Research shows there are interactions between fungi and bacteria (see "Living in a fungal world" by Wietse de Boer for a nice review on soil bacteria and fungi). Within the soil, we tend to think of these interactions as mostly competitive since bacteria and fungi compete for available substrates. Bacteria can produce anti-fungal agents and fungi can produce anti-bacterial agents. These interactions may definitely be mediated by temperature. As temperature increases, soil fungi lose the competitive edge since they have lower optimal temperatures. I'm sure there may be positive interactions between these two groups, but I can't think of any specific studies in the soil. Outside of the soil environment, I'm always impressed by the ants that farm fungi and use a bacterium to protect their farms (http://www.nature.com/nature/journal/v398/n6729/abs/398701a0.html).