Production of thermostable pectinase and xylanase for their potential application in bleaching of kraft pulp

Abstract

A very high level of alkalophilic and thermostable pectinase and xylanase has been produced from newly isolated strains of Bacillus subtilis and Bacillus pumilus respectively. Enzyme production for pectinase was carried out under SSF using combinations of cheap agricultural residues while xylanase was produced under submerged fermentation using wheat bran as substrate to minimize the cost of production of these enzymes Among the various substrates tested, the highest yield of pectinase production was observed by using combination of WB + CW (6592 U/g of dry substrate) supplemented with 4% yeast extract when incubated at 37 degrees C for 72 h using deionized water of pH 7.0 as moistening agent. The biobleaching effect of these cellulase free enzymes on kraft pulp was determined. Both xylanase and pectinase showed stability over a broad range of pH from 6 to 10 and temperature from 55 to 70 degrees C. The bleaching efficiency of the pectinase and xylanase on kraft pulp was maximum after 150 min at 60 degrees C using enzyme dosage of 5 IU/ml of each enzyme at 10% pulp consistency with about 16% reduction in kappa number and 84% reduction in permanganate number. Enzyme treated pulp when subjected to CDED(1)D(2) steps, 25% reduction in chlorine consumption and upto 19% reduction in consumption of chlorine dioxide was observed for obtaining the same %ISO brightness. Also an increase of 22 and 84% in whiteness and fluorescence respectively and a decrease of approximately 19% in the yellowness of the biotreated pulp were observed by pretreatment of the pulp with our enzymatic mixture.

Xylanase production using agro-residue in solid-state fermentation from Bacillus pumilus ASH for biodelignification of wheat straw pulp

“…Whereas 20 and 10% saving in chlorine and chlorine dioxide consumption, respectively, using xylanase from Bacillus pumilus ASH were reported in kraft pulp biobleaching ). Further, a reduction of 25 and 19% in chlorine and chlorine dioxide consumption by using pectinase and xylanase from Bacillus subtilis and Bacillus pumilus, respectively, had been reported (Ahlawat et al 2007). Xylanase enzyme isolated from Thermomyces lanuginosus SSBP reduces chlorine dioxide consumption by 2.5 kg/t in case of wheat straw pulp (Shirkolaee et al 2008).…”

Endoglucanase production with the newly isolated Myceliophtora sp. i-1d3b in a packed bed solid state fermentor

“…However, it is not recommended that the optimal experimental conditions found in glass flasks tests be immediately transposed to the bioreactors tests, since the dynamic conditions observed in the fermentors are quite different (1). From several SSF bioreactor configurations, the fixed bed (FB) is cheaper, easier to operate, and demands lower maintenance.…”

A new xylanase from thermoacidophilic Alicyclobacillus sp. A4 with broad-range pH activity and pH stability

“…Therefore, the xylanase used in this process requires pH stability and activity over a wide pH range. XynA4, as a potential candidate, can reduce the use of chlorine and chlorine Values represent the mean ± standard deviation (SD, n = 3) relative to the untreated control samples b ND not determined dioxide in the paper-making process [43,44], thus reducing the whole production cost.…”