Environmental algal phage isolates and their impact on production potential for food and biofuel applications

Aims: The United States Department of Energy is aiming to bring microalgal biofuels into commercial use by 2030 at the price of $3 per gasoline gallon equivalent. Large-scale production of biofuel faces many challenges including naturally occurring algal phages; and characterizing this threat is the aim of this study. Methods and Results: Bench-scale experiments were performed to study the impact of viral infectivity on the production of microalgal in bioreactors. All environmental samples were tested positive for algal phages which showed various levels of infectivity against Synechocystis PCC 6803 and the environmental isolates of microalgae. The viral attachment to algal cells was observed under transmission electron microscopy (TEM) and to determine the shape and size of the viral particles. All the viruses detected were c. 50–60 nm icosahedral particles. Viral infection resulted in 48% reduction in the biomass of the infected algal culture in 22 days. Conclusions: This study has lead to the conclusion that the microalgal phages prevalent in natural environment may cause infections in broad range of microalgae used for biofuel production. Significance and Impact of the Study: This study has detected and quantified the phages that can infect algal populations in natural freshwater habitats and laboratory cultures of microalgal strains. The impact of viral threat to health of commercial algal production operations has been identified in this study.