Indigenous Microflora Research Articles

Efficient production of hydrogen through bioaugmentation of the organic fraction of municipal solid waste by the newly isolated Clostridium sartagoforme SA1

Bio-hydrogen from organic waste holds promise as renewable energy. However, its large-scale production is limited by technical challenges, with low H2 yields and the absence of robust microbial strains being the major ones.To address these limitations, H2-producing microbes have been isolated from a full-scale anaerobic digestor treating complex organic waste. Clostridium sartagoforme SA1 was selected because of high H2 yields from glucose, soluble starch, and carboxymethylcellulose. The strain was then tested for H2 production from the Organic Fraction of Municipal Solid Waste (OFMSW), rich in starch and cellulose, with productions up to 55 mLH2 g/VS. Additionally, C. sartagoforme SA1 confirmed high H2 performances even in the presence of OFMSW’s indigenous microflora, increasing the H2 yield by 38 % and highlighting its robustness in a highly competitive environment. This is the first report describing the efficient adoption of a C. sartagoforme strain for bioaugmentation of non-sterile OFMSW towards high H2 yields.

Experimental assessment of the relationship between the indigenous composition of the intestinal microflora and the elemental status of the common carp (Cyprinus caprio) against the background of the use of new feed additive

Relevance. Aquaculture is an intensively developing industry worldwide and is an important source of food for the population. Satisfaction of nutritional needs in micronutrients is a physiologically significant part of fish nutrition and, as a result, ensures their health. Currently, various approaches are being used to ensure the resistance of fish to diseases of various etiologies and to increase their productivity. One of the promising methodological approaches is the study of the fish microbiome as a sustainable alternative to improve aquaculture methods.The aim of the study was to study the degree of relationship between the composition of the intestinal microflora and the level of essential elements in the body of carp (Cyprinus caprio) against the background of the use of feed additives “Bubitan” and “Intebio”.Methods. The object of research was carp yearlings (n = 60) grown in the conditions of LLC “Irikla-fish” (Orenburg region). Feed additives “Intebio” and “Butitan” were used as growth and development regulating factors. Dynamic indicators of changes in the species composition of the intestinal microbiome and elemental status were carried out using metagenomic sequencing, atomic emission (NPP-ISP) and mass spectrometry (MS-ISP) methods.Results.The data obtained indicate a significant effect of the tested phytobiotics on the indices of indigenous microflora. The closest indicators of the distribution of taxonomic groups of intestinal microbiocenosis in relation to the control were registered against the background of the use of the phytobiotic «Butitan». Correlation analysis of the data allows us to state with a high level of reliability that a significant increase in the number of microorganisms of the genus Hydrotalea and Flavobacterium has a positive effect on the degree of assimilation of macro- and microelements from the feed.

Modeling of the conditions of the process of biotransformation of fish raw materials by bacterial starter cultures

Abstract In food biotechnology, special attention is given to the biotransformation by promising strains of bacterial starter cultures to obtain food products with improved quality characteristics and functional properties. Biotransformation using bacterial starter cultures may be a means to increase the shelf life of fish products, enhance their organoleptic properties, and increase their nutritional value through the formation of metabolites of their activity, which are the main factors of bioconservation and synthesis of vitamins and other biologically active substances. The probiotic properties of bacterial starter cultures will significantly influence the optimization of the indigenous microflora of the gastrointestinal tract, thereby strengthening the human body and its immune system overall to maintain a healthy lifestyle. The development of this trend is associated with the interest of the Russian population in products with a probiotic focus. In this regard, an analysis of data on the justification of the use of bacterial starter cultures for the biotransformation of fish raw materials has been conducted, and the necessary bacterial starter cultures have been selected. Based on theoretical and practical foundations, mathematical models of the biotransformation process by bacterial starter cultures have been constructed depending on the properties of fish raw materials and the biotechnological characteristics of the introduced microorganisms. The conducted research has been used to develop subsequent technological regimes for the biotransformation of fish raw materials by bacterial starter cultures as the basis for the formulations of “fast food” products containing functional components, which is justified by the accelerated pace of life and the desire of modern society to monitor their diet by consuming products that support a healthy lifestyle.

