MINERALIZATION OF LOW-CHLORINATED BIPHENYLS BY BURKHOLDERIA SP. STRAIN LB400 AND BY A 2-MEMBERED CONSORTIUM UPON DIRECTED INTERSPECIES TRANSFER OF CHLOROCATECHOL PATHWAY GENES

The biphenyl-mineralizing bacterium Burkholderia in sp. strain LB400 a lso utilized 3-chloro-, 4-chloro-, 2,3'-dichloro- and 2,4'-dichlorobip henyl for growth. By the attack of the initial enzyme a chlorine was e liminated dioxygenolytically from position 2 of one of the aromatic ri ngs when hydrogens of both were substituted by chlorine. The strain mi neralized 3-chloro- and 2,3'-dichlorobiphenyl via the central intermed iate 3-chlorobenzoate through its chlorocatechol pathway enzymes, but excreted stoichiometric amounts of 4-chlorobenzoate from 4-chloro- and 2,4-dichlorobiphenyl. These two compounds were mineralized by a co-cu lture of strain LB400 and a derivative of the (methyl-) benzoate-degra ding strain Pseudomonas putida mt-2 (TOL). The complete degradation wa s achieved upon transfer of a cluster of at least five genes, encoding the regulated chlorocatechol pathway operon, from strain LB400 to str ain mt-2. This transfer was demonstrated by the polymerase chain react ion.