Microflora of sputum and autopsy material of patients with COVID-19.

The rapid spread of a new coronavirus infection in the country actualizes the conduct of bacteriological studies of clinical material obtained from the respiratory tract of patients with COVID-19. During the experiments, 230 sputum samples and 260 autopsy lung samples from patients with COVID-19 were analyzed. 946 high-risk strains were isolated and identified by MALDI-ToF mass spectrometry on a Microflex LT instrument (Bruker®). According to the results of bacteriological cultures of sputum, a predominance of gram-positive ones was revealed, amounting to 50.5% (222 strains) of the total number of isolated pathogens. However, falling into this group is manifested by natural representatives of the microflora of the human mucous membranes from the genera Streptococcus, Rothia and Lactobacillus (109 strains in total), which can be manifested by the detection of improper sputum collection, causing contamination by the substance of intense salivation and nasopharyngeal discharge. In turn, the "classic" gram-positive causative agents of pneumonia were detected much less frequently: S. aureus in 5 cases, S. pneumoniae in 6 patients. The causative agents in the order Enterobacterales are represented by 42 strains, among which the most likely species are K.pneumoniae (27 strains). In the group of non-fermenting gram-negative bacteria, A. baumanii (29 strains) prevailed, and P. aeruginosa was also identified in 2 cases. When analyzing the results of a microbiological study of autopsy material (lungs) of patients with COVID-19, significant differences in the qualitative and quantitative composition of the microflora were revealed, compared with sputum. In the group of gram-positive bacteria, 15 strains of the natural microflora of the mucous membranes were identified, while sensitive species dominated among gram-negative pathogens: K. pneumoniae (102 strains), A. baumanii (75 strains), P. aeruginosa (11 strains). Regular microbiological monitoring is essential for antibiotic therapy and prevention of secondary bacterial infection. In the event of a fatal outcome, the results of microbiological analysis of autopsy material can determine the cause of death of the patient.

[Microbial community of freshwater sponges in Lake Baikal].

The microbial community of Baikal sponges has been studied in five species belonging to the genera Swartschewskia, Baicalospongia, and Lubomirskia of the endemic family Lubomirskiidae. The results show that the total numbers of bacteria and bacterioplankton production have an effect on the growth of L. baicalensis body. Bacteria of the genera Pseudomonas, Bacillus, Micrococcus, Sarcina, Flavobacterium, Arthrobacter, and Acinetobacter living in the sponges are representatives of the Baikal bacterioplankton. Actinomycetes of the genera Streptomyces and Micromonospora are a permanent component of the cultivable sponge microbial community. The numbers and enzyme activities of heterotrophic, oligotrophic, and psychrophilic bacteria isolated from different sponge species and the surrounding water in autumn and in winter have been estimated.

[Response of microbial communities of Lake Baikal to extreme temperatures].

The survival rate, metabolic activity, and ability for growth of microbial communities of Lake Baikal after exposure to extremely low temperatures (freeze-thawing) for different lengths of time have been first studied. It has been shown that short-term freezing (1-3 days) inhibits the growth and activity of microbial communities. The quantity of microorganisms increased after 7- and 15-day freezing. In the periods of maximums, the total number of microorganisms in the test samples was twice as high as in the control. It was established that after more prolonged freezing the microorganisms required more time after thawing to adapt to new conditions. In the variants with 7- and 15-day freezing, the activities of defrosted microbial communities were three or more times higher than in the control. The survival rate and activity of Baikal microorganisms after freeze-thawing confirms the fact that the Baikal microbial communities are highly resistant to this type of stress impact.

[The classification and the monitoring of the state of mouth riverine and lacustrine ecosystems in lake Baikal based on the composition of local microbiocenoses and their activity]. / Struktura mikrobiotsenozov i ikh aktivnost' kak osnova klassifikatsii i monitoringa sostoianiia rechnykh i priust'evykh lokal'nykh ékosistem Baikala.

The paper presents the results of the long-term investigation of microbial communities in the technogenically vulnerable mouth riverine and lacustrine ecosystems of Lake Baikal. The structural and functional parameters of the microbial communities were analyzed from the standpoint of developing destructive processes. The analysis showed that the total number of microorganisms (TNM), the number of saprophytic bacteria (NSB), and bacterial production (BP) were greater in the river-mouth water than in the near-mouth lake water. In the offshore direction, TNM and NSB decreased by a factor of 1.5 to 2, and BP decreased by a factor of 4 to 7. Based on TNM, NSB, and BP data, we classified the Lake Baikal rivers with respect to the degree of the impact of human activities on them. The degrading capability of the riverine microbial communities was found to be such that they degrade daily from tenths of a percent to 3.5% of the total amount of organic compounds polluted the river waters.

[Theoretical analysis of the continuous two-stage process of the biosynthesis of a metabolic product]. / Teoreticheskii analiz nepreryvnogo dvukhstadiinogo protsessa biosinteza produkta metabolizma.

A mathematical model for continuous biosynthesis of a metabolite in a battery of two apparatuses with ideal agitation is described and analysed. In the first apparatus of the battery it is advisable to maintain a high specific rate of culture growth for continuous accumulation of young active biomass while in the second apparatus a low growth rate is expedient which provides a change in the culture metabolism to biosynthesis of the required product. To make the continuous two-stage process efficient, it is necessary to add an extremely concentrated solution of the nutrients to the second apparatus of the battery. Influence of the oxygen transport velocity on the maximum attainable concentration of the biomass and the process capacity by the required product was studied.

[Optimization of oxytetracycline biosynthesis]. / Optimizatsiia biosinteza oksitetratsiklina.

