To minimize the problems associated with the use of acid and/
or alkali for biodiesel production, a lipase-catalyzed process has
been proposed and extensively researched in the last decade
[18]. Advantages of the enzyme-based biodiesel process include:
(1) simplified production process; (2) lower energy consumption;
(3) higher purity of glycerol by-product; (4) no soap formation in
the system; (5) easy separation and reuse of immobilized enzymes.
Although the enzyme catalyst has some drawbacks, mainly associated
with lower reaction rates, higher costs, and loss of activity or
enzyme inhibition, the enzymatic route for biodiesel production is
nowadays considered as an environmentally-friendly alternative
that is becoming more realistic as new, more efficient and less
expensive enzymes are being developed [39]. To minimize enzyme
costs, the enzymatic catalyst can be reused by immobilization,
which leads to improved efficiency of biodiesel recovery. In addition,
the enzyme catalytic activities can be enhanced by screening
and selection of high alcohol-tolerant microorganisms and by
genetic engineering [40].