Chlorella is a genus of unicellular green microalgae that has been considered a candidate for bioenergy and bioremediation owing to its ability to grow fast, uptake nutrients in wastewaters, and synthesize a large amount of triglycerides or carbohydrates in cells.  

However, biological contamination occurs frequently in Chlorella mass culture in the widely used cultivation systems including circular and raceway ponds. Flagellates and ciliates are the most common contaminations threatening Chlorella cultivation. 

In order to improve the efficiency of large-scale cultivation and reduce the losses of biomass, researchers from the Microalgae Biotechnology Research Group of Wuhan Botanical Garden developed a simple and efficient chemical method to control the contamination of predatory flagellates and ciliates in Chlorella mass culture.   

Results showed that the widely used household detergent, sodium dodecyl benzene sulfonate (SDBS), was able to eliminate the contaminants Poterioochromonas sp. and Hemiurosomoida sp. with a minimal effective concentrations of 8 and 10 mg L^-1, respectively, while had little effect on the photosynthesis and viability of Chlorella. 

Chlorella mass cultures in 5, 20, and 200 m² raceway ponds further validated the efficiency of SDBS in controlls zooplanktonic predators.   

This research proposes a chemical method using 10 mg L^-1 SDBS as pesticide to control predatory flagellate or ciliate contamination in Chlorella mass culture and this promising method is cheaper than other methods. Therefore, SDBS may be a broad spectrum of anti-biocontaminations, which can be expected to apply for a sustained microalgae biomass production and utilization, especially for biofuel production. 

This work was supported by the National Natural Science Foundation of China. The results have been published in Biotechnology for Biofuels entitled “Controlling of two destructive zooplanktonic predators in Chlorella mass culture with surfactants”. 

Application of surfactant SDBS for controlling zooplanktonic predators in Chlorella mass culture (Image by WBG)