Characteristics of pectate lyase formation by Hypomyces solani f. sp. cucurbitae

Polysaccharide lyases

Polysaccharide lyases (or eliminases) are a class of enzymes (EC 4.2.2.-) that act to cleave certain activated glycosidic linkages present in acidic polysaccharides. These enzymes act through an eliminase mechanism, rather than through hydrolysis, resulting in unsaturated oligosaccharide products. Acidic polysaccharides are ubiquitous and so are the lyases that degrade them. This review article examines lyases that act on acidic polysaccharides of plant, animal, and microbial origin. These lyases are predominantly of microbial origin and come from a wide variety of both pathogenic and nonpathogenic bacteria and fungi. The lyases discussed include alginate lyase (EC 4.2.2.3), pectin lyase (EC 4.2.2.10), pectate lyase (EC 4.2.2.2), oligogalacturonide lyase (EC 4.2.2.6), exopolygalacturonate lyase (EC 4.2.2.9), chondroitin lyases (EC 4.2.2.4 and EC 4.2.2.5), hyaluronate lyase (EC 4.2.2.1), heparin lyase (EC 4.2.2.7), heparan lyase (EC 4.2.2.8), and other unclassified lyases. This review examines the sources, regulation, purification, and properties of these polysaccharide lyases.

Polygalacturonate lyase production by Bacillus subtilis and Flavobacterium pectinovorum

Nutritional factors relating to the production of polygalacturonate lyases by strains of Bacillus subtilis and Flavobacterium pectinovorum were examined. Studies were carried out in shake flask cultures. In the case of B. subtilis the enzyme was produced constitutively, whereas in the case of F. pectinovorum it was only produced in quantity in the presence of pectic substances. Glucose was the most suitable carbon source for production of the polygalacturonate lyase of B. subtilis; of the nitrogen sources examined, the highest activities per milliliter of supernatant and per milligram of cells were obtained with glutamine and ammonium sulfate, respectively. The pattern of enzyme production and growth was similar although enzyme production ceased at pH 5.3. Sodium polypectate was the best inducer of polygalacturonate lyase with F. pectinovorum. Highest activity per milliliter of cell-free supernatant was obtained with skin milk powder as nitrogen source, although ammonium sulfate gave highest enzyme production per unit of biomass. Growth of F. pectinovorum occurred between pH 5.7 and 7.2. Enzyme production occurred during active growth and was independent of the pH of the medium.