Purification and properties of lipase from Torulopsis

The First Comprehensive Biodiversity Study of Culturable Fungal Communities Inhabiting Cryoconite Holes in the Werenskiold Glacier on Spitsbergen (Svalbard Archipelago, Arctic)

Cryoconite holes on glacier surfaces are a source of cold-adapted microorganisms, but little is known about their fungal inhabitants. Here, we provide the first report of distinctive fungal communities in cryoconite holes in the Werenskiold Glacier on Spitsbergen (Svalbard Archipelago, Arctic). Due to a combination of two incubation temperatures (7 °C and 24 ± 0.5 °C) and two media during isolation (PDA, YPG), as well as classical and molecular identification approaches, we were able to identify 23 different fungi (21 species and 2 unassigned species). Most of the fungi cultured from cryoconite sediment were ascomycetous filamentous micromycetes. However, four representatives of macromycetes were also identified (Bjerkandera adusta, Holwaya mucida, Orbiliaceae sp., and Trametes versicolor). Some of the described fungi possess biotechnological potential (Aspergillus pseudoglaucus, A. sydowii, Penicillium expansum, P. velutinum, B. adusta, and T. versicolor), thus, we propose the Arctic region as a source of new strains for industrial applications. In addition, two phytopathogenic representatives were present (P. sumatraense, Botrytis cinerea), as well as one potentially harmful to humans (Cladosporium cladosporioides). To the best of our knowledge, we are the first to report the occurrence of A. pseudoglaucus, C. allicinum, C. ramotenellum, P. sumatraense, P. velutinum, P. cumulodentata, B. adusta, and T. versicolor in polar regions. In all likelihood, two unassigned fungus species (Orbiliaceae and Dothideomycetes spp.) might also be newly described in such environments. Additionally, due to experimenting with 10 sampling sites located at different latitudes, we were able to conclude that the number of fungal spores decreases as one moves down the glacier. Considering the prevalence and endangerment of glacial environments worldwide, such findings suggest their potential as reservoirs of fungal diversity, which should not be overlooked.

Purification and some properties of the staphylococcal extracellular lipase

Staphylococcal lipase has been purified by application of a multistep procedure involving ammonium sulfate precipitation, and hydrophobic interaction chromatography followed by gel filtration through Sepharose CL-4B. A purified enzyme was obtained which appeared to be homogeneous by molecular sieving, polyacrylamide gel electrophoresis and sucrose gradient centrifugation. The enzyme was then subjected to physicochemical analysis. It has been found that staphylococcal lipase appears in two molecular forms: light (45 kDa) and heavy (300 kDa). Amino acid analysis indicates that lipase contains 17 amino acids with a prevalence of hydrophobic amino acids. No sulfur-containing amino acid was found in the enzyme molecule. The lipase contains about 2% sugars and some amount of lipids. The lipase preparation is stable within pH 5.0 to 9.0 and exhibits maximal activity at pH 8.0. The optimal temperature for the enzymatic reaction was established at 55 degrees C.

Lipase synthesis in hydrocarbon fermentation

A study was undertaken to establish conditions and relationships for the production of lipases during hydrocarbon fermentation. A culture of Candida lipolytica was isolated by a kerosene enrichment technique from oil-soaked soil and this microbe was used to study the production of lipase on a kerosene-mineral salts medium. The optimum pH, medium, and temperature for lipase synthesis were established and the properties of the isolated enzyme in terms of its activity and lipid specificity were studied.

The lipolytic activities of the isolated cell envelope fracttions of Baker's yeast

1. The existence of phospholipase and lipase activities in the isolated cell envelopes of baker's yeast was demonstrated. 2. The content of phospholipase was found to be markedly higher than that of lipase. 3. After partial enzymic digestion of the isolated cell envelopes, the bulk of the lipolytic activities was recovered in the sedimentable preparations, which consisted of the fragments of the plasma membrane. 4. During repeated washings, the lipase was completely released from the cell envelopes, as were also the bulk of the lipid components and most of the Mg(2+)-dependent adenosine triphosphatase, an enzyme connected with the plasma membrane. The phospholipase was more firmly bound to the preparation but not so firmly as the external saccharase. 5. These results indicate that the lipolytic enzymes found in the cell envelopes are mostly located in the plasma membrane.

Lipase from Pseudomonas fragi. II. Properties of the Enzyme

The optimal pH value of a lipase from Pseudomonas fragi was between 7.5 and 8.9, and a high reaction rate was observed at 54 C. Heating the enzyme solution at 63 C for 30 min inactivated only 27.6% of its activity; however, total inactivation was observed at 66 C after 1 hr and at 71 C after 10 min. The lipase was inhibited strongly by Fe and Fe ions, and to a lesser extent by Co, Cu, Zn. No inhibition was observed with Ca or NaF. Ethylenediaminetetraacetate was effective in removing the toxicity of Fe. The activity of the enzyme was inhibited markedly by p-chloromercurobenzoate, but the effects of N-ethylmaleimide and iodoacetate were moderate. The enzyme was able to hydrolyze natural fats, synthetic triglycerides, and alcohol esters. The order of the rate of hydrolysis of some triglycerides under experimental conditions was, from the fastest to the lowest, trilaurin, tricaprin, tricaprylin, tripalmitin, tributyrin, tricaproin, and tristearin. The enzyme was capable of hydrolyzing methyl butyrate, but the rate of hydrolysis was about one-fifth that for triolein and one-thirteenth that for coconut oil. The enzyme lost its activity rapidly when held frozen, at 20 C, and at the extremes in pH. Glutathione, cysteine, and mercaptoethanol did not preserve the activity of the enzyme.