Lipid production of Botryococcus braunii in high-altitude dystrophic Lake Shirakoma, Japan

Abstract

The green algae Botryococcus braunii is known for its considerable production of hydrocarbons. Recently, we found B. braunii growing in Lake Shirakoma, which is situated at a high altitude ( 2 , 115 m ) in the Nagano Prefecture, Japan. We examined the nature of lipid production and the niche of B. braunii in the lake by conducting genetic, stable isotopic and lipid compositional analyses on natural and cultured algal strains. Using lipid and genetic analyses, B. braunii from Lake Shirakoma was identified as A race and phylogenetically close to B. braunii Yamanaka ( HM 245352 ) isolated from Lake Yamanaka in the Yamanashi Prefecture. Because both lakes are situated at high altitude and are usually or often covered by ice in winter, these species may have a similar ability to adapt to a cold climate. Lipids and stable isotopic compositions suggested that B. braunii is not consumed by zooplankton in Lake Shirakoma. Natural algal samples contained up to 0 . 045 % of hydrocarbons by weight. Meanwhile, the cultured strain produced up to 12 . 5 % of hydrocarbons by weight. Thus, B. braunii from Lake Shirakoma also has the potential to produce abundant hydrocarbons, when placed under optimum growing conditions.