High-temperature optima phosphatases from the cold-tolerant Arctic fungus Penicillium citrinum

Fifty-six fungal isolates from Arctic soils were subjected to primary screening for their ability to solubilize insoluble inorganic phosphate. Nine of the isolates were further analysed quantitatively for phosphatase production using para-nitrophenylphosphate as substrate. Amongst these, a cold-tolerant fungus, Penicillium citrinum strain PG162 was found to be the best producer of intracellular acid phosphatase. Further characterization of the enzyme showed that it is most active in the temperature range of 40-60°C and pH range of 4.2-4.8. The dried enzyme extract is stable at a temperature of up to 50°C for at least 1 h. Its activity is affected by presence of metal ions. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS–PAGE) analysis suggests the molecular weight of the enzyme to be between 20 and 29 kDa. The present study is important with respect to our understanding of the kind of enzymatic reactions that take place in the polar microbes, and the extent to which their activity is sustained.Keywords: acid phosphatase; enzyme; para-nitrophenylphosphate; Pikovskaya medium; psychrotolerant; SDSPAGE(Published: 9 August 2012)Citation: Polar Research 2012, 31, 11105, http://dx.doi.org/10.3402/polar.v31i0.1110

High-temperature optima phosphatases from the cold-tolerant Arctic fungus Penicillium citrinum

Fifty-six fungal isolates from Arctic soils were subjected to primary screening for their ability to solubilize insoluble inorganic phosphate. Nine of the isolates were further analysed quantitatively for phosphatase production using para-nitrophenylphosphate as substrate. Amongst these, a cold-tolerant fungus, Penicillium citrinum strain PG162 was found to be the best producer of intracellular acid phosphatase. Further characterization of the enzyme showed that it is most active in the temperature range of 40–60°C and pH range of 4.2–4.8. The dried enzyme extract is stable at a temperature of up to 50°C for at least 1 h. Its activity is affected by presence of metal ions. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS–PAGE) analysis suggests the molecular weight of the enzyme to be between 20 and 29 kDa. The present study is important with respect to our understanding of the kind of enzymatic reactions that take place in the polar microbes, and the extent to which their activity is sustained

Studies on diversity of soil microfungi in the Hornsund area, Spitsbergen

We assessed culturable soil microfungal diversity in various habitats around Hornsund, Spitsbergen in the High Arctic, using potato dextrose agar (PDA) medium. Thermal growth classification of the fungi obtained was determined by incubating them in 4°C and 25°C, permitting separation of those with psychrophilic, psychrotolerant and mesophilic char− acteristics. In total, 68 fungal isolates were obtained from 12 soil samples, and grouped into 38 mycelial morphotypes. Intergenic spacer regions of these morphotypes were sequenced, and they represented 25 distinct taxonomic units, of which 21 showed sufficient similarity with available sequence data in NCBI to be identified to species level. Soil under ornithogenic influence showed the highest species diversity, including sequences assigned to Mortierella macrocystis, M. elongata, Mortierella sp., Cudoniella sp., Varicosporium elodeae, Beauveria bassiana, Geomyces pannorum, Penicillium sp. and Atradidymella muscivora. Fourteen taxa were classified as psychrophilic, seven mesophilic, and four psychrotolerant