Ramza Berzhanova

RECHAR-M2C: MICROBIAL ISOLATION FROM LEGACY-CONTAMINATED SOILS The present study aimed to isolate Zn-solubilising and metal-tolerant microbial strains from legacy-contaminated soils affected by potentially toxic elements (PTEs), persistent organic pollutants (POPs), or their combination. A total of 242 microbial strains were isolated. Subsequent sequential screening for Zn-solubilisation potential identified 13 isolates with solubilisation indices exceeding 1.5. Of these, four isolates (S21, S56, TA5, and TE32) exhibited strong tolerance to 0.03–0.06% Zn, with relative growth intensities (RGIs) ranging from 86.6% to 104%, while S56 and TE32 maintained sufficient tolerance at a Zn concentration of 0.12%. Regarding Ni tolerance, only TE32 exhibited sufficient resistance at a Ni concentration of 0.03%, with an RGI of 47.2%. For Cu tolerance, isolates S21, S56, and TE32 demonstrated strong resistance at a Cu concentration of 0.03%, with RGIs of 92.8%, 82.4%, and 79.6%, respectively. Furthermore, TE32 maintained sufficient tolerance at 0.06% Cu, with an RGI of 63.0%. Based on these results, three isolates (S21, S56, and TE32) were selected for comprehensive characterisation of their enzymatic (amylolytic, cellulolytic, lipolytic, and proteolytic) and plant growth-promoting traits, including siderophore, extracellular polymeric saccharide (EPS), and indole-3-acetic acid (IAA) production. Strain S21 exhibited moderate proteolytic activity, siderophore production, and superior IAA synthesis, reaching a peak concentration of 38.7 ± 3.29 µg mL−1. Strain S56 demonstrated moderate proteolytic activity, strong lipolytic and proteolytic activities, siderophore production, and moderate IAA synthesis, with a maximum concentration of 17.5 ± 1.48 µg mL−1. In contrast, strain TE32 exhibited strong amylolytic activity, proteolytic activity, EPS production, and the lowest IAA-producing capacity, reaching a peak concentration of 12.8 ± 0.88 µg mL−1. Future research will focus on the development of microbe–biochar complexes through the immobilisation of microbial cells onto biochar surfaces, followed by validation of the developed complexes in marginal and/or contaminated soils to enhance plant growth. Keywords: legacy soil contamination; potentially toxic elements; Zn-solubilising microorganisms; tolerance to heavy metals; plant growth-promoting microorganisms.

Exopolysaccharides (EPS) represent an important tool for application in bio- and phytoremediation technologies due to their ability to enhance water and nutrient retention, support microclimate stability, and protect plants from environmental stress. In the present study, xanthan-like EPS produced by Xanthomonas translucens TRK8 was precipitated by ethanol and isopropanol, with the former yielding 9.2 g L⁻¹ compared with 6.7 g L⁻¹ obtained with the latter. The monosaccharide profile of the TRK8-derived EPS indicated a branched structure composed of rhamnose, mannose, glucose, and galactose residues, containing both α- and β-type pyranose units. The rheological properties of the studied EPS were compared with those of commercial xanthan at concentrations of 1–3 wt.%. Fitting the obtained data to the Ostwald–de Waele power-law model revealed that the flow behaviour index (n) values were below 1 (−0.338, −0.499, and −0.647, respectively), indicating shear-thinning behaviour (i.e., pseudoplasticity). The potential of the TRK8-derived EPS as a plant protection agent was validated by coating barley seeds with 2 wt.% EPS, resulting in a 28.6% increase in shoot length and a 64.7% increase in root length relative to the oil-stressed control.

Characterization of PGPM microorganisms is an important step in selecting strains as bioinoculants. In this study, the PGPM properties of 98 isolates recovered from soil, rhizosphere, and plant tissues grown in oil-contaminated soil were assessed. Of the 98 isolates tested, 21.4% exhibited proteolytic activity, 24.4% exhibited amylolytic activity, and 9.2% exhibited cellulolytic activity on agar media with specific substrates. After the initial screening, 20 isolates (N9, N11, MSM12, MSM3, MSM20, MSM21, MSM25, MSM20, V16, L5-2, L5-5, L5-6, L10-2, L10-6, L10-12, L10-10, KP5, KB9, KP10 and C10) demonstrating high double or triple hydrolytic activity were selected. The stepwise screening methodology allowed the selection of strains demonstrating more than one or several properties with PGPR properties that ensure plant growth such as: phytohormone production, nitrogen fixation, IAA secretion, production of iron chelating compounds, phosphate solubility and synthesizing hydrolytic enzymes. Therefore, multifunctional strains with PGPR properties can be used as the most promising inoculants to improve the efficiency of phytoremediation of oil-contaminated soils. Keywords: IAA, bacteria that promote plant growth, siderophores, phytohormones, phosphates, nitrogen fixation, protease, cellulase, amylase.

