An Oxalic Acid Producing Penicillium.’

Oxalic acid formation by fungi has received the attention of several investigators since de Bary2 observed that the mycelium of Sclerotinia sclerotiorum became incrusted with an oxalate in its older stages. The most elaborate study of the problem was made byWehmer.3 His results were published in a series of twent,y-three papers. Tabulated data showing oxalic acid production under various conditions were given for Aspergillus niger and Penicillium glaucum. No ot,her molds were considered in detail. Wehmer reviewed his own work and also that of other investigators up to 1906 in his chapter on the chemical action of Aspergillaceac contributed to Lafar’s Handbuch der technischen Myl~ologie.4 More recent literature contains several casual references to citric acid production in small qunntities by various fungi but records no systematic study of the problem. Wehmer states that the only acids produced by either Aspergillus or Penicillium in notable quantities are oxalic and citric. He con.cludes that investigators who have reported lactic, formic, and acetic acids did not work with pure cultures. Oxalic acid fermentation in its true sense, the production of free oxalic acid, according to Wehmer has been observed only in cultures of Aspergillus niger. Aspergillus glaucus, Penicillium glaucum, Botrytis cinerea, Sclerotinia sclerotiorum, and Rhizopus nigricans produce oxalic acid only in traces and only as the media is maintained close to the neutral point. Wehmer studied t,he various conditions which influence oxalic acid production. He found it was favored by low temperature, abundant carbohydrate food supply, the presence of an insoluble calcium salt as calcium phosphate or carbonate, and the presence of substances from which the mold can produce basic material such as organic nitrogenous compounds and salts of organic acids.