Mannanase production by solid state fermentation using recombinant Aspergillus sojae AsT3

Solid state fermentation (SSF) has been well known as an alternative to the liquid culture fermentation method in the production of value-added industrial products such as enzymes and biofuels, as it is cheaper and environmentally friendly. SSF is used in the evaluation of solid wastes because it creates a suitable environment for microorganism growth on moist solids. In this study, mannanase production was carried out using Aspergillus sojae AsT3 by fermentation from different lignocellulosic biomass (barley husk, wheat bran, rye bran, oat husk) due to its cheap and abundant availability. For this purpose were carried out on five different substrates (barley husk, wheat bran, rye bran, oat husk and mixture) and at three different inoculation rates (3, 5 and 7%) solid state fermentations. In addition, the production of mannooligosaccharides (MOS) which is one of the uses of the β-mannanase enzyme produced by solid state fermentation, was also investigated. The best carbon source was selected and 10 different fermentation trials determined by Plackett-Burman Design (PBD) were conducted to examine the effect of independent variables. In order to increase MOS production, while fermentation determined by PBD was carried out, coffee wastes known to contain mannan were added to the best carbon source. It was according that these results, the highest β-mannanase activity (983.53 U/mg) was achieved in rye bran using a 7% inoculation rate. The effect of independent variables in non-mannanase and MOS production under conditions determined by PBD was examined and as a result it was determined that the fermentation conditions with 7% inoculation rate and initial pH 7.0 at 30°C for 7 days the best were found. Coffee waste added to the fermentation medium inhibited the enzyme production, but increased MOS production. The highest values of MOS components and total MOS values in fermentations performed under conditions determined with PBD were 80.59 ppm for mannobiose (6th trial), 69.94 ppm for mannotriose (1st trial), 210.37 ppm for mannotetrose (3rd trial), 391.87 ppm for mannopentose (1st trial), 533.40 ppm for mannohexose (9th trial) and 1086.45 ppm for total MOS (9th trial). In addition, as a result of the fermentations performed with PBD, it was determined that the incubation temperature was effective in the production of β-mannanase. In this study, the production of mannanase and MOS production by using recombinant Aspergillus sojae AsT3 (ATCC 11906) by solid culture fermentation method was aimed. When the results are examined, it has been determined that SSF is suitable for β-mannanase and MOS production due to the evaluation of wastes, low energy requirement and because it is a suitable environment for microorganism development. KEYWORDS: Solid-state fermentation, lignocellulose, mannanase, recombinant Aspergillus sojae, mannooligosaccharide