Sulfate-reducing consortium HQ23 stabilizes metal(loid)s and activates biological N-fixation in mixed heavy metal-contaminated soil

Sulfate-reducing bacteria (SRB) are used in the remediation of mine pollution; however, the mechanism of stabilizing multiple heavy metal(loid)s by the SRB consortium under low oxygen conditions needs further study. Indigenous microflora were extracted from non-ferrous metal-contaminated soil co-inoculated with enriched SRB consortium and assembled as the HQ23 consortium. The presence of Desulfovibrio (SRB) in HQ23 was confirmed by 16S rRNA sequencing and qPCR. The effects of culture media, dissolved oxygen (DO), SO42¯, and pH on the HQ23 growth rate, and the SO42¯-reducing activity were examined. Data indicates that the HQ23 sustained SRB function under low DO conditions (3.67 ± 0.1 mg/L), but the SRB activity was inhibited at high DO content (5.75 ± 0.39 mg/L). The HQ23 can grow from pH 5 to pH 9 and can decrease mobile or bioavailable Cr, Cu, and Zn concentrations in contaminated soil samples. FTIR revealed that Cu and Cr adsorbed to similar binding sites on bacteria, likely decreasing bacterial Cu toxicity. Increased abundances of DSV (marker for Desulfovibrio) and nifH (N-fixation) genes were observed, as well as an accumulation of nitrate-N content in soils suggesting that HQ23 stimulates the biological N-fixation in soils. This study strongly supports the future application of SRB for the bioremediation of heavy metal-polluted sites.

The promise of coupling piezo-catalysis and activated persulfate using dual-frequency ultrasound: A novel synergistic method of natural water disinfection

Piezo-coupled catalysis, which is driven by dual-frequency ultrasound (DFUS) at high frequencies (>100 kHz), has emerged as a promising technique for intensifying the oxidation processes in aqueous media. This study aimed at evaluating the performance of high-frequency DFUS (0.12 + 1.7 MHz) coupled with ZnO microparticles (1 µm) and persulfate (S2O82−) for disinfection of filtered natural surface water, spiked with E. coli and E. faecalis, as well as unfiltered natural water with indigenous microflora. Despite the longer treatment times required (as compared to deionized water), this hybrid system provided the fastest inactivation, exhibiting a synergy between DFUS+ZnO and DFUS+S2O82− processes and a high energy-efficiency (231.5 and 91.3 CFU/J for E. coli and E. faecalis, respectively). The obtained results revealed the feasibility of DFUS-driven piezo-coupled catalysis using persulfate for advanced water disinfection.

The enhanced effect of key microorganisms in chromium contaminated soil in Cr(VI) reduction

The escalating threat of Cr(VI) pollution to the environment and human health can be effectively controlled through microbial methods, which are promising, safe, and ecofriendly. To enhance Cr(VI) removal efficiency, scholars have been optimizing strains. However, synergies between in-situ soil particles and crucial microorganisms in soil have rarely been investigated. In this study, Cr(VI) was removed by collaborating with in-situ soil particles and key microorganisms in the soil. The results indicated that within 48 hours, the removal rate of Cr(VI) reached over 99% in the soils+microflora system, which was 45% higher than that of the microflora system alone. Factors such as Cr(VI) concentration, soil dosage, pH level, oxygen availability, and electron donors influenced the removal efficiency of Cr(VI) in the soils+microflora system. The cyclic experiments showed that soil particles effectively prevented chromium invasion on microflora, promoting the growth of crucial microorganisms. The addition of microflora can effectively regulate the composition of soil flora and enhance the efficiency of chromium reduction. Moreover, two strains each of Ochrobactrum sp. and Paenarthrobacter sp., exhibiting remarkable tolerance to Cr(VI), were successfully isolated from these soils, significantly enhancing the reduction capacity of the indigenous microflora towards Cr(VI). Additionally, 16S rRNA-PCR sequence analysis revealed that in-situ soil particles not only synergistically collaborated with the resident microflora for efficient removal of Cr(VI), but also facilitated the proliferation of key microbiota such as Ochrobactrum sp. and Paenarthrobacter sp. Remarkably, when exposed to an initial concentration of 50 mg/L Cr(VI), complete removal was achieved by Paenarthrobacter-2 within a time frame as short as 60 hours. This research found four novel highly efficient strains for reducing Cr(VI) and provides an innovative method for the synergistic interaction between indigenous soil microflora and soil particles to remove heavy metal ions from wastewater.

