Authors:Y. Bakri, Y. Akeed, M. Jawhar, and M.I.E Arabi
Xylanase (EC18.104.22.168) is an industrially important enzyme that hydrolyzes xylan by breaking the hemicelluloses of the plant cell wall and produces xylooligosaccharides, xylobiose, and xylose ( B eg et al., 2001 ; P aes et al., 2012 ). This
Authors:S.M. Fiszman, P. Varela, A. Salvador, A. Gámbaro, A. Giménez, G. Ares, E. Wittig De Penna, L. López, and M.E. López
Three independent studies were conducted in Chile, Spain and Uruguay to assess the effects of the addition of enzymes on the shelf life of brown pan bread.Four batches of brown bread were prepared in each country: a control batch with no added enzymes, a second batch with amylase, a third batch with xylanase and a fourth batch with a 1:1 mixture of amylase and xylanase. Three sensory texture parameters were evaluated (softness, size of the soft area and cohesiveness) and a consumer study was conducted to determine the acceptability of the samples. In each country, the doses of each enzyme and enzyme mixtures (1:1) added to doughs have to be adapted to obtain good dough handling characteristics and minimise adhesiveness and stickiness of the corresponding flour in the traditional formulation.In all three countries the addition of the enzyme mixture gave the best results, achieving a longer shelf life, while the addition of xylanase accelerated bread staling.
Authors:Balázs Lemmer, Szabolcs Kertész, Gábor Keszthelyi-Szabó, Kerime Özel, and Cecilia Hodúr
Membrane separation processes are currently proven technologies in many areas. The main limitation of these processes is the accumulation of matter at the membrane surface which leads to two phenomena: concentration polarization and membrane fouling. According to the publications of numerous authors permeate flux could be increased by sonication. Our work focuses on separation of real broth by sonicated ultrafiltration. The broth was originated from hydrolysis of grounded corn-cob by xylanase enzyme. The filtration was carried out in a laboratory batch stirred cell with a sonication rod sonicator. In our work the effect of the stirring, the intensity of sonication and the membrane-transducer distance was studied on the efficiency of the ultrafiltration and on the quality of separated enzymes. Results reveal that xylanase enzyme can be effectively separated from real fermentation broth by ultrafiltration and enzymes keep their activity after the process. Enzyme activity tests show that low energy sonication is not harmful to the enzyme.
Authors:T. Prokopov, M. Nikolova, G. Dobrev, and D. Taneva
Enzyme-assisted extraction of carotenoids from tomato peels of the Bulgarian cultivar “Stela”, one of the most widely used cultivars by the canning industry, was examined in this study. The carotenoid content in raw tomato peels was established by HPLC analysis. A two-step protocol was followed: the tomato peels were first treated with enzymes and then extracted by the use of acetone as a solvent for 30 min at 20±1 °C and solid/liquid ratio of 1:30. The total carotenoid, lycopene, and β-carotene extraction yields were increased by the use of pectinase, cellulase, endo-xylanase, and proteinase enzymes in comparison with the non-enzyme-treated samples. The increase in the extraction yield was affected by the enzymes used, the enzyme concentration, the pretreatment time and temperature. Maximum total carotenoid (55.15 mg/100 g d.w.), β-carotene (35.85 mg/100 g d.w.), and lycopene (15.44 mg/100 g d.w.) extraction yields were obtained in peels pretreated with mixed cellulase (100 U g−1) and endo-xylanase (400 U g−1) for 4 h at 50 °C. Carotenoid recovery by mixed cellulolytic and hemi-cellulolytic enzyme pretreatment of tomato peels is a good approach, which can be used for waste utilization.
Authors:C. Roets, S.H. Rose, M. Muller, and M. Manley
The effect of a pure endoxylanase (Xyn2) and endoglucanase (EgII) from Trichoderma reesei on bread flour quality were compared to a commercial endoxylanase from Aspergillus niger (Com-xyl) and a cellulase-xylanase cocktail from T. reesei (Cel-xyl). Effects of these enzymes on dough quality, bread weight, height and crumb softness were analysed. Results obtained during commercial-scale baking tests often differed from those obtained during laboratory-scale tests; indicating that results from laboratory-scale baking tests cannot be extrapolated to commercialscale bread production. Low levels of endoxylanase activity benefited bread height and volume without affecting slice brightness in commercial-scale tests. The addition of endoglucanases and α-amylases can also be advantageous resulting in less endoxylanase activity required to obtain similar results.
The effect of the addition of extracts of agro-industrial wastes to the culture media on the production of ß-glucosidase, xylanase, laccase, manganese-dependent and independent peroxidases by the edible fungus Pleurotus ostreatus was determined. The relationship between cultivation parameters and the enzyme activities was assessed by spectral mapping technique combined with non-linear mapping. It was proved that extracts enhanced markedly the activities of laccase, manganese-dependent and independent peroxidases. Multivariate mathematical-statistical methods indicated that the enzyme activities were the highest in culture containing pepper extract. It was further demonstrated that the selectivity of the enzyme production was negligible up till 14 days of fermentation and reached the maximum at the 28 th day.
Authors:Á. Tóth, E. Baka, Sz. Luzics, I. Bata-Vidács, I. Nagy, B. Bálint, R. Herczeg, F. Olasz, T. Wilk, T. Nagy, B. Kriszt, I. Nagy, and J. Kukolya
Thermobifidas are thermophilic, aerobic, lignocellulose decomposing actinomycetes. The Thermobifida genus includes four species: T. fusca, T. alba, T. cellulosilytica, and T. halotolerans. T. fusca YX is the far best characterized strain of this taxon and several cellulases and hemicellulases have been cloned from it for industrial purposes targeting paper industry, biofuel, and feed applications. Unfortunately, sequence data of such enzymes are almost exclusively restricted to this single species; however, we demonstrated earlier by zymography that other T. alba and T. cellulosilytica strains encode the same enzyme sets. Recently, the advances in whole genome sequencing by the use of next generation genomics platforms accelerated the selection process of valuable hydrolases from uncharacterized bacterial species for cloning purposes. For this purpose T. cellulosilytica TB100T type strain was chosen for de novo genome sequencing. We have assembled the genome of T. cellulosilytica strain TB100T into 168 contigs and 19 scaffolds, with reference length of 4 327 869 bps, 3 589 putative coding sequences, 53 tRNAs, and 4 rRNAs. The analysis of the annotated genome revealed the existence of 27 putative hydrolases belonging to 14 different glycoside hydrolase (GH) families. The investigation of identified, cloned, and heterologously multiple cellulases, mannanases, xylanases, and amylases may result in industrial applications beside gaining useful basic research related information.
). The functionality of rye AXs can be investigated by enzymatic treatments. It has been shown that the encapsulation of proteins by AX can be reduced by the addition of xylanase ( Grossmann et al., 2016 ; Döring et al., 2017 ). The treatment of rye
Authors:I. Mitrović, J. Grahovac, J. Dodić, A. Jokić, Z. Rončević, and M. Grahovac
agitation rates to improve cellulase-free xylanase production by thermotolerant Streptomyces sp. Ab 106 and repeated fed-batch cultivation using agricultural waste . J. Biosci. Bioeng. , 95 ( 3 ), 298 - 301 . 10.1016/S1389-1723(03)80033-6 Yen , H