Effects of amoebae on the growth of microbes isolated from moisture-damaged buildings

Dampness, moisture, and mold in buildings are associated with adverse health outcomes. In addition to fungi and bacteria, amoebae have been found in moisture-damaged building materials. Amoebae and a growing list of bacteria have been shown to have mutual effects on each other's growth, but the interactions between amoebae and microbes common in moisture-damaged buildings have not been reported. We co-cultivated the amoeba Acanthamoeba polyphaga with bacteria and fungi isolated from moisture-damaged buildings in laboratory conditions for up to 28 days. The microbes selected were the bacteria Streptomyces californicus, Bacillus cereus, and Pseudomonas fluorescens, and the fungi Stachybotrys chartarum, Aspergillus versicolor, and Penicillium spinulosum. Fungi and bacteria generally benefited from the presence of the amoebae, whereas the growth of amoebae was hindered by Streptomyces californicus, Stachybotrys chartarum, and Bacillus cereus. Pseudomonas fluorescens slightly enhanced amoebae viability. Amoebae were indifferent to the presence of Aspergillus versicolor and Penicillium spinulosum. Thus, our results show that amoebae can alter the survival and growth of some microbes in moisture-damaged buildings.