REMEDIATION OF OIL-CONTAMINATED SOILS WITH COMPOSITIONS BASED ON HUMIC ACIDS

In addition to conventional methods, nowadays new approaches and technologies based on combined application of sorbents and microorganisms are intensively developed for efficient control of oil contaminations. As a biotechnological solution for remediation of various oil-contaminated soils, biocompositions based on an organic matrix – humic acids of peat, and a biological component – a single strain/or an association of oil degrading microorganisms of the genera Rhodococcus and Pseudomonas, have been studied. The efficiency assessment of oil contamination biodegradation using biocompositions was carried out on different types of model oil-contaminated soils with different levels of contamination: grey forest soil, Black Sea pebbles (fraction 20-50mm), constructional broken stone (fraction 10-20mm). Natural soil contaminated with oil products and samples of railroad broken stone (fractions 5-30mm and 35-50mm) were also used. It has been shown that the biocompositions based on three strains of microorganisms – ‘HA R. X5 R. S67 Ps. NF142' – possessed the highest capability of degrading oil hydrocarbons in all systems under study. Biodegradation of oil hydrocarbons upon addition of this biocompositions varied between 62 and 82% depending on the type of oil-contaminated soil, the level of contamination being very high. Monobacterial biocomposition ‘HA Ps.NF142’ has proven to be promising for remediation of oil-contaminated soil ecosystems with a high and very high level of contamination. The increase of the level of biodegradation of oil contamination of soils appears to be due to the combined action of humic acids comprising both the stimulating effect of humic acids on microorganisms – the components of biocompositions and indigenous microflora of model systems, and the detoxifying effect of humic acids in respect of oil hydrocarbons. For citation: Grechishcheva N.Yu., Dmitrieva E.D., Starodubtseva K.A. Remediation of oil-contaminated soils with compositions based on humic acids. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 7. P. 136-143. DOI: 10.6060/ivkkt.20246707.6927.

Evaluating efficacy of Pseudomonas sp. EN-4 to lower the toxic potential of 4-bromophenol and assessing its competency in simulated microcosm

An indigenous bacterium Pseudomonas sp. EN-4 had been reported earlier for its ability to co-metabolise 4-bromophenol (4-BP), in presence of phenol (100 mg/L) as co-substrate. The present study was undertaken to validate the efficacy of biotransformation by comparing the toxicity profiles of untreated and EN-4 transformed samples of 4-BP, using both plant and animal model. The toxicity studies in Allium cepa (A. cepa) indicated to lowering of mitotic index (MI) from 12.77% (water) to 3.33% in A. cepa bulbs exposed to 4-BP + phenol, which reflects the cytotoxic nature of these compounds. However, the MI value significantly improves to 11.36% in its biologically treated counterpart, indicating normal cell growth. This was further supported by significant reduction in chromosomal aberrations in A. cepa root cells exposed to biologically treated samples of 4-BP as compared to untreated controls. The oxidative stress assessed by comparing the activity profiles of different marker enzymes showed that the activities of superoxide dismutase (SOD), ascorbate peroxidase (APX) and guaiacol peroxidase (GPX) were reduced by 56%, 72%, and 37% respectively, in EN-4 transformed samples of 4-BP + phenol compared to its untreated counterpart. Similar trends were evident in the comet assay of fish (Channa punctatus) blood cells exposed to untreated and biologically treated samples of 4-BP. The comparative studies showed significant reduction in tail length (72.70%) and % tail intensity (56.15%) in fish blood cells exposed to EN-4 treated 4-BP + phenol, compared to its untreated counterpart. The soil microcosm studies validated the competency of the EN-4 cells to establish and transform 4-BP in soil polluted with 4-BP (20 mg/kg) and 4-BP + phenol (20 + 100 mg/kg). The isolate EN-4 achieved 98.08% transformation of 4-BP in non-sterile microcosm supplemented with phenol, indicating to potential of EN-4 cells to establish along with indigenous microflora.

