Bacteria Bacteria Bacteria (; common noun bacteria, singular bacterium) are a type of biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a number of shapes, ranging from spheres to rods and spirals. Bacteria were among the first life forms to appear on Earth, and are present in most of its habitats. Bacteria inhabit soil, water, acidic hot springs, radioactive waste, and the deep portions of Earth's crust. Bacteria also live in symbiotic and parasitic relationships with plants and animals. Most bacteria have not been characterised, and only about half of the
Pink algae Pink algae Pink algae is a growth of pink, slimey bacterial matter which can sometimes occur in pools and sometimes in laboratory tubings. The title is a misnomer, because, as noted before, pink algae is actually caused by a bacterium, in the genus methylobacterium. The color of the bacterial growth comes from pigments within its cells. The slime formed around the bacteria provides it with a relatively high level of protection from external threats. Like other species in its genus, pink algae is a methane consuming bacterium. It has an affinity for the matrix of PVC plastics, and will attach