A review on the effect of blue green 11 medium and its constituents on microalgal growth and lipid production

The rapid dwindling of fossil fuels coupled with the ever-increasing energy needs has led to increased focus on the usage of other renewable sources of energy. Microalgae is one of the sustainable options, as a feedstock, for the production of biodiesel. A variety of growth media have been studied and used for microalgal isolation, growth and production of commercially valuable products including lipids, carbohydrates and pigments. Blue green 11 (BG-11) medium has been widely reported as a mainstream medium for microalgal biomass and lipid production, especially for freshwater microalgae. The need for enhanced microalgal biomass production led to a planned alteration and optimization of the BG-11 composition such as nitrogen, phosphorus, carbon or wastewater supplementation, depending on the mode of cultivation. A number of studies have corroborated the effects of both modified and unmodified versions of BG-11 composition, on different microalgal species, in terms of both biomass and lipid production. This review attempts to discuss the effect of varying the BG-11 composition on biomass and lipid productivity from a few freshwater microalgae that are largely employed to produce biodiesel. The paper specifically chooses BG-11 as the workhorse microalgal medium in the laboratory scale unlike other literature which describe the use of most of the media. The microalgal genera considered for the review include Chlorella, Scenedesmus, Botryococcus and Chlorococcum. These form the largest part of freshwater microalgae in the literature and a study of these would present a bird's eye view of growth characteristics of most of the freshwater microalgae. Certain other marine microalgae and cyanobacteria have also been included wherein BG-11 medium and/or its variations have led to a considerable increase in biodiesel production.