Differential grazing of selected marine algivorous amoebae on microalgae and bacteria

Abstract

Production of biofuels derived from the mass of photosynthetic organisms is gaining attractiveness as climate change, resource shortage, and pollution events make it less sensible to continue current modes of fossil fuel consumption. The high oil-toweight ratio of algae yields potential as a sustainable source of biodiesel, but current cultivation systems are plagued with contamination events leading to crop failure. Protozoic amoebae are the culprits of this invasion and while their feeding preferences or abilities are well known in regards to bacteria, with algae they are not. To begin implying an index of susceptibility between amoebic strains and marine algae, isolated Neoparamoeba sp., Paramoeba sp., and Thecamoeba sp. specimens from Hawai’i were given treatments of marine algae (Chaetoceros sp., Pleurochrysis carterae, Nanochloropsis sp., Skeletonema marinoi, Isochrysis sp.) in f/2- (silicon absent) media and algal density correlated to spectrophotometer absorbance values. Also, bacterial treatments were smeared in a uni-directional “raceway” on f/2- agar and the distance that amoebae from one end of the strip recorded as average migration rate per day. These methods proved successful in illustrating that the feeding abilities or preferences of marine amoebae vary greatly across algal and bacterial species. This valuable insight may inform managerial decisions in the event of contamination discovery and highlight directions for further research into the specific relationships between marine algae, bacteria, and amoebae that might either support or suppress the successful commercial cultivation of algae as a feedstock for biodiesel.