Critical assessment of protozoa contamination and control measures in mass culture of the diatom Phaeodactylum tricornutum
Qinglin He, Hanwen Zhang, Mingyang Ma, Yue He, Jing Jia, Qiang Hu, Yingchun Gong
Abstract
The diatom Phaeodactylum tricornutum is considered a promising “cell factory” for high-value products fucoxanthin and EPA. But its potential has not been realized due largely to microbial contamination. In this study, seven protozoan strains were identified, of which a heterolobosean amoeba was identified as the most frequently occurring and destructive predator in P. tricornutum culture. The addition of 400 mg L−1 NH4HCO3 inhibited amoeba proliferation with little impact on algal growth. Halting culture mixing at night induced a hypoxia environment that further inhibited amoeba growth. Regardless of culture systems employed, a periodical supply of proper amounts of NH4HCO3 alone or in combination with halting culture mixing at night may prevent or treat protozoa contamination in mass culture of P. tricornutum.