It was shown that rising of temperature up to 30 degrees C at the stage of the oxytetracycline-producing organism growth promoted acceleration of the culture growth rate and increasing of the antibiotic concentration by the 114th hour of the biosynthetic process. For the apparatus used in the study optimal aeration and agitation conditions were developed. To provide optimal parameters during biosynthesis of oxytetracycline, it was recommended to use the aeration rate of 1 v/v.min and the specific mechanical power for mixing of not less than 1 kW/m3.

[Conditions for the standardization of the process of cephalosporin biosynthesis]. / Issledovanie uslovii masshtabirovaniia protsessa biosinteza tsefalosporina.

Dependence of the final results of cephalosporin biosynthesis on the parameters of the operating conditions and the design of fermentors was shown. The value of the specific power input for agitation had a significant effect on the biosynthetic process. An equation for estimating the final results of the biosynthetic process by the values of the operating conditions and the fermentor design parameters is presented.

[Effect of mass exchange conditions on the biosynthesis of oxytetracycline]. / Izuchenie vliianiia uslovii massoobmena na biosintez oksitetratsiklina.

An increase in the power input for agitation from 0.4 to 2.7 kw/m3 in oxytetracycline biosynthesis stimulated the antibiotic production due to an accelerated use of carbohydrate and nitrogen and an earlier transition of the culture to the phase of the antibiotic biosynthesis. The procedure for determination of the aeration and agitation conditions by the maximum rate of the oxygen uptake is described. The procedure is recommended for the use in the studies on determination of such conditions for the biosynthesis of of oxytetracycline in large apparatus.

[Effect of temperature on the kinetics of the oxytetracycline biosynthesis process]. / Vliianie temperatury na kinetiku protsessa biosinteza oksitetratsiklina.

Short-term experiments on the effect of temperature on the rate of oxytetracycline biosynthesis and consumption of carbohydrates, ammonium nitrogen and inorganic phosphorus were performed under various conditions of mass exchange. Complete fermentation cycles were also carried out at the same temperatures. It was shown that the temperature optimal under conditions of a short-term experiment was not optimal for the complete fermentation cycle. In the latter case the results also depended on the aeration and agitation conditions. It is suggested that temperature has a nonspecific effect by changing the conditions of oxygen supply to the microbial culture.

[Effect of the growth conditions for the inoculum on cephalosporin biosynthesis]. / Vliianie uslovii vyrashchivaniia posevnogo materiala na biosintez tsefalosporina.

It was shown that intensification of cephalosporin biosynthesis is possible with the use of the inoculum grown on the seed medium enriched with the sources of carbon and organic nitrogen. The inoculum grown on the initial medium is usually added to the fermentation medium by the 31st-33rd hour of the growth, while with the use of the enriched medium it is added to the fermentation medium by the 36th-38th hour. The intensity of the culture respiration is recommended to be used as a technological parameter for estimation of the time when the inoculum may be added to the fermentation medium.

[Experimental study of the dynamics in the biochemical parameter changes in the oxytetracycline biosynthesis process in apparatus of varying capacity]. / Eksperimental'noe izuchenie dinamiki izmeneniia biokhimicheskikh parametrov v protsesse biosinteza oksitetratsiklina v apparatakh razlichnogo masshtaba.

An increase in the input of the mechanical power speeds up the culture growth, which correlates with the rate of carbohydrate and nitrogen consumption during the first phase of the process, the time of the biosynthesis phase onset and the level of the antibiotic production during this phase. During the second half of the process the antibiotic biosynthesis markedly decreases, especially in the apparatus with a high input of the mechanical power. Deficiency in carbon and nitrogen is one of the causes of this decrease. The activity level at the end of the biosynthesis in such apparatus does not differ significantly, since it depends on the biosynthesis rate during the whole cultivation period.

[Annual production of bacterioplankton in the deep sea area of Southern Baikal]. / Produktsiia bakterioplanktona v pelagiali Iuzhnogo Baikala v godovom tsikle

The time of generation of bacterioplankton in the pelagic zone of Baikal differs in various seasons of the year: the minimum time is in December (25 hours), the maximum time is in October of 1970 (580 hours) and in June of 1971 (560 hours). Monthly production of bacteria for a layer of 0 to 50 m varies from 0.07 g in January to 49 g of wet weight per 1 m2 in September. Annual production of bacterioplankton in a layer of 0 to 50 m is 118.5 g of wet weight per 1 m2 of the lake surface. The P/B coefficient of micro-organisms varies from 0.02 in January to 1.1 in December. The most favourable conditions for bacterial growth therefore are in April, July--September, and December. The annual P/B is 4.42.

[Generation time of pure cultures of heterotrophic microorganisms isolated from Lake Baikal]. / Vremia generatsii chistykh kul'tur geterotrofnykh mikroorganizmov Baikala

Generation time was determined in pure cultures of heterotrophic microorganisms in the conditions similar to those of Baikal in June--July of 1972. Generation time was found to be 37+/-7, 16+/-2.5, 16+/-3.2, and 10+/-2.5 hours, respectively, when the cultures had been diluted with Baikal water in the following rations: 1 : 0,1 : 5,1 : 10, and 1 : 20. No differences in the growth rate were found among 11 cultures of heterotrophic microorganisms isolated from Baikal. Conditions limiting the microbial growth improve from the dilution of 1 : 0 to the dilution of 1 : 5. The mean time of generation is 27 hours for June--July. Generation time determined for pure cultures of heterotrophic microorganisms in the conditions similar to natural can be used to calculate production of the bacterial biomass for a definite period of the year.