The microalga Parachlorella kessleri––A novel highly efficient lipid producer

Abstract

The alga Parachlorella kessleri, strain CCALA 255, grown under optimal conditions, is characterized by storage of energy in the form of starch rather than lipids. If grown in the complete medium, the cultures grew rapidly, producing large amounts of biomass in a relatively short time. The cells, however, contained negligible lipid reserves (1-10% of DW). Treatments inducing hyperproduction of storage lipids in P. kessleri biomass were described. The cultures were grown in the absence or fivefold decreased concentration of either nitrogen or phosphorus or sulfur. Limitation by all elements using fivefold or 10-fold diluted mineral medium was also tested. Limitation with any macroelement (nitrogen, sulfur, or phosphorus) led to an increase in the amount of lipids; nitrogen limitation was the most effective. Diluted nutrient media (5- or 10-fold) were identified as the best method to stimulate lipid overproduction (60% of DW). The strategy for lipid overproduction consists of the fast growth of P. kessleri culture grown in the complete medium to produce sufficient biomass (DW more than 10 g/L) followed by the dilution of nutrient medium to stop growth and cell division by limitation of all elements, leading to induction of lipid production and accumulation up to 60% DW. Cultivation conditions necessary for maximizing lipid content in P. kessleri biomass generated in a scale-up solar open thin-layer photobioreactor were described.

Elevated production of carotenoids by a new isolate of Scenedesmus sp.

“…Final biomass for C. vulgaris was, however, much lower due to use of half-nutrient medium [20]. When using full medium (as in our experiment), the closely related species Parachlorella kessleri produced up to 13 g biomass L −1 DW after 16 d cultivation, even under less favorable light and temperature conditions [27]. A lower biomass yield achieved in Scenedesmus sp.…”

Characterization of cell growth and starch production in the marine green microalga Tetraselmis subcordiformis under extracellular phosphorus-deprived and sequentially phosphorus-replete conditions

“…This may be because cells in the higher ICD cultures were exposed to less light and the consequent slower cell growth required less phosphorus, so there was less intracellular stored phosphorus mobilized and less stress on the cells, leading to less starch accumulation. The negative correlation between inoculum size and lipid or carbohydrate content as well as the optimization of ICD to achieve maximum biomass and lipid or carbohydrate productivity has been reported Ho et al 2012;Li et al 2013). ICD can be used to regulate intracellular phosphorus concentrations in parallel with the degree of subsequent stress to induce starch accumulation under extracellular phosphorus deprivation.…”

Accumulation of energy reserves in algae: From cell cycles to biotechnological applications

“…Strains can differ even within a single species. In some strains (e.g., Parachlorella kessleri, and some strains of Chlorella), oil production is inducible (Fernandes et al, 2013;Li et al, 2013;Přibyl et al, 2013), whereas in others (e.g., some strains of Chlorella, Tetraselmis, and Chlamydomonas), starch production is inducible.…”

“…28 Macroelement (nitrogen, sulfur, or phosphorus) limitation is the most widely explored strategy and so far the most successful strategy for enhancing starch accumulation (Ball et al, 1990;Brányiková et al, 2011;Dragone et al, 2011) as well as for accumulating lipid reserves (Breuer et al, 2013;Li et al, 2013;Wu et al, 2013) and it is a viable and environmentally friendly option for the control of the cell cycle as a crucial condition for this enhancement.…”