Effect of organic acids on the growth and lipid accumulation of oleaginous yeast Trichosporon fermentans

In our present work, we investigated for the first time the effect of ten representative organic acids in lignocellulosic hydrolysates on the growth and lipid accumulation of oleaginous yeast Trichosporon fermentans cells. In contrast to previous reports, we found that the toxicity of the organic acids to the cells was not directly related to their hydrophobicity. It is worth noting that most organic acids tested were less toxic than aldehydes to the cells, and some could even stimulate the growth and lipid accumulation at a low concentration. Unlike aldehydes, most binary combinations of organic acids exerted no synergistic inhibitory effects on lipid production. The presence of organic acids decelerated the consumption of glucose, whereas it influenced the utilization of xylose in a different and complicated way. In addition, all the organic acids tested, except furoic acid, inhibited the malic activity of T. fermentans. Furthermore, the inhibition of organic acids on cell growth was dependent more on inoculum size, temperature and initial pH than on lipid content.This work provides some meaningful information about the effect of organic acid in lignocellulosic hydrolysates on the lipid production of oleaginous yeast, which is helpful for optimization of biomass hydrolysis processes, detoxified pretreatment of hydrolysates and lipid production using lignocellulosic materials.Biodiesel, a mixture of long-chain monoalkyl fatty acid esters, has been considered a good alternative to conventional petrodiesel oil because of its green and renewable characteristics [1]. Although it has been used in many countries around the world, the high production cost, of which oil feedstock accounts for about 75%, has become a hurdle, and the sustainable and stable supply of cheap lipids is crucial for their further development and wide application [2]. Nowadays, the most commonly used feedstocks in biodiesel production are vegetable oils and waste oils from restaurants or industry.