Enhancing the Production of Thermostable Mangrovibacter plantisponsor Xylanase for Application in Breadmaking

Xylanase was isolated from a newly isolated Mangrovibacter plantisponsor UMTKB-3 strain. The response surface methodology was employed to optimize extracellular xylanase production; the best experimental value (25 ± 0.12 U/mL) was obtained when using 16 g/L of tryptone, 15 g/L of yeast extract, 15 g/L of NaCl, and an initial optical density of 0.2 at 600 nm. The optimized xylanase production was enhanced by five-fold compared to the pre-optimized conditions. Maximum xylanase activity was measured at 50 °C and pH 6, using xylan as the substrate. The enzyme maintained more than 98.9% of its initial activity at temperatures ranging from 45 to 60 °C. Xylanase exhibited a higher stability in the presence of metal ions: residual activities of 190%, 97.1%, and 81.1% were measured in the presence of MnCl2, FeSO4, and NiCl2, respectively. Moreover, the application of M. plantisponsor xylanase to improve bread quality was investigated. The rate of increase in firmness during storage was lower in xylanase-supplemented bread compared with control bread. Supplementing the bread with xylanase resulted in increased elasticity and extensibility, as well as an increase in volume and a decrease in density. These findings suggest that our enzyme is a promising candidate for food industry applications, particularly in the baking industry, for promoting human health.