During biodiesel production fatty acids from triglycerides are esterified to short chain alcohols, such as methanol. This transesterification is catalyzed by lipases. Surprisingly, industrial lipases are often inactivated by methanol at the concentrations required for the process. The mechanism for this inhibition is poorly understood. Practically speaking, lipase inactivation by methanol is a major problem for implementing biodiesel production at larger scale.

Marina Lotti State University of Milano Bicocca, Milano, Italy, and colleagues summarize the current knowledge about the basis of lipase inactivation and possible mechanisms to overcome this problem. The team proposes that substrate inhibition and protein unfolding are the main characteristics of methanol inactivation. Strategies to modify methanol-sensitive lipases by mutagenesis are suggested, to create more stable biocatalysts.
In addition, approaches for improved processing conditions are summarized. These include solvents as well as different batch and continuous bioreactor set ups, strategies, and reactor designs.

Accoring to the researchers, their article will help finding the optimal bioreactor conditions and may lead to the creation of improved lipases for better biodiesel production.

• Effects of methanol on lipases: Molecular, kinetic and process issues in the production of biodiesel,
  M. Lotti, J. Pleiss, F. Valero, P. Ferrer,
  Biotechnol. J. 2014.
  DOI: 10.1002/biot.201400158