Briana Beatty

Microbial communities are composed of many species sharing the same environment, and these species often interact in important ways. In forest soils, microbial communities are responsible for decomposing organic matter, including that of other dead microbes. Dead fungal biomass (referred to as “necromass”) is a significant pool of carbon that is broken down by both bacteria and other fungi. The activities of these decomposers is highly ecologically relevant, but remains understudied. The interactions between bacteria and fungi in this environment are completely unknown, even though they may greatly affect this process. Additionally, it is unknown how these interactions might depend on the traits of the fungal necromass, such as its resource availability. Here, we classify the bacterial-fungal interactions that may arise during necromass decomposition, and their dependence on resource availability, using a lab-based interaction assay. We found that fungi had the potential to increase bacterial growth, but this only occurred in resource-rich environments. Additionally, bacterial isolates did not affect fungal growth, and were less adapted than fungi to breakdown resource-depleted necromass. This gives the first insights into how bacteria and fungi might interact during fungal necromass decomposition, and improves our understanding of the general drivers of microbial interactions.