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Bioresource Technology 121 (2012) 54–60

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Bioresource Technology
journal homepage: www.elsevier.com/locate/biortech

Characterization of the lipid accumulation in a tropical freshwater microalgae Chlorococcum sp.
Theresia Umi Harwati a,b,⇑,1, Thomas Willke a, Klaus D. Vorlop a
a b

Institute of Agricultural Technology and BiosystemsEngineering, Johann Heinrich von Thünen Institut (vTI), Bundesallee 50, D-38116 Braunschweig, Germany Research Centre for Biotechnology, Indonesian Institute of Sciences (LIPI), Cibinong 11691, Indonesia

h i g h l i g h t s
" Chlorococcum sp. accumulated high lipid up to 56% of dry weight. " Lipid production was enhanced under mixotrophic conditions. " The major fatty acids were C16:0, C18:1,C18:2 and C18:3. " The lipids in Chlorococcum sp. have prospective applications for biodiesel.

a r t i c l e

i n f o

a b s t r a c t
A green microalgae strain, Chlorococcum sp. was obtained from tropical freshwater in Indonesia. The effects of pH on growth, effects of salt, carbon dioxide level, nitrate, acetate, and photoperiod on biomass and lipid production were studied. The fatty acidscomposition was also investigated. This study shows that the strain had an optimum pH value for growth ranging from pH 8.0 to 8.5. The biomass concentration and lipid content were influenced by different concentrations of salt, CO2 and nitrate. The lipid productivity ranged from 2 to 90.8 mg LÀ1 dÀ1 in different mediums. The highest biomass concentration and total lipid content achieved were 1.75g LÀ1 and 56% of dry weight, respectively. Moreover, the major fatty acid methyl esters were C16:0, C18:1, C18:2 and C18:3. The high lipid content and the fatty acid composition make the strain Chlorococcum sp. a potential resource for food, cosmetics and biodiesel. Ó 2012 Elsevier Ltd. All rights reserved.

Article history: Received 9 March 2012 Received in revised form 27 June 2012 Accepted 28June 2012 Available online 6 July 2012 Keywords: Biomass Lipid content Lipid productivity Freshwater Microalgae

1. Introduction Microalgae are unicellular photosynthetic microorganisms that are able to absorb solar energy to digest water and CO2, and then release O2 in atmosphere. A number of microalgae strains are able to produce high amounts of lipids under unfavorable conditions. Most ofthese are marine microalgae, but a few species are freshwater algae. Many studies have been aimed at producing lipids from marine microalgae, but research regarding lipid production from tropical freshwater microalgae is relatively scarce. The lipid products from microalgae include oil/hydrocarbons, fatty acids (e.g., saturated fatty acids and unsaturated fatty acids), fat-soluble pigments(carotenoids), and fat-soluble vitamins with

⇑ Corresponding author at: Institute of Agricultural Technology and Biosystems Engineering, Johann Heinrich von Thünen Institut (vTI), Bundesallee 50, D-38116 Braunschweig, Germany. Tel.: +49 531 596 4276; fax: +49 531 596 4199. E-mail addresses: umi.harwati@vti.bund.de, theresia.umi.harwati@lipi.go.id (T.U. Harwati). 1 Tel.: +62 21 875 4587; fax: +62 21 8754588.
0960-8524/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.biortech.2012.06.098

potential applications in energy, food, cosmetics, and pharmaceuticals. Algae lipids have gained attention in recent decades due to their application potential in many areas. Algae lipids are composed of polar and non polar lipids. Polar lipids are produced in thegrowth phase, and are enriched in the chloroplast and cell membrane system (Guckert and Cooksey, 1990; Harwood et al., 1998). Non polar lipids accumulate triacylglycerols (TAGs) in the stationary phase to form lipid droplets, located in the cytoplasm, as a form of storage for carbon and energy. The growth of cells and lipid accumulation by microalgae is influenced by nutrient and environmental...