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In this study, the antimicrobial efficacy of a cloud-point extract (CPE) derived from the peels of horned melon (Cucumis metuliferus) was evaluated. By employing cloud-point extraction, a cutting-edge extraction technique, bioactive phytochemicals were effectively isolated from the peels, yielding a rich concentration of antioxidants and antimicrobial agents. The antifungal activities of the extract, including growth inhibition, minimal inhibitory concentration (MIC), and time-kill kinetics, were tested against phytopathogenic fungal species isolated from fruits, namely Aspergillus sp., Penicillium sp., Trichoderma sp., and Geotrichum sp. The extract exhibited notable antimicrobial properties, with inhibition zones measuring between 16 and 31 mm, and MIC values ranging from 3.75 to 60 mg/mL. High-performance liquid chromatography (HPLC) analysis identified several phenolic compounds within the CPE, including p-hydroxybenzoic acid, gallic acid, protocatechuic acid, caffeic acid, catechin, syringic acid, and vanillic acid. These findings suggest that the CPE of horned melon peels holds noteworthy promise as a natural antimicrobial agent, with potential applications in food preservation and safety. Furthermore, this research indicates the potential of suppressing fungal growth on fresh fruit samples as well, since the work included monitoring the development of fungal contamination on grape samples coated with CPE extract, encouraging the sustainable extraction and application of natural bioactive compounds.

Modern trends in phytochemical extraction from alternative crops support the use of alternative technologies, such as ultrasound- and microwave-assisted extractions. Considering the reduction of toxic solvents, rapid and effective extraction process, the abovementioned technologies have become the foundation of green chemistry approaches in a wide range of applications. These extractions have not been studied on Satureja kitaibelii Wierzb. ex Heuff, which is a highly potent plant when considering its aromatic and medicinal properties. This preliminary study presents an in vitro evaluation of biological activities of ultrasound- and microwave-assisted extracts of S. kitaibelii, for the first time. Furthermore, it offers a totally green, modern, fast and reproducible method for extraction of phytochemicals from S. kitaibelii herba (Rtanj Mountain, Serbia). This short communication suggests that the applied microwave-assisted extraction, using only water as the solvent, can be a promising approach for obtaining green products with commercial potential. Keywords: ultrasound-assisted extraction; microwave-assisted extraction

Kombucha as a tea-based fermented beverage has become progressively widespread, mainly in the functional food market, because of health-improving benefits. As part of a daily diet for adults and children, kombucha was a valuable non-alcoholic drink containing beneficial mixtures of organic acids, minerals, vitamins, proteins, polyphenols, etc. The influence of the specific surface area of the vessel, the inoculum size, and the initial tea concentration as operating factors and fermentation time as output variable on the efficiency of kombucha fermentation was examined. The focus of this study is optimization and standardization of kombucha fermentation conditions using Box-Behnken experimental design and applying an artificial neural network (ANN) predictive model for the fermentation process. The Broyden-Fletcher-Goldfarb-Shanno iterative algorithm was used to accelerate the calculation. The obtained ANN models for the pH value and titratable acidity showed good prediction capabilities (the r2 values during the training cycle for output variables were 0.990 and 0.994, respectively). Predictive ANN modeling has been proven effective and reliable in establishing the optimum kombucha fermentation process using the selected operating factors.

As a secondary industrial product, peach waste (PW) presents an ecological problem, but is potentially a rich source of natural antioxidants. A potential and novel way to improve the phytochemical stability of waste rich in phytochemicals is encapsulation in yeast cells that possess good structural characteristics. In the present study, PW extract was encapsulated in non-plasmolyzed, plasmolyzed and living Saccharomyces cerevisiae cells using the freeze-drying method. HPLC analysis revealed that β-carotene is the most abundant carotenoid, while epicatechin and catechin are the most abundant phenolics in PW. The highest encapsulation efficiency of carotenoids (86.59 %), as well as phenolics (66.98 %), was obtained with freeze-dried non-plasmolyzed yeast cells used as carriers. Although plasmolysis can cause some changes in the structure and properties of yeast cells, it did not enhance the encapsulation efficiency of present phytochemicals. Successful encapsulation of PW extract in yeast cells was confirmed by FTIR spectroscopy and SEM imaging. The obtained results present the encapsulation of sensitive compounds in yeast cells by freeze-drying as an excellent method for preserving valuable compounds and their potential use in the food and pharmaceutical industries.

