BACTERIOLOGY OF SARDINES 193 



SESSIONAL PAPER No. 38a 



Litmus Milk. — In 24 hours mucli froth on shaking, violaceus for 1 cm. from 

 surface, remainder paler; in 3 days partly coagulated soft curd, violaceus; 

 in 9 days digestion proceeding, fluid yellowish; in 14 days blue rim at surface, 

 medium 5/6 digested, reddish brown tint ; in 5 weeks slight flocculence, curd 

 at base of tube, remainder partially cleared and tinted dark purpureus to 

 heliotrope. 



Aesculin agar. — I loop from peptone broth culture streaked on plates. In 24 

 hours growth but no definite black reaction; later assumes brown to black tint, 

 moderate growth. 



Aesculin hroth. — ^In 24 hours black reaction. 



MucCorikey's N.R.B. Broth. — No reduction to canary yellow in 24 hours. 



Gelatine colonies. — (1st appearance) room temperature, in 72 hours liquefaction 

 well advanced; individual colonies up to 3 mm. diameter, round, saucer- 

 shaped, entire edges; liquefaction typical of the proteus group, cenne ol 

 colony dark white spot -25 mm. diameter, remainder of colony varying from 

 clear space to fine precipitated granules. Under the low power objective 

 opaque centre, edges entire; medium tinted green, and distinct earthy smell. 



Agar colonies. — 20 hours at 37°C., growth moderate, surface colonies round, con- 

 cave, glistening, raised, distinctly radiate; by transmitted light young colonies 

 bluish, older colonies becoming whiter, more opaque and darker in centre. 

 Sub-surface colonies small but well defined, white. Under low power object- 

 ive surface colonies distinctly yellowish with entire edges; on focussing 

 through, dense and dark; structure cannot be defined; smaller colonies dark 

 centre, then pale yellow, and near the edges almost transparent. Sub- 

 surface colonies well defined, edges entire, yellow to dense. 



Temperature Relations: — 



Thermal death point. — 10 minutes' exposure in nutrient broth at 60°C. 



Optimum temperature. — Cultures incubated at room temperature and at 37° C. 

 grow well. Most satisfactory growth at 37°C. 



Vitality on Culture Media. — The culture survives several months in artificial 

 medium, agar or gelatine. 



Relation to Oxygen. — The culture is a facultative anaerobe; incubated for 36 hours 

 under anaerobic conditions moderate growth on glucose agar as discrete colonies 

 along track of needle 1-2' mm. diameter; by transmitted light convex, dark white 

 centres, paling to blue at edges. Growth is not so luxuriant as under aerobic con- 

 ditions. 



Biochemical Reactions: — 



Indol production : Indol not produced. 

 Reduction of nitrates : Nitrates to nitrites. 

 Voges-Proskauer reaction: Positive. 

 Methyl red reaction: Alkaline. 



Fermentation of Carbohydrates. — This culture does not rapidly ferment many of 

 the carbohydrates. In 24 hours lactose is but feebly fermented to acid; 

 saccharose, mannite and xylose are fermented to acid and gas with profuse 

 frothing; arabinose and inulin give slight gas; while gas appears in glycerine 



