The Use of the Schizonticidal Agent Quinine Sulfate to Prevent Pond Crashes for Algal-Biofuel Production

• Main Authors: Chunyan Xu, Kangyan Wu, Steve W. Van Ginkel, Thomas Igou, Hwa Jong Lee, Aditya Bhargava, Rachel Johnston, Terry Snell, Yongsheng Chen
• Format: Article
• Language: English
• Published: MDPI AG 2015-11-01
• Series: International Journal of Molecular Sciences
• Subjects: biodiesel production; algae pond crash; toxicity; quinine sulfate; rotifer
• Online Access: http://www.mdpi.com/1422-0067/16/11/26035

Algal biofuels are investigated as a promising alternative to petroleum fuel sources to satisfy transportation demand. Despite the high growth rate of algae, predation by rotifers, ciliates, golden algae, and other predators will cause an algae in open ponds to crash. In this study, Chlorella kessleri was used as a model alga and the freshwater rotifer, Brachionus calyciflorus, as a model predator. The goal of this study was to test the selective toxicity of the chemical, quinine sulfate (QS), on both the alga and the rotifer in order to fully inhibit the rotifer while minimizing its impact on algal growth. The QS LC50 for B. calyciflorus was 17 µM while C. kessleri growth was not inhibited at concentrations <25 µM. In co-culture, complete inhibition of rotifers was observed when the QS concentration was 7.7 µM, while algal growth was not affected. QS applications to produce 1 million gallons of biodiesel in one year are estimated to be $0.04/gallon or ~1% of Bioenergy Technologies Office’s (BETO) projected cost of $5/gge (gallon gasoline equivalent). This provides algae farmers an important tool to manage grazing predators in algae mass cultures and avoid pond crashes.