Microbial community evolution influenced by photoelectrons in the photic zone of estuary and offshore area of the Yellow Sea, China

The photoelectrons produced by semiconducting minerals influenced the microbial communities in terrestrial environments, such as rock varnish, Karst stone and red soil. The semiconducting mineral particles are abundant in marine systems. With the energy of sunlight in photic zone, photoelectrons were stimulated and could be used by microorganisms and sustain their metabolism. In order to study the effects of photoelectrons triggered from semiconducting mineral by solar energy on the marine microbial growth, metabolism, and community structure, a dual-chamber electrochemical system was established by incubating seawater microbial community with varying simulated electrochemical conditions. The absolute quantifications of bacteria, archaea and eukaryote by RT-PCR indicated that bacteria and archaea increased 2 and 1 magnitude(s) after incubated with simulated photoelectrons. However, eukaryote growth did not show any response to photoelectrons with different energy. The bacterial and archaeal communities were shaped by the supplement of photoelectron, also not for the eukaryotic community. Proteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria accounted for over 80% of the total bacterial community. Photoelectrons with appropriate energy could stimulate the diversity and maintain the community structure of bacteria and archaea while lower or higher electric potential caused lower diversity and more divergent microbial assemblages. This study proposed the potential impact of photoelectrons produced by semiconducting minerals on microorganisms under sunlight in the marine photic zone environments.