Page:Bergey's manual of determinative bacteriology.djvu/100

 Discussion: In spite of the fact that several able bacteriologists have studied this species and the actinomycete that has a similar physiology, several important points are left in doubt; the most important of these is whether Beijerinck was right in thinking the actinomycete something distinct from his Bacillus oligocarbophilus, or whether Lantzsch (Cent. f. Bakt., II Abt., 57, 1922, 309) was right in thinking of them as but stages in the growth cycle of a single species. Definite data in regard to the Gram reaction would be helpful in clarifying this situation. If the species is to be accepted as non-motile but related to polar-flagellate bacteria, it must be Gram-negative. If an actinomycete, it would be Gram-positive. Lantzsch reports the organism he studied (which was an actinomycete) to be Gram-Positive.

Source: Isolated from garden soil.

Habitat: Presumably widely distributed in soil.

FAMILY III. THIOBACTERIACEAE JANKE, 1924. (Allgem. Tech. Mikrobiol., Dresden and Leipzig, I Teil, 1924, 68.)

Thi.o.bac.te.ri.a′ce.ae. M.L. neut. n. Thiobacterium type genus of the family; -aceae ending to denote a family; M.L. fem. pl. n. Thiobacteriaceae the Thiobacterium family.

Coccoid, straight or curved rod-shaped bacteria. Oxidize sulfur compounds, usually depositing free sulfur granules within or without the cells. Never filamentous. Colorless sulfur bacteria that are sometimes embedded in gelatinous pellicles or in gelatinous bladder-like colonies. Polar flagellate when motile. Presumably Gram-negative. Found in places where hydrogen sulfide occurs or may oxidize free sulfur, thiosulfates or related compounds.

While all of the species placed in this family have been described as colorless sulfur bacteria, they are still inadequately known and may not all deserve to be designated as sulfur bacteria. It is hoped that placing them together in one family will cause comparative studies to be made.

The type genus is Thiobacterium Janke.

I. Free sulfur granules deposited within or without the cells. Usually found in sulfurous waters or soil.


 * A. Cells coccoid or straight rods.


 * 1. Non-motile so far as known.


 * 2. Motile by means of polar flagella so far as known.


 * a. Cells rod-shaped, very large.


 * aa. Cells round to ovoid, large.


 * B. Cells large, curved rods, somewhat pointed.

II. Oxidize free sulfur, thiosulfates and related sulfur compounds to sulfates. Autotrophic or facultatively autotrophic.