Soil contamination in industrial areas often involves complex mixtures of contaminants, making remediation a significant challenge. Microbe-assisted phytoremediation offers a promising solution, yet its success depends on understanding interaction between plants, microorganisms, and contaminants in rhizosphere. This study examined the effects of organic (oil sludge) and inorganic (Zn) contaminants, applied individually and in combination, on the rhizosphere bacterial community of Miscanthus × giganteus Greef et Deu (M×g), with emphasis on strains exhibiting plant growth-promoting, hydrocarbon-degrading, and metal-tolerant traits. A one-season greenhouse experiment included soils spiked with Zn (1650 mg kg⁻¹) and/or oil sludge (15 mL kg⁻¹). Oil sludge exerted a stronger influence on the taxonomic structure of rhizobacterial communities than Zn, largely shaping the patterns observed under co-contamination. Zn exposure increased the relative abundance of Actinobacteriota, whereas oil sludge favoured Proteobacteriota. Both contaminants, individually and together, enhanced the proportion of Sphingomonadaceae. Across all treatments, taxa with potential plant-growth-promoting traits were present, while co-contaminated soil harboured microorganisms capable of hydrocarbon degradation, heavy metal tolerance, and plant growth promotion. These findings highlight the adaptive capacity of the M×g rhizobiome and support its application in phytoremediation. The isolation and characterisation of rhizosphere-associated strains provide basis for developing microbial bioagents to enhance biomass production and remediation efficiency in multi-contaminated environments.

Currently, about 5% of the earth's population suffers from gluten-related disorders. Modern technologies for gluten-free diets and filling the protein deficit are aimed at manufacturing gluten-free (GF) pasta products using non-conventional plant raw materials with high biological value. GF grains and crops (rice, corn, buckwheat, amaranth, quinoa, etc.) are used to produce GF pasta products. However, there is a scarcity of studies that comprehensively understand GF flour addition on the nutritive, sensory and cooking properties. Therefore, the scope of this literature review covers the main types of non-conventional raw materials for GF pasta products and summarizes the research on pasta products made from them. Results indicate that the rheological and sensory attributes of pasta made from pure GF flours such as rice or corn still requires a deeper study of technological processes in producing GF pasta. Incorporating nutrient-dense ingredients such as amaranth, quinoa, sorghum, and chia flours not only enhances the nutritional profile of gluten-free pasta but also offers opportunities for diverse culinary applications. The improvement of sensory attributes in rice-, corn-, buckwheat-based pasta, coupled with the effective use of cooking enhancers like xanthan gum, transglutaminases, inulin, and alternative starches, paves the way for creating more palatable gluten-free options. As techniques such as high-temperature treatment, extrusion cooking, and starch pregelatinization become more refined, future developments may focus on optimizing these processes to further improve the texture, taste, and overall quality of gluten-free pasta. Continued research and innovation in ingredient selection and processing technologies will be crucial for meeting the growing demand for gluten-free products that do not compromise on culinary experience or nutritional value.

The current study aimed to examine 271 bacterial isolates from the plant rhizosphere and oil-contaminated soil for the ability to produce extracellular bioemulsifiers. The bacterial isolates were screened for bioemulsifier production using several tests, including oil displacement, parafilm M destabilization, droplet collapse, and the emulsification index (E-24). The most effective strains were characterized by 8 isolates displaying an E-24 index greater than 60%. Among these, 6 strains isolated from plant rhizospheres demonstrated the ability to form mucus on solid media. The remaining two strains, Z2 and D1, were isolated from oil-contaminated soils and exhibited robust growth in a medium supplemented with oil and diesel. Surface tension was measured using the Wilhelmy plate method, finding low surface tension values of 57.6 ± 0.6 and 55.6 ± 0.6 mN/m for the culture supernatants of strains Z2 and D1, respectively. Further, a study on the cell hydrophobicity of strains Z2 and D1 revealed values above 70%, indicating high hydrophobicity. Strains Z2 and D1 were selected for their high emulsifying activity in the presence of edible oils and petroleum hydrocarbons, suggesting their potential as bioemulsifier producers.

