Microbial degradation of phthalate esters. V. Microbial population and identification of phthalate ester-utilizlng microorganisms in activated sludge inoculated with microorganisms.

Abstract

In the population in each of activated sludges, the ratio of all Nocardia erythropolis cells to total cells increased from 5.6% immediately after inoculation to 16.1% 26 days later in the inoculated sludge in which DEHP was fed, and from 6.1% to 13.9% 22 days later in the ino-culated sludge in which DBP was fed. In particular, strains of Nocardia erythropolis isolated from the inoculated activated sludges, which were morphologically, biochemically and im-munologically identical with Nocardia erythropolis S-1 inoculated, were predominant in the total phthalate ester-utilizing microorganisms. The species which shared the highest ratio to the population in each of activated sludges were members of the genus Pseudomonas. They were unable to grow on phthalate esters but able to utilize the intermediates such as phthalate. These Pseudomonas species comprised about 30% of total cells. Phthalate ester-utilizing microorganisms isolated from the inoculated activated sludge were Nocardia erythropolis, Nocardia calcarea, Nocardia restricta, Pseudomonas cepacia and Pseudomonas fluorescens, and those from the uninoculated activated sludge also were Nocardia erythropolis, Pseudomonas ce-pacia and Pseudomonas acidovorans. Bacillus brevis and other bacteria were found in the milky turbid treated water from the deflocked control sludge, but Nocardia erythropolis was not.