Pure Cultures Of Bacteria Research Articles

Fermentation properties and potential prebiotic activity of HCl-breadfruit resistant starch type III by Lactobacillus plantarum ATCC 13649 and L. brevis ATCC 8287

HCl-breadfruit resistant starch type III (HCl-BFRS3) is a type of resistant starch (RS) produced from breadfruit (Artocarpus altilis). Generally, RS is the non-digestible starch fraction that resists digestion in the gastrointestinal tract, and is completely or partially fermented in the colon which gives it beneficial physiological effects as a potential prebiotic. The present work assessed the fermentation properties of HCl-BFRS3 produced by local underutilised food crops. HCl-BFRS3 with 57.86% of RS content was analsyed for its fermentation properties. In vitro fermentability of HCl-BFRS3 with pure cultures of lactic acid bacteria, LAB (Lactobacillus plantarum ATCC 13649 and L. brevis ATCC 8287), was studied. Their growth patterns, pH changes, and prebiotic activity score (PAS) along with four other different carbohydrate sources (glucose, inulin, fibersol-2, and breadfruit starch) and a control sample against Escherichia coli ATCC 11775 was evaluated after 72 h of fermentation. It was found that HCl-BFRS3 selectively supported the growth of both lactobacilli and E. coli ATCC 11775, in the range of 6.21 to 9.20 log10 CFU/mL. HCl-BFRS3 also decreased the pH from the fermentation by L. plantarum ATCC 13649 and L. brevis ATCC 8287 after 24 h. The highest PAS was obtained by L. plantarum ATCC 13649 grown on HCl-BFRS3 (+1.69) as compared to inulin and fibersol-2. In conclusion, HCl-BFRS3 could be exploited as a prebiotic that benefits human health. Nevertheless, further assessment on the suitability of HCl-BFRS3 as a prebiotic material needs to be carried out.

Removal of Antimony in Wastewater by Antimony Tolerant Sulfate-Reducing Bacteria Isolated from Municipal Sludge.

Antimony (Sb), a global and priority controlled pollutant, causes severe environmental issues. Bioremediation by microbial communities containing sulfate-reducing bacteria (SRB) is considered to be among the safest, economical, and environmentally friendly methods to remove Sb from wastewater. However, the roles of SRB species in these communities remain uncertain, and pure cultures of bacteria that may be highly efficient have not yet been developed for Sb removal. In this study, an Sb tolerant community was enriched from municipal sludge, and molecular ecological analysis showed that Escherichia (40%) and Desulfovibrio (15%) were the dominant bacteria. Further isolation and identification showed that the enriched SRB strains were closely related to Cupidesulfovibrio oxamicus, based on the molecular analyses of 16S rRNA and dsrB genes. Among them, a strain named SRB49 exhibited the highest activity in removal of Sb(V). SRB49 was able to remove 95% of Sb(V) at a concentration of 100 mg/L within 48 h under optimum conditions: a temperature of 37–40 °C, an initial pH value of 8, 4 mM of sulfate, and an initial redox potential of 145–229 mV. SEM-EDX analysis showed that SRB49 did not adsorb Sb(V) but reduced and precipitated Sb(V) via the formation of Sb2S3. The results demonstrated the potential roles that pure cultures of SRB species may play in Sb removal and the use of Sb-tolerant SRB strains for Sb remediation.

