Correlation of Browning, Fluorescence, and Amino Nitrogen Change with Destruction of Methionine by Autoclaving with Glucose

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Abstract
The growth of a methionineless mutant of Neurospora crassa No. 38706 on a medium to which variously pretreated methionine was added was compared with the brown color, fluorescence, and alpha-amino N content of the corresponding methionine solns. The methionine was exposed to one of 3 treatments (1) autoclaved alone for 2 hrs. at 120[degree]C, (2) autoclaved in glucose soln. containing 2 g. of methionine in 100 ml. of 8% aqueous glucose, and (3) autoclaved with dry glucose, 2 g. of methionine plus 8 g. of glucose. The amt. of methionine added to each culture was 0.1, 0.2, 0.4, 0.6, 0.8, or 1 mg. Avg. wts. of Neurospora grown in cultures to which 0.6 mg. of methionine had been added were 54.2 mg., 51.3 mg. and 6.5 mg., respectively, for methionine autoclaved alone, methionine autoclaved in glucose soln., and methionine autoclaved with dry glucose. The optical density of the brown color developed upon autoclaving, the fluorescence equivalents, and the % of the theoretical amt. of alpha-amino N detectable for soln. of methionine which had been autoclaved alone were 0.0 units, 0.0 units, and 102%, respectively; corresponding values for methionine which had been autoclaved with glucose soln. were 5.6, 0.965, and 93.7; and for methionine which had been autaclaved with dry glucose, 180, 14.25, and 15.1. Thus browning, fluorescence, and decreased alpha-amino N are associated with destruction of methionine by autoclaving with glucose as evidenced by the correlation between degree of development of these properties and the growth promoting potency for methionineless mutant of Neurospora. Water evidently protects the methionine from destruction by autoclaving with glucose.