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Cryptococcus laurentii strain AL27 demonstrating significant potential for intracellular phytase production was selected by 2-step screening of Antarctic yeasts. The strain showed increased phytase activity in a culture medium with 40 g/L sucrose, KH2PO4 providing 5 mg/L phosphorus, and cultivation temperature of 24 °C, which relates it to psychrotrophic microorganisms. The enzyme kinetic characteristics according to sodium phytate were K m = 0.98 mmol/L, v lim = 33.3 μmol g−1 min−1. The enzyme had maximum activity at 40 °C and acted within a wide pH range: from 2.0 to 5.5, which is of positive significance for its direct inclusion into the feed of monogastric animals. [ABSTRACT FROM AUTHOR]

Beta-galactosidases (beta-D-galactoside-galactohydrolases (EC 3.2.1.23), lactases) are important industrial enzymes used for the hydrolysis of lactose from milk and milk whey. These enzymes are produced by different organisms and purified by multi-step procedures. The multi-step purification schemes are cost and time ineffective which can also lead to poor yield, denaturation and loss of enzymatic activity. In our study, extracellular beta-galactosidase from mutant strain Aspergillus oryzaeH26-10-7 was purified by a two step procedure, Metal-ion Affinity Chromatography (IMAC) followed by size-exclusion separation. Purified enzyme was characterized by sodium dodecyl Sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and zymographic analysis. This fungal beta-galactosidase was characterized as a protein corresponding to 113 kDa. Enzyme from mutant strain was found to have five times higher catalytic activity on the synthetic substrate o-nitrophenyl-beta-D-galactopyranoside (ONPG) compared to the wild type enzyme. Moreover, the mutant enzyme was more thermo resistant compared to the wild type. This highly important technological characteristic can be exploited in food industry. Moreover, based on the IMAC patterns of wild type and mutant enzymes, similarities in their His topography were supposed., (Copyright 2006 John Wiley & Sons, Ltd.)