Impact assessment of thiamethoxam on microbial and enzymatic activity in mango rhizosphere

Thiamethoxam is a globally used neonicotinoid insecticide in mango ecosystem which can cause hazardous impact on soil environment. The current study was carried out to assess the impact of 0.2 (T1/treament) and 2.0 g kg−1 (T2) concentrations of thiamethoxam on mango rhizospheric microbial community, enzyme activity along with its degradation. Indigenous microflora degraded thiamethoxam from 5.62 to 41.17 mg kg−1 at 0 day to 0.60 and 2.10 mg kg−1 in soil after 60 days of application of 0.2 and 2.0 g kg−1 doses, respectively. Thiamethoxam dissipated via pseudo first-order kinetics with t1/2 (half-life) values (23.00 and 14.00) days and K values (1.99–17.14) and (21.42–183.6) at T1 and T2, respectively. At bacterial count of 5.5 × 107 in soil, fluorescein diacetate (FDA) and dehydrogenase (DHA) showed that there was no change occurred in control soil after 60 days, while in thiamethoxam treated soil DHA was marginally increased from 0.164 to 0.168 µg g−1 and from 0.155 to 0.157 µg g−1 at lower and higher doses, respectively. While, FDA values were slightly decreased from 0.761 to 0.717 µg g−1 at T1 but no significant change was observed in T2. However, changes in fungal population were not significant but increase in bacterial population with the degradation of thiamethoxam was observed, which indicated the presence of thiamethoxam degrading beneficial bacteria in mango rhizosphere soil.

The study on the development of the composition of chewable lozenges with probiotic properties. 1. Substantiation of the active substance

In recent times, a new understanding of the concept of probiotics has emerged – the use of their metabolites instead of living cells of microorganisms. They can both inhibit the development of pathogenic bacteria and effectively stimulate the reproduction of indigenous microflora. It is possible that metabiotics will be more effective than traditional live probiotics. Taking into account the prospects of new-generation probiotic drugs and the rapid growth of interest of pharmaceutical market entities in such a new dosage form as lozenges, we have proposed to create chewable lozenges containing Lactobacillus exometabolites, which pharmacological action is aimed at preventing and treating an imbalance of the oral cavity microflora.Aim. To theoretically and experimentally substantiate the choice of the exometabolite complex of lactobacilli as the active substance of a medicinal product with probiotic properties in the form of chewable lozenges.Materials and methods. The exometabolite complex of the Lactobacillus plantarum UCM-2693 strain was used as the study object. Acidity, the lactic acid content, the optical density of a microbial suspension, as well as the quantitative count of lactobacilli were determined in accordance with the generally accepted methods specified in the State Pharmacopoeia of Ukraine (SPhU).Results and discussion. The bacteriotropic effect of the exometabolite complex of L. plantarum UCM-2693 was detected on lactobacilli of the probiotic drug “Lactobacterin-Biopharma” when cultured on a medium with exometabolites compared to the control sample. This technique has a stimulating effect on the acid formation, proliferation of probiotic microorganisms, changes the characteristics of their growth phases, namely reduces the lag phase, accelerates the exponential phase, which can accelerate the onset of the therapeutic effect, and is the proof of the feasibility of using this active substance in the composition of chewable lozenges with probiotic properties.Conclusions. The choice of the exometabolite complex of lactobacilli as the active substance of a new drug from the group of metabiotics in the form of chewable lozenges has been substantiated. The exometabolite complex of lactobacilli has been obtained, and its bacteriotropic effect has been studied.

Antibacterial and antibiofilm activity of halogenated phenylboronic acids against Vibrio parahaemolyticus and Vibrio harveyi.

