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ABSTRACT: Forty-three fungal producers for glycolipid biosurfactants, mannosylerythritol lipids (MELs), were isolated from leaves and smuts of sugarcane plants. These isolates produced MELs with sugarcane juice as nutrient source. The strains were taxonomically categorized into the genera Pseudozyma and Ustilago on the basis of partial sequences of the ribosomal RNA gene.
Bioscience Biotechnology and Biochemistry 09/2012; 76(9):1788-91. · 1.28 Impact Factor
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ABSTRACT: Mannosylerythritol lipids (MELs) are glycolipid biosurfactants excreted by fungal strains. They show not only excellent surface-active properties but also versatile biochemical actions. Ustilago scitaminea NBRC 32730 has been reported mainly to produce a mono-acetylated and di-acylated MEL, MEL-B, from sucrose as sole carbon source. In order to make biosurfactant production more efficient, we focused our attention on the use of sugarcane juice, one of the most economical resources. The fungal strain produced MEL-B at the yield of 12.7 g/L from only sugarcane juice containing 22.4% w/w sugars. Supplementation with organic (yeast extract, peptone, and urea) and inorganic (sodium nitrate and ammonium nitrate) nitrogen sources markedly enhanced the production yield. Of the nitrogen sources, urea gave the best yield. Under optimum conditions, the strain produced 25.1 g/L of MEL-B from the juice (19.3% sugars) supplemented with 1 g/L of urea in a jar fermenter at 25 °C over 7 d. The critical micelle concentration (CMC) and the surface-tension at the CMC for the present MEL-B were 3.7×10(-6) M and 25.2 mN/m respectively. On water-penetration scan, the biosurfactant efficiently formed the lamella phase (L(α)) and myelins over a wide range of concentrations, indicating excellent surface-active and self-assembling properties. More significantly, the biosurfactant showed a ceramide-like skin-care property in a three-dimensional cultured human skin model. Thus, sugarcane juice is likely to be effective in glycolipid production by U. scitaminea NBRC 32730, and should facilitate the application of MELs.
Bioscience Biotechnology and Biochemistry 07/2011; 75(7):1371-6. · 1.28 Impact Factor
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ABSTRACT: An ustilaginomycetous anamorphic yeast species isolated from the leaves of Saccharum officinarum (sugarcane) in Okinawa, Japan, was identified as a novel Pseudozyma species based on morphological and physiological aspects and molecular taxonomic analysis using the D1/D2 domains of the large subunit (26S) rRNA gene and the internal transcribed spacer 1 (ITS1)-5.8S-ITS2 regions. The name Pseudozyma churashimaensis sp. nov. was proposed for the novel species, with JCM 16988(T) as the type strain. Interestingly, P. churashimaensis was found to produce glycolipid biosurfactants, a mixture of mannosylerythritol lipids (MELs), including a novel tri-acetylated derivative (MEL-A2), from glucose. The observed critical micelle concentration (CMC) and the surface tension at CMC of MEL-A2 were 1.7 × 10⁻⁶ M and 29.2 mN/m, respectively. Moreover, on a water-penetration scan, MEL-A2 efficiently formed different lyotropic liquid crystalline phases, including the lamella phase at a wide range of concentrations, indicating its excellent surface-active and self-assembling properties. The novel strain of the genus Pseudozyma should thus facilitate the application of glycolipid biosurfactants in combination with other MEL producers.
Journal of Bioscience and Bioengineering 05/2011; 112(2):137-44. · 1.79 Impact Factor
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ABSTRACT: Biosurfactants (BS) are produced by a variety of microorganisms from renewable resources, and have unique properties compared to chemical surfactants. In order to attain efficient production of BS from low-cost materials, we focused our attention on the use of sugarcane molasses. Fifteen yeast strains that are known as BS producers were examined for BS productivity from a culture medium consisting of only molasses and water. Among the strains tested, only Starmerella bombicola NBRC 10243 produced sophorolipids (SL), which are glycolipid BS. The culture conditions for the yeast were then investigated in a shake-flask culture. SL production was significantly affected by the pH of the medium and was highly accelerated at pH 6. Under the optimum conditions, the amount of SL reached 14.4 g/L after 120 h from a medium containing 150 g/L of total sugars. We tried to improve the production of SL further by feeding the molasses using a jar fermentor. Interestingly, the amount of SL increased up to 22.8 g/L after 120 h; the production rate was 1.6-fold higher than that in the shake-flask culture. These results suggest that the present yeast should have great potential for the low-cost production of SL, and facilitate the application of BS in various fields.
Journal of oleo science 01/2011; 60(5):267-73. · 1.42 Impact Factor