Microbiological features of the salt lakes of the Kulunda lake system

The object of the study was the water and bottom sediments of the Bolshoye Yarovoye and Burlinskoye salt lakes located in the Kulunda steppe lowland and having recreational value. The aim of this work is to study the antibacterial and anti-candidiasis properties of water and bottom sediments of lakes in the Kulunda lake region in the context of their ecological state. The main factors affecting the basins of lakes B. Yarovoe and Burlinskoe are the intensification of the recreational load due to the development of domestic tourism, the activities of industrial enterprises, and, as a consequence, the washout of pollutants, the extraction and transportation of salt (in Lake Burlinskoe) and the almost complete extraction of silt mud. (in Lake B. Yarovoe), plowing of adjacent territories. No causative agents of infectious diseases were found in the water and bottom sediments, and the total microbial count is about 102 CFU / ml. The predominant group of microorganisms found on agar culture media are non-spore-bearing bacteria. The water of the salty lake B. Yarovoe, filtered from microorganisms, possesses inhibitory properties in relation to all studied 14 gram-positive and gram-negative test strains of microorganisms, and the water of Lake Burlinskoye in relation to nine strains: gram-negative bacteria Salmonella sonnei 32, Klebsiella pneumonia В-4894, Рseudomonas mirabilis 160205, Serratia marcescens d, Pseudomonas aeruginosa ATCC 9027, Escherichia coli 6645 ATCC 25922, gram-positive bacteria Staphylococcus aureus ATCC 6538, Mycobacterium smegmatis GK and regarding the causative agent of candidiasis Candida albicans 620. It was also shown that pure cultures of spore-forming bacteria isolated from the water and bottom sediments of the studied lakes also have antagonistic activity. The ecological stability of lake ecosystems, in spite of anthropogenic transformation and climatic changes affecting the water and salt regime, is based on biogenic processes that provide resistance to microorganisms introduced from outside, including pathogenic ones, and their elimination.

Development of an isothermal recombinase-aided amplification assay for the rapid and visualized detection of Klebsiella pneumoniae.

Klebsiella pneumoniae is a zoonotic opportunistic pathogen, leading to severe infections in dairy cows and humans. Efficient, on-site and accurate detection of K. pneumoniae is necessary to reduce the harm of cow mastitis and human infections. The objective of this study was to establish a recombinase-aided amplification (RAA) method combined with lateral flow dipstick (LFD) for rapid detection of K. pneumoniae. The primer concentration, incubation temperature and incubation time of the RAA reaction were optimized. When the primer concentration was 100 nmol L-1 , the strongest band could be obtained by incubation at 37 °C for 20 min. The RAA-LFD method had high specificity to K. pneumoniae and showed no cross-reaction with other pathogens. In addition, the detection limit of RAA-LFD for K. pneumoniae was 20 fg genomic DNA and 2.5 × 102 CFU mL-1 of bacteria in pure culture, which is 100 times higher than that of polymerase chain reaction (PCR) detection. Moreover, the RAA-LFD method can detect K. pneumoniae at initial concentrations as low as 2.5CFU per 25 mL in artificially spiked milk samples after at least incubation for 6h. Importantly, RAA-LFD had a high agreement with a test accuracy of 96.9%, compared with the biochemical identification method. Also, the detection accuracy of RAA-LFD was higher than that of the PCR assay (95.3%). The results demonstrated that the RAA-LFD assay is an accurate, sensitive, simple and point-of-use detection method for K. pneumoniae, which could be used as a potential application in the research laboratory and for disease diagnosis. © 2021 Society of Chemical Industry.

Mesophilic and Thermophilic Anaerobic Digestion of Wheat Straw in a CSTR System with 'Synthetic Manure': Impact of Nickel and Tungsten on Methane Yields, Cell Count, and Microbiome.

Lignocellulosic residues, such as straw, are currently considered as candidates for biogas production. Therefore, straw fermentations were performed to quantitatively estimate methane yields and cell counts, as well as to qualitatively determine the microbiome. Six fully automated, continuously stirred biogas reactors were used: three mesophilic (41 °C) and three thermophilic (58 °C). They were fed every 8 h with milled wheat straw suspension in a defined, buffered salt solution, called ‘synthetic manure’. Total reflection X-ray fluorescence spectrometry analyses showed nickel and tungsten deficiency in the straw suspension. Supplementation of nickel and subsequently tungsten, or with an increasing combined dosage of both elements, resulted in a final concentration of approximately 0.1 mg/L active, dissolved tungsten ions, which caused an increase of the specific methane production, up to 63% under mesophilic and 31% under thermophilic conditions. That is the same optimal range for pure cultures of methanogens or bacteria found in literature. A simultaneous decrease of volatile fatty acids occurred. The Ni/W effect occurred with all three organic loading rates, being 4.5, 7.5, and 9.0 g volatile solids per litre and day, with a concomitant hydraulic retention time of 18, 10, or 8 days, respectively. A maximum specific methane production of 0.254 m3 CH4, under standard temperature and pressure per kg volatile solids (almost 90% degradation), was obtained. After the final supplementation of tungsten, the cell counts of methanogens increased by 300%, while the total microbial cell counts increased by only 3–62%. The mesophilic methanogenic microflora was shifted from the acetotrophic Methanosaeta to the hydrogenotrophic Methanoculleus (85%) by tungsten, whereas the H2-CO2-converter, Methanothermobacter, always dominated in the thermophilic fermenters.

