Phytobacter

Phytobacter is a genus of Gram-negative bacteria recently emerging from the grouping of isolates previously assigned to various genera of the family Enterobacteriaceae. This genus was first established on the basis of nitrogen fixing isolates from wild rice in China,[1] but also includes a number of isolates obtained during a 2013 multi-state sepsis outbreak in Brazil [2] and, retrospectively, several clinical strains isolated in the 1970s in the United States that are still available in culture collections.[3] Standard biochemical evaluation panels are lacking Phytobacter spp. from their database, thus leading to misidentifications with other Enterobacterales species.[2] Bacteria belonging to this genus are not pigmented, are chemoorganotrophic and able to fix nitrogen. They are lactose fermenting, cytochrome-oxidase negative and catalase positive. Glucose is fermented with the production of gas. Colonies growing on MacConkey agar (MAC) are circular, convex and smooth with non-entire margins and a usually elevated center. Two species are currently included in Phytobacter.[2]

Colonies of P. diazotrophicus on MacConkey agar.