So these can be very, very dangerous bacteria. And these three types of bacterial cells essentially are obligate anaerobes. And what that means is they cannot survive in the presence of oxygen and they only utilize fermentation to produce their ATP molecules. So the takeaway lesson from this lecture is the fact that glycolysis by itself is not a perfect process. And if it's left alone, then it will eventually end because it will run out of that supply of the coenzyme NAD plus. And so to regenerate that NAD plus and to make sure that the NAD plus is continually used and glycolysis is continually taking place in producing ATP molecules in our cells, we have to metabolize the Pyruvate under aerobic conditions.