THE EFFICIENCY OF THE WATER PURIFICATION PROCESS FROM BACTERIA DEPENDING ON THE GAS NATURE

A study of the influence of different gas nature on the efficiency of water purification from rod-shaped bacteria of the Bacillus cereus type is presented. The action of oxygen, carbon dioxide and inert argon and helium were used. The investigated water was model microbial water obtained on the basis of deaerated distilled water with the introduction of a pure culture of bacteria in the amount of 7 · 104 CFU/cm3. The total duration of the process was 2 hours at a reaction medium with temperature of 288 ± 1 K. The change in the number of microorganisms from the duration of gas bubbling is shown, depending on its nature. The degrees of destroyed microorganisms were calculated after each sampling of water (Dd), which was taken after each 30 min of the process. Studying the influence of different modes of water treatment, the largest number of destroyed bacterial cells was studied in an atmosphere of carbon dioxide (Dd = 91.0 %), and the smallest - in an atmosphere of oxygen (Dd = 34.73%). A two-stage process of number of microorganisms change was detected in the oxygen atmosphere: an increase in the first stage during 1800 s and a subsequent decrease in the second stage. After CO2 bubbling with a rate of 0.2 cm3/s through an aqueous medium with a volume of 75 cm3, the microbial count decreased by two orders of magnitude, which is apparently due to an increase in the acidity of the test medium. Having found a high efficiency of CO2 on the process of bacterial cells destruction, this gas should be used in water treatment processes, as well as in combination with other reagents or physical methods of water treatment to enhance the destructive effect on micro-objects.

The effects of Pinus brutia bark extract on pure and mixed continuous cultures of rumen bacteria and archaea, and fermentation characteristics in vitro

The aim of the study was to investigate the effects of Pinus brutia bark extract, which is rich in polyphenolic compounds of tannins, on both pure and mixed continuous cultures of rumen bacteria and archaea, as well as on rumen fermentation characteristics in vitro. Antimicrobial susceptibility assay with pure cultures was carried out in an anaerobic chamber. Pinus brutia bark extract exhibited a potential inhibitor activity (P<0.05) against pure cultures of Ruminococcus flavefaciens, Eubacterium ruminantium, and Methanobacterium formicicum while a growth stimulatory effect (P<0.05) was observed for Ruminoccocus albus, Butyrivibrio fibrisolvens, and Streptococcus bovis. Pinus brutia bark extract only had a potential inhibitor effect (P<0.05) on R. albus at the highest dose (1200 µg/mL). Pinus brutia bark extract also stimulated (P<0.05) the growth of pure cultures of Fibrobacter succinogenes, while it did not affect Megasphaera elsdenii, except at the highest dose. The effects of two doses (75 and 375 mg/L) of P. brutia bark extract on in vitro mixed cultures and rumen fermentation parameters were determined by the rumen simulation technique (Rusitec). Supplementation with P. brutia bark extract led to a quadratic decrease (P<0.05) in the cell numbers of R. flavefaciens. Production of total and individual short chain fatty acids (SCFA), acetate to propionate ratio (C2/C3), total protozoa, ruminal pH, and dry matter digestibility (DMD) did not change in the presence of P. brutia bark extract. Supplementation with both doses of P. brutia bark extract decreased (P<0.05) the ammonia-N concentrations. Ammonia-N concentration was lowest in the high-supplemented group (P<0.05). As a conclusion, inhibitory effects of P. brutia bark extract on some species in the pure cultures were in the same direction as with mixed ruminal cultures, while stimulatory effects disappeared. The lack of inhibitory effects on protozoa and on a large number of Gram-positive rumen bacteria in the mixed cultures suggests that its mechanism of action is not exactly similar to antibiotics. Although P. brutia bark extract did not alter ruminal SCFA, it could have potential to improve ruminal protein utilization without depressing rumen microbial fermentation.