As one of the main non-covalent relations in microbiological-based systems, cell surface hydrophobicity (CSH) can be observed as a relevant parameter for biodegradation capability and suggested bacterial behaviour and biofilm formation during a bioremediation process. On the other hand, the role of ureolytic bacteria in bioremediation has subsequently led to the examination of this bacterial type in different engineering fields. In order to optimize the operating parameters of microbial adhesion to hydrocarbons test (MATH) for ureolytic bacteria, Box–Behnken experimental design was conducted for five ureolytic bacteria isolated from soils, as well as for the reference strain Sporosarcina pasteurii DSM 33. The optimization was completed with and without the essential substrate for the targeted metabolic reaction, with the aim to compare differences in bacterial hydrophobicity. A vortex time of 2 min, a hydrocarbon volume of 0.5 mL, and a phase separation time of 15 min are recommended as MATH operating parameters for all tested ureolytic bacteria. Although all bacteria are hydrophobic, lower CSH values in the presence of urea were observed for the same bacterium, which could be explained by the interaction of urea with the organic phase of the separation system, as well as a rapid ureolysis process that also occurs during the application of ureolytic bacteria in biotechnology systems.

In the past decades, the bioremediation process based on denitrification by aerobic heterotrophic bacteria was extensively studied for different engineering approaches. Besides the fact that only non-pathogenic and non-biofilm forming bacteria must be used, it is very important to isolate bacteria or a group of bacteria in nature with the capacity to remove completely nitrate without accumulation of nitrogen oxides or ammonia as intermediates. In this article, the denitrification capacity of 43 bacterial strains isolated from slightly alkaline and calcite soils along the Danube River were investigated by artificial neural network (ANN) modelling. According to the obtained results, an ANN model was developed for the prediction of denitrification capacity of bacterial soil strains based on six signification denitrification indicators: biomass and N2 gas production, nitrate and nitrite concentration as well as nitrite and ammonia formation. The ANN model showed a reasonably good predictive capability of the outputs (overall R2 for prediction was 0.958). In addition, the experimental verification of the ANN in laboratory testing indicated that the ANN could predict the denitrification capacity of soil bacteria during the denitrification process in laboratory conditions.

Increased consumption, big production units and very efficient delivery service networks of fresh vegetables and salads caused a higher number of foodborne illnesses in the last two decades all over the world. In this study 15 fresh vegetable salads from different marketplaces in Novi Sad were tested by reference microbiological methods (detection of Salmonella spp., enumeration of Listeria monocytogenes, mesophilic aerobic bacteria, yeasts and molds, sporogenic mesophilic aerobic bacteria, sporogenic sulfite-reducing bacteria, Bacillus cereus, Enterobacteriaceae, Escherichia coli and coagulase positive staphylococci). Salmonella spp. was found in one sample which, according to the safety criteria for such a product (if treated as ready-to-eat), was considered to be microbiologically unsafe. The number of Listeria monocytogenes in all tested samples was

In the effort to overcome the increase in antimicrobial resistance of different pathogens, natural products from microbial sources appear to be the most favorable alternative to current antibiotics. Production of antimicrobial compounds is highly dependent on the nutritional conditions. Hence, in order to achieve high product yields, selection of the media constituents and optimization of their concentrations are required. In this research, the possibility of antimicrobial substances production using Bacillus subtilis ATCC 6633 was investigated. Also, optimization of the cultivation medium composition in terms of contents of glycerol, sodium nitrite and phosphates was done. Response surface methodology and the method of desirability function were applied for determination of optimal values of the examined factors. The developed model predicts that the maximum inhibition zone diameters for Bacillus cereus ATCC 10876 (33.50 mm) and Pseudomonas aeruginosa ATCC 27853 (12.00 mm) are achieved when the initial contents of glycerol, sodium nitrite and phosphates were 43.72 g/L, 1.93 g/L and 5.64 g/L, respectively. The results of these experiments suggest that further research should include the utilization of crude glycerol as a carbon source and optimization of composition of such media and cultivation conditions in order to improve production of antimicrobial substances using Bacillus subtilis ATCC 6633.

