Oidium lactis, the milkmould, and a simple 

 method to obtain pure cultures of anaerobes 



by means of it. 



Proceedings of the Section of Sciences, Kon. Akademie van Wetenschappen, Amster- 

 dam, Vol. XXT, 1919, p. 12191226. - - Verscheen onder den titel Oidium lactis, de 

 melkschimmel en een eenvoudige methode om met behulp daarvaa anaeroben zuiver 

 te kweeken in Verslagen Kon. Akademie van Wetenschappen, Wis-en Natuurk. Afd.. 

 Amsterdam, Deel XXVII, 1019, biz. 10891097. 



The many methods recommended for the pure culture of anaerobes, - - whose 

 multitude proves that none of them quite satisfies the investigators, - - may be 

 distinguished in chemical and biological. As to the former, of which N o v y's ex- 

 siccator method is certainly the best, everything has been tried. This cannot be said 

 of the biological methods based on the use of living organisms in particular aerobic 

 microbes for the removing of the oxygen. For myself only after using the milkmould 

 tc that end I have obtained results worth fixing once more the attention on it. 



Some chief points from the life history of Oidium lactis important for experi- 

 ments with this species may precede; a complete description is not necessary here. 



Properties of the milkmould. 



The milkmould possesses a number of properties which render it very fit for ex- 

 periments in relation to respiration, nutrition, growth and symbiosis. It unites the 

 character of the moulds to that of the yeasts, in particular with regard to the growth 

 in and upon the substrate which takes place without being accompanied by fermen- 

 tation, as also without the formation of conidia which currents of air might spread. 

 Within the substrate the long-celled mycelium is found, on the surface the chains of 

 conidia which, even when extending free in the air, cohere and never contaminate 

 the environment as moulds may do. 



It is easily obtained. A rich growth results when market milk is left a few days 

 in an open glass in a warm room; the milk then always covers with an Oidium film. 

 Lactic acid ferments also develop and by their production of acid further the growth 

 of Oidium, whilst they themselves are favoured in their development by Oidium, because it 

 oxidises the lactic acid to carbonic acid and water. In garden soil Oidium is generally 

 spread as may be shown by inoculating feebly acidified malt infusion with soil and 

 keeping it at 25 to 30 C. The film which finally covers the liquid contains besides 

 Mycoderma, always Oidium. Pressed yeast, long whey, sour milk, cheese, the output 



