Lactobacillus plantarum

Lactobacillus plantarum is a widespread member of the genus Lactobacillus, commonly found in sauerkraut, pickles, brined olives, Korean kimchi, Nigerian ogi, sourdugh and other fermented plant material and also in some cheeses and fermented sausages. It is also present in saliva (from which it was first isolated). This microorganism is Gram (+), grows at 15 but not at 45 °C, and produces both isomers of lactic acid (D and L). It has the ability to liquefy gelatin. L. plantarum has one of the largest genomes known among the lactic acid bacteria and is a very flexible and versatile species.

L. plantarum and related lactobacilli are unusual in that they can respire oxygen but have no respiratory chain or cytochromes—the consumed oxygen ultimately ends up as hydrogen peroxide. The peroxide probably acts as a weapon to exclude competing bacteria from the food source. In place of the protective enzyme superoxide dismutase present in almost all other oxygen-tolerant cells, this organism accumulates millimolar quantities of manganese polyphosphate. Because the chemistry by which manganese complexes protect the cells from oxygen damage is subverted by iron, these cells contain virtually no iron atoms; in contrast, a cell of Escherichia coli of comparable volume contains over one million iron atoms.

L. plantarum is the most common bacterium used in silage inoculants.