Nitrifying bacteria are classified as obligate chemolithotrophs. This simply means that they must use inorganic salts as an energy source and generally cannot utilize organic materials. They secrete a sticky slime matrix, which they use to attach themselves. They have evolved to become extremely efficient at converting ammonia and nitrite. One disadvantage is, they have a very slow reproductive rate.
Nitrifying bacteria reproduce by binary division.
Under optimal conditions, Nitrosomonas may double every 7 hours and Nitrobacter every 13 hours. More realistically, they will double every 15-20 hours. Nitrobacter and Nitrosomonas bacteria have limited tolerance ranges and are individually sensitive to pH, dissolved oxygen levels, salt, temperature, and most chemicals. They cannot survive any drying process without killing the organism. Doc Conrad will disagree with the drying process part of that statement but until he supplies me with scientific data, non-anecdotal, science on this subject isn't on his side.