Hyphomicrobium  Hyphomicrobium is a genus of Gram-negative, non-spore-forming, rod-shaped bacteria from the family of Hyphomicrobiaceae. It has a large polar or sub-polar filiform prostheca very similar to that of "Caulobacter". In addition to having a nutritional function, the prostheca also plays a role in the initiation of DNA replication. Reproduction in "Hyphomicrobium" begins when its hyphal filament (prostheca) grows from one end of the cell (this happens when the cell no longer has a flagellum) and the bud grows from the tip of the prostheca that eventually differentiates into a new swarmer cell.