Peptostreptococcus is a genus of Gram-positive, anaerobic bacteria that are part of the normal human flora, particularly in the oral cavity, gut, and genitourinary tract. They can cause opportunistic infections. Genomic DNA from Peptostreptococcus is used to study its role in polymicrobial infections and its contribution to the human microbiome. It aids in developing diagnostics for anaerobic infections.