Acidobacteria

The phylum acidobacteria is distributed across nearly all ecosystems. Acidobacteria are particularly abundant in acidic soils, peatlands and environments with rich iron minerals.^[1][2]  Most acidobacteria prefer acidic conditions (pH3.0-6.5) for growth,^[1] but multiple members also live in alkaline soils.^[3]

Acidobacterium

The characteristics of acidobacteria are gram-negative (gram staining negative), non-spore-forming and with multiple shapes. In most cases, they reproduce through binary fission (separate a body into two new parts). Most acidobacteria get energy from chemical substances (chemoheterotrophs), but some get it from light.^[2]

Due to the most acidobacteria's capacity to live with a low level of nutrients, acidobacteria are hard to culture on the conventional growth media in the laboratory. Hence, they were underrepresented until gene analysis in recent decades.^[1] Currently, acidobacteria have 26 subdivisions based on the results of DNA analysis.^[4]

Acidobacteria has a large proportion of the genes encoding proteins that can transport nutrients from the environment into cells, which facilitates acidobacteria to acquire a wide range of nutrients, helping them to survive in nutrient-poor environments.^[1]

Ecological roles

Modulation of biogeochemical cycles

Acidobacteria contains genes that help them in degrading sugar polymers. They can act as decomposers in soil and recycle organic matters produced by plants, fungi and insects.^[5] Acidobacteria is likely to supplement their energy intake with carbon monoxide(CO), but this remains to be confirmed.^[3] They significantly contribute to the carbon cycle in these two major parts: degradations of sugars and CO oxidation.^[3]

Acidobacteria can process nitrogen in many different forms and they play a central role in the nitrogen cycle in plant-soil ecosystems.^[1]

Some members of acidobacteria can do anaerobic respiration (respiration without oxygen) and promote the global sulfur cycle.^[1]

Some acidobacteria can breathe oxygen at atmospheric and at very low oxygen concentrations. They have survival advantages in soils with a low level of oxygen.^[1]

Some strains can consume hydrogen (H₂) at the atmospheric level and this contributes to the global hydrogen cycle.^[6]

Production of complex sugars

Acidobacteria species can produce and send complex sugars to the outside of their cells , which could help plant roots uptake nutrients and water from soils by modifying the properties of soils around roots.^[1] These sugars also support bacteria to adhere to the root surfaces.^[7]

Influencing plant growth

Acidobacteria species could actively produce important compounds that stimulate plant growth.^[7]