Page:Bergey's manual of determinative bacteriology.djvu/324

 it was one of the commonest species to be found in polluted waters. The description given in the Manual (1st ed., 1923, 135) is taken directly from the Frankland's trans- lation of Eisenberg's original description of this species. As Eisenberg's description makes no mention of certain characteristics, e.g. Gram stain, type of flagellation and action on nitrates, now regarded as very important for the identification of species of this t.ype, Bergey added these characters out of his own studies made on Schuylkill River water; these added characters are indicated above. Related species : The Franklands (Micro- organisms in Water. London, 1894, 461) state that the Bacillus liquefaciens of Eisen- berg resembles very closely the Bacillus liquefaciens of Lustig {op. cit., 1890, 99). They then describe the similar organism that they isolated from unfiltered, Thames River water under the name Bacillus li- quidus. This species differs from the Eisen- berg organism in that it produces a thick, flesh-colored, moist expansion on potato. It is also stated to reduce powerfully ni- trates to nitrites. Horrocks (Bact. Exam, of Water. London, 1901, 54) discusses all of these common, gelatin-liquefying bac- teria found in water and adds a description of Bacillus liquefaciens based on his own studies of cultures. Additional characters are given. He states that no gas is produced in a glucose gelatin stab, that milk remains unchanged, that there is a diffuse growth in broth with an abundant deposit of sedi- ment, that nitrates are reduced to nitrites and ammonia, that no indole is produced and that there is no chromogenesis on agar. He adds that it is a short, motile bacillus, often occurring in pairs, that neither forms spores nor grows well at 37° C. His descrip- tion of the chromogenesis produced on po- tato indicates that he regards the B. li- quidus of the Franklands as identical with the B. Uqxiefaciens of Eisenberg. Horrocks describes the growth on potato as variable: sometimes it has a light yellow color, at other times it has a flesh-colored tint chang- ing to reddish brown. Because none of the early students of this organism made flagella stains and be- cause one of the most conspicuous of the gelatin-liquefying species that would occur on the gelatin plates used so commonly be- fore 1900 in isolating water bacteria is Pseu- domonas fluorescens Migula, it is noteworthy that there is no mention of greenish fluo- rescence in any of the descriptions referred to above. Likewise, the chromogenesis of P. fluorescens on potato is described by earl}' students of this species as an unchar- acteristic brown (Fliigge, Die Mikroorgan- ismen, 2 Aufl., 1886, 289) or as a rather thick, yellowish gray, spreading growth which gradually becomes a light sepia-brown (Mi- gula, Syst. d. Bakt., S, 1900, 886). In search- ing for cultures of a peritrichous, gelatin- liquefying water organism, the organism most likely to be mistaken for it would be a non-fluorescent strain of P. fluorescens. From the fact that several investigators have recently searched for an organism that has the characters of Achromobacter liquefaciens Bergey et al. without finding a peritrichous species that conforms in all respects with the description of Bacillus liquefaciens as given here, it appears that early statements reporting this organism as common in water are based on a failure to distinguish between polar flagellate and peritrichous gelatin-liquefying water or- ganisms. Source: Isolated from water. Habitat: Found in water. 2. Achromobacter iophagus (Gray and Thornton, 1928) Bergey et al., 1930. {Bacterium iophagum Gray and Thornton, Cent. f. Bakt., II Abt., 73, 1928, 89; Bergey et al.. Manual, 3rd ed., 1930, 204.) i.o'pha.gus. Gr. noun ius poison; Gr. v. phagein to devour; M.L. adj. iophagus poi- son-devouring. Rods 0.8 to 1.0 by 1.0 to 5.0 microns. Mo- tile by means of peritrichous flagella. Gram- negative. Gelatin colonies: Quicklj^ liquefied. Gelatin stab: Liquefaction. Agar colonies: Circular or amoeboid, whitish, flat, raised, smooth, translucent, entire. Agar slant: Filiform, white to buff, flat, undulate. Broth: Turbid. Litmus milk: Unchanged.