In the recent years, extensive studies have been conducted on the application of bioremediation in order to prevent and solve the global problem of nitrate accumulation especially in water and soil. In the studies related to the biological denitrification, Pseduomonas stutzeri is usually used as a model microorganism due to its ability of performing a complete reduction of nitrate. The aim of this work is to establish a culture medium at a laboratory level for maximizing the biomass production of Pseduomonas stutzeri ATCC 17588 and Pseudomonas stutzeri D1, previously isolated from the Danube (Novi Sad, Serbia) by using a Box-Bhenken experimental design and response surface methodology. The selected independent variables (+, 0, - levels) were: glucose (0, 1 and 2 g/L), KNO3 (1, 2 and 3 g/L), and peptone (0.4, 2 and 4 g/L), while the number of viable cells (log/mL) was chosen as a dependent factor (response). Based on the obtained results, it can be noticed that the maximum number of P. stutzeri ATCC 17588 viable cells is achieved when the initial content of glucose, KNO3 and peptone in the medium are 0 g/L, 2 g/L and 4 g/L, respectively. In the case of P. stutzeri D1, the most appropriate media for enhancing the biomass production consists of glucose (1 g/L), KNO3 (3 g/L) and peptone (4 g/L). Тhe obtained results can be used for further technoeconomic analysis and scale up of the P. stutzeri biomass production. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III45008]

A large volume of industrial waste of biological origin is produced annually worldwide, causing a serious disposal problem even though it is a huge source of beneficial compounds which may be used for their high nutritional and bioactive properties. The bio-potential of blackberry pomace (waste) obtained after juice separation from the Čačanska bestrna and Thornfree cultivars was evaluated. Higher amounts of total and monomeric anthocyanins, total phenolics, and total flavonoids were found in Thornfree pomace extract and demonstrated stronger 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity (2.12 mmol TEAC g-1) than Čačanska bestrna pomace extract (1.03 mmol TEAC g-1). Both extracts highly increased apoptosis/necrosis ratios in all investigated cell lines. The highest cell growth inhibition effects (EC50=52.5 - 64.7 μg mL-1) and the highest increase of apoptosis (AI=12.2) were obtained in breast adenocarcinoma cell line. Both blackberry pomace extracts inhibited the growth of all tested microorganisms. In the reference and wild bacterial strains MIC and MBC/MFC were achieved in the 0.39-25 mg mL-1 and 0.78-25 mg mL-1 range, respectively. Blackberry cultivar pomaces are rich source of phytochemicals with significant health promoting properties that could be further utilized as beneficial food ingredients. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. TR 31044]

The food industry has recognized a pressing need for highly effective disinfection protocols to decrease the risk of pathogen emergence and proliferation in food products. The integration of antimicrobial treatments in food production has occurred as a potential strategy to attain food items of superior quality with respect to microbiological safety and sensory attributes. This study aims to investigate the individual and synergistic effects of heat and peroxyacetic acid on the inactivation of bacterial cells, considering various contact times and environmental conditions. Four Salmonella serotypes, isolated from industrial meat production surfaces, were employed as model organisms. By systematically assessing the impacts of individual factors and synergistic outcomes, the effectiveness of bacterial cell inactivation and the efficiency of heat and peroxyacetic acid could be predicted. To better approximate real-world food processing conditions, this study also incorporated a bovine albumin-rich condition as a simulation of the presence of organic loads in processing steps. The findings revealed the essential need for a synergistic interplay of investigated parameters with the following optimized values: 1.5% concentration of peroxyacetic acid, temperature range of 60–65 °C, and contact time of 3 min for the complete effect regardless of the degree of contamination. [ABSTRACT FROM AUTHOR]

This work aimed to determine the influence of biopolymer coatings based on pumpkin oil cake, with and without the addition of Mentha piperita essential oil, on the quality and shelf-life of the Afus Ali variety of grapes, stored at room temperature and in the refrigerator. Furthermore, a 10% (w/w) aqueous solution of composite pumpkin oil cake (PuOC) with the addition of 30% glycerol was prepared at 60 °C and pH 10. The active biopolymer coating was prepared similarly by adding 1% (v/v) Mentha piperita essential oil. The quality of packed grapes was tested by determining the dry matter content, total sugar content, total acidity, alcohol content, total phenolic compounds content, and total flavonoid content, as well as by determining the antioxidant activity, through the application of the DPPH, FRAP and ABTS tests. Additionally, microbiological parameters were investigated: total aerobic microbial count, yeasts, and molds. The obtained results proved that in all tested samples, over a certain period of time, the content of dry matter, content of phenolic and flavonoids substances and sugar content decreased as a consequence of the spoilage of grapes, that is, the consumption of sugar for the production of alcohol, which consequently leads to the total acidity increasing. The application of lower storage temperatures and active coating (with Mentha piperita essential oil) had a positive effect on all inevitable reactions. Grapes' antioxidant potential may be enhanced or maintained by applying PuOC coating with or without Mentha piperita essential oil, which is best observed in the case of the DPPH test. The uncoated sample stored at room temperature had the largest decrease in DPPH values during storage, with changes ranging from 2.119 mg/g to 1.471 μmol mg/g. The samples, coated with PuOC and PuOC with the addition of essential oil, had uniform DPPH values throughout the entire storage period. Additionally, regarding phenolic content, at the end of storage period the highest phenolic content was observed in samples with active coating stored at room temperature (734.746 ± 2.462) and at refrigerator temperature (680.827 ± 0.448) compared with untreated samples and with samples with plain PuOC coating. The presence of active essential oil in the applied coating significantly affected the microbiological profile of grapes during the storage period. Besides the positive impact of the applied lower storage temperature, the effectiveness of the applied active packaging is even greater (microbiological results were in the order of PuOC+essential oil < PuOC < Control). The developed artificial neural networks were found to be adequate for modeling the microbiological profile, antioxidant activity, phenolic and flavonoid content. [ABSTRACT FROM AUTHOR]

