a dose of 0.0017 g/L activated the release of nauplii from cysts by 9-41 % of the control, while increasing the dose to 0.17 g/L led to a decrease in the proportion of hatched crustaceans. Thus, if the correct dosage were identified, it would make it possible to accomplish two important tasks at once: to obtain the live feed with probiotic properties for fish larvae and to increase the yield of nauplii.

The initial screening of probiotic strains in vitro, carried out by different methods, may omit strains that are promising from the point of view of biotechnology or, conversely, mark as promising strains those that will lose activity when transferred in vivo. It is known that the release of metabolites by probiotic bacteria, in particular, lactobacilli, is highly dependent on the biochemical context. In this work, we modified the method that was previously successfully used for the selection of probiotics for poultry, based on their antioxidant and DNA-protective properties. A comparison was made of this activity on standard media and on an artificial intesti-nal medium that mimics the intestines of a bird. As a result, three Lactobacillus strains were selected, which not only exhibit antioxidant and DNA-protective properties but also do not lose these activities in an artificial in-testinal medium.

The article examines the influence of the oilcakes of lavender, camelina, nigella, mustard on the microbiota composition in the model of the bird's intestines. It has been shown that the cakes of mustard, camelina and lavender exhibit prebiotic activity in a model of an artificial intestinal environment inoculated with a starter from the gastrointestinal tract of chickens. Nigella cake in this model does not show activity. The activity lies in the fact that the presence of oilcake in the environment reduces the content of proteobacteria, among which there are many representatives of pathogenic microflora, and increases or does not affect the content of probiotic lacto- and bifidobacteria. The effect develops gradually and is dosedependent. It was found that the cake of the studied plants at a concentration of 1% and higher increased the pH of the medium, which may be one of the mechanisms of influence on the balance of the intestinal microbiota.

The possibility of using bacteria of the order Bacillales as agents of biological control of phytopathogenic fungi of the genus Fusarium was studied. In the work, 28 soil samples were studied, from which antagonist bacterial strains were isolated. Antagonism was detected by cultivating a pasteurized soil suspension with a culture of the fungus Fusarium graminearum on wort agar. In the course of this work, 1040 antagonist bacterial strains were isolated. Subsequently, the influence of the selected strains of microorganisms on the germination winter wheat seeds and several other morphometric parameters was studied.

Probiotic preparations are used in medical treatment and in agricultural practice. They modulate numerous activities in eukaryotic hosts, such as: inhibition of pathogenic microbiota; stimulation of immunological responses; and production of antioxidants, anti-mutagens, and DNA protectors. Also, probiotic bacteria are used as a preventive measure to prevent bacterial diseases of the gastrointestinal tract. Solid-phase fermentation is reported as being used in the production of probiotic formulations where a solid substratum, such as soy and oil meal, is utilized for the growth of beneficial microorganisms. However, there are insufficient reports in the literature related to methodological approaches enabling evaluation of the final products of solid-phase fermentation. We suggest a novel method enabling evaluation of probiotic solid-state fermentation dry powders and observation of their morphology, ultrastructure, and elucidation of the quantitative distribution of probiotic microorganisms in solid substrates using electron microscopy. •The method is intended for ultrastructure microphotography of dry substances - for example, ultrastructure of solid-phase fermentation products.•The method allows preserving the ultrastructure of substrates that are damaged when soaking.•The method does not require additional equipment and reagents and can be used in all laboratories using electron microscopy.

The study aims at investigating the effect of preparations of two bacilli strains on laying hens and roosters. Preparations were based on the strains Bacillus subtilis KATMIRA1933 and Bacillus amyloliquefaciens B-1895. Several groups of roosters and hens received a preparation based on either strain, or a mixture of both, from the first day to the last day of poultry in production. These preparations improved egg production, quality of sperm production, quality/hatchery of eggs, and slowed down the reproductive aging of hens. These observations were confirmed by the mathematical model proposed herein. At the molecular level, the slowing down of aging was confirmed by a decrease in the amount of mitochondrial DNA damage. Monitoring the physiological parameters of the experimental and control groups of birds showed that live weight gain in all experimental groups was higher than in the control group, and the reproductive organs of hens were more developed. There was also an improvement in the biochemical parameters of blood, the quality of the sperm of roosters, the laying of laying hens, and the morphological and biochemical parameters of the eggs. One of the most significant results is an increase in egg fertilization and a decrease in embryo death during the first 7 days of incubation.

