Oleaginous microorganisms ranging from yeast, molds, and algae to bacteria have the ability to accumulate lipid to the levels greater than 20% of their biomass. Some yeasts, such as Lipomyces starkeyi, Rhodosporidium toruloides, and Rhodotorula glutinis, can accumulate lipids in their cells in the form of triacylglycerols (TAGs) to more than 65% of their cell dry weight. L. starkeyi is one of the most known oleaginous microorganisms and is able to accumulate up to 72.3% of dry cell weight as TAG. Thus, L. starkeyi is a unique yeast species of great industrial potential as an excellent lipid producer. Recently, the genome sequence of L. starkeyi was revealed and many functional genes are expected to be analyzed. Genetic and metabolic engineering of L. starkeyi via gene-manipulation techniques may result in improved lipid production and also understanding of the mechanisms responsible for lipid droplet formation and lipid biosynthesis pathways. However, such methods for molecular breeding have not been established for L. starkeyi. This review describes the lipid production and the development of an integrative transformation system, a highly efficient gene-targeting system, and a multicopy-integration system in L. starkeyi. Furthermore, we also describe about the possible usage toward engineering of lipid production with new features.

Accumulation of carbon dioxide by fossil fuel has caused global warming. Biodiesel fuel by plant lipid esterification is used for inhibiting the carbon dioxide increased. It is necessary that plant lipid can be obtained with microorganism on different environment from plant, because global warming has a bad influence upon agriculture. A new method for Lipomyces screening of neutral lipid high accumulating ability was performed with many number combinations of renewable carbon sources and strains. The new method for estimating lipid accumulation ability consists of plate cultures, micrographs and measurements of the volume of lipid globule, which is a morphological feature of Lipomyces. Yeast strain of the high accumulating ability has high neutral lipid conversion efficiency and has leakage ratio of neutral lipid from lipid globule. Methods for breakdown of lipid globule membrane and cell membrane for efficient recovery of lipid globule neutral lipid were examined. Trends in microbial lipid production research are also reviewed.

Fatty acid methyl ester (FAME) is widely used as an important material for industrial uses such as biodiesel fuel and surfactant. FAME is made from edible fats and oils such as palm oil, rape-seed oil and so on. In view of the future food problem caused by the increase in world population, alternative their source is required. On the other hand, glycerol as a byproduct of FAME production increases year by year, and its utilization is demanded. In recent years, we explored the optimal culture conditions and media for the oleaginous yeast strain called Lipomyces yeast, which grows vigorously on glycerol to produce triacylglycerol. In this article, we would like to introduce the possibility of cultivation and production of triacylglycerol using not only high purity glycerol but also crude one as carbon sources.