Biodegradation of fipronil: current state of mechanisms of biodegradation and future perspectives.

Fipronil is a broad-spectrum phenyl-pyrazole insecticide that is widely used in agriculture. However, in the environment, its residues are toxic to aquatic animals, crustaceans, bees, termites, rabbits, lizards, and humans, and it has been classified as a C carcinogen. Due to its residual environmental hazards, various effective approaches, such as adsorption, ozone oxidation, catalyst coupling, inorganic plasma degradation, and microbial degradation, have been developed. Biodegradation is deemed to be the most effective and environmentally friendly method, and several pure cultures of bacteria and fungi capable of degrading fipronil have been isolated and identified, including Streptomyces rochei, Paracoccus sp., Bacillus firmus, Bacillus thuringiensis, Bacillus spp., Stenotrophomonas acidaminiphila, and Aspergillus glaucus. The metabolic reactions of fipronil degradation appear to be the same in different bacteria and are mainly oxidation, reduction, photolysis, and hydrolysis. However, the enzymes and genes responsible for the degradation are somewhat different. The ligninolytic enzyme MnP, the cytochrome P450 enzyme, and esterase play key roles in different strains of bacteria and fungal. Many unanswered questions exist regarding the environmental fate and degradation mechanisms of this pesticide. The genes and enzymes responsible for biodegradation remain largely unexplained, and biomolecular techniques need to be applied in order to gain a comprehensive understanding of these issues. In this review, we summarize the literature on the degradation of fipronil, focusing on biodegradation pathways and identifying the main knowledge gaps that currently exist in order to inform future research. KEY POINTS: • Biodegradation is a powerful tool for the removal of fipronil. • Oxidation, reduction, photolysis, and hydrolysis play key roles in the degradation of fipronil. • Possible biochemical pathways of fipronil in the environment are described.

Phenolic compounds promote the horizontal transfer of antibiotic resistance genes in activated sludge

Phenolic compounds are common organic pollutants in wastewater. During the wastewater treatment process, these compounds may influence the microbial community structure and functions. However, the impact of the phenolic compounds in the wastewater treatment plants on the horizontal transfer of antibiotic resistance genes (ARGs) has not been well assessed. In this study, we investigated the horizontal transfer of ARGs under the stress of phenolic compounds. The results showed that in pure culture bacteria system, p-nitrophenol (PNP), p-aminophenol (PAP) and phenol (PhOH) (10–100 mg/L) can significantly increase the horizontal transfer frequency of ARGs by 2.2–4.6, 3.6–9.4 and 1.9–9.0 fold, respectively. And, the RP4 plasmid transfer from Escherichia coli HB101 (E. coli HB101) to the bacteria in activated sludge increased obviously under the stress of phenolic compounds. Further investigation revealed that the PNP and PhOH at the concentration of 10–100 mg/L increased the production of reactive oxygen species and the permeability of cell membrane in the donor and recipient, which could be the causes of horizontal transfer of RP4 plasmid. In addition, it was also found that PNP, PAP and PhOH stress inhibit the expression of the global regulatory genes korB and trbA in the RP4 plasmid, and increase the expression level of the traF gene, thereby promoting the conjugative transfer of the RP4 plasmid. Taken together, these results improved our understanding of the horizontal transfer of ARGs under the stress of phenolic compounds and provided basic information for management of the systems that treat wastewater containing phenolic compounds.

