Pseudozyma Sp Research Articles

Utilization of agro-industrial residues for pectinase production by the novel strain Pseudozyma sp. SPJ under solid state cultivation

Production of high titers of an alkaline, extracellular and thermo-tolerant pectinase by a newly isolated yeast Pseudozyma sp. SPJ was carried out in solid state fermentation (SSF). Among all the agro-industrial residues used as substrate, citrus peel was found to be the best. Maximum pectinase production was observed after 72 h of incubation at 32°C. The moistening agent containing MgSO4⋅7H2O, KH2PO4 and (NH4)2SO4, at pH 7.0 with a substrate-to-moisture ratio of 1:3, was found to be most effective. No additive was required to supplement the substrate for production of the enzyme. Use of an economical substrate (citrus peel) and only a little mineral salt solution without any other supplement, made pectinase production cost-effective. A commendable enzyme titer (279,600 ± 897 U g−1 solid substrate) by Pseudozyma sp. SPJ under such an economic solid state cultivation is reported for the first time. This enzyme could be applied in various industries (works within a good temperature and pH range) and in biodegradation of citrus waste.

Polygalacturonase secreted by yeasts from Brazilian semi-arid environments

Microbial pectinolytic enzymes are known to play a commercially important role in a number of industrial processes. The objective of this study was to investigate the extracellular polygalacturonases of yeasts isolated from Brazilian semi-arid environments. Among the 250 colonies tested, only 33 produced extracellular polygalacturonases: Aureobasidium pullulans (18 isolates), Candida boidinii (one isolate), Trichosporonoides sp. (three isolates), Kluyveromyces marxianus (one isolate), Cryptococcus liquefaciens (one isolate), Pseudozyma sp. (four isolates), and yeast-like related to fungal endophyte (five isolates). The highest activity of polygalacturonase was observed in Pseudozyma sp. CCMB 300 (14.17±0.08 µmol acid galacturonic released/min/mg protein). This study shows the potential of yeasts and yeast-like organisms isolated from Brazilian semi-arid environments to produce pectinolytic enzymes.

The isolation and characterization of Pseudozyma sp. JCC 207, a novel producer of squalene

In examining the production of valuable compounds by marine microorganisms, we isolated a novel yeast strain that produces a large amount of squalene and several polyunsaturated fatty acids. Molecular and phylogenetic analyses of the ribosomal DNA suggest that the isolate belongs to the genus Pseudozyma, which comprises ustilaginomycetous anamorphic yeasts. The nucleotide sequence of an internally transcribed spacer region from isolate Pseudozyma sp. JCC207 showed 98% similarity with those of Pseudozyma rugulosa and Pseudozyma aphidis, which are close relatives of the isolate. In considering use of Pseudozyma sp. JCC207 for squalene production, the efficiency of squalene production was investigated under different conditions. Glucose was the best carbon source for the production of squalene. In the presence of yeast extract, squalene production was activated and an optimum ratio of glucose to yeast extract was 4.5. For the optimal squalene production, the concentration of glucose was 40 g l(-1) and the best nitrogen source was sodium nitrogen. Pseudozyma sp. JCC207 was shown to produce up to 5.20 g/L of biomass and 340.52 mg/L of squalene. In an optimal condition, the content and yield of squalene produced by Pseudozyma sp. JCC207 were much greater than those obtained from microorganisms previously reported as squalene producers. We identified, classified, and characterized Pseudozyma sp. JCC207 as a novel squalene producer. The squalene production rate of Pseudozyma sp. JCC207 makes it an ideal candidate for the commercialization of microbial squalene.

