Heavy oils, principally long-chain n-alkanes secreted by Aureobasidium pullulans var. melanogenum strain P5 isolated from mangrove system.

Abstract

In this study, the yeast strain P5 isolated from a mangrove system was identified to be a strain of Aureobasidium pullulans var. melanogenum and was found to be able to secrete a large amount of heavy oil into medium. After optimization of the medium for heavy oil production and cell growth by the yeast strain P5, it was found that 120.0g/l of glucose and 0.1% corn steep liquor were the most suitable for heavy oil production. During 10-l fermentation, the yeast strain P5 produced 32.5g/l of heavy oil and cell mass was 23.0g/l within 168h. The secreted heavy oils contained 66.15% of the long-chain n-alkanes and 26.4% of the fatty acids, whereas the compositions of the fatty acids in the yeast cells were only C16:0 (21.2%), C16:1(2.8%), C18:0 (2.9%), C18:1 (39.8%), and C18:2 (33.3%). We think that the secreted heavy oils may be used as a new source of petroleum in marine environments. This is the first report of yeast cells which can secrete the long-chain n-alkanes.