BIVERTICILLATA-SYMMETRICA 645 



isolated from deteriorating military equipment in tropical and subtropical 

 areas and submitted for identification. 



Strains of Penicillium purpuroge7ium not infrequently develop as para- 

 sites on species of Aspergillus, particularly members of the Aspergillus niger 

 series (Thom, 1930). They seldom kill the host, but markedly restrict its 

 growth and development. When present on strains used for acid produc- 

 tion in industry, they seriously interfere with these fermentations. The 

 characteristic picture of one of these molds parasitizing an Aspergillus is 

 beautifully shown in a photograph by Dr. Edward Yuill reproduced in this 

 ]\Ianual as figure 23. 



Palei and Osuicheva (1936) isolated a heat-resisting substance (named 

 "penicillin") from the metabolism solution of Penicillium luteum-purpuro- 

 geniim which interfered with citric acid formation by Aspergillus niger. 



Members of the present series, referred to as the Penicillium luteum- 

 purpurogenum group, received considerable attention as producers of 

 gluconic acid by May, Herrick, and others in the U. S. Department of 

 Agriculture several years ago. One culture, P. purpurogenum var. ruhri- 

 sclerotium, Thom's No. 2670, gave unusually good yields of acid in surface 

 cultures upon a solution containing 20-25 percent glucose and various in- 

 organic salts (May, et al., 1927). A year later Herrick and May (1928) 

 defined the optimum cultural conditions for acid production by this strain, 

 and in 1929 May, et al., described production methods on a semi-plant scale 

 using large shallow pans of high purity ahmiinum. When in subsequent 

 work, selected strains of P. chrysogenmn (May, et al., 193-1 and Moyer, et al., 

 1936) and Aspergillus niger (Wells, et al., 1937, Moyer, et al., 1937, and 

 Gastrock, et al., 1938) were successively foimd to produce even higher 

 yields in submerged culture, attention was naturally directed to them. 

 The latter species is now generall}^ used for the commercial production of 

 gluconic acid. 



Following the paper of May, et al. (1929), other workers erroneously 

 adopted the designation Penicillium luteum-purpurogenum as a specific 

 name to be applied to particular strains, presmned to belong to the species 

 P. purpurogenum. or the P. purpurogenum series. Angeletti and co-workers 

 published a series of papers (1931, 1932a, 1932b, and 1934a) in which the 

 production of various organic acids by a culture designated P. luteum- 

 purpurogenum was reported. The addition of 0.01145 gm./l. of Fe (as 

 FeCl3-6H20) was found to increase the yield of gluconic acid from glu(;ose 

 by 11.5 percent (1934b). 



Yuill (1934) investigated acid production by a Penicillium "with affini- 

 ties in the P. luteum-purpurogenuin group" which was isolated as a parasite 

 on Aspergillus niger. When the mold was grown in the presence of CaCOs, 

 the Ca salt of an acid insoluble in water but soluble in alcohol was formed 



