Ondersoekinge oor die afbraak van aromatiese verbindings deur mikro-organismes

English: 1. In a survey of the relevant literature the methods of investigation, the systematic and biochemical aspects and the significance of microbial degradation of aromatic compounds has been discussed. 2. In a preliminary investigation it was found that nonselectivily isolated strains of streptomycetes dit not grow on a mineral salt medium with a simple aromatic compound as sole source of carbon. 3. Bacteria, fungi and one Nocardia strain able to use aromatic compounds as sole source of carbon and energy, were isolated from enrichment cultures. 4. From turbidimetric growth measurements it was found that optimum cell development of the bacteria and actinomycete investigated in a medium with a low concentration of aromatic substrate in most cases took place within two days. 5. The oxidation of a number of aromatic compounds by the bacteria and actinomycete isolated, was studied with the aid of the direct method of Warburg. 6. The method used for the calibration of manometers and Warburg flasks is described. 7. The technique of sequential induction was applied to determine the pathway of microbial degradation of the aromatic compounds investigated. With this technique the following hitherto unpublished reactions of bacteria have been found: (i) Salicylic acid - gentisic acid. (ii) Saligenin - salicylic aldehyde - salicylic acid - catechol and gentisic acid. (iii) Syringic acid - gallic acid. (iv) Guaiacol - catechol. (v) Vanillin - vanillic acid - protocatechuic acid. (vi) Veratric aldehyde - veratric acid - vanillic acid - protocatechuic acid. The degradation of phenol, benzoic acid, mandelic acid, p-cresol, m-hydroxybenzoic acid and anisic acid by bacteria, and of toluene by Nocardia sp., as studied with manometrical methods, was found to be identical with the pathway already described for bacteria and fungi. The degradation pathway of o- and m-cresol could not be established with certainty with the method used.