Actinobacteria: which are so important to a healthy microbiome that we can even take probiotic supplements of them, are the most common microbes on our skin and are commensal to our mouths and genitals too. It is in fact the suborder Propionibacteria that is the most frequent inhabitant of our skin. Some bacteria play different roles in male versus female microbiomes – and Actinobacteria happen to crop up a lot in the female camp. These microbes are major components of the female urinary microbiome and are also affected by changes caused by pregnancy. Gender differences aside, people with psoriasis have less of these bugs but people with ulcerative colitis tend to have more. Actinobacteria are also the most common bacteria in our noses. Beyond the microbiome, these microbes are found predominantly in soil and freshwater, and strains are known to produce a variety of biologically active compounds including antibiotics, antifungals, and plant and animal growth factors. The phylum Actinobacteria is made up of only one, eponymous, class (Source Ubiome).