ФОСФАТМОБИЛИЗУЮЩИЕ БАКТЕРИИ ИЗ ПОЧВ АЛМАТИНСКОЙ ОБЛАСТИ КАЗАХСТАНА

Phosphate-mobilizing bacteria were isolated from the soybean fields of the Almaty region of Kazakhstan. It was found that their content in the soil was low and amounted to 3-12% of the total number of bacterial microflora. 32 pure cultures of phosphate-mobilizing bacteria were obtained, on the basis of which a collection of these bacteria was created. The main cultural-morphological and biochemical characteristics of phosphate-mobilizing bacteria have been studied and their primary identification has been carried out. The isolated bacteria were found to belong to the genera Bacillus, Pseudomonas, Bacterium, and Agrobacterium.

Isolation of bacteria from artificial bronchoalveolar lavage fluid using density gradient centrifugation and their accessibility by Raman spectroscopy

Raman spectroscopy is an analytical method to identify medical samples of bacteria. Because Raman spectroscopy detects the biochemical properties of a cell, there are many factors that can influence and modify the Raman spectra of bacteria. One possible influence is a proper method for isolation of the bacteria. Medical samples in particular never occur in purified form, so a Raman-compatible isolation method is needed which does not affect the bacteria and thus the resulting spectra. In this study, we present a Raman-compatible method for isolation of bacteria from bronchoalveolar lavage (BAL) fluid using density gradient centrifugation. In addition to measuring the bacteria from a patient sample, the yield and the spectral influence of the isolation on the bacteria were investigated. Bacteria isolated from BAL fluid show additional peaks in comparison to pure culture bacteria, which can be attributed to components in the BAL sample. The isolation gradient itself has no effect on the spectra, and with a yield of 63% and 78%, the method is suitable for isolation of low concentrations of bacteria from a complex matrix.Graphical abstract

SUSTENANCE, THE SAFETY OF PLANTS AND FEED OF Galega orientalis (Lam.)

Conducted a comprehensive comparative study of the nutritional and biological value Galega orientalis (Lam.): the solubility of the protein in vitro - Galega’s seeds, leaves, hay, which was harvested in the phase of budding - beginning of flowering. It is believed to be the essential influence of feed type on the solubility of the protein. According to the conducted studies it has revealed that the solubility of the feed protein is in the range from 37.0% to 50.0%. The rate of solubility of Galega orientalis (Lam.) seed protein is 50.0%, litestock - 40.0%, and hay - 37.0% from its total. The research results indicate that the protein of Galega orientalis (Lam.) refers to the feed with the average level of punct solubility. It has researched qualitative assessment of the biologically active substances content in organs of Galega orientalis’ (Lam.) plants. It has identified the highest content of flavonoids and saponins in rosette leaves and ascorbic acid in the organs of plants and petals. There is the high content of tannins found in the petals of Galega orientalis (Lam.). There is a high content of coumarins and water-soluble polysaccharides in the roots of the studied plants. Phytochemical studies of the plant Galega orientalis (Lam.) indicates the absence in it of cardiac glycosides and antrahlikozydiv. It was first conducted testing on antimicrobial activity of a plant Galega orientalis (Lam.) on the growth pure cultural of bacteria Gram-positive (Micrococcus luteus), Gram-negative (Escherichia coli XL1, DH5) and yeasts (Saccharomyces cerevisiae W303). The material for the study was dried vegetative mass Galega orientalis (Lam.) in the phase of budding and early flowering. As a result of the experiment was revealed that 20% concentration of aqueous extract of this plant had inhibitory effects on the growth of pure cultures of bacteria and yeast. It has grounded reasonably possible relationship between the antimicrobial activity of the extract of this plant and the lack of bloating in cows. It has outlined prospects of further researches of this problem

Identification of <i>Pseudomonas cichorii</i> (Swingle 1925) Stapp 1928 in hydroponic culture of lettuce in Russia