Vibrios are associated with live seafood because they are part of the indigenous marine microflora. In Asia, foodborne infections caused by Vibrio spp. are common. In recent years, V. parahaemolyticus has become the leading cause of all reported food poisoning outbreaks. Therefore, the halogenated acid and its 33 derivatives were investigated for their antibacterial efficacy against V. parahaemolyticus. The compounds 3,5-diiodo-2-methoxyphenylboronic acid (DIMPBA) and 2-fluoro-5-iodophenylboronic acid (FIPBA) exhibited antibacterial and antibiofilm activity. DIMPBA and FIPBA had minimum inhibitory concentrations of 100 μg/mL for the planktonic cell growth and prevented biofilm formation in a dose-dependent manner. Both iodo-boric acids could diminish the several virulence factors influencing the motility, agglutination of fimbria, hydrophobicity, and indole synthesis. Consequently, these two active halogenated acids hampered the proliferation of the planktonic and biofilm cells. Moreover, these compounds have the potential to effectively inhibit the presence of biofilm formation on the surface of both squid and shrimp models.

The unexpected effect of the compound microbial agent NP-M2 on microbial community dynamics in a nonylphenol-contaminated soil: the self-stability of soil ecosystem.

Nonylphenol (NP) is widely recognized as a crucial environmental endocrine-disrupting chemical and persistent toxic substance. The remediation of NP-contaminated sites primarily relies on biological degradation. Compound microbial products, as opposed to pure strains, possess a greater variety of metabolic pathways and can thrive in a wider range of environmental conditions. This characteristic is believed to facilitate the synergistic degradation of pollutants. Limited research has been conducted to thoroughly examine the potential compatibility of compound microbial agents with indigenous microflora, their ability to function effectively in practical environments, their capacity to enhance the dissipation of NP, and their potential to improve soil physicochemical and biological characteristics. In order to efficiently eliminate NP in contaminated soil in an eco-friendly manner, a simulation study was conducted to investigate the impact of bioaugmentation using the functional compound microbial agent NP-M2 at varying concentrations (50 and 200 mg/L) on the dynamics of the soil microbial community. The treatments were set as follows: sterilized soil with 50 mg/kg NP (CK50) or 200 mg/kg NP (CK200); non-sterilized soil with 50 mg/kg NP (TU50) or 200 mg/kg NP (TU200); non-sterilized soil with the compound microbial agent NP-M2 at 50 mg/kg NP (J50) or 200 mg/kg NP (J200). Full-length 16S rRNA analysis was performed using the PacBio Sequel II platform. Both the indigenous microbes (TU50 and TU200 treatments) and the application of NP-M2 (J50 and J200 treatments) exhibited rapid NP removal, with removal rates ranging from 93% to 99%. The application of NP-M2 further accelerated the degradation rate of NP for a subtle lag period. Although the different treatments had minimal impacts on the soil bacterial α-diversity, they significantly altered the β-diversity and composition of the bacterial community. The dominant phyla were Proteobacteria (35.54%-44.14%), Acidobacteria (13.55%-17.07%), Planctomycetes (10.78%-11.42%), Bacteroidetes (5.60%-10.74%), and Actinobacteria (6.44%-8.68%). The core species were Luteitalea_pratensis, Pyrinomonas_methylaliphatogenes, Fimbriiglobus_ruber, Longimicrobium_terrae, and Massilia_sp003590855. The bacterial community structure and taxon distribution in polluted soils were significantly influenced by the activities of soil catalase, sucrase, and polyphenol oxidase, which were identified as the major environmental factors. Notably, the concentration of NP and, to a lesser extent, the compound microbial agent NP-M2 were found to cause major shifts in the bacterial community. This study highlights the importance of conducting bioremediation experiments in conjunction with microbiome assessment to better understand the impact of bioaugmentation/biostimulation on the potential functions of complex microbial communities present in contaminated soils, which is essential for bioremediation success.

Potential of phytic acid in synergy with sodium chloride as a natural-borne preservative to inactivate Escherichia coli O157:H7 and inhibit natural microflora in fresh noodles at room temperature

