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
Mycorrhiza helper bacteria fact, the plant could grow with the presence of multiple bacteria. It has been hypothesized that rhizosphere helper bacteria, in the soil, have developed traits to aid them in competition for inoculating fungi in their environment. Thus, it is plausible that MHBs select for certain fungi and developed some specificity towards a fungus that favours the bacteria. MHB help mycorrhiza establish symbiotic associations in stressful environments such as those high in toxic metals. In harsh environments, the bacteria assist in acquiring more nutrients such as nitrogen and phosphorus. MHB helps to prevent the uptake of toxic metals including lead, zinc,