Dissimilation of Methionine by Fungi

Abstract

Soil fungi that attacked methionine required a utilizable source of energy such as glucose for growth. This is an example of co-dissimilation. Experiments with one of the fungi, representative of the group, are reported. In the absence of glucose, pregrown mycelium, even when depleted of energy reserves, oxidatively deaminated methionine with accumulation of a-keto-y-methyl mercapto butyric acid and ahydroxy-,y-methyl mercapto butyric acid. When glucose was provided, all of the sulfur of methionine was released as methanethiol, part of which was oxidized to dimethyl disulfide. No sulfate, sulfide, or hydrosulfide products were detected. Evidence was obtained that deaminase and demethiolase were constitutive. Deamination preceded demethiolation and a-keto butyric acid accumulated as a product of the two reactions. Other carbon residues were a-hydroxy butyric acid and a-amino butyric acid. Inability of the fungus to metabolize a-keto butyrate was responsible for its inability to utilize methionine as a source of carbon and energy. Several other fungi isolated from soil grew on a-amino butyrate but could not grow on methionine owing to inability to demethiolate it.

The application of thermal desorption‐gas chromatography‐mass spectrometry to the analyses of flower volatiles from five varieties of oilseed rape (Brassica napus spp. oleiferd)

“…The headspace volatiles of whole and macerated Brussica and Sinapis plants have previously been reported (Tollsten and Bergstrom, 1988;Evans and Allen-Williams, 1992), as have the volatile constituents from cauliflower and other crucifers (Wallbank and Wheatley, 1976). Cruciferous plants including oilseed rape are characterized by high contents of sulphurcontaining compounds such as methionine and S-methylcysteine sulphoxide (Griffiths and MacFarlane Smith, 1989) from which dimethyl disulphide may be released by chemical or enzymatic degradation (Ruiz-Herrera and Starkey, 1969;Lewis and Pahavizas, 1970), and this may well be the origin of the dimethyl disulphide and dimethyl trisulphide found in this study.…”

Lipids ofKlebsiella pneumoniae: The presence of phosphatidyl choline in succinate‐grown cells

“…It has long been established that phospholipids and lipid-synthesizing enzymes in bacteria are associated with the cell membrane (1). The culture and growth conditions influence the biosynthesis and activity of membrane-bound enzymes (2)(3)(4) with concomitant variation in the content and the composition of lipids (5)(6)(7)(8)(9). Succinic dehydrogenase is the only enzyme of the tricarboxylic acid cycle (TCA) that is membrane bound in Escherichia coli (10).…”

The association of two distinct b cytochromes with the respiratory nitrate reductase of Escherichia coli

“…5 rather than cytochrome bs58. Cytochrome b nr has previously been identified as a cytochrome with an absorbance peak at 555 nm [16] at 77°K. A value of 555.5 nm was found for the fractionated material (Fig.…”