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    A novel Lactiplantibacillus plantarum strain: probiotic properties and optimization of the growth conditions by response surface methodology
    (Springer, 2024) Gokmen, Goekhan Gurur; Sariyildiz, Seda; Cholakov, Remzi; Nalbantsoy, Ayse; Baler, Biray; Aslan, Emek; Duzel, Ahmet
    The objective of this study is to explore the probiotic properties and optimal growth conditions of Lactiplantibacillus plantarum BG24. L. plantarum BG24 exhibited a remarkable ability to utilize lactose, and to grow under acidic conditions and in the presence of high levels of bile salts. The strain showed the highest antibacterial activity against L. monocytogenes Scott A (zone of inhibition: 26 mm). L. plantarum BG24 was found to be resistant to 8 of the tested 19 antibiotics using the disc diffusion method.and its multiple antibiotic resistance (MAR) index was calculated as 0.421. The adhesion rate to human intestinal epithelial Caco-2 cells was determined as 37.51%. The enzyme profile of L. plantarum BG24 was investigated using API ZYM test kit and the highest enzymatic activities were found for Leucine arylamidase, beta-glucosidase, Valine arylamidase, beta-galactosidase and N-acetyl-beta-glucosaminidase. L. plantarum BG24 strain showed higher microbial growth under static conditions (6.60 OD600) compared to 100 rpm (5.73 OD600) and 200 rpm (5.02 OD600) shaking speed due to its facultative anaerobic characteristic. However, different inoculation rates and glucose addition did not make a statistically significant difference on biomass formation (p > 0.05). The specific growth rate of L. plantarum BG24 was 0.416 h(-1), the doubling time was 1.67 h, and the biomass productivity value was 0.14 gL(-1) h(-1) in the original MRS broth (pH 5.7) while higher values were found as 0.483 h(-1), 1.43 h and 0.17 gL(-1) h(-1), respectively, in MRS broth (pH 6.5) medium enriched with 5 g/L yeast extract. The stirred tank bioreactor was used to optimise the growth of BG24 strain. The process variables was optimized at 0.05 vvm of aeration rate, 479 rpm of agitation speed, 3% of inoculation rate and 18 h of incubation time. The maximum biomass (g/L) production was obtained as 3.84 g/L at the optimized conditions.
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    Öğe
    Production of xylanase intended to be used in bread-making: laboratory scale and pilot scale studies
    (Taylor & Francis Ltd, 2024) Ongen, Gaye Ongen; Sahinbas, Dilek; Duzel, Ahmet; Duzdemir, Gizem Ezgi; Altinel, Burak; Tuluk, Kubra; Sargin, Sait
    In this study, submerged and solid-state fermentation studies were performed for xylanase production simultaneously to determine ideal carbon and nitrogen sources together with necessary production parameters from the laboratory scale to the pilot scale. The results showed that barley malt sprout is effective as a nitrogen and a good carbon source. Under optimum conditions, xylanase activities 71.74 +/- 2.70 U/mL, 56.95 +/- 3.6 U/mL, 65.8 +/- 8 U/mL and 46.05 +/- 0.1 U/mL were achieved in shake flasks, 2, 10 and 30 L bioreactors, respectively. In solid-state fermentation studies, maximum activity in flasks was 759.15 +/- 36.16 U/g production media, and maximum activity in pilot-scale tray bioreactor productions was 1312 +/- 137.85 U/g dry substrate. Bread-making trials showed that using xylanase at 100 U/100g flour resulted in a significant increase in the loaf volume of wheat flour bread and whole wheat flour bread.
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    Öğe
    Selection of DNA aptamers for the aptamer-assisted magnetic capture of the purified xylanase from Aspergillus niger
    (Elsevier, 2024) Duzel, Ahmet; Bora, Burhan; Ozgen, Gaye Ongen; Evran, Serap
    Xylanases are a group of enzymes that catalyze the hydrolysis of xylan. Xylanases have wide industrial applications, and they can produced by various organisms. In this study, we aimed to develop aptamers for the capture of xylanase produced by a wild-type Aspergillus niger strain. Xylanase was produced by Aspergillus niger in a 5-liter stirred-tank bioreactor and then purified by column chromatography. Magnetic bead-based SELEX (Systematic Evolution of Ligands by Exponential Enrichment) was performed to select DNA aptamers specific to the purified xylanase. After nine rounds of selection, next-generation sequencing (NGS) analysis was performed. Four aptamers, namely AXYL-1, AXYL-2, AXYL-3, and AXYL-4, were identified for further characterization. The binding properties of the selected aptamers were characterized by fluorescence quenching (FQ) analysis and an enzyme-linked aptamer assay (ELAA). The Kd values were found to be in the low mu M range. Then, each aptamer was immobilized on streptavidin-coated magnetic particles, and the recovery ratio of xylanase was determined. Although AXYL-1 wasn't effective, AXYL-2, AXYL-3, and AXYL-4 were proven to capture the xylanase. The maximum recovery rate of xylanase was found to be approximately 54 %.