Effects of alcohol compounds on the growth and lipid accumulation of oleaginous yeast Trichosporon fermentans.

Abstract

The inhibitors present in dilute acid-treated lignocellulosic hydrolysates would show great effect on the growth and product formation of microorganisms. To understand their inhibitory law and mechanism on oleaginous microorganism could help improving the efficiency of lignocellulose hydrolysis, detoxification, and lipid fermentation. The effects of four representative alcohol compounds present in lignocellulosic hydrolysates, including furfuryl alcohol, vanillyl alcohol, catechol, hydroquinone on the cell growth and lipid accumulation of Trichosporon fermentans were systematically investigated in this work. The toxicity of selected alcohol compounds was well related to their log P value except furfuryl alcohol, whose log P value was the minimum but with the highest toxicity to T. fermentans. The inhibition of all the alcohol compounds on the growth of T. fermentans was more serious than on the lipid synthesis. Also, the growth of T. fermentans was more sensitive to the variation of inoculum size, temperature, and initial pH than lipid synthesis in the presence of alcohol compounds. Initial pH had more profound influence on the lipid fermentation than inoculum size and cultural temperature did. Careful control of fermentation conditions could be helpful for improving lipid yield of T. fermentans in lignocellulosic hydrolysates. Among the four alcohol compounds tested, most alcohol compounds showed inhibition on both sugar consumption and malic enzyme activity of T. fermentans. However, vanillyl alcohol had little influence on the malic enzyme activity. Similarly, all alcohol compounds except vanillyl alcohol exerted damage on the cell membrane of T. fermentans.