Biotechnological production and statistical optimization of fungal xylanase by bioconversion of the lignocellulosic biomass residues in solid-state fermentation

Abstract

Most of the lignocellulosic biomass residues are decomposed and transformed by a variety of microbes in the natural environment. The xylanase production from Aspergillus niger strain BG has been produced using wheat bran under solid-state fermentation (SSF). One factor at a time approach (OFAT) was used to optimize the effect of the incubation period, initial pH, moisture content, and cultivation temperature on the xylanase production. Furthermore, experiments were designed with a Box–Behnken design (BBD) on the same variables using response surface methodology (RSM). Analysis of variance (ANOVA) was carried out and the xylanase production was expressed with a mathematical equation depending on the factors. Maximum xylanase yield after OFAT approach and RSM optimization was significant with maximum values of 4008.25 ± 3.73 U/g of dry substrate (U/gds) and 5427.51 ± 4.4 U/gds which have been recorded respectively compared with the initial conditions (1899.02 ± 1.6 U/gds) after 7 days of fermentation. The effects of individual, interaction, and square terms on xylanase production were represented using the non-linear regression equations with significant R2 and p values. The optimum conditions established by RSM method for the maximum xylanase production were obtained with a pH media of 2.5 at 37 °C using wheat bran as 84% humidified substrate after 66 h of incubation, this conditions resulted in 65.01% increased level of the xylanase production than produced in the initial conditions. Xylanase production from Aspergillus niger strain BG using RSM is considered advantageous for bioconversion of the agriculture residues.