Phytase activity in Cryptococcus laurentii ABO 510

Area of Science:

• Microbiology
• Enzymology
• Biochemistry

Background:

• Phytate is an anti-nutritional factor in plant-based animal feeds, reducing phosphorus bioavailability.
• Microbial phytases are enzymes that hydrolyze phytate, releasing phosphorus.
• Identifying novel phytases with desirable properties is crucial for improving animal nutrition.

Purpose of the Study:

• To screen Cryptococcus strains for phytase activity.
• To characterize the phytase from the most active strain, Cryptococcus laurentii ABO 510.
• To evaluate the potential application of this phytase as an animal feed additive.

Main Methods:

• Screening of ten Cryptococcus strains for phytase activity.
• Biochemical characterization of the enzyme, including temperature and pH optima, thermostability, substrate specificity, and inhibition patterns.
• Determination of kinetic parameters (Km) for phytic acid.

Main Results:

• Cryptococcus laurentii ABO 510 exhibited the highest phytase activity.
• The cell wall-associated enzyme had optimal activity at 62°C and pH 5.0.
• The enzyme was thermostable at 70°C and showed broad substrate specificity, with phytic acid as the preferred substrate (Km = 21 µM).
• Activity was inhibited by inorganic phosphate, phytic acid, and certain divalent metal ions (Hg2+, Zn2+, Cd2+, Ca2+).

Conclusions:

• The phytase from C. laurentii ABO 510 possesses favorable enzymatic properties, including high activity and thermostability.
• Its ability to hydrolyze phytate suggests significant potential as a feed additive.
• This enzyme could enhance phosphorus utilization in animal diets, reducing the need for inorganic phosphorus supplementation.