Ecology of mycophagous collimonas bacteria in soil

Abstract

Bacteria belonging to the genus Collimonas consist of soil bacteria that can grow at expense of living fungal hyphae i.e. they are mycophagous. This PhD studies deals with the ecology of mycophagous bacteria in soil using collimonads as model organisms. Collimonads were found to be widely distributed in different types of soils albeit at low densities. Highest numbers were present in fungal-rich grassland soils and lowest numbers in fungal-poor arable soils. Yet, no significant positive correlation between numbers of collimonads and fungal biomass densities was obtained when all soils were included in the analysis. Actual growth of indigenous collimonads in soils upon invasion by fungal hyphae was demonstrated using a newly, developed Collimonas-specific qPCR assay. The fungal-induced increase in numbers of collimonads was moderate and did not result in an increased turn-over of fungal biomass. In contrast to the effects on fungal-biomass turn-over, effects of presence of collimonads on soil fungal community composition were strong. This implies that collimonads can change the competitive relationships between soil fungal species. Hence, our conclusion is that a small component of the soil microbial community can have a huge impact on this community.