828 MANUAL OF DETERMINATIVE BACTERIOLOGY 



Suborder II. Caulobacterhneae Breed, Murray, and Kitchens.* 



{Caulobacteriales Henrici and Johnson, Jour. Bact., 29, 1935, 3; ibid., SO, 1935, 83; 

 Breed, Murray and Kitchens, Bact. Rev., 8, 1944, 255.) 



Non-filamentous, attached bacteria growing characteristically upon stalks, some- 

 times sessile. The stalked cells are asymmetrical in that gum, ferric hydroxide or 

 other material is secreted from one side or one end of the cell to form the stalk. Mul- 

 tiply by transverse fission. In some species the stalks are very short or absent. In 

 the latter case the cells maybe attached directly to the substrate in a zoogloeic mass. 

 Cells occur singly, in pairs or short chains, never in filaments; not ensheathed. Non- 

 spore-forming. Typically aquatic in habitat. 



Key to the families of suborder Caulobacteriineae. 



I. Long axis of cell transverse to long axis of stalk; stalks dichotomously branched. 



A. Stalks lobose, composed of gum, forming zoogloea-like colonies. 



Family I. Nevskiaceae, p. 830. 



B. Stalks are bands of ferric hydroxide. 



Family II. Gallionellaceae , p. 830. 

 II. Long axis of cell coincides with axis of stalk. 



A. Reproducing by transverse fission, stalks unbranched. 



Family III. Caulobacteriaceae, p. 832. 

 III. Sessile, capsulated colonies of cocci and short rods attached to water plants. 

 A. Deposit of ferric hydroxide about a zoogloeic mass. 



Family IV. Siderocapsaceae, p. 833. 



As a result of discussions that have taken place since the fifth edition of the Man- 

 ual was issued, certain readjustments have been made in the arrangement of the 

 stalked bacteria. The organisms in all of the typical species are simple rigid bac- 

 teria which are like ordinary bacteria except that they develop a stalk. For this 

 reason the group has been made a suborder of the order Eubacter tales. 



Stanier and Van Niel (Jour. Bact., 4^, 1941,454) emphasize the fact that the family 

 Pasteuriaceae includes species which reproduce by methods (longitudinal fission, 

 budding) different from those found in other groups of bacteria, and Kenrici and 

 Johnson (loc. cit., 81) state that it is at least doubtful whether these species are 

 phylogenetically related to the other stalked bacteria. While waiting for pure cul- 

 ture studies and a clarification of these relationships, this family has been placed 

 in an appendix to the suborder Caulobacteriineae. 



The family Siderocapsaceae has been included in the suborder as the absence of a 

 stalk in attached forms is a natural modification. As stated by Cholodny (Die 

 Eisenbakterien, Jena, 1926, 34-58), these bacteria are similar in morphology and 

 physiology to those found in the family Gallionellaceae. This is an arrangement 

 that retains all of the simple non-filamentous types of iron bacteria in one general 

 group. 



The stalked bacteria studied by Kenrici and Johnson {loc. cit.) were of fresh water 

 origin. Bacteria of this type are found, however, equally if not more abundantly in 

 marine habitats where they play their part in starting the fouling of underwater 

 surfaces. ZoBell and Upham (Bull. Scripps Inst. Oceanography, La Jolla, Cali- 



* Completely revised by Prof. A. T. Kenrici, University of Minnesota, Minneap- 

 olis, Minnesota, December, 1938; further revision by Prof. Robert S. Breed, New 

 York State Experiment Station, Geneva, New York, July, 1946. 



