What are antagonistic bacteria? are these dangerous?

Bacterial community: Bacteria, just like people, are vying for space and resources all the time. There are generally 'good' bacteria -which help with digestion, defending the body against invaders (pathogens), and that can be used to produce food (think yogurt). Then, there are the 'bad' guys - the 'germs' - that produce disease. Antagonistic bacteria are interfering with other species of microbes. A doc can explain