The increase in consumer demand and the high cost of maintaining a cold chain during distribution emphasize the need for preservative technology to ensure the microbiological quality of fresh noodles with a moisture content of 32–40%. However, few studies have been conducted to increase the storage stability of fresh noodles by using a preservative with a significant inhibitory effect against microorganisms and/or minimizing the use of synthetic antimicrobial agents. This study aimed to propose a synergistic natural-borne antimicrobial that could interact with NaCl, an essential component of noodles, for extended preservation of fresh noodles at room temperature. NaCl (0–1.6% (w/w) based on the total weight of the noodle dough) and phytic acid (0–1.0% (v/w)) were applied to fresh noodles. The bactericidal effect on Escherichia coli O157:H7 and the inhibitory effect on the indigenous microflora were assessed within 21 days at 30 °C. After cooking fresh noodles, physicochemical/textural and sensory characteristics (whiteness, pH, water activity; hardness, adhesiveness, springiness, chewiness; appearance, odor, overall acceptance) were further evaluated as objective and subjective quality parameters. In fresh noodles preserved with 0.6% phytic acid and 1.6% NaCl, the E. coli O157:H7 population was eliminated below the detection limit (>5.8 log reduction; P < 0.05) within 4 days of storage. This preservative significantly inhibited (P < 0.05) the mesophilic bacterial and total yeast/mold counts naturally present in fresh noodles for 12 days, while the largest antimicrobial activity was observed in noodles supplemented with 1.0% phytic acid combined with 1.0–1.6% NaCl. Although the objective parameters were significantly affected by the preservatives, analysis of the subjective parameters demonstrated that all samples were slightly or moderately favored by the panelists (P > 0.05). Considering the normal range of objective parameters for fresh noodles, the optimal preservative was determined to be 0.6% phytic acid and 1.6% NaCl. This study suggests the potential use of phytic acid as a natural-borne preservative that combines with NaCl in fresh noodles and exerts a synergistic effect. The developed method is expected to be applicable to extending the shelf life of other grain-based foods containing NaCl as an essential ingredient.

Bioreceptivity of unused building materials: effects on microbial colonisation and diversity—a Polish–Indian study

The colonisation of building materials by microorganisms is the first step in terms of a subsequent biodeterioration and an occurrence of potential building-associated health hazards. Contrary to many studies to date, focusing mainly on old buildings with symptoms of biocorrosion, this research focuses on the bioreceptivity of selected unused building materials and the factors determining the intensity of their colonisation. The experiments were carried out in parallel in India and Poland, with the use of indigenous microflora from a given region. They revealed the similar dynamics of the microbial multiplication in concrete and plasterboard and the extreme intensity of the process: after only 10 weeks under favorable conditions, the number of bacteria and fungi reached 107 CFU/g of dry weight of the material. The stimulation of microbial growth by individual environmental factors was slightly different in Indian and Polish studies: in India, the strongest stimulating factor was the periodic increase in humidity, while in Poland, the highest intensification of growth was observed in samples enriched with organic matter. Mould biodiversity turned out to be higher in India, although some types of fungi common to both regions were isolated.

Adaptive characteristics of indigenous microflora in an organically contaminated high salinity groundwater

Salinity, a critical factor, could directly or indirectly affect the microbial community structure and diversity. Changes in salinity levels act as environmental filters that influence the transformation of key microbial species. This study investigates the adaptive characteristics of indigenous microflora in groundwater in relation to external organic pollutants under high salinity stress. A highly mineralized shallow groundwater in Northwest China was conducted as the study area, and six representative sampling points were chosen to explore the response of groundwater hydrochemical parameters and microflora, as well as to identify the tolerance mechanisms of indigenous microflora to combined pollution. The results revealed that the dominant genera found in high salinity groundwater contaminated with organic pollutants possess the remarkable ability to degrade such pollutants even under challenging high salinity conditions, including Halomonas, Pseudomonas, Halothiobacillus, Sphingomonas, Lutibacter, Aquabacterium, Thiomicrospira, Aequorivita, etc. The hydrochemical factors, including total dissolved solids (TDS), sulfide, nitrite, nitrate, oxidation reduction potential (ORP), NH3–N, Na, Fe, benzene series, phenols, and halogenated hydrocarbons, demonstrated a significant influence on microflora. High levels of sulphate and sulfide in groundwater can exhibit dual effects on microflora. On one hand, these compounds can inhibit the growth and metabolism of microorganisms. On the other hand, they can also serve as effective electron donors/receptors during the microbial degradation of organic pollutants. Microorganisms exhibit resilience to the inhibitory effects of high salinity and organic pollutants via a series of tolerance mechanisms, such as strengthening the extracellular membrane barrier, enhancing the synthesis of relevant enzymes, initiating novel biochemical reactions, improving cellular self-healing capabilities, responding to unfavorable environmental conditions by migration, and enhancing the S cycle for the microbial metabolism of organic pollutants.

