Researches on the formation of diastase by Aspergillus niger. II

1) A culture solution which contains a reducing sugar together with a neutral phosphate is coloured yellow or light brown during sterilising; this must be caused by substances which are formed by the alkali out of the glas and the sugar; acid phosphate binds the alkali, so that the sugar remains unaltered. 2) These substances retard growth; they promote the formation of amylase when fructose is used, they prevent it in other sugars. 3) It is indifferent for the formation of amylase whether K2HP04 or KHoP04 is used. 4) Glucose and amylum further the formation of amylase; fructose, mannose, lactose and inuline prevent it; galactose does not prevent the enzyme production, but its metabolic substances do; this holds true also for mannose. 5) The results, mentioned under 4) were completed by investigating cultures on worked out culture solutions to which glucose was added and by growing the fungus on mixtures of substances which were favourable and unfavourable for the formation of amylase. 6) Glycerine does not favour the formation of amylase but neither prevents it when mixed with another substance which is conducive to it. 7) Not all sorts of sugar are assimilised to the same degree; galactose and lactose appear to be bad sources of nutrition. 8) An hypothesis is formed that there must be a certain narrow relation of structure between the amylase molecule and that of the substance which is given as food supply or which is formed during the life time of the fungus, if amylase is to be formed. 9) The researches were made with 3 tribes which probably were not distinct races. 10) Apparently in many cases where races of fungi are accepted, we have to deal with modifications only. Before I close I have great pleasure in thanking professor Dr. G. van Iterson for his kindly allowing me to work in his laboratory and for putting at my disposal all its facilities. I also wish to express my heartfelt thanks for his very valuable suggestions and personal interest which encouraged me to make this investigation.