The family Hyphomonadaceae

Abstract

The family Hyphomonadaceae comprises strict aerobic and stalked and non-stalked species. Cells in this family can have two differing cell cycles. Species of the genera Algimonas, Maricaulis, Oceanicaulis, Ponticaulis, Robiginitomaculum, and Woodsholea divide by binary fission of the cell leading to flagellated offsprings. Species of the genera Hellea, Hirschia, Hyphomonas, and Litorimonas divide by budding, forming a flagellated cell at the tip of the prosthecum. All flagellated cells are mobile but later develop a stalk, shed the flagella, and become sessile. These two-cell different cycles are both optimal for living in oligotrophic habitats where the competition for food is fierce and should be minimized between siblings. The genus Henriciella is currently the only genus with species lacking any stalks. With the possible exception of Hyphomonas polymorpha, all species are marine isolates and require sodium chloride for optimal growth. Species of Hyphomonadaceae occupy various habitats in the oceans where they are usually found in oligotrophic niches from the Antarctic to deep sea vents. Only few isolates can grow on minimal media with defined carbon sources; however, most species require complex growth factors for growth. Polar lipids for most species are monoglycosyl and monoglucuronosyl diacylglycerols. Common phospholipids are phosphatidylglycerols and many species possess sulfoquinovosyl diacylglycerols and glucuronopyranosyl diacylglycerol taurine amides as well. Most species reduce nitrate and are alkaline phosphatase and leucine arylamidase positive.