The complete waste streams (solid waste residue, wastewater, and hydrolate) from the essential oil production of basil, chamomile, lavender, rosemary, and hyssop plants were used as a cultivation media for fermentations of a health-beneficial beverage called kombucha. Considering that these waste streams have not been used as a medium for obtaining kombucha, the main focus of this study was on the biological profiling and sensory analysis of newly-obtained kombucha beverages. According to fermentation parameters and advanced mathematical modelling, it can be concluded that kombucha made from chamomile essential oil by-products achieved the fastest successful kombucha fermentation, with a maximal titratable acidity of 7.2 g/L and a minimal pH value of 2.8. The results of other kombucha fermentations varied between the chosen plant and the waste stream used for beverage production. The obtained phenol and flavonoid contents were in the range of 12.4–56.46 mg GA/100 mL and 0.25–5.07 mg RU/100 mL, respectively. Higher antioxidant capacity as well as anti-inflammatory and antihyperglycemic activities of all kombucha beverages were observed compared to controls. Briefly, achieved DPPH, ABTS, and reducing power values were in the range 30.28–73.70, 192.25–683.29, and 19.37–82.76 mmol TE/100 mL, respectively. According to sensory analysis, the best performance or complete acceptability was noted for kombucha beverages made from lavender and hyssops (in the case of solid waste stream mixed with hydrolate) as well as basil (in the case of concentrated wastewater and hydrolate). [ABSTRACT FROM AUTHOR]

In this study, the effect of cultivation time on xanthan biosynthesis by different Xanthomonas campestris and Xanthomonas euvesicatoria strains, isolated from crucifers and pepper leaves, respectively, was examined. Xanthan was produced by submerged cultivation on crude glycerol-based medium at a laboratory level under aerobic conditions at 30 °C and 150 rpm for 168 h and 240 h. Bioprocess efficacy was estimated based on the xanthan concentration in media at the end of bioprocess and its average molecular weight. According to the obtained results, Xanthomonas strains have statistically significant effect on xanthan concentration in cultivation media when biosynthesis is performed by X. euvesicatoria strains, and cultivation time has significant effect on this parameter only when bioprocess is performed by X. campestris strains. The combination of Xanthomonas strains and cultivation time has a statistically significant effect on xanthan concentration in medium for both groups of isolates. The obtained results show that all applied Xanthomonas strains and cultivation time as well as their combination have statistically significant effect on average molecular weight of xanthan produced in applied experimental conditions. It is found that X. euvesicatoria strains produce higher amount of xanthan in a shorter period of time (168 h) when compared to the X. campestris strains. Xanthan of higher average molecular weight was produced when cultivation of both groups of isolates was performed for 240 h in applied experimental conditions. Results obtained in this research suggest that X. euvesicatoria strains have the greatest potential for application in biotechnological production of xanthan on crude glycerol-based medium. [ABSTRACT FROM AUTHOR]

