(12f) Production of Heavy Oil Liamocin in Fermentation By Aureobasidium Pullulans: Kinetics, Process Optimization and Economic Analysis

Aureobasidium pullulans is a ubiquitous fungus that is well known for producing exopolysaccharide pullulan, polymalic acid (PMA), and many useful industrial enzymes such as xylanase and lipase. Some strains of A. pullulans can also produce extracellular heavier-than-water oils known as liamocins. Liamocins are esters composed of a single mannitol headgroup O-acetylated with 3 or 4 3,5-dihydroxydecanoic ester groups, and can be used as biosurfactant, antimicrobial agent against some Streptococcus spp., anti-cancer agent, and biofuels. The objectives of this research were to study the liamocin fermentation kinetics and scale up the process in bioreactors for industrial application. We have screened several liamocin-producing strains. In shake-flasks, the best strain A. pullulans NRRL 62031 produced liamocin from glucose at a final titer of 29.5 g/L and yield of 0.30 g/g in a medium containing 12% (w/v) glucose and the C/N (w/w) ratio of 175 in 11 days. Fermentation was scaled up in a 5-L stirred-tank bioreactor, achieving a 0.20 g/g yield in 216 hours. Our preliminary process simulation and cost analysis showed that liamocin can be produced at a cost of $3.2/kg, which is significantly lower than the market price for biosurfactants. The effects of dissolved oxygen, pH, and glucose feeding strategies on liamocin fermentation in bioreactors and production cost will be reported in this paper.