STUDIES ON A MIXED BACTERIAL CULTURE FROM SOIL WHICH DEGRADES THE HERBICIDE LINURON

A stable mixed bacterial culture which degrades the herbicide linuron was isolated from soil by enrichment with linuron in a liquid mineral medium. Radio-respirometry studies showed that the culture mineralised linuron completely. No intermediate degradation products were detecte d in the medium. The culture was able to utilise linuron as a source o f both nitrogen and carbon and was also able to degrade the related he rbicides monolinuron and chlorbromuron and the possible intermediate d egradation products of linuron: 3,4-dichlorophenyl-1-methylurea, 3,4-d ichlorophenylurea and 3,4-dichloroaniline. The culture was unable to d egrade the 1,1-dimethyl substituted ureas monuron, diuron or metoxuron . The culture contained Gram-negative aerobic rods, and Gram-positive aerobic non-spore-forming rods and cocco-bacilli. Of 124 isolates from the mixed culture, none degraded linuron in pure culture, indicating that a consortium of organisms is involved. Further investigation sugg ested that Pseudomonas spp. were important components of the populatio n responsible for degradation.