Yeasts are considered an extraordinary alternative source of natural carotenoids and pigmented terpenoids with multiple applications. Production of carotenoids by yeast fermentation technology has many benefits; it is cost-effective, easily scalable, and safe. The aim of this research is the isolation of yeasts from natural resources and selection of the most potent bioagent for carotenoid production. Additionally, an upgraded carotenoid extraction protocol we established, which implies the testing of four methods for cell lysis (hydrochloric acid treatment, ultrasound treatment, milling treatment, and osmotic pressure treatment), three extraction methods (conventional extraction, ultrasound extraction, and conventional + ultrasound extraction), and three extraction solvents (acetone, isopropanol/methanol (50:50), and ethanol). For the first time, the obtained results were further modeled by an artificial neural network (ANN). Based on the obtained maximal carotenoid yield (253.74 ± 9.74 mg/100 g d.w) for the best-performing Rhodotorula mucilaginosa, the optimized extraction procedure involving milling treatment (for cell lysis) and conventional extraction with acetone (for carotenoid extraction) convincingly stood out compared to the other 35 tested protocols. Therefore, the selected carotenoid extraction protocol was verified with respect to its universality for all other yeast isolates, demonstrating its simplicity and effectiveness. [ABSTRACT FROM AUTHOR]

The microbiologically induced calcite precipitation (MICP) has been extensively studied for geotechnical engineering through simultaneous action of natural phenomena and engineering processes. The focus of bacterial contribution to the MICP has been directed to calcium carbonate productivity, while the additional bacterial role as a crystal nucleation center was not explained especially from a mathematical prediction modeling point of view. Therefore, this study provides explanations and a mathematical modeling approach of bacterial influence on the MICP induced by newly‐isolated ureolytic Bacillus strains and Sporosarcina pasteurii DSM 33. Using the obtained results of low‐cost, rapid, and simple assays, artificial neural network modeling was applied for cell surface predispositions, pH changes as well as calcium‐involved function in biofilm formation during the MICP, for the first time. Based on the obtained contribution of the alkalophilic/alkaloresistant bacteria, calcite precipitation can be significantly directed by the presence, of ureolytic bacterial cells as nucleation centers during CaCO3 precipitation as well as their morphology, surface characteristics, potential to form a biofilm, and/or generate pH changes. [ABSTRACT FROM AUTHOR]

Kombucha is a fermented tea beverage, which is traditionally prepared by fermenting sweetened black tea with tea fungus, which is a consortium of yeasts and acetic acid bacteria. In this paper, viability of selected wild strains of lactobacilli during Kombucha fermentation, their interaction with tea fungus and their contribution in obtaining a beverage of increased functional characteristics were tested. Five wild strains which were isolated from traditionally fermented foods were separately added on the second day of Kombucha fermentation. Count of yeasts, acetic acid bacteria and lactobacilli, as well as pH, titratable acidity, and content of L- and D-lactic acid during Kombucha fermentation were determined. Wild strains of lactobacilli demonstrated a differentiated survivability and the counts in fermentation broth (i.e. Kombucha beverages) depending on the strain applied. The addition of wild Lactobacillus spp. during Kombucha fermentation had no effect on the physiological activity of tea fungus, but they contributed to a significant increase in lactic acid content in the beverage. The highest lactic acid content during Kombucha fermentation was produced by the strain of Lactobacillus plantarum isolated from 40-day-old cream, while the strain of Lactobacillus hilgardii (from sour dough) showed the highest viability. [ABSTRACT FROM AUTHOR]

Beetroot pomace is an industrial by-product and ecological problem, as well as a potential rich source of natural antioxidants and pigments. In the present study, beetroot pomace extract (BPE) was encapsulated in non-plasmolysed, plasmolysed, and living Saccharomyces cerevisiae yeast cells by a freezedrying method. Living and dead yeast cells were microscopically assessed by using Neubauer chamber in order todetermine how the freeze-drying procedure affects changes in the yeast cell number. Total and surface phenolic contents were determined using the Folin-Ciocalteu method and encapsulation efficiency (EE) was calculated. The best EE was achieved in the case when BPE was encapsulated in living yeast cells. The successful encapsulation of BPE in yeast cells was confirmed by Fourier Transform Infrared Spectroscopy (FT-IR). These results report the encapsulation of sensitive compounds in yeast cells by freeze-drying, showing that it is a good method for valuable compound preservation and has a potential use in food and pharmaceutical industries. [ABSTRACT FROM AUTHOR]

