Evidence for the interference of aluminum with bacterial porphyrin biosynthesis.
Aluminum (0.74 mM) was found to retard bacterial growth, and enhance porphyrin formation and excretion in Arthrobacter aurescens RS-2. Coproporphyrin III was shown to be the main porphyrin excreted by aluminum-exposed A. aurescens RS-2 cultures and by RS-2 cultures grown under anoxic conditions. Synthesis and excretion of porphyrins in A. aurescens RS-2 increased in a dose-dependent manner when the bacteria were exposed to increasing aluminum concentrations. Incubation of A. aurescens RS-2 with delta-aminolevulinic acid (delta-ALA, 1.2 mM) brought about the intense formation and excretion of porphyrins by the cells, in the presence or absence of aluminum. delta-ALA slightly enhanced the toxicity of aluminum towards RS-2 bacteria. Furthermore, the intracellular concentration of heme was reduced by 63.9 +/- 8.67% in aluminum-exposed RS-2 bacteria when compared with control cultures. The results are discussed in light of the recent finding concerning aluminum toxicity and porphyrin biosynthesis in microorganisms.
Scharf
R
R
Department of Environmental Engineering, Faculty of Civil Engineering Technion-Israel Institute of Technology, Haifa.
Mamet
R
R
Zimmels
Y
Y
Kimchie
S
S
Schoenfeld
N
N
D000535:Aluminum / Q000494:pharmacology*; D000622:Aminolevulinic Acid / Q000494:pharmacology; D001173:Arthrobacter / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D001426:Bacterial Proteins / Q000096:biosynthesis; D003306:Coproporphyrins / Q000096:biosynthesis*; D004305:Dose-Response Relationship, Drug; D011166:Porphyrins / Q000096:biosynthesis*; D013054:Spectrophotometry, Atomic
D001426:Bacterial Proteins; D003306:Coproporphyrins; D011166:Porphyrins; C026971:coproporphyrin III; D000622:Aminolevulinic Acid; D000535:Aluminum