PORPHYRIN SYNTHESIS IN MICROORGANISMS 631 



uroporphyrin has not received the attention it deserves (c/. Section 8.2.). 

 In the adult of the human and most other mammahan species, no uropor- 

 phyrin is deposited in the bones and only traces are formed, while in the fox 

 squirrel formation of uroporphyrin and deposition in the bones is a normal 

 occurrence (Turner, 2836). 



These studies, particularly the finding of coproporphyrin I in the 

 developing egg, show that the increased porphyrin formation in 

 embryonic and fetal tissue is due to a still incomplete coordination of 

 hemoglobin synthesis rather than to a breakdown of hemoglobin to 

 porphyrin occurring before the normal breakdown to bile pigments 

 has been established. The latter had been assumed by Garrod and 

 other workers. 



7.3. Porphyrin Synthesis in Microorganisms 



7.3.1. Porphyrin Synthesis in Bacteria. A variety of anaerobic or faculta- 

 tive anaerobic bacteria and fungi possess the ability to synthesize porphyrin. 

 The porphyrin is mostly coproporphyrin; occasionally traces of protopor- 

 phyrin have been found. The findings on porphyrin synthesis by intestinal 

 bacteria are still contradictory. Vannotti believes that the synthesis of 

 porphyrin by intestinal l)acteria contributes little to the porphyrin metab- 

 olism in humans. Mallinckrodt-Haupt (184.9) assumes that all the copro- 

 porphyrin I may be formed in this way, while Jacob {1396) found the intes- 

 tinal bacteria to form coproporphyrin III, not I. Mallinckrodt-Haupt found 

 a great variety of intestinal bacteria able to form coproporphyrin with 

 asparagine as source of nitrogen. The intestinal porphyrin formation may 

 be influenced by dyspepsia and changes in the intestinal flora. Gram-negative 

 bacteria are considered to be the stronger porphyrin formers by Mallinckrodt- 

 Haupt. Escherichia coli is said to produce more porphyrin when carbo- 

 hydrates are present in the intestine, whicli may occur in dyspepsia. Urbach 

 {2841), however, believes that Gram-positive organisms form more por- 

 phyrin. He describes cases of light dermatoses with increased porphyrin in 

 the feces, not in the urine, which could be cured by abolishing the bacterial 

 imbalance in the intestine by replacement of the bacteria with E. coli. 



Porphyrin-producing bacteria have been observed in the mouth and on 

 the tongue as well as on the skin {405,491). Pathogenic fungi also produce 

 porphyrin (Carrie and co-workers, 405-407,1849; Cortese, 491)- 



Coproporphyrin* and its complex zinc salt have been observed in Coryne- 

 hacterium diphtheriae (Coulter aud Stone, 504,505,2672; Dhcre, 583). The 

 latter was first erroneously believed to be a hemochrome. The identity of 

 porphyrin and bacterial toxin has also been suggested, but this has been 

 disproved {2901,3041). Coproporphyrin copper has been claimed to occur in 

 Pseudomonas phosphorescens. 



* Whereas Pappenheimer {310.'ta) assumed the porphyrin to be hematoporphyrin. 

 Gray and Holt {10S9a) have shown that it is coproporphyrin III. 



