3.2. Cell growth and lipid accumulation by C. curvatus using carbon source derived from macroalgae by single batch cultivation system
Most of the microorganisms can synthesize lipids, but only the oleaginous strains may accumulate more than 20% W/W lipids on dry cell basis (Papanikolaou and Aggelis, 2011a). Microorganisms synthesize lipids by either de novo processes that utilizes hydro-philic substances as substrates, or by ex novo processes that utilize hydrophobic substances as substrates. In this research, all lipid synthesis occurred by de novo processes. In de novo
processes, lipid accumulation always happens after depletion of nitrogen (or to a lesser extent of other essential nutrient like phosphorus or sulfate) from the medium (Papanikolaou and Aggelis, 2011b). In addition, to ensure that VFAs are mostly converted into lipids rather than to biomass, these carbon sources should be added to a mediumcontaining enough cells (Fontanille et al., 2012).