In some embodiments, a system may reduce contaminants in water. A system may include a biofilm in a container. The biofilm may be formed from one or more bacteria coupled to one or more substrates. The bacteria may be selected to maximize the reduction of contaminants in water. The system may include one or more bacteria generators to provide bacteria to the biofilm and/or one or more air sources to provide an air bubble stream to the container and/or the bacteria generator. In some embodiments, bacteria may be preserved in a starvation phase. Bacteria may be incubated until they reach a starvation phase. The bacteria may then be preserved as beads or immobilized on a substrate. The preserved bacteria may be used in a system for the reduction of contaminants in water.