BACILLUS MESENTEBIGUS 



851 



Agar Plate. — Round or oval, 4 mm. in diameter, raised greyish- 

 yellow, opaque colonies with entire edge. Surface is smooth 



in centre and tends to be wrinkled towards periphery. 



Consistency membranous or friable ; not adherent to 



medium ; eaudsification difficult. 

 Agar Slope. — Profuse, confluent, raised, greyish-yellow, dull, 



opaque, wrinkled growth, with finely granular surface, and 



smooth or undulate edge ; membranous and difficult to 



emulsify. Membrane on water of condensation. 

 Oelatin Stab. — Filiform growth ; rapid hquefaction, infundibulo- 



saccate, with heavy surface membrane and deposit. 

 Broth. — Forms thick surface scum, which falls to the bottom, but 



re-forms ; turbidity moderate at first, later clears, with 



heavy tough membranous deposit. 

 Blood Serum. — Moderate, confiuent, greyish-yellow growth, with 



uneven or nodular surface ; slight liquefaction. 

 Potato. — Thick, creamy yellow, coarsely wrinkled, viscous growth, 



surface mealy and yellowish. 

 Metabolism. — Aerobe, facultative anaerobe. Opt. temp. 37° C. 



Limits 12-55° C. 

 Biochemical. — Acid in glucose and sucrose, but not lactose or 



mannitol. Indole — ; M.R. — ; V.P. T ; nitrates reduced 



to nitrites. HjS — ; NH3 + ; methylene blue not reduced ; 



catalase +. Litmus milk decolorized, and peptonized from above downwards. 



Starch is hydrolysed. 

 Pigment. — Slight yellowish or brownish-red. 



Haemolysis. — /^-haemolysis on horse blood agar plate by some strains. 

 Nutritional. — Grows freely on ordinary media. Growth not improved by blood, serum, 



or glucose. 

 Antigenic Structure. — Spore antigen differs from that oi B. subtilis. According to Sievers 



(1942), the vegetative bacilli may be sub-divided into at least four groups by means 



of precipitation tests. 

 Pathogenicity. — 1 ml. 24-hours' broth culture may kill mice injected intraperitoneally. 



Otherwise non-pathogenic. 



Fig. 187. — B. vulgatus. 



In stab gelatin, 4 

 days, 20° C, show- 

 ing n a pi form 

 liquefaction. 



Bacillus mesentericus (Fliigge) Migula 



Synonyms. — B. mesentericus vulgatus ; B. mesentericus Juscus ; potato bacillus. 



Habitat. — Found in dust, soil, water, mill?,. 



Morphology. — Slender rods, 1-3 jj, X 0-5-0-7 /.i ; rounded ends, occurring singly or in 



paii's. Motile. Spores ovoid, 1-1-5 /i X 00 /i, formed sub -terminally, do not 



cause bulging of the cell, and germinate by comma-shaped expansion (Lamanna 



19406). Non-capsulated. Gram-positive. Non-acid-fast. 

 Agar Plate. — Raised, whitish, irregular colonies of moderate size, with smooth glistening 



surface and entire or undulate edge. 

 Agar Slope. — Abundant, glistening, smooth, whitish growth with undulate edge. 

 Gelatin Stab. — Filiform growth with slow stratiform liquefaction. 

 Broth. — Marked turbidity without formation of pellicle and with cottony sediment, 



followed gradually by sedimentation and clearing. 

 Potato. — Abundant, glistening, whitish growth. 

 Metaholism.—Kevohe. Opt. temp. 37° C. Limits 12-55° C. 

 Biochemical. — Acid in glucose, maltose, mannitol and sucrose. Indole — ; M.R. - ; 



V.P. ^ ; nitrates not reduced to nitrites ; HjS — ; catalase -\- ; Litmus milk 



decolorized, coagulated, and slowly peptonized. Starch not hydrolysed. 



