Viral infection to the raphidophycean alga Heterosigma akashiwo affects both intracellular organic matter composition and dynamics of a coastal prokaryotic community

Abstract

The primary production by marine microalgae and the consumption of the produced organic matter by prokaryotes significantly contribute to biogeochemical cycling. Microalgae are often infected by viruses, and in infected cells (virocells), the viruses modulate host metabolism for propagation and endo-metabolites. However, the impact of microalgal virocells on prokaryotic communities is not fully understood. This study investigates effects of lysates from virocells of Heterosigma akashiwo , a globally distributed harmful bloom-forming raphidophycean alga, on the prokaryotic community. Our data suggest that changes in biochemical properties in H. akashiwo virocells promoted the growth of specific bacterial populations that appeared to have metabolic capacity to utilize certain organic compounds enriched in the lysate. Additionally, as those populations included fish-pathogenic bacteria, we propose that viral infection to H. akashiwo can indirectly affect higher trophic-level consumers in marine ecosystems.