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    Optimization of culture conditions for the production and activity of recombinant xylanase from microalgal platform
    (Elsevier, 2023) Yildirim, Arzu; Ilhan-Ayisigi, Esra; Duzel, Ahmet; Mayfield, Stephen Patrick; Sargin, Sait
    Xylanases are enzymes responsible for the hydrolysis of the heteropolymer xylan. They have wide applications ranging from the bakery, animal husbandry, and textile to pulp and paper industry and biofuel productions. Recombinant xylanase production has been previously reported from different hosts such as bacteria and yeast. Microalgae offer a safe and cost-effective photosynthetic platform for producing recombinant proteins, including therapeutics and industrial enzymes. In this study, we optimized the production of recombinant xylanase expressed and secreted from the green alga, Chlamydomonas reinhardtii. The growth of the culture was optimized using response surface methodology (RSM) based on central composite design (CCD), with two numeric (culture incubation time and agitation rate) and one categoric (light intensity) factors. The optimum biomass concen-tration was obtained as 0.71 mg/mL from the CCD values. In addition, bubble column photobioreactors were set and compared for the culture growth, the protein concentration, and the enzyme activity under different light intensities and air flows. Increasing the aeration rate from 1 vvm to 2 vvm resulted in improved enzyme activity from 5330.5 U/g to 6277.7 U/g under 3500 lux illumination on the 3rd day of the culture. This study may lead to the further large-scale production of xylanase with high enzyme activity and reveal the advantage of the microalgae as a sustainable platform.
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    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.