GENETIC MANIPULATION OF ACID FORMATION PATHWAYS BY GENE INACTIVATION IN CLOSTRIDIUM-ACETOBUTYLICUM ATCC-824

Integrational plasmid technology has been used to disrupt metabolic pa thways leading to acetate and butyrate formation in Clostridium acetob utylicum ATCC 824. Non-replicative plasmid constructs, either clostrid ial phosphotransacetylase (pta) or butyrate kinase (buk) gene fragment s, were integrated into homologous regions on the chromosome. Integrat ion was assumed to occur by a Campbell-like mechanism, inactivating ei ther pta or buk. Inactivation of the pta gene reduced phosphotransacet ylase and acetate kinase activity and significantly decreased acetate production. Inactivation of the buk gene reduced butyrate kinase activ ity, significantly decreased butyrate production and increased butanol production.