Purpose and Background
Fossil fuels play an extraordinary role in the modern world; however, such fuels are being rapidly consumed as developing countries with further development of their industrial production and also as advanced countries with their expanded technologies. According to the estimation made in 2012, the life of an oil well for drilling will be about 54.2 years (Serive, Kaas, Bérard, Pasquet, Picot, & Cadoret, 2012). Recently, in response to the decline in oil availability, biological production of fossil oils is well paid attention. Among them, microalgae, particularly producing a large amount of lipid components, have attracted as a new energy source alternative to fossil fuels (Agency for Natural Resources and Energy, 2014; Sheehan, Dunahay, Benemann, & Roessler, 1998). Therefore, the present chapter aimed to collect and isolate microalgae producing industrially valuable lipids through sampling several water from a natural environment around National Institute of Technology, Okinawa College (hereinafter referred to as “NIT, Okinawa”), where the northern part of Okinawa's main island is called “Yambaru”. This area has abundant exotic biological resources derived from the subtropical climate. For the purpose of discovery of new species of microalgae having lipid component, it was hypothesized that microalgae found in this area would be useful as a biomass. In the present chapter, our efforts in NIT, Okinawa group were described in analysis of lipids produced by microalgae harvested and isolated from the area around Okinawa, Japan.
Microalgae for Lipid Producing
Microalgae comprise a group of very small algae that are invisible to the naked eye. Some microalgae accumulate lipids in their cells. It has been estimated that some algae strains can provide about 21% of the annual consumption of petroleum in Japan (Ministry of Agriculture, Forestry and Fisheries, Japan, 2014), if this cultured in an area of 396,000 ha, which corresponds to the entire area of land not cultivated in Japan (Sheehan, Dunahay, Benemann & Roessler, 1998). Among microalgae, it is known that species of both genus Botryococcus and Aurantiochitrium have high lipid production efficiency. Since these microalgae have been proposed as potential sources of an algal biomass (Agency for Natural Resources and Energy, 2014; Sheehan, Dunahay, Benemann & Roessler, 1998; Oya, Kanno, Watanabe, Tamura, Nakagawa & Tomishige, 2015), furthermore, then many groups are searching for new lipid-producing all over the world. Therefore, it is expected that additional valuable strains are found for lipid-producing microalgae.
In lipids produced by microalgae, triacylglycerol, a neutral lipid, consists of three long-chain fatty acids bound to one glycerol through an ester bond (Figure 1 (a)). Triacylglycerol is a lipid component, which exists most abundantly within a living organism and functions as a storage form of metabolic energy (BP Statistical Review of World Energy, 2015). There are mainly two types of fatty acids consisting of triacylglycerol chemical structures with saturated fatty acids and unsaturated fatty acids (Yoshimoto, Kaneko & Onodera, 2009).