Xylooligosaccharide production from cotton and sunflower stalks

Ak, Özlem
In this study, the aim was enzymatic xylooligosaccharide production from cotton and sunflower stalks, two of main agricultural residues in Turkey. In first two parts of the study, alkali extracted xylan from both of the stalks was hydrolyzed by commercial xylanases Veron and Shearzyme. The effect of temperature, pH, enzyme and substrate concentrations were investigated to determine optimum enzymatic hydrolysis conditions of xylan. Sunflower and cotton stalk xylans were hydrolyzed by Shearzyme more efficiently than Veron under the conditions studied. Shearzyme produced different product profiles containing xylobiose (X2), xylotriose (X3), xylotetrose (X4) and xylopentose (X5) from cotton and sunflower stalk xylan. On the other hand, Veron hydrolyzed both xylan types to produce X2, X3, X5, X6 and larger xylooligosaccharides without any change in product profiles. In the third part of the study, home produced xylanase from Bacillus pumilus SB-M13, was also investigated for the production of xylooligosaccharides from both cotton and sunflower stalk xylan. The main products obtained by hydrolysis of both substrates by pure B. pumilus xylanase were X5 and X6, while crude B. pumilus xylanase generated X4 and X5 as the main products. Xylooligosaccharide production from pretreated cotton stalk without alkali extraction of xylan was the final part of the study. Three different pretreatment methods including biomass pretreatment by Phanerochaete chrysosporium fermentation, cellulase pretreatment and hydrothermal pretreatment were investigated to break down complex lignocellulosic structure of cotton stalk to improve the subsequent enzymatic hydrolysis of xylan in pretreated cotton stalk for xylooligosaccharide production. However, xylooligosaccharide was not effectively produced from pretreated cotton stalk. Shearzyme inhibiton was observed after all the pretreatment methods during further hydrolysis of pretreated cotton stalk probably due to production of inhibitory compounds of the enzyme.


Co-production of xylanase and itaconic acid by aspergillus terreus nrrl 1960 on agricultural biomass and biochemical characterization of xylanase
Kocabaş, Aytaç; Bakır, Ufuk; Department of Biotechnology (2010)
Production of xylanase and itaconic acid (IA) from Aspergillus terreus NRRL 1960 from agricultural residues was investigated in this study. Two different media were tested and the medium having itaconic acid inducing capacity was chosen for further studies due to its high xylanase and IA production capacity. The best xylan concentration was found as 2% (w/v). Addition of commercial xylanase to production culture resulted in higher initial simple sugar concentration which increased IA production slightly but...
Functional analysis of a mirna putatively involved in powdery mildew disease susceptibility in barley
Dağdaş, Gülay; Akkaya, Mahinur S.; Department of Biotechnology (2009)
Barley is one of the most important crop species in Turkey and powdery mildew is one of the most common pathogen decreasing yield in barley. For this problem, agricultural biologists apply breeding technologies in order to select and propagate resistant barley cultivars. However, this is not a permanent solution since pathogens evolve rapidly to overcome plant resistance mechanisms. On the other hand, molecular plant pathologists are trying to understand basic mechanisms underlying plant-pathogen interactio...
Xylanase and itaconic acid production by Aspergillus terreus NRRL 1960 within a biorefinery concept
Kocabas, Aytac; Ögel, Zümrüt Begüm; Bakir, Ufuk (Springer Science and Business Media LLC, 2014-03-01)
Production of two industrially important products, xylanase and itaconic acid (IA), by Aspergillus terreus NRRL 1960 from agricultural residues was investigated within a biorefinery concept. Biological pretreatment was applied to lignocellulosic materials by using A. terreus, which produced xylanase while growing on agricultural residues. For IA production, already grown cells were transferred into a new medium. The first step provided not only the pretreatment of lignocellulosic material in order to be use...
Comparison of benzaldehyde lyase production capacity in recombinant Escherichia coli and recombinant Bacillus species
Kaya, Hande; Çalık, Pınar; Department of Chemical Engineering (2006)
In this study, the benzaldehyde lyase (BAL, EC production in E. coli BL21 (DE3) pLySs as intracellular and in Bacillus species as extracellular were investigated, and comparison of the production capacity of the enzyme in the developed recombinant microorganisms were compared. For this purpose, firstly, PCR amplified bal gene was cloned into pRSETA vector which is under the control of strong T7 promoter and expressed in E. coli BL21 (DE3) pLysS strain. With developed recombinant E. coli BL21 (DE3)...
Growth of agriculturally important Pseudomonas spp. and Azotobacter Chroococcum on beer waste and observation of their survival in peat
Abat, Benek; Hamamcı, Haluk; Department of Food Engineering (2006)
In this study agriculturally important Pseudomonas spp. which may solubilize phosphate and Azotobacter chroococcum which can fix atmospheric nitrogen were grown on waste beer with 4 different concentrations and conditions for best growth were determined. Having potential of use as biofertilizers, they were put in the carrier material peat and survivals of them were observed for 3 months at three different temperatures. Biofertilizer can be defined as a substance which contains living microorganisms which, w...
Citation Formats
Ö. Ak, “Xylooligosaccharide production from cotton and sunflower stalks,” Ph.D. - Doctoral Program, Middle East Technical University, 2008.