Relevance.Lettuce (Latin: Lactúca satíva) is a species of annual herbaceous plant in the genus Lettuce of the Asteraceae family. As a vegetable crop, it is cultivated everywhere in the world, and its hydroponic cultivation technology has received special development in recent years. One of the common pathogens of lettuce is Pseudomonas cichorii, causing bacterial diseases of several important cultivated plants. In this regard, the study of the occurrence of this pathogen is important.Material and methodology.The study was conducted on the basis of the Department of Agrobiotechnology of the ATI of RUDN University. The samples were provided by a commercial manufacturer of lettuce grown on a flow-through hydroponic line under conditions of minimal microbial contamination. The study of phytopathogenic bacteria includes a number of stages: isolation of bacteria on semi-selective culture media and obtaining a pure culture of bacteria; setting a test for pathogenicity (virulence); studying the phenotypic properties of bacteria; determining the taxonomic position of the isolated strains by molecular methods. All studies were conducted in accordance with the standard methods of identification of phytopathogenic bacteria.Results.As a result of the work, the distribution of the species Pseudomonas cichorii in the hydroponic culture of lettuce in the Russian Federation was confirmed. Although, according to the EPPO database, P. cichorii was first described in Russia in 1965 by microbiological methods, but isolated bacteria are not available in microbiological collections to confirm this conclusion with appropriate diagnostic methods. Twelve isolates of P. cichoriiwere studied by a biochemical and phytopathological tests, and four isolates (01, 04, 06, and 12) that showed the greatest aggressiveness on host plants and tobacco leaves were identified by DNA sequencing of the 16S rRNA gene fragment. The obtained DNA fragments showed a high similarity (99-100%) with the sequences of P. cichoriifrom the Genebank. Evaluation of the virulence of the isolated isolates on a number of other cultivated plants, and the uniformity of their biochemical characteristics showed that they represent a group of bacteria specialized in lettuce.

BIOSAFETY ASSESSMENT OF FLOUR AND YEASTS FOR BAKERY NEEDS ACCORDING TO MICROBIOLOGICAL INDICATORS

The problem of non-compliance with microbiological safety indicators of finished bakery products and flour of different types is formulated. It is noted that the reason for the development of bread disease, which is caused by pathogenic and opportunistic microorganisms, is poor quality flour. The solution of the problem is offered by use of symbiosis of lactic acid bacteria as a part of leaven which possess antagonistic properties in relation to many activators.
 According to the results of microbiological research, pathogens of bread disease in wheat, spelled, oat and rye types of flour have been identified.The pathogenic micro­organisms present in the flour lead to accelerated spoilage of bread, reducing its nutritional value and safety in terms of microbiological parameters.
 It is proposed to test the effectiveness of the use of biotechnological principles, which are based on the antagonistic properties of lactic acid bacteria. To determine the biosafety of the obtained yeast, microbiological studies were performed by seeding yeast samples on elective nutrient media Saburo, Blikfeldt, GMF agar, bifido- and lactoagar.
 An improved leaven formulation for baking needs with an increased titer of lactic acid bacteria, which have powerful antagonistic powers, has been developed. Experiments have shown the effectiveness of the use of symbiosis of pure cultures of lactic acid bacteria in the composition of leavens to suppress diseases of bread, namely pathogens – Aspergillus niger, Mycormucedoand Bacillus subtilis.
 The use of unleavened leavens with a high content of pure cultures of lactic acid bacteria in the practice of baking unleavened bread based on gluten-free types of flour contributes to the expansion of the range of functional bakery products.

Purification of the key enzyme complexes of the anammox pathway from DEMON sludge.

