Biosynthetic Potentialities of Higher Fungi

SUMMARY

Fifty-three separate experiments were conducted with fifty different strains and species of higher fungi. All experiments were conducted in such manner that the following analyses could be made: gms of glucose utilized, gms of carbon dioxide evolved and gms of mycelium formed; in addition to these analyses, changes in pH and titratable acidity of the culture medium were also measured. The results and conclusions may be summarized as follows:

1.	An index to the biosynthetic potentialities of a fungus may be obtained by calculating the percentage of utilized substrate carbon converted to mycelium carbon and carbon dioxide carbon. To provide a more accurate index, however, the average per day conversion of substrate carbon to carbon of other metabolic products should also be taken into account. This latter, however, represents additional calculations rather than additional analyses.
2.	In general, economic coefficient values vary inversely with percentages of substrate carbon converted to mycelium carbon and carbon dioxide carbon; however, this relationship does not represent a close correlation, and economic coefficient alone is not considered an adequate basis for evaluation of the biosynthetic potentialities of a fungus.
3.	The Ascomycete and Basidiomycete species studied were shown to vary quite widely in their biosynthetic potentialities when these were judged on the basis of percentage of utilized substrate carbon converted to assimilation carbon and carbon dioxide carbon. Thus, with Verpa conica only 10 percent of the carbon of the sugar utilized was recovered as mycelium and carbon dioxide while with Bulgaria inquinans 93 percent was so recovered.
4.	As a group the test organisms are considered to have rather high potentialities, since in 39 out of 53 experiments these fungi converted less than 50 percent of the utilized substrate carbon to mycelium and carbon dioxide.
5.	When CO2 carbon/mycelium carbon ratios were calculated, they were found to vary from 0.37 to 5.36—a range closely approximating that found by Whitaker in his work with wood-rotting Basidiomycetes but much more narrow than that found by Raistrick and his co-workers in their studies of a large number of fungi of the “mold” type. More significant than this difference in range, however, was the distribution of fungi within the range. In the present study over 90 percent of the test organisms had ratios less than 2.0, and over 50 percent had ratios less than 1.0.
6.	Acid metabolic products were formed in extremely small quantities by all of the organisms studied—a finding which leads to the suggestion that the type of metabolism existent in these fungi may be fundamentally different from that exhibited by many of the much-studied fungi of the “mold” type.