Abstract
In the course of the studying the microbial degradation of organic compounds in the sea, the degradations of phenol, benzoic acid, o-hydroxybenzoic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, o-cresol, m-cresol and p-cresol in sea water were examined. Degradation mixtures were prepared from sea water, collected in Kure Bay, by addition of each substrate, respectively. Then the mixtures were incubated in the dark at 20°C. Decrease of the substrate was determined on the basis of a quantitative analysis by use of high performance liquid chromatography (HPLC). Judging from the incubation conditions and observations of the degradation mixtures incubated, it was assumed that the microbial degradations of substrates were produced by the bacterial population in sea water. The bacterial population in the mixtures more actively degraded hydroxybenzoic acids and benzoic acid than phenol. To degrade phenol, the bacterial population required an acclimation period of one or two days. However, no or little acclimation was necessary for the degradation of hydroxybenzoic acids and benzoic acid. Cresols were more nondegradable than the other substrates. One or two days acclimation was required for bacterial degradation of cresols, and a considerable proportion of the cresols had not been degraded after 17 days incubation. The degradation curves of cresols showed remarkable differences. It was revealed that degradation of the cresols was influenced by the position of the functional group. On the other hand, no marked difference, arising from their molecular structures, was recognized in the degradation curves of hydroxybenzoic acids.
