detection of the oil-producing microalga Botryococcus braunii in natural freshwater environments by targeting the hydrocarbon biosynthesis gene SSL-3

Abstract

the green microalga Botryococcus braunii produces hydrocarbon oils at 25–75% of its dry weight and is a promising source of biofuel feedstock. Few studies have examined this species’ ecology in natural habitats, and few wild genetic resources have been collected due to dififficulties caused by its low abundance in nature. This study aimed to develop a real-time P#R assay for specififfic detection and quantififfication of this alga in natural environments and to quantify spatiotemporal variations of wild B. braunii populations in a tropical pond. We designed P#R primers toward the hydrocarbon biosynthesis gene SSL-3 and examined amplififfication specififficity and efifficiency with 70 wild strains newly isolated from various environments. The results demonstrated that this P#R assay specififfically amplififfied B. braunii especially that of race strains, and can be widely used to detect wild B. braunii strains in temperate and tropical habitats. Field-testing in a tropical pond suggested a diurnal change in the abundance of B. braunii in surface water and found B. braunii not only in surface water, but also at 1–1.5 m deep and in bottom sediments. This method can contribute to efifficient genetic resource exploitations and may also help elucidate the unknown ecology of B. braunii.