Effect of Nitrogen Limitation on the Growth and Lipid Composition of the Green Alga Botryococcus braunii Kutz IPPAS H-252

Abstract

INTRODUCTIONThe green alga Botryococcus braunii attracts attention because of its surprising ability to form a considerable amount of liquid hydrocarbons. Their composition is determined by the nature of a respective algal race (A, B, or L), and their content is believed to depend also on growth conditions [1]. Provision of biogenic elements, mainly nitrogen, is one of the main factors affecting algal metabolism. The change in the carbon/nitrogen ratio in a medium is known to result in a change in the directionality of metabolism. In many algae, an increase in this ratio results in an accumulation of neutral lipids, mainly triacylglycerols and/or carbohydrates [2][3][4][5] and is accompanied by considerable rearrangements in FA composition. These rearrangements consist in an increase in the content of saturated acids and a decrease in polyenoic acids [4,6,7]. Moreover, a decrease in the concentration of chlorophyll a accompanied by an increase in the content of carotenoids were noticed under the conditions of nitrogen limitation [8].Unfortunately, studies devoted to investigating the effect of nitrogen concentration on the biochemical composition of B. braunii are few in number and are mainly related to the production of hydrocarbons. For instance, a study showed that an increase in the nitrate content in a growth medium resulted in an increase in the duration of exponential phase of growth [9] and, consequently, in an increase in algal yield. In this case, the relative hydrocarbon content decreased; however, their total yield increased by 25% due to a higher biomass yield. On the contrary, culturing of the alga in a medium with decreased nitrogen content resulted in a decrease in both biomass and hydrocarbon content [10].Abstract -The effect of nitrogen limitation in a medium on the composition of intracellular lipids in the alga Botryococcus braunii Kütz IPPAS H-252 in the course of culture development was investigated. Under the conditions of nitrogen limitation, the alga under investigation accumulated lipids as triacylglycerols, and this process was accompanied by substantial changes in the total fatty acid (FA) composition, which were manifested in a decrease in trienoic acids (from 52.8-57.2 to 19.5-24.7% of total FAs) and an increase in the content of oleic (from 1.1-1.2 to 17.1-24.4%) and saturated (from 23.7-26.0 to 32.9-46.1%) acids. In the control culture, the directionality of FA redistribution was less marked, and these changes were noticed at the later stages of culture development. Under nitrogen limitation, marked changes in the FA composition of polar lipids occurred by the 13th day, and they were characterized by an increase in the content of saturated acids (up to 76.8%) and a dramatic decrease in the content of all polyenoic acids (up to 6.8%). The changes in the FA composition of triacylglycerols were noticed as early as by the 7th day; these changes consisted in an increase in the content of oleic acid, and its high content (28.4-38.4%) was maintained up to the end of culturing. In the cont...

Effect of Various Pretreatment for Extracting Intracellular Lipid fromNannochloropsis oculataunder Nitrogen Replete and Depleted Conditions

“…In N. oculata, the oleic acid content increased from 35.21% to 44.68%. This result was in better agreement with previous study conducted by Zhila et al [32].…”

Effects of alginate oligosaccharide mixtures on the growth and fatty acid composition of the green alga Chlamydomonas reinhardtii

“…Fatty acids in zooplankton are derived from their microalgal diet. The fatty acid compositions of selected species of algae can be altered by temperature and nutrient limitation (26)(27). However, while these environmental effects could induce industrially desirable fatty compositions in grazed phytoplankton, they could also decrease the maximum microalgal yield.…”

Manipulation of carbon flux into fatty acid biosynthesis pathway in Dunaliella salina using AccD and ME genes to enhance lipid content and to improve produced biodiesel quality

“…while also reported 54% deacrease in USFA/FAME. Zhila et al (2005) while tried to enhance lipid accumulation using N-starvation treatment on Botryococcus braunii, observed an increase in the SFAs content (up to 76.8%) and a decrease in the PUFA content (up to 6.8%).…”