The use of platinum-based anticancer drugs is limited by both their side effects and their effect on normal microflora's metagenome. Drugs that possess mutagenic and genotoxic properties may cause mutations in microbial genomes that contribute to the emergence of resistance to antimicrobial preparations and the development of complications after chemotherapy. The effects of cisplatin and oxaliplatin on microorganisms were studied using bacterial biosensors-E. coli strains MG1655 pKatG-lux, which reacts to the generation of hydrogen peroxide; MG1655 pSoxS-lux, which reacts to the superoxide anion radical; and the MG1655 pColD-lux strain, which detects DNA damage. The biosensor tests demonstrated high levels of genotoxicity for both drugs and some differences in the spectrum of reactive oxygen species generated. Ascorbate reduced genotoxicity of cisplatin by 41%. Nonlethal doses of cisplatin induced a three- to sevenfold increase in the frequency of the mutations that confer the resistance of E. coli to rifampicin and ciprofloxacin. Ascorbate also reduced frequency of the mutations by 65%. Thus, the effect of these drugs was probably associated with the generation of reactive oxygen species and induction of SOS response. The risk of secondary antibiotic-resistant infections may be decreased by applying antioxidants and antimutagens. At the same time, these increases may also decrease the anti-tumoral action of these compounds.

Mitochondria have long been studied as the main energy source and one of the most important generators of reactive oxygen species in the eukaryotic cell. Yet, new data suggest mitochondria serve as a powerful cellular regulator, pathway trigger, and signal hub. Some of these crucial mitochondrial functions appear to be associated with RNP-granules. Deep and versatile involvement of mitochondria in general cellular regulation may be the legacy of parasitic behavior of the ancestors of mitochondria in the host cells. In this regard, we also discuss here the perspectives of using mitochondria-targeted compounds for systemic correction of phenoptotic shifts.

The capability of the dioxidine drug to cause bacterial resistance to antibiotics was studied. The study was performed with the use of a bioluminescent test and the recombinant E. coli strains MG 1655 (pSoxS-lux), MG1655 (pKatG-lux), MG1655 (pRecA-lux), and MG1655 (pColD-lux). The strains harbored plasmids with the operon luxCDABE from the photobacteria Photorhabdus luminescens under control of the corresponding E. coli stress-inducible promoters. The mutation frequency of the stable mutants was found by conventional methods for nonpathogenic and opportunistic strains of E. coli, Bacillus amyloliquefaciens, and Klebsiella pneumoniae. Dioxidine was shown to induce the promoters PrecA and Pcda in E. coli MG1655, which suggests the induction of the SOS-response in bacterial cells. The Pcda induction was higher than with PrecA. The value of the induction coefficient was highest if the dioxidine concentration was 2.25 × 10–5 M. Moreover, this drug enhanced the induction of the SoxS and KatG promoters responding to the superoxide anion radical and hydrogen peroxide, which suggests possible participation of oxidative mechanisms in dioxidine DNA damage. The maximal value of the induction coefficient was also observed under conditions of 2.25 × 10–5 M. Dioxidine can induce mutations leading to antibiotic resistance in all bacterial strains studied. An increase in mutation frequency was observed for rifampicin (twofold), ciprofloxacin (sixfold), and azithromycin (fourfold). These data show the necessity for an antibiogram for every patient who is taking or has taken dioxidine.

Oligopeptides present in the living cell were found to have antioxidative activity and to be involved in the regulation of antioxidant balance by interaction with the redox-dependent cellular signaling cascades. Experiments on animal models have shown that the introduction of oligopeptides causes geroprotective and adaptogenic effects. In the present work, we investigate the biological action of a number of synthetic oligopeptides using bacterial biosensors. This approach allows us to precisely estimate the antioxidant properties of the compounds without affecting their participation in regulatory cascades typical to eukaryotic cells. It has been shown that the ability of oligopeptides to protect cells from action of physical prooxidant factors (UV irradiation) is related to the presence of a lysine residue in the molecule. For chemical pro-oxidants (dioxidine), we have observed a similar, though less strict pattern. This effect also correlates with DNA-protective activity of the investigated oligopeptides.