It is known that long-term storage of cultures with the help of periodic reseeding does not always ensure the stability of morphological, cultural and physiological characteristics. In this regard, the question arises of the need to study the range of variability of individual characters and the influence of the environment on the heterogeneity properties of collection cultures and study their morphophysiological properties. We considered it appropriate to return to the study of the main taxonomically significant phenotypic characters of these yeasts. As a result, it was noted that the culture of Candida sphaerica KM95 does not show natural variability, which would be expressed in the macromorphological heterogeneity of the population: almost all colonies had similar characteristics. The culture of Candida kefyr var. kumis 17 when sieving on a dense medium, a noticeable variability is observed in a number of morphological features. Thus, the population composition is represented by several types of colonies that differ from each other in size, color, shape, structure, etc. In search of cultures that ferment lactose intensively, 25 yeast strains isolated from shubat and assigned to the genus Candida were tested. As a result of a comparative study of enzymatic activity, by examining the ability of different strains to ferment lactose, the most active of them were identified - C. sphaerica 1M and C. sphaerica 3M. According to our observations, the studied cultures are able to ferment maltose after their long-term cultivation on wort agar, however, the ability to grow on a medium with lactose is lost.

Extensive laboratory and field tests have shown that the gelation response of gellan gum to saline water makes it a promising candidate for enhanced oil recovery (EOR). The objective of this mini-review is to evaluate the applicability of gellan gum in EOR and compare its efficiency to other precursors, in particular, hydrolyzed polyacrylamide (HPAM). At first, the “sol-gel” phase transitions of gellan gum in aqueous-salt solutions containing mono- and divalent cations are considered. Then the rheological and mechanical properties of gellan in diluted aqueous solutions and gel state are outlined. The main attention is paid to laboratory core flooding and field pilot tests. The plugging behavior of gellan in laboratory conditions due to “sol-gel” phase transition is discussed in the context of conformance control and water shut-off. Due to its higher strength, gellan gum gel provided ~6 times greater resistance to the flow of brine in a 1 mm-width fracture compared to HPAM gel. The field trials carried out in the injection and production wells of the Kumkol oilfield, situated in Kazakhstan, demonstrated that over 6 and 11 months, there was an incremental oil recovery of 3790 and 5890 tons, respectively. To put it into perspective, using 1 kg of dry gellan resulted in the incremental production of 3.52 m³ (or 22 bbls) of oil. The treatment of the production well with 1 wt.% gellan solution resulted in a considerable decrease in the water cut up to 10–20% without affecting the oil flow rate. The advantages and disadvantages of gellan compared to HPAM are analyzed together with the economic feasibility of gellan over HPAM. The potential for establishing gellan production in Kazakhstan is emphasized. It is anticipated that gellan gum, manufactured through fermentation using glucose–fructose syrup from Zharkent and Burunday corn starch plants, could be expanded in the future for applications in both the food industry and oil recovery.