Efficient production of mannosylerythritol lipids with high hydrophilicity by Pseudozyma hubeiensis KM-59

Mannosylerythritol lipids (MELs) are one of the most promising biosurfactants known because of their multifunctionality and biocompatibility. A previously isolated yeast strain, Pseudozyma sp. KM-59, mainly produced a hydrophilic MEL, namely MEL-C (4-O-[4'-O-acetyl-2',3'-di-O-alka(e)noyl-beta-D: -mannopyranosyl]-D: -erythritol). In this study, we taxonomically characterize the strain in detail and investigate the culture conditions. The genetic, morphological, and physiological characteristics of the strain coincided well with those of Pseudozyma hubeiensis. On batch culture for 4 days under optimal conditions, the yield of all MELs was 21.8 g/l; MEL-C comprised approximately 65% of the all MELs. Consequently, on fed-batch culture for 16 days, the yield reached 76.3 g/l; the volumetric productivity was approximately 4.8 g l(-1) day(-1). We further examined the surface-active and self-assembling properties of the hydrophilic MELs produced by the yeast strain. They showed higher emulsifying activities against soybean oil and a mixture of hydrocarbons (2-methylnaphtarene and hexadecane, 1:1) than the synthetic surfactants tested. On water penetration scans, they efficiently formed lyotropic liquid crystalline phases such as myelines and lamella (L alpha) in a broad range of their concentrations, indicating higher hydrophilicity than conventional MELs. More interestingly, there was little difference in the liquid crystal formation between the crude product and purified MEL-C. The present glycolipids with high hydrophilicity are thus very likely to have practical potential without further purification and to expand the application of MELs especially their use in washing detergents and oil-in-water-type emulsifiers.

Fungi Associated with Biological Soil Crusts in Desert Grasslands of Utah and Wyoming

Biological soil crusts of arid and semiarid regions of the world are recognized as one of the least explored niches occupied by fungi. The principal species of fungi associated with biocrusts in desert grasslands and their associated soils in two geographically separated sites were identified and compared with species from a similar community in which the active crust had been destroyed by grazing. The results confirm the existence of a highly diverse and to some degree a host specific assemblage (mycosociety) of fungi. Comparison of the prevalent species by presence and commonness at the undisturbed and disturbed sites revealed both quantitative and qualitative changes. The forms absent or with a markedly reduced occurrence in the disturbed site were three dark-colored anamorphs of loculoascomycetes (Bipolaris sp., Embellisia tellustris, Phoma anserine) and two loculoascomycetes (Graphyllium permundum, Pleospora richtophensis). Fungi present at all sites included Chrysosporium/Geomyces pannorum, Embellisia tellustris and Pseudozyma sp. Crust associated fungi not previously reported from soil included a basidiomycete (Cyphellostereum sp.), five loculoascomycetes (Kalmusia utahensis, Macroventuria wentii, Pleospora richtophensis, Phaeospora sp., Preussia sp.) and three mitosporic species (Heteroconium sp., Sclerococcum sp., Taeniolella sp.). Overall, the commonly encountered crust-associated fungi were dark-colored mitosporic and sterile forms apparently adapted to desert environments.

Fungi associated with biological soil crusts in desert grasslands of Utah and Wyoming

Biological soil crusts of arid and semiarid regions of the world are recognized as one of the least explored niches occupied by fungi. The principal species of fungi associated with biocrusts in desert grasslands and their associated soils in two geographically separated sites were identified and compared with species from a similar community in which the active crust had been destroyed by grazing. The results confirm the existence of a highly diverse and to some degree a host specific assemblage (mycosociety) of fungi. Comparison of the prevalent species by presence and commonness at the undisturbed and disturbed sites revealed both quantitative and qualitative changes. The forms absent or with a markedly reduced occurrence in the disturbed site were three dark-colored anamorphs of loculoascomycetes (Bipolaris sp., Embellisia tellustris, Phoma anserine) and two loculoascomycetes (Graphyllium permundum, Pleospora richtophensis). Fungi present at all sites included Chrysosporium/Geomyces pannorum, Embellisia tellustris and Pseudozyma sp. Crust associated fungi not previously reported from soil included a basidiomycete (Cyphellostereum sp.), five loculoascomycetes (Kalmusia utahensis, Macroventuria wentii, Pleospora richtophensis, Phaeospora sp., Preussia sp.) and three mitosporic species (Heteroconium sp., Sclerococcum sp., Taeniolella sp.). Overall, the commonly encountered crust-associated fungi were dark-colored mitosporic and sterile forms apparently adapted to desert environments.