In recent years, demand for fatty acid methyl esters (biodiesel)
being used as fuel in diesel engines and heating systems increased
due to recent rises in petroleum prices, increments in earth population and energy necessity, and development of government measures such as The EU Directive 2003/30/EC and The US Energy
Policy Act (EPAct, 1992) (Vicente et al., 2007). Transesterification
of vegetable oils to obtain biodiesel consists in replacing the glycerol
of triglycerides with a short chain alcohol in the presence of a catalyst. Transesterification reaction can be catalyzed by both homogeneous (basic or acidic) and heterogeneous (basic, acidic or
enzymatic) catalysts (Mittelbach, 1990). Recent studies show that
biodiesel can be produced enzymatically by lipase-catalyzed transesterification which has become more attractive in biodiesel production since the glycerol can be recovered easily and the purification
process for biodiesel is simple (Vicente et al., 1998). In addition,
the use of lipase in biodiesel production tolerates the water content
of oil and increases biodiesel yield by avoiding the soap formation