Acquisition of the ability to grow under autotrophic conditions by heterotrophic bacteria through the introduction of DNA fragments from hydrogen-oxidizing bacteria

Abstract

Pseudomonas oxalaticus OX1 carrying recombinant plasmid pFUS and 29 gramnegative bacteria were used as donor and recipients, respectively, for conjugations. The plasmid pFUS contains genes necessary for chemolithoautotrophic growth in a hydrogen-oxidizing bacterium,Alcaligenes hydrogenophilus. By the conjugal transfer of plasmid pFUS, 12 strains acquired the ability to grow in a mineral salts medium under a gas mixture containing H₂, O₂, and CO₂.Pseudomonas cepacia carrying pFUS had hydrogenase and ribulose-1,5-bisphosphate carboxylase activities, and could grow at a rate almost equivalent to the growth rates of ordinary hydrogen-oxidizing bacteria.Pseudomonas acidophila carrying plasmid pFUS expressed indigenous antibiotic secretion under chemolithoautotrophic conditions. Plasmid pFUS could be stably maintained in these strains in the absence of selection pressure created by the addition of an antibiotic or chemolithoautotrophic conditions. This study shows that introduction of DNA fragments responsible for chemolithoautotrophic growth into a producer of valuable substances could be a promising technique for CO₂ recycling.