Strategies of preserving lipids in microorganism after fermentation.

Microbial oil is accumulated by microorganisms as stored energy during cultivation, and will be degraded to generate energy when they are not able to obtain external energy source. As the lipid is the desired production, the in situ degradation of oil by microorganisms after fermentation or during downstream processing has to be prevented. This study investigated the effect of pH, thermal, salinity, bead milling, ultrasonication, and microwave treatment on the viability of Trichosporon oleaginosus when it was used for lipid production. The cells in broth were completely inactivated with the treatment of pH 1 and 2 for 1h, temperature 80 °C for 10 min, ultrasonication for 8 min, and microwave for 6 min, respectively. It was observed that these treatments had no impact on final product (biodiesel) composition and were considered as safe and efficient methods to preserve lipid in cells.