BACTERIA AND DAIRYING

Hauraki Plains Gazette, Volume XXXV, Issue 4753, 19 September 1924, Page 2

BACTERIA AND DAIRYING

LECTURE BY MR. HUGHES. TOWN MILK SUPPLIES. An illustrated lecture of interest to the community in general, and the dairying industry iu particular, was delivered under the auspices of the N.Z. Co-op. Dairy Co. Round Table Club (stated the “Waikato Times). The subject was “Bacteria in the Dairying Industry,” and the lecturer, Mr E. W. Hughes, B.Sc. (Agriculture), and he used a nhmber of very fine lantern slides, prepared by Mr G. Cartwright, to demonstrate his subject. Mr Morice presided. Mr Hughes stated that he intended dealing with bacteria in many ways. He would first show what bacteria really were, how they grow and live, and how they depend on us, and how we depend upon them, and how are isolated in the laboratory. Thescience of bacteriology has made pro- - gress as regarded the effects of bacteria, and all the work has been done during the last 10 years, and was of interest to all. Human, animal, and plant diseases, normal and abnormal alterations in foodstuffs, the numerous bi-chemical processes taking place in sewerage, manure, and in soil are due to bacteria. Bacteria is continually at work in the soil, and from plant products animals feed, and in tui’n become animal products, from which we get industrial products, and they iii turn are used for food'and clothing of man, which shows the complete interdependence of man and. micro organisms, one not being able to live without the other. Bacteria are characterised by their extreme minuteness, and take various- forms. They multiply by dividing in two, the . multiplication being unique in the rapidity of dividing, one every 25 minutes taking place under favourable condilionts. Some bacteria under favourable conditions produce what knowr. as spores, which is a means of survival.

A number of slides illustrating the isolation and incubation of bacteria in the laboratory were shown. Environment affected the growth of bacteria organisms, and there was a temperature at which tttey grew best. Fortunately, disease germs are easily killed and growth at low temperature slow. Milk when fresh contains 5000 bacteria per cubic centimetre; after 24 hours at 42 degrees, 2400 (a decrease, the cooling effect retarding the growth) ; at 50 degrees, 7000 ; at 65 degrees, 280,000; and at 90 degrees, 125,000,000 per c.c. Heat kills bacteria, but cold only retards growth.' The theory of pasteurising is that immediately after cooling the colonies are checked and the growth retarded. Sunlight is one of the best germicides, and exposure to sunlight weakens very much and often kills the germs of typhoid, and in cities and dark places germs flourish. An intensely interesting slide that demonstrated the point was one taken on the Claudelands Racecourse, and one in the Dairy Company Buildings, which made the matter easily to the audience.

Dealing with sources of contamination, it was necessary to have sheds and factories where milk is handled in a position to obtain plenty of light Cows must be kept clean, and the utensils used in the dairying industry are a great source of bacteria contamination, being responsible for 90 per cent, hi the treatment of milk cans, in a series of experiments it was shown that cans badly washed (milky water present) contained 11,600,000 bacteria per e.c.; apparently clean but wet, 2,000,000 ; ; apparently clean, but dry, 84,600 ; and steamed and dried with hot air, 500, which showed the vital necessity fot cleanliness of dairying utensils. Speaking of town supplies, Mr Hughes said that three things were necessary, being chemical purity, freedom from disease germs, and in general clean milk free from other germs Much of the town milk we get nowadays is nothing ’ morg than diluted sewerage, and contained much more bacteria. The lectuier favoured a municipal milk supply, and said milk should be sold under clean conditions. To obtain the best retailer, producer and housewife must be prepared to take the same precautions that are adopted in hospitals. In conclusion he said that the time was right for education of the producer and general public on bacteriological lines.