Синдром мальабсорбції після перенесеного гастроентериту в дітей, оптимізація терапії

The period of convalescence after gastroenteritis in children in modern circumstances is often complicated by the development of post-infectious malabsorption syndrome, in the pathogenesis of which the development of bacterial overgrowth syndrome (BOS) is important. At present, the issue of treatment of BOS in children has not been finally resolved. The use of modern enterosorbents can be considered a good alternative to antibacterial therapy of BOS. Purpose - to evaluate the effectiveness of the inclusion of highly dispersed silicon dioxide in the complex therapy of malabsorption syndrome after gastroenteritis in children. Materials and methods. 30 children aged from 3 to 12 years with malabsorption syndrome after gastroenteritis during the last 6 months were under observation. Patients on the background of standard treatment were prescribed highly dispersed silicon dioxide for 3-5 days. In dynamics, subjective complaints of patients and/or their parents were assessed, clinical symptoms and results of coprological and bacteriological examination of feces were evaluated. Results. While including highly dispersed silicon dioxide into the treatment, in the vast majority of patients (according to individual indicators, 75-85%), a rapid normalization of the frequency and consistency of stools, a decrease in the frequency and severity of flatulence, improvement of digestion and assimilation of nutrients according to the indicators of a coprological study, which had a positive effect on the general condition, were noted. The results of the bacteriological examination of feces in dynamics showed a significant decrease in the frequency of detection and the number of opportunistic bacteria, fungal flora and tendency to increase the number of representatives of the indigenous microflora. Conclusions. The results of the work make it possible to recommend the inclusion of enterosorption with the usage of highly dispersed silicon dioxide in the complex of restorative therapy in children with malabsorption syndrome after gastroenteritis. The research was carried out in accordance with the principles of the Helsinki Declaration. The study protocol was approved by the Local Ethics Committee of the institution mentioned in the work. The informed consent of the children’s parents was obtained for the conducting the studies. No conflict of interests was declared by the authors.

A biodegradable chitosan-based polymer for sustained nutrient release to stimulate groundwater hydrocarbon-degrading microflora

Petroleum hydrocarbon-contaminated groundwater often has a low indigenous microorganism population and lacks the necessary nutrient substrates for biodegradation reaction, resulting in a weak natural remediation ability within the groundwater ecosystem. In this paper, we utilized the principle of petroleum hydrocarbon degradation by microorganisms to identify effective nutrients (NaH2PO4, K2HPO4, NH4NO3, CaCl2, MgSO4·7H2O, FeSO4·7H2O, and VB12) and optimize nutrient substrate allocation through a combination of actual surveys of petroleum hydrocarbon-contaminated sites and microcosm experiments. Building on this, combining biostimulation and controlled-release technology, we developed a biodegradable chitosan-based encapsulated targeted biostimulant (i.e., YZ-1) characterized by easy uptake, good stability, controllable slow-release migration, and longevity to stimulate indigenous microflora in groundwater to efficiently degrade petroleum hydrocarbon. Results showed that YZ-1 extended the active duration of nutrient components by 5–6 times, with a sustainable release time exceeding 2 months. Under YZ-1 stimulation, microorganisms grew rapidly, increasing the degradation rate of petroleum hydrocarbon (10 mg L−1) by indigenous microorganisms from 43.03% to 79.80% within 7 d. YZ-1 can easily adapt to varying concentrations of petroleum hydrocarbon-contaminated groundwater. Specifically, in the range of 2–20 mg L−1 of petroleum hydrocarbon, the indigenous microflora was able to degrade 71.73–80.54% of the petroleum hydrocarbon within a mere 7 d. YZ-1 injection facilitated the delivery of nutrient components into the underground environment, improved the conversion ability of inorganic electron donors/receptors in the indigenous microbial community system, and strengthened the co-metabolism mechanism among microorganisms, achieving the goal of efficient petroleum hydrocarbon degradation.

