The Effect of Nutrient Limitation on the Competition between an H2-uptake Hydrogenase Positive (Hup+) Recombinant Strain of Azotobacter chroococcum and the Hup- Mutant Parent in Mixed Populations

Abstract

Competition studies in continuous culture between a Hup− mutant of Azotobacter chroococcum and its presumed isogenic Hup+ recombinant showed that Hup activity benefited the organism under N2-fixing, sucrose- or phosphate-limiting conditions but was ineffective or disadvantageous under O2-, sulphate- or iron-limitation.