by way of comparison a test test 3r was carried out without hydrogen peroxide and catalase being introduced all the other conditions being identical to those in tests 1 and 2 no growth of the microorganisms was observed the results obtained are also shown in fig1 by curve 3r by way of comparison another test test 4r was carried out without introducing hydrogen peroxide and catalase the free space of the culture container is swept by a current of air at a rate of 0 5 l min the other conditions are identical to those in tests 1 2 and 3r the results obtained are shown in fig1 by curve 4r examination of the tests shown in fig1 shows that the replacement of oxygen by hydrogen peroxide does not alter the growth of candida biodinii a quantity of 200 ml of aqueous solution containing the same mineral compounds and these in the same proportion as in example 1 as well as 0 5 methanol 0 1 mg biotin per liter 1 0 mg thiamine per liter 0 63 ml catalase and 0 2 difco yeast extract is introduced into a wide necked erlenmeyer flask yeasts of the candida biodinii type are injected into the medium in proportions such that the initial optical density of the suspension measured at 436 nm is 3 9 a current of nitrogen free from oxygen sweeps the free space of the culture vessel the culture temperature is maintained at 30 u00b0 c by means of a thermostat and the culture medium is agitated.