Discovery of Pseudozyma rugulosa NBRC 10877 as a novel producer of the glycolipid biosurfactants, mannosylerythritol lipids, based on rDNA sequence

Abstract

The search for a novel producer of glycolipid biosurfactants, mannosylerythritol lipids (MEL) was undertaken based on the analysis of ribosomal DNA sequences on the yeast strains of the genus Pseudozyma. Pseudozyma rugulosa NBRC 10877 was found to produce a large amount of glycolipids from soybean oil. Fluorescence microscopic observation also demonstrated that the strain significantly accumulates polar lipids in the cells. The structure of the glycolipids produced by the strain was analyzed by (1)H and (13)C nuclear magnetic resonance and gas chromatography-mass spectrometry methods, and was determined to be the same as MEL produced by Pseudozyma antarctica, a well-known MEL producer. The major fatty acids of the present MEL consisted of C8 and C10 acids. Based on high performance liquid chromatography, the composition of the produced MEL was as follows: MEL-A (68%), MEL-B (12%), and MEL-C (20%). To enhance the production of MEL by the novel strain, factors affecting the production, such as carbon and nitrogen sources, were further examined. Soybean oil and sodium nitrate were the best carbon and nitrogen sources, respectively. The supplementation of a MEL precursor, such as erythritol, drastically enhanced the production yield from soybean oil at a rate of 70 to 90%. Under the optimal conditions in a shake culture, a maximum yield, productivity, and yield coefficient (on a weight basis to soybean oil supplied) of 142 g l(-1), 5.0 g l(-1) day(-1), and 0.5 g g(-1) were achieved by intermittent feeding of soybean oil and erythritol using the yeast.

Biosurfactant-producing yeasts widely inhabit various vegetables and fruits

“…The major fatty acids were C 8 and C 10 . 29) On the other hand, the fatty-acid profile of MEL-B produced by strain SS15 closely resembled that of MEL-B by Pseudozyma tsukubaensis. The major fatty acids were C 8 , C 12 , and C 14 .…”

“…Strain SS11 appeared to be a promising MEL producer, considering our previous result that Pseudozyma rugulosa, a high-level MEL producer, provided a yield coefficient of 0.5 g/g from soybean oil. 29) Although strain SS12 showed the lowest yield among the strains tested, the amount of MELs reached 8.5 g/L.…”

Identification of Pseudozyma graminicola CBS 10092 as a Producer of Glycolipid Biosurfactants, Mannosylerythritol Lipids

“…In addition, they show high binding affinity toward different immunoglobulins 12,13) and lectins 14) . On conventional high-level MEL producers such as P. antarctica T-34 2,15) , P. aphidis DSM 70725 16,17) and P. rugu- 18) , the product is consistently a mixture of MEL-A, -B and -C ( ); MEL-A is the major component and comprises more than 70% of all the MELs. However, MEL-A has a drawback in handling of the aqueous solution due to its very low water-solubility and/or hydrophilicity: this has partially limited practical application of MELs.…”

“…The compounds on the plates were located by charring at 110 for 5 min after spraying the anthrone reagent as previously reported 23) . The purified MEL fraction, including MEL-A, -B and -C prepared as reported previously 18) , was used as a standard.…”

Glycolipid Biosurfactants, Mannosylerythritol Lipids, Repair the Damaged Hair

“…The concentrated MELs were dissolved in chloroform and then purified by silica-gel (Wako-gel C-200; Wako, Japan) column chromatography using a gradient elution of chloroform/acetone (10:0 to 0:10, vol/vol) mixtures as solvent systems 13) . The purified MEL-A and MEL-B were used in the following experiments.…”