STUDIES OF THE RESPIRATION OF THE MYCELIUM OF THE FUNGUS MYROTHECIUM VERRUCARIA

There is relatively little knowledge concerning the respiration of filamentous fungi. This paper describes some of the features of the tespiration,of a strain of Myrothecium verrucaria (Alb. and Schw.) Dit. ex Fr. and methods developed in handling such a septate fungus in respirometry. A review of the few published papers dealing with fungus respiration shows that wide differences exist among the results of various workers, and it is possible that much of the variability can be ascribed to differences in methodology rather than to real differences in physiology of the organisms concerned. The difficulty encountered in evaluating such differences is aggravated by the lack of supporting information such as development curves, pH data, environmental effects, etc. Some of the criticisms leveled against the older work have been stated by Wassink (1934). This literature based on analytical methods is not considered in any detail here, but attention is given in this short summary only to those papers using manometric or volumetric methods. None of the papers has undertaken a unified evaluation of fungus respiration with particular attention to the effects of technique. The need for the standardization of methods and the integration of the data concerning age, physiological condition, nutrition, etc. is emphasized. Various methods have been used by the several investigators in preparing fungi for respirometry. Usually pieces of mycelial mats taken from unshaken cultures have been used directly in the respirometers. In these cases it is often impossible to ascertain the homogeneity of the material with respect to vegetative and sporulating types. Dry weights, if determined, were taken at the end of the experiment. Although most of the papers were aimed at more specialized problems, some information about "normal" respiration can be extracted from them. Giese and Tatum (1946) reported a Qo2 ([tl.O2 consumed /mg. dry wt./hr.) from 10 to 55 for endogenous respiration of Neurospora. They were of the opinion that the rather wide variation was due to the age of the culture or its state of nutrition. Wolf (1947) using washed 6?/2-day-old mycelial pellets of Penicillium notatum suspended in buffer reported Qo2 values between 3.11 and 8.97 in fifty-five runs. The oxygen uptake of pellets of P. chrysogenum and P. notatum reported by Koffler and co-workers (1945) taken in the propagation medium reached a peak on the third to fifth day with Qo2 values around 30; the Qo2 then rapidly fell off to about 2 on the seventh day. This latter value is of about the same magnitude as that of Sordaria fimicola as deter