Browsing by Author "Rojo, Fernando"

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Open Access
Assemblage of ortho cleavage route for simultaneous degradation of chloro- and methylaromatics
(1987) Rojo, Fernando; Pieper, Dietmar H.; Engesser, Karl-Heinrich; Knackmuss, Hans-Joachim; Timmis, Kenneth N.
Genetic engineering is a powerful means of accelerating the evolution of new biological activities and has considerable potential for constructing microorganisms that can degrade environmental pollutants. Critical enzymes from five different catabolic pathways of three distinct soil bacteria have been combined in patchwork fashion into a functional ortho cleavage route for the degradation of methylphenols and methylbenzoates. The new bacterium thereby evolved was able to degrade and grow on mixtures of chloro- and methylaromatics that were toxic even for the bacteria that could degrade the individual components of the mixtures. Except for one enzymatic step, the pathway was fully regulated and its component enzymes were only synthesized in response to the presence of pathway substrates.
Open Access
Simultaneous degradation of chloro- and methylaromatics via ortho pathway by genetically engineered bacteria and natural soil isolates
(1989) Engesser, Karl-Heinrich; Pieper, Dietmar H.; Rojo, Fernando; Timmis, Kenneth N.; Knackmuss, Hans-Joachim
The simultaneous bacterial metabolism of chloro- and methylaromatics via ortho- or metapathway, normally results in incomplete degradation and death of the organisms. This is caused by misrouting of central intermediates. i.e. substituted catechols into unproductive pathways and suicide inactivation of the key enzyme of meta pathway, (catechol 2,3-dioxygenase). The meta pathway proved to be definitely unsuited for productive metabolism of chloroaromatics. Therefore two strategies were used for simultaneous degradation of mixtures of chloro- and methylaromatics via ortho pathways: Methyllactons or certain mixtures of chloro- and methylaromatics were used as enrichment substrates, yielding strains which metabolized these compounds almost exclusively via the desired pathway. Alternatively relevant enzymes from five different catabolic pathways of three distinct soil bacteria were combined in a patchwork fashion generating a functional ortho cleavage route for methylaromatics coexisting with the ortho cleavage pathway of chloroaromatics.