Microscopic prokaryotic cells are known as eubacteria, or “true bacteria.” Most eubacteria isn’t harmful, but some, such as E.coli, can cause serious diseases. Food poisoning and strep throat could be causes of eubacteria. On the other hand, some eubacteria can be used for good. The picture below is of typical yogurt. What does yogurt have to do with eubacteria? Well, putting milk and eubacteria together in a controlled environment allows the bacteria to ferment. This fermenting creates yogurt, a similar process of turning milk into cheese.