Effects of sulfide availability on the metabolic activity and population dynamics of cable bacteria in freshwater sediment

Cable bacteria occur in many natural environments, and their electrogenic sulfide oxidation (e-SOx) may influence sediment biogeochemistry. The environmental factors determining the growth and diversity of cable bacteria are poorly known, especially in freshwater sediments. We conducted a laboratory incubation experiment, using freshwater sediments with different sulfide supply levels, to study how sulfide availability in sediment affects the metabolic activity and population dynamics of cable bacteria. A moderate increase in the sulfide availability in sediment significantly promoted metabolic activity and the proliferation of the cable bacteria population, as revealed by enhanced e-SOx intensity and increased bacteria abundance. In high-sulfide treatments there was a more significant increase in the population of cable bacteria in the deeper sediment layers, indicating that increased sulfide availability may expand the vertical scale impact of cable bacteria activities on sediment biogeochemistry. The relative proportions of coexisting species in the cable bacteria population also changed with sulfide supply levels, indicating that sulfide availability can be involved in determining the interspecies relationships of cable bacteria. Our findings provide new insight into the relationship between sediment sulfide availability and the growth, depth distribution, and species composition of cable bacteria, implying the consideration of regulating environmental sulfide availability as a potential management practice for the development of cable bacteria-based environmental biotechnologies.

Automated summary

The study showed that the availability of sulfide in sediments significantly promotes the metabolic activity and population proliferation of cable bacteria, especially in groups with moderate increase in sulfide supply. In the high-sulfide treatments, there was a more significant increase in the population of cable bacteria in deeper sediment layers, indicating that increased sulfide availability may expand the vertical impact of cable bacteria activities on sediment biogeochemistry.