Түйін Тағамдық биотехнология саласында ірімшік биологиялық және нутрицевтикалық құндылығы жоғары сүт өнімі ретінде белгілі. Организммен биосіңірілуі жоғары болғандықтан тұтынушылар арасында мол сұранысқа ие. Пайдалы қасиеттерін нақтылау мақсатында қазіргі таңда ірімшік өндірісіндегі базалық құрам-бөлік – бактериялық ұйытқы дақылдарын белсенділік деңгейлері бойынша іріктеудің маңыздылығы жоғары. Ұйытқы дақылының құрамына енетін лактобактерия штамдарының протеолитикалық қасиеттерін зерттеудің өзектілігі бұл штамдардың соңғы өнімнің органолептикалық қасиеттері мен биологиялық құндылығына тікелей әсер етуімен негізделеді. Лактобактериялардың өнімммен бірге адам организміне енген сәттен бастап асқазан – ішек жолындағы микробиомды қалыпқа келтіруге қызмет етуі соңғы өнімнің (ірімшіктің) функционалдылығын нақтылайды. Мақалада функционалды бағыттағы ірімшік өндірісінде қолданылатын бактериялық ұйытқының құрамына кіретін лактобактерия штамдарының технологиялық маңызды протеолитикалық қасиеттерін зерттеу нәтижелері берілген. Зерттеу объектілерінің барлығы дерлік казеин протеолизіне қатыса алатындығы зерттелінді. Жоғары белсенділікке ие штамдар: Lactiplantibacillus plantarum CHE37 Сһ-1 - 19,0±0,5 мм, Lactococcus lactis subsp. lactis S5K8 СМ-14 және Lactococcus lactis 1881 Сһ-8 дақылдарында - 12,0±0,2 мм мөлшерінде мөлдірлену аймағы анықталды. Сонымен қатар, желатинді протеолиздеу қарқындылығы жоғары штамдар Lactococcus lactis subsp. lactis S5K8 СМ-14 және Streptococcus macedonicus LAB 617 СМ-16 штамдары екендігі белгілі болды. Олар ЕПЖ (ет-пептонды желатин) қоректік ортасында пробирка бойымен және пробирка түбінде тұнба түзу арқылы өсу ерекшелігін көрсетіп, жартылай қатты ЕПЖ қоректік ортасын толықтай сұйылтты. Жұмыс қорытындысы бойынша протеолитикалық белсенділіктері жоғары сүтқышқылды бактериялар штамдары функционалды бағыттағы ірімшік өндірісі үшін қолданылатын ұйытқы дақылдарының құрамына енуіне толық негіз бар. In the field of food biotechnology, cheese is known as a dairy product with high biological and nutraceutical value. Due to the high bioavailability of the body, it is in great demand among consumers. In order to clarify the useful properties, currently in the production of cheese, it is of great importance to select the activity levels of lactobacillus cultures that are part of the starter culture. The relevance of the study of morphological, cultural and proteolytic properties of lactobacillus strains that are part of the starter culture is due to the direct influence of these strains on the organoleptic properties and biological value of the final product. Lactic acid bacteria in the starter culture should serve to normalize the microbiome of the gastrointestinal tract, thereby ensuring the functionality of the final product (cheese). The article presents the results of a study of the morphological, cultural and proteolytic properties of lactobacillus strains that are part of the bacterial starter culture used in the production of functional cheeses. It was revealed that all the objects of the study can participate in the proteolysis of casein. Active strains that have shown high results are Lactiplantibacillus plantarum CHE37 Ch-1 - 19.0± 0.5 mm, Lactococcus lactis subsp. lactis S5K8 CM-14 andLactococcus lactis 1881 Ch-8, the zone of enlightenment in the latter - 12.0± 0.2 mm. Only two strains can participate in gelatin proteolysis - Lactococcus lactis subsp. lactis S5K8 СМ-14 и Streptococcus macedonicus LAB 617 СМ-16. According to the results of the work, there is every reason to believe that strains of lactic acid bacteria with high proteolytic activity can be part of the starter culture used for the production of functional cheeses.

The effect of inoculation of Miscanthus × giganteus Greef et Deu by the plant growth promoting rhizobacteria (PGPRs) to the phytoremediation process and physio-biochemical plant’s parameters was investigated in soil contaminated with the trace elements (TEs) from the Tekeli mining complex, Kazakhstan. Yeast Trichosporon sp. CA1, strains Rhizobium sp. Zn1-1, Shinella sp. Zn5-6, and Pseudomonas sp. CHA1-4, resistant to Zn and Pb, were isolated from the rhizosphere of M × g when the plant was cultivated in the same contaminated soil. Results illustrated that inoculation improved M × g adaptability to TEs toxicity by increasing the tolerance index to 2.9. The treatment enhanced the aboveground biomass yield by up to 163%, root biomass by up to 240%, chlorophyll content by up to 30%, and Chl_a/b ratio by up to 21%. Through M × g active growth and development, the peak activity of antioxidant enzymes was observed: activity of superoxide dismutase and glutathione reductase was induced, while the activity of catalase and ascorbate peroxidase was inhibited. Based on bioconcentration and translocation factors it was revealed that PGPRs selectively increased the uptake of TEs or stabilised them in the M × g rhizosphere. Inoculation with PGPRs increased the stabilization of Pb, V, Cr, Co, Ni, Cu, Cd, As, and Ba in the soil and plant tissues. Further research should focus on ex situ experiments using isolated PGPRs.