6. Nitrobacter 



Only one culture labeled 'Nitrobacter was obtained, namely 

 'Nitrobacter agilis, ATCC 12812 (Fig. 5). The original liquid cul- 

 ture did not show motility, but staining showed a fair proportion 

 of the bacteria with Hagella. The organisms were very small, often 

 coccoid, with a single flagellum which was not polar. The flagella- 

 tion is perhaps best described as lateral monotrichous. Further 

 study of this organism should be made to be sure it is not peri- 

 trichous. 



7. Hydrogenoftionas 



Two cultures labeled Hijdrogenomoruis were studied: Hydro- 

 genomonas pantotropha NRRL, B-935 and Hijdrogenomonas facilis, 

 ATCC 11228 (Fig. 6). The first of these was nonflagellated. H. 

 facilis was well flagellated with polar monotrichous flagella of 

 average wavelength of 1.8 microns. The wavelength was quite 

 variable ranging from 1.3 to 2.2 microns. 



8. Thiobacillus 



Two species of the genus Thiobacillus were studied, namely, 

 Thiobacillus thiooxidans and Thiobacillus thioparus (Fig. 7). A 

 strain of each species was received from Dr. Robert Starkey of 

 Rutgers University, and a strain of each species from Dr. J. D. 

 Stout of the Ministry of Agriculture in New Zealand. The Starkey 

 strains were isolated from soil in the United States. The Stout 

 strain of T. thiooxidans was isolated from the water of a hot spring 

 in New Zealand and the T. thioparus strain from New Zealand 

 soil. The four strains appeared to be strict autotrophs but further 

 identification was not made by the author. 



Flagellar Characteristics 



The two T. thiooxidans cultures were very similar, with normal 

 polar monotrichous flagella. The Starkey culture of T. thioparus 

 appeared nonmotile and flagella could not be demonstrated. The 

 Stout culture of T. thioparus showed undulant polar monotrichous 

 flagella, often at both ends. No distinct variants were observed in 

 any of the cultures. 



The wavelength of T. thiooxidans averaged 1.63 microns with 

 amplitude of 0.55 micron. The wavelength of T. thioparus could 

 not be measured accurately but was about 4.0 microns. 



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