Characterization of cold-active pectate lyases from psychrophilic Mrakia frigida

Aims: This study was conducted to determine optimal conditions for pectate lyase (PL) production by two psychrophilic yeast strains and to compare the properties of the cold-active enzymes using mesophilic PL as reference enzyme. Methods and Results: Two psychrophilic yeasts isolated from remote geographical locations (European Alps, north Siberia) produced extracellular cold-active PL. Both strains were identified as Mrakia frigida by analysis of ITS and large subunit (LSU) rRNA sequences. Maximum enzyme production occurred at a cultivation temperature of 1 or 5 degrees C. The apparent optimum for enzyme activity was observed at 30 degrees C and pH 8.5-9. The enzymes were thermolabile, but were resistant to repeated freezing and thawing. Conclusion: We describe for the first time alkaline PL-producing representatives of the yeast species M. frigida. The two strains produce cold-active PL with similar properties, but have a different enzyme production pattern. Significance and Impact of the Study: The enzymes described in this study could be useful for a wide range of applications, such as low-temperature pretreatment of wastewater containing pectic substances.