Antagonism between bacteria and fungi: substrate competition and a possible tradeoff between fungal growth and tolerance towards bacteria

Bacteria and fungi often share a common substrate, and their spatial proximity in many environments has lead to either synergistic or antagonistic interactions. In this paper, the interaction of bacterial and fungal decomposers from an aquatic environment was studied. We found indications of a tradeoff between fungal growth and tolerance towards bacteria. Fungal strains growing best in absence of bacteria were most severely affected by bacterial presence, while those less suppressed during co-existence with bacteria had lower maximal growth rates in bacterial absence. Additionally, we show that the antagonism between bacteria and fungi is connected to competition for substrate, but that this competition can be drastically altered if fungi are given an opportunity to establish before inoculation of bacteria. Established fungi out-competed bacteria, and gained higher biomass than in simultaneously inoculated treatments with higher substrate concentrations.