Evaluation of maximum growth rate of Listeria monocytogenes in ready-to-eat fresh-cut papaya and melon

Listeria monocytogenes has been identified on minimally processed fruit and vegetables, and can transmit a severe foodborne disease through the consumption of ready-to-eat (RTE) fresh-cut produce, mostly if the storage conditions are incorrect, and the cold chain is not abided to. The aim of the present work was to evaluate the behaviour of L. monocytogenes in RTE fresh-cut papaya and melon, two low-acid fruits stored in temperature-abuse conditions (10 and 8°C, respectively) during the shelf-life indicated by the producer (7 d). A microbiological challenge test was performed to assess the maximum growth rate (MGR) and the duplication time (Td) of the pathogen, testing three strains separately. We also assessed the behaviour of the indigenous microflora of the fruits. Results demonstrated that papaya and melon were two favourable substrates for L. monocytogenes. The MGR was 0.044 log CFU/g/h with a Td of 6.77 h for papaya, and 0.029 log CFU/g/h with a Td of 10.24 h for melon. The storage of RTE fresh-cut papaya and melon at an abusive temperature above 8°C could encourage the growth of L. monocytogenes with a possible risk to public health.

Enhancement of Textural and Sensory Characteristics of Wheat Bread Using a Chickpea Sourdough Fermented with a Selected Autochthonous Microorganism.

A traditional Greek sourdough, based on the fermentation of chickpea flour by an autochthonous culture, was evaluated as a wheat bread improver. The dominant indigenous microflora (Clostridium perfringens isolates) was identified by 16S rDNA analysis, and a selected strain (C. perfringens CP8) was employed to ferment chickpea flour to obtain a standardized starter culture (sourdough) for breadmaking. In accordance with toxin-typed strain identification, all isolates lacked the cpe gene; thus, there is no concern for a health hazard. Loaf-specific volumes increased with the addition of liquid, freeze-dried, and freeze-dried/maltodextrin sourdoughs compared to control bread leavened by baker's yeast only. Following storage (4 days/25 °C), the amylopectin retrogradation and crumb hardness changes (texture profile analysis) revealed a lower degree of staling for the sourdough-fortified breads. Modifications in the protein secondary structure of fortified doughs and breads were revealed by FTIR analysis. High amounts of organic acids were also found in the sourdough-supplemented breads; butyric and isobutyric acids seemed to be responsible for the characteristic 'butter-like' flavor of these products (sensory analysis). Overall, the addition of liquid or freeze-dried chickpea sourdough in wheat bread formulations can improve the specific volume, textural characteristics, and sensorial properties of loaves, along with extending bread shelf life.

Efficient denitrification of liquid digestate with its indigenous microflora

It has been a common way to recycle digestate after biogas production as a biofertilizer. However, the huge generation of digestate especially its liquid part surpasses the market consumption quantity, which in turn hinders the sustainable operation of a biogas plant. Biotreatment of liquid digestate (LD) with microorganisms is one way to reduce chemical oxygen demand (COD) and nitrogen content. This study enriched three microflorae from environmental water, liquid and solid digestate. After community structure analysis, the microflora from LD itself exhibits superior nitrogen removal function to the other two microflorae, and its predominant microbial strains are from Aliidiomarina, followed by Parapedobacter. The microflorae can grow at pH range from 7 to 10. pH and ammonium concentration show synergistic effect on the growth of microflorae. The microflora from LD can completely realize nitrogen removal in man-made medium within 48 h, and remove 93.7 % ammonia nitrogen (NH3-N) and 88.1 % COD from LD at optimum C/N ratio of 9. Sodium acetate and the fermented mash from grain ethanol production process are the preferable carbon sources to improve the removal of nitrogen and COD. The re-inoculation of indigenous microflora into LD can realize 2.9∼10.9 % increase of NH3-N removal with or without addition of carbon sources, and 0.1∼11.7 % improvement on COD removal with addition of carbon sources except glycerol. It means that the enrichment of the indigenous microflora combined with the addition of proper carbon source is a potential way to enhance the nitrogen and COD removal from LD.