Genetic manipulation of microalgae for improvement of biodiesel production

Microalgae is considered the most promising source for biodiesel production for the near future. Various characteristics that promote its potential include high and rapid biomass production rate, ability to accumulate high amount of lipid up to 80% of its cell mass, low cultivation cost and no competing for arable land for crop plants. Selection of high performance strains is the important key for the efficient biodiesel production with competitive production cost. However, strains isolated from nature so far only possess one or a few of the required characteristics. Therefore, they are insufficient for the performance demands for the biodiesel production. To obtain microalgal strains that are comprised of the required key characteristics, genetic manipulation is the most plausible approach to reach this goal. In this review, key characteristics of microalgae that are required for efficient biodiesel production are discussed for their possibility to be manipulated by either mutagenesis or gene transformation. Forward and reverse genetics in microalgae system in functional genomic era are described regarding the benefits obtaining from genome sequences that will contribute to gene function analysis and algal strain improvement. Furthermore, methods for genetic transformation are described for pros and cons of each method. Finally, the bottlenecks in many aspects of microalgae strain improvement are underlined as future challenges.