Biodiesel production from yeast Cryptococcus sp. using Jerusalem artichoke

• Various acids were used for making Jerusalem artichoke (JA) medium.
• Nitric acid showed a best efficiency in this process.
• Cryptococcus sp. can grow well in the JA medium.
• Lipid productivity from JA medium was better than defined medium having fructose.
• Cryptococcus oil was generally satisfied as a transportation fuel.

Jerusalem artichoke was investigated as a cheap substrate for the heterotrophic production using a lab yeast strain Cryptococcus sp. Using Response Surface Method, 54.0% of fructose yield was achieved at 12% of dried Jerusalem artichoke powder, 0.57% of nitric acid concentration, 117 °C of reaction temperature, and 49 min of reaction time. At this optimal condition, nitric acid showed the best catalytic activity toward inulin hydrolysis and also the resulting fructose hydrolyte supported the highest microbial growth compared with other acids. In addition, lipid productivity of 1.73 g/L/d was achieved, which is higher than a defined medium using pure fructose as a substrate. Lipid quality was also found to be generally satisfactory as a feedstock for fuel, demonstrating Jerusalem artichoke could indeed be a good and cheap option for the purpose of biodiesel production.