CHEESE STARTERS

Otago Daily Times, Issue 22610, 29 June 1935, Page 14

CHEESE STARTERS

INFECTED BY BACTERIOPHAGE A REMARKABLE DISCOVERY (Peb United Press Association) PALMERSTON N, June 28. A remarkable discovery has been made by research workers in the Dairy Research Institute. It is the presence in cheese starters of a germ which produces such a powerful inhibitory substance that it practically prevents the growth of another. Speaking to the National Dairy Association Conference to-day, Mr Riddett, director of the institute, declared that it was the first case on record that such a thing bad happened in cheese starter cultures, though it had been known in medicine for many years. The discovery was made in February of tins year by Dr Whitehead, when endeavouring to discover why pure strains of cheese starter died suddenly from an unknown cause. At first this seemed an insuperable barrier, but a chance observation made in the course of conducting a test revealed the astounding fact that the cultures, apparently pure bacteriologically, may be infected with a kind of virus known as bacteriophage. This bacteriophage was somewhat similar to the viruses which affect plants and animals, for example the mosaic disease in potato plant and foot-and-mouth disease in cattle, both due to virus infections. The casual factor would not be observed under a microscope, and it passed through the finest filters which were used in the laboratories for separating the bacteria from the liquor in which they were suspended. This bacteriophage was a remarkable thing.. It had the unique property when present in infinitely small amounts—e.g., one part several millions—of . suddenly destroying the starter organisms, and it worked with enormous rapidity. Within an hour it might completely destroy the starter which previously had been normal. This might happen in a cheese vat. The starter might grow normally during the first hour or two of the manufacturing process and then be destroyed by bacteriophage, thus rendering it • practically impossible to produce cheese of the best quality. This bacteriophage condition had been known in medicine for many years, but it was the first time on record that its presence had been revealed in any part of the world in starter cultures. It was not known where the bacteriophage starters originated, and, as could be realised, this was extremely difficult to deter mine. Nevertheless, now that its presence was known and its action recognised there was something definite to look for and the finding of means to prevent its action was only a matter of time. At the moment there was not yet an adequate solution of the problem of overcoming it in starters or of avoiding it, but there was some hope along the lines of getting strains immune to it. Indeed, already some strains had been worked up which were definitely less sensitive than others. It was abundantly clear that this fundamental work on starters provided an invaluable clue to a real understanding of how the starters lost their vitality when given every care. Later in the conference Mr Riddet said the institute for a long while had been looking for this " needle in the haystack " of cheese-making difficulties, and now that it had been discovered it would not be long before the starter troubles would be overcome.