Pectinases are a big group of enzymes that break down pectic polysaccharides of plant tissues into simpler molecules like galacturonic acids. It has long been used to increase yields and clarity of fruit juices. Since pectic substances are a very complex macromolecule group, various pectinolytic enzymes are required to degrade it completely. These enzymes present differences in their cleavage mode and specificity being basically classified into two main groups that act on pectin "smooth" regions or on pectin "hairy" regions. Pectinases are one of the most widely distributed enzymes in bacteria, fungi and plants. This review describes the pectinolytic enzymes and their substrates, the microbial pectinase production and characterization, and the industrial application of these enzymes.

b-Xylosidases are hydrolytic enzymes which play an important role in xylan degradation, hydrolyzing xylobiose and xylooligosaccharides to xylose from the nonreducing end. Filamentous fungi are particularly interesting producers of this enzyme from an industrial point of view, due to the fact that they secrete b-xylosidases into the medium. Besides, fungal b-xylosidases are highly advantageous for their elevated activity levels and specificity. Interest in xylanolytic enzymes has been increasing, for their possible application in many biotechnological processes. This fact has driven the isolation, purification and characterization of several b-xylosidases. In this review, the mechanisms of action, substrate specificities, physicochemical characteristics, regulation at molecular level, molecular cloning and classification of filamentous fungal b-xylosidases are described. The potential industrial applications of fungal b-xylosidases will also be presented.

Two xylanases from the crude culture filtrate of Penicillium sclerotiorum were purified to homogeneity by a rapid and efficient procedure, using ion-exchange and molecular exclusion chromatography. Molecular masses estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis were 23.9 and 33.1 kDa for xylanase I and II, respectively. The native enzymes' molecular masses of 23.8 and 30.8 kDa were estimated for xylanase I and II, respectively, by molecular exclusion chromatography. Both enzymes are glycoproteins with optimum temperature and pH of 50 degrees C and pH 2.5 for xylanase I and 55 degrees C and pH 4.5 for xylanase II. The reducing agents beta-mercaptoethanol and dithio-treitol enhanced xylanase activities, while the ions Hg(2+) and Cu(2+) as well the detergent SDS were strong inhibitors of both enzymes, but xylanase II was stimulated when incubated with Mn(2+). The K (m) value of xylanase I for birchwood xylan and for oat spelt xylan were 6.5 and 2.6 mg mL(-1), respectively, whereas the K (m) values of xylanase II for these substrates were 26.61 and 23.45 mg mL(-1). The hydrolysis of oat spelt xylan by xylanase I released xylobiose and larger xylooligosaccharides while xylooligosaccharides with a decreasing polymerization degree up to xylotriose were observed by the action of xylanase II. The present study is among the first works to examine and describe an extracellular, highly acidophilic xylanase, with an unusual optimum pH at 2.5. Previously, only one work described a xylanase with optimum pH 2.0. This novel xylanase showed interesting characteristics for biotechnological process such as feed and food industries.

No abstract

No abstract