Biosynthesis of intracellular 5-aminolevulinic acid by a newly identified halotolerant Rhodobacter sphaeroides.

Of 23 strains of halotolerant (up to 12% w/v NaCl) photosynthetic bacteria isolated from various sources, one isolate, SH5, accumulated intracellular 5-aminolevulinic acid (ALA) at 0.45 microg/g dry cell wt (DCW) growing aerobically in the dark. The strain was identified as Rhodobacter sphaeroides using 16S rDNA sequencing. Biosynthesis of ALA was enhanced to 14 microg/g DCW using modified glutamate/glucose (50 mM) medium with the addition of 10 mM levulinic acid after 24 h cultivation. Addition of 30 microM Fe(2+) to this medium increased the yield to 226 microg/g DCW.