Study of a fructose-negative mutant of Rhizobium meliloti

Abstract Rhizobium meliloti grows on fructose as sole carbon source. Following nitrosoguanidine mutagenesis, a mutant of R. meliloti M5N1 was isolated as unable to grow on fructose. Enzyme assays with cell-free extracts showed it to lack significative phosphoglucose isomerase activity. Other enzymes were present at low levels. Both fructose and fructose 6-phosphate were accumulated within this mutant. The in vitro inhibition of fructokinase by fructose 6-phosphate was show. Symbiotic properties remained unaffected in the mutant strain.