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ABSTRACTS
Flies may be responsible for the bacterial spoilage of milk either falling directly
or via utensils into milk, and quite likely, they often carry coliform organisms and
other pathogenic types like, Vibrio comma, Shigclla spp. etc., when they alight on
faeces and sewage. The insecticide D.D.T. alone cannot be successfully used to
minimise their population but quick disposal of manure from farm dairy buildings
and careful attention to hygiene at all times, minimise the population of flies to a
considerable degree.
Water supply on a farm should be adequate and free from saprophytic and
pathogenic bacteria. Seventy seven per cent of farm water supplies in mid Wales
were unsatisfactory during 1930-47, on a standard of not more than 10 coliform
organisms per 100 ml., as advocated for Potable water by the Ministry of Health
[1937]. Fifty six per cent of samples were condemned as they showed 50 or more
presumptive coli per 100 ml. of water. If an endeavour is made to protect the
source of water supply from contamination with surface water and sewage, the
bacteriological quality of farm water supplies may be improved. (V. L.)
Types or organisms present in commercially pasteurised milk. EGDELL J. W. and
BIRD E. R. (1950). J. Soc. Dairy Tech., 3, 171
A BACTERIOLOGICAL survey of 21 samples of milk from the pasteuriser and
21 samples from bottled milk obtained from eleven dairies, was carried out.
The procedure followed was to plate the samples on yeasterel milk agar and
incubate the plates at 37°, 30° and 22°C. for determining the distribution of the
various groups of micro-organisms in the samples. On the basis of certain preliminary
tests the organisms which were isolated from each of these plates were classified under
one of the five groups, viz., (1) aerobic spore-forming bacteria (2) streptococci (3)
microbacteria (4) micrococci and (5) gram negative rods and coccobacilli. An
assessment of the percentage distribution of these groups at various temperatures
showed that at 37°C. streptococci constituted 48 per cent micrococci 28 per cent,
and spore forming rods 16 per cent of the total number of colonies. At 30°C.
microbacteria were found to be dominant, constituting 47 per cent of the total,
whereas micrococci, streptococci and aerobic spore-forming rods were 20, 16 and
12 per cent respectively of the total number of colonies on the plates.
When the plates were incubated at 22°C. there was an overwhelming majority of
micro-bacterium colonies, they being nearly 65 per cent whereas other groups
oomprised less than of the total 17 per cent. The spore forming rods were negligible in
oocurrence.
A detailed study of 128 isolates selected from each of these five groups showed
that streptococci were largely represented by S. thermophillus. Some cells of S.
lactis which must have escaped heat-treatment were also met with. Microbacterium
group consisted largely of Microbacterium- lacticum. Among the micrococci, M.
varians and M. luteus were the predominant types while among the aerobic spore-
forming rods, strains of Bacillus cereus, B. subtillis and B. licheniformis were
identified. Presence of certain strains of A. aerogenes indicated that some cells must
have escaped heat-treatment. Yeasts, molds and actinomycotes were only rarely
met with and were found only on plates incubated at 22°C. (S.N. A.)