Anaerobic Ammonium Oxidation ("anammox") is a bacterial process in which nitrite and ammonium are converted into nitrogen gas and water, yielding energy for the cell. Anammox is an important branch of the global biological nitrogen cycle, being responsible for up to 50% of the yearly nitrogen removal from the oceans. Strikingly, the anammox process uniquely relies on the extremely reactive and toxic compound hydrazine as a free intermediate. Given its global importance and biochemical novelty, there is considerable interest in the enzymes at the heart of the anammox pathway. Unfortunately, obtaining these enzymes in sufficiently large amounts for biochemical and structural studies is problematic, given the slow growth of pure cultures of anammox bacteria when high cell densities are required. However, the anammox process is being applied in wastewater treatment to remove nitrogenous waste in processes like DEamMONification (DEMON). In plants using such processes, which rely on a combination of aerobic ammonia-oxidizers and anammox organisms, kilogram amounts of anammox bacteria-containing sludge are readily available. Here, we report a protein isolation protocol starting from anammox cells present in DEMON sludge from a wastewater treatment plan that readily yields pure preparations of key anammox proteins in the tens of milligrams, including hydrazine synthase HZS and hydrazine dehydrogenase (HDH), as well as hydroxylamine oxidoreductase (HAO). HDH and HAO were active and of sufficient quality for biochemical studies and for HAO, the crystal structure could be determined. The method presented here provides a viable way to obtain materials for the study of proteins not only from the central anammox metabolism but also for the study of other exciting aspects of anammox bacteria, such as for example, their unusual ladderane lipids.

Thermophilic aerobic organoheterotrophic soil bacteria from anthropogenically changed territories of Saint Petersburg and Leningrad region

Anthropogenically altered soils of Saint Petersburg and Luga (Leningrad Region) were investigated for the presence of thermophilic aerobic chemoorganoheterotrophic bacteria, potentially capable of decomposing hydrocarbons at elevated temperatures (60C). 6 strains of pure spore-forming cultures of bacteria were isolated. Analysis of the nucleotide sequences of the 16S rRNA genes showed that they belong to the genera Geobacillus and Aeribacillus. For the first time, we obtained information on the presence of representatives of the genus Aeribacillus, which are typical inhabitants of hot springs and zones with geothermal activity, in the soils of the regions of Saint Petersburg and the Leningrad Region.

Optimization of nutrient medium composition to increase biomass of propionic acid bacteria and acidophilic bacteria

Numerous studies have shown that it is very important that the microorganisms included in the composition be in a strong symbiotic relationship when selecting vents for fermented dairy products. Therefore, it is the primary task to identify the relationship between microorganisms in the preparation of the starter. Strains that retain biochemical activity for a long time, depending not only on external factors (composition of nutrient medium, temperature, etc.), but also on the ratio between biochemical active and inactive cells in populations of microorganisms, which determines the viability of the culture, its practical value, are considered valuable. Microorganisms of the genus Lactobacillus are widespread in nature and are members of human microflora. They have high biological and functional activity, which determines their practical use as probiotics and in food production. Propionic acid bacteria are considered as promising probiotics, the positive impact of which on human health is generally recognized. The scientific results show the expediency of using strains of propionic acid bacteria in the production of functional dairy bio-products for the purpose of enrichment with probiotics cells and their useful exometabolites. As a result of the co-cultivation of propionic acid bacteria and acidophilic bacterium, a stable microbial association with high probiotic and biotechnological properties (inoculum) has been developed. A scheme for preparing an inoculum for producing a bacterial concentrate using pure cultures of propionic acid bacteria and an acidophilic bacterium has been developed. This article presents the results of studies on the selection of nutrient medium in order to increase the yield of biomass and the accumulation of certain metabolic products by microorganisms.

Sensitive dual readout assays based on rolling circle amplification for fluorescent and colorimetric detection of Cronobacter spp. in powdered infant formula

