The Influence of Trace Elements on the Metabolism of Aromatic Compounds by Soil Fungi

Abstract

SUMMARYThe effect of copper, iron, manganese and zinc on the metabolism of catechol, o-, m-and p-hydroxybenzoic, o-, m-and p-methoxybenzoic, 3 :4-dimethoxybenzoic and vanillic acids was investigated. Aspergillus niger, Hormodendrum sp. and Penicillium sp. mycelia which were deficient in the various trace elements were the organisms used. Only iron had any marked effect on the rates of metabolism and on the accumulation of intermediate products of metabolism in the substrate solutions. The intermediate products identified were : protocatechuic acid from mand p-hydroxybenzoic and p-methoxybenzoic acids ; catechol from o-hydroxybenzoic acid; vanillic acid from 3:$-dimethoxybenzoic acid; o-, m-and p-hydroxybenzoic acids from the corresponding mono-methoxybenzoic acids.

The Metabolism of Aromatic Compounds Related to Lignin by some Hyphomycetes and Yeast-like Fungi of Soil

“…The replacement experiments showed that the soil organisms used in the present work metabolize aromatic compounds in essentially the same way as did those studied previously (Henderson & Farmer, 1955 ;Henderson, 1960). The principal difference lay in the reduction of vanillin to vanillyl alcohol and possibly also of p-hydroxybenzaldehyde and syringaldehyde to their corresponding alcohols.…”

“…Adaptation studies with whole organisms and cell-free extracts confirmed previously proposed metabolic pathways (Henderson & Farmer, 1955;Henderson, 1960). It was shown that protocatechuic acid is an intermediate in the metabolism of vanillin and ferulic acid.…”

“…Previous incubation with vanillin, vanillic acid, ferulic acid, p-hydroxybenzaldehyde or p-hydroxybenzoic acid resulted in the elimination of the lag period which preceded the oxidation of protocatechuic acid, thus linking the metabolism of the compounds in a common pathway. Although it was not demonstrated by isolation from cultures on vanillin or vanillic acid that protocatechuic acid was an intermediate in their metabolism, in previous experiments with Aspergillus niger (Henderson, 1960) an indication of its production from vanillic acid was obtained. Also, vanillic acid is known to induce the synthesis of protocatechuic acid oxidase in Neurospora crassa (Gross & Tatum, 1955).…”

“…product of the metabolism of o-hydroxybenzoic acid by fungi (Henderson, 1960) and is the most common intermediate in bacterial metabolism. However, Mitoma, Posner, Reitz & Udenfriend (1956) obtained gentisic acid from o-hydroxybenzoic acid when it was subjected to a hydrolysing system found in liver microsomes.…”

“…The results from the present experiments showed that protocatechuic acid was an intermediate product in the metabolism of p-hydroxybenzoic, m-hydroxybenzoic and benzoic acids, while p-hydroxybenzoic acid is itself an intermediate in the metabolism of p-hydroxybenzaldehyde and p-methoxybenzoic acid. Previously the formation of protocatechuic acid, by other fungi, from m-hydroxybenzoic acid (Henderson, 1960) and from p-hydroxybenzoic acid (Henderson, 1957) was demonstrated; protocatechuic acid is also well known as an intermediate in the metabolism of various aromatic compounds by bacteria. Thus the metabolism of protocatechuic acid itself appears to be a: focal point in the metabolism of aromatic compounds.…”