Microbiologically induced CaCO3 precipitation (MICP) is a well-known bio-based solution with application in environmental, geotechnical, and civil engineering. The significance of the MICP has increased explorations of process efficiency and specificity via natural bacterial isolates. In this study, comprehensive profiling of five soil ureolytic Bacillus strains was performed through a newly formed procedure that involved six steps from selection and identification, through kinetic study, to the characterization of the obtained precipitates, for the first time. To shorten the whole selection procedure of 43 bioagents with the MICP potential, Standard Score Analysis was performed and five selected bacteria were identified as Bacillus muralis, B. lentus, B. simplex, B. firmus, and B. licheniformis by the MALDI-TOF mass spectrometry. Despite following the targeted activity, kinetic studies were included important aspects of ureolysis and the MICP such as cell concentration, pH profiling, and reduction in calcium ion concentration. At the final step, characterization of the obtained precipitates was performed using FTIR, XRD, Raman, DTA/TGA, and SEM analysis. Although all tested strains showed significant potential in terms of precipitation of calcite or calcite and vaterite phase, the main differences in the MICP behavior can be observed at the bacterial strain level. B. licheniformis showed favorable behavior compared to the reference Sporosarcina pasteurii DSM 33. [ABSTRACT FROM AUTHOR]

Kombucha beverage was produced using effluent from clarifying the grape must. Substrate for fermentation was prepared by diluting sterilized winery effluent to 70, 50, and 30 g/L of total sugars. Fermentation lasted for nine days at 20, 25, and 30 °C. A pleasant taste kombucha was produced. The beverage was ready to drink after three days of fermentation. From 300 mL fermentation volume, more than 40 g/L of biomass was produced at maximum temperature and sugar content. Acetic acid was the acid, with a peak concentration of 14.63 g/L after nine days at 30 °C and 70 g/L. Tartaric acid originated from the grape. Oxalic acid content was higher at the lower fermentation temperature. Produced kombucha had good antimicrobial properties. Higher temperature and sugar content promote antimicrobial activity against both Gram-positive and Gram-negative bacteria. No activity against yeast was observed. Antimicrobial properties against bacteria and acetic, tartaric, and oxalic acids content were modelled using RSM. Correlation analysis showed a positive relationship between acetic and tartaric acid content and antimicrobial activity. • The winery effluent was successfully used for kombucha fermentation. • The novel kombucha product had good antimicrobial properties. • A wide variety of organic acids was determined in the obtained products. • Antimicrobial properties and organic acids content were modelled using RSM. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Agregation behavior of two newly synthesized thiazolium salts are studied. • Introduction of –CH 3 on thiazolium ring increase thermal stability and decrease CMC. • Micelle formation reduces the toxicity of salts. • Additional methylation also reduces toxicity. Abstract Two new thiazolium-based surfactants namely N -dodecylthiazolium bromide, [NddTz][Br] and N -dodecyl-4-methylthiazolium bromide, [4mNddTz][Br], were synthesized and investigated as new surface active and antimicrobial agents. Their thermal stability is determined by TG/DSC measurements, and the self-assembly behaviour in aqueous solutions systematically studied applying experimental and molecular dynamics (MD) approach. Obtained results of surface tension and electrical conductivity showed that both newly synthesized salts possess a similar surface activity in aqueous solutions compared to imidazolium-based surface active N -dodecyl-3-methylimidazolium bromide, [NddmIm][Br], ionic liquid. Also, thermodynamic parameters of micellization are calculated and compared with the results obtained by volumetric measurements. Antimicrobial activity of these salts is tested by microdilution method on Gram-positive and Gram-negative bacteria and yeasts. In vitro cytotoxicity study has been performed using human fetal lung fibroblasts (MRC-5) and colon adenocarcinoma (HT-29) cell line. [ABSTRACT FROM AUTHOR]

The microbiologically induced calcite precipitation (MICP) has been extensively studied for geotechnical engineering through simultaneous action of natural phenomena and engineering processes. The focus of bacterial contribution to the MICP has been directed to calcium carbonate productivity, while the additional bacterial role as a crystal nucleation center was not explained especially from a mathematical prediction modeling point of view. Therefore, this study provides explanations and a mathematical modeling approach of bacterial influence on the MICP induced by newly-isolated ureolytic Bacillus strains and Sporosarcina pasteurii DSM 33. Using the obtained results of low-cost, rapid, and simple assays, artificial neural network modeling was applied for cell surface predispositions, pH changes as well as calcium-involved function in biofilm formation during the MICP, for the first time. Based on the obtained contribution of the alkalophilic/alkaloresistant bacteria, calcite precipitation can be significantly directed by the presence, of ureolytic bacterial cells as nucleation centers during CaCO 3 precipitation as well as their morphology, surface characteristics, potential to form a biofilm, and/or generate pH changes., (© 2021 Wiley-VCH GmbH.)