Physiological effects of plasmid DNA transformation on <i>Azotobacter vinelandii</i>

Abstract

Genetic transformation of Azotobacter vinelandii by the introduction of broad-host-range plasmid DNA (i.e., pRK2501, RSF1010, or pGSS15) causes a number of physiological changes. As shown here, the capacity for nitrogen fixation, mean cell size, and synthesis of siderophores are decreased, whereas the production of capsular slime is enhanced. These findings suggest that the presence of plasmid DNA imposes a "metabolic load" on Azotobacter vinelandii. Therefore, it cannot be assumed a priori that the introduction of plasmid DNA into Azotobacter vinelandii will not disrupt some normal physiological processes. The implications of these findings are discussed, specifically in the context of developing Azotobacter vinelandii as an effective bacterial fertilizer by genetic manipulation.