Cronobacter spp. are important opportunistic foodborne pathogens in powdered infant formula (PIF). In this study, a sensitive and specific assay was developed for fluorescent and colorimetric detection of Cronobacter spp. in PIF samples by using ligase chain reaction and rolling circle amplification (LCR-RCA) dual-amplification strategy. A pair of gap-padlock probes was designed to induce specific genomic DNA recognition and initiate the LCR. Hyperbranched rolling circle amplification (HRCA) combined with fluorescent dye and linear rolling circle amplification (LRCA) with AuNP probes were performed to achieve fluorescent or colorimetric detection of Cronobacter spp. The limits of detection (LODs) of the proposed assays were 8.6 × 101 CFU/mL (fluorescence) and 7.5 × 102 CFU/mL (colorimetric) in pure culture and 9.2 × 102 CFU/mL (fluorescence) and 8.4 × 103 CFU/mL (colorimetric) in spiked PIF samples, respectively. After 5–7 h enrichment, the proposed methods could detect as low as 100 CFU/mL bacteria in pure culture and PIF sample. The recovery of both methods was in the range of 89.4%–103.8% in pure culture or spiked PIF samples. The proposed assay has the potential to be a rapid and efficient method for detection of Cronobacter spp. in PIF.

STUDY OF ANTIBACTERIAL ACTIVITY OF THE PREPARATIONS WITH DIOXIDINE AND LEVOFLOXACIN ON MAIN PURULENT-INFLAMMATORY PROCESSES PATHOGENS

The aim: Study of antibacterial activity of the preparations, containing antiseptic dioxidine and antibiotic levofloxacin in vitro on standard strains of main optional-anaerobic pathogens of purulent-inflammatory processes of surgical wounds S. aureus, E. coli, P. aeruginosa and definition of more effective ones on them. Materials and methods: Solutions of dioxidine 1.2 %, dioxidine 1.2% with decamethaxin, Dioxisole, water soluble ointment with dioxidine 1.2% and levofloxacin 0.1% with decamethaxin were used in experiment. Antibacterial activity was studied on standard strains of S. aureus АТСС 25923, E. coli АТСС 25922, P. aeruginosa АТСС 27853. Distinguishing and identification of pure cultures of bacteria was done according to generally accepted microbiological methods. Determination of purulent-inflammatory processes pathogens sensitivity was done by disco-diffuse method on Mueller-Hinton medium. Antibacterial activity of solutions and ointments was studied with the help of agar diffusion method (“well” method) according to methodic recommendations. Each investigation was repeated 6 times. Method of variation statistics was used for the research results analysis. Results: All antibacterial preparations under study are effective and highly effective on S. aureus АТСС 25923, E. coli АТСС 25922, P. aeruginosa АТСС 27853. Solution with 1.2 % dioxidine with decamethaxin and ointment with 0.1 % levofloxacin and decamethaxin have larger growth retardation zones towards S. aureus and P. aeruginosa. E. coli strains are more sensitive to the solution of Dioxisole and ointment with 1.2 % dioxidine. Conclusions: All strains are sensitive, most of them are highly sensitive, up to 5 antibacterial preparations under study in vitro.

ISOLATION AND CHARACTERIZATION OF PHENANTHRENE DEGRADATING BACTERIA FROM DAIRY WASTE SAMPLES

Phenanthrene is the commonly used hazardous chemical in various industries and the detoxification is a big problem till today. In this study, phenanthrene degrading bacteria were isolated from dairy waste samples, characterized by molecular techniques. A total of 10 samples were collected respectively from different spots of dairy industry. Minimum salt agar medium with phenanthrene composition was used to isolate the pure culture of resistant bacterium. Morphological, biochemical tests were done to identify the phenanthrene degrading bacteria. The colonies of the isolates were circular to irregular in dairy samples. Phenanthrene tolerant bacteria were isolated after the dairy waste soil samples was serially diluted and transferred onto M9 minimal agar medium amended with 10mg/l of phenanthrene. A concentration of 10 mg/l was chosen based on the prevailing concentration. Four Phenanthrene tolerant bacteria from dairy waste (HW2, HW1, HW3, HW5) were isolated. From the biochemical and 16srRNA PCR amplification, the bacterium identified was Micrococcus leuteus. The resistance to Phenanthrene by the isolate was tested with various concentrations of Phenanthrene from 0 to 10mM. The Micrococcus luteus showed a MTC value of 28Cfu/ml at 8mM and Bacillus cereus showed least.