Propionibacteria cutaneous

Nutritional requirements. P. avidum is relatively insensitive to oxygen, but oxygen inhibits the growth of P. acnes and P. granulosum. The latter two species have more complex nutritional requirements than P. avidum, which may be explained by the different places of their habitation. P. acnes and P. 

Morphology. In young cultures P. acnes forms long irregular rods similar to the cells of C. diphtheria. The cells of P. acnes (0.5-1.5 pm long) are slightly curved (Fig. 1.19). In old cultures all the strains form spherical cells. Colonies are typical for propionic acid bacteria, and they are formed only under anaerobic conditions. The cell anatomy of P. acnes is similar to that of P. shermanii (Fig. 1.20). 

Extracellular enzymes. Cutaneous propionibacteria secrete nucleases, neuraminidases and hyaluronidases (Ingham et al, 1979 Hoffler, 1979 Holland et al, 1979 von Nicolai et al, 1980), acid phosphatases (Ingham et al, 1980), lecithinases (Werner, 1967) and other lipases (Ingham et al, 1981) (Table 1.6). The presence of P. acnes in blackheads is associated (Holland et al, 1981) with its capacity to produce the above mentioned 

It was suggested (Puhvel and Reisner, 1972) that hyaluronidase can split extracellular substances of the cell wall of sebaceous ducts and thus increase the permeability of epithelial follicles. Neuraminidase can damage cell and tissue membranes, affecting the sialic acid residues on the surface of the cells. Under the action of proteases of P. acnes, which also possesses keratinolytic activity, small chemotactic peptides are produced that may have a role in the onset of inflammation. Proteolytic activity may be significant (Ingham, 1983) in complement activation. It was shown (Ingham, 1983) that a preparation of extracellular proteases from P. acnes P-37 contained at least three types of proteases with different molecular masses. The secretion of proteinases is used as a criterion in the classification of these bacteria. 

Reticulostimulin (RS). It was shown (Prevot, 1975) that aerobic corynebacteria do not synthesize RS, which is produced only by anaerobic forms, if they are not lysogenic. Stimulation of the RES by RS is accompanied by the stimulation of synthesis of several serum proteins, i.e. proceeds on the basis of natural RES defenses (nonspecific immunity) by both cellular and humoral mechanisms. 

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Since the main habitat of anaerobic coryneforms is human skin, they are referred to as cutaneous propionibacteria, whereas species isolated from... 

Cutaneous propionibacteria are also known as anaerobic coryneforms or anaerobic diphtheroids. Initially, 12 species of anaerobic corynebacteria were described (Prevot and Fredette, 1966), but later, when some 80 strains had been evaluated for their cell wall composition and DNA homology (Johnson and Cummins, 1972), the number of species was reduced to three, namely, P. acnes, P. granulosum and P. avidum. Cutaneous propionibacteria are not restricted to the normal skin surface. They can be isolated from facial blackheads, less frequently from stomach contents, wounds, bone marrow, blood, and tissue abscesses. Thus, classical and cutaneous propionibacteria differ principally by their typical natural habitats. 

Table 1.6. Extracellular enzymes produced by cutaneous propionibacteria...

Diagnostic features of the species are summarized in Table 1.7 Table 1.7. Characters used for identification of cutaneous propionibacteria... 

Cell extracts of P. shermanii VKM-103 (wild type), P. shermanii KM-82 mutant (superproducer of vitamin B12), P. acnes CCM 322 and propionic add cocci P. coccoides) were tested as possible sources of antimutagens. The first two strains represented classical propionic acid bacteria, and P. acnes represented cutaneous propionibacteria. In the assay for antimutagenic activity S. typhimuhum TA 1535 his mutant) was used as the test organism (base pair substitution mutations tester). 

Concerning the cutaneous propionibacteria, the data on their bacteriocins are scarce. Two bacteriocin-like substances were partially purified from a strain of P. acnes acnecin CN-8 and bacteriocin RTT108 (Fujimura and Nakamura, 1978). Acnecin was inhibitory to other strains of P. acnes, and bacteriocin RTT108 was active against both Gram-negative and Grampositive anaerobes. 

It has been suggested (Wilkinson, 1975) that the activating factor of cutaneous propionibacteria, at least in part, is represented by a peptide that has affinity to the membrane of mononuclear phagocytes, in which it activates such processes as exocytosis, endocytosis, motility. After a short period of activation an increase in protein synthesis is observed in macrophages. But the molecular basis of the immunostimulating properties of anaerobic coryneforms requires further studies. 

An additional clinically important activity was discovered in cutaneous propionibacteria. Phospholipid substances isolated from the cells stimulated... 

The results of experimental and clinical trials of cutaneous propionibacteria are regularly discussed at international colloquia, one of which entitled Bacteria and Cancer was held in Bologna in 1982. 

Recently, it has been shown (Perez-Chaia et al., 1998) that a strain of P. acidipropionici stimulated immunological responses of the host like the cutaneous propionibacteria discussed above, and could be useful in the prevention of intestinal infections or tumor development. Immunomodulatory effects of some classical propionibacteria, i.e., stimulation of the cell populations involved in nonspecific resistance, have also been reported (Roszkowski et al, 1990). 

On the other hand, the boundaries of the genus were extended by including four species of anaerobic corynebacteria that inhabit human skin. Using the methods of traditional, numerical and molecular taxonomy, anaerobic corynebacteria were shown to be different from the other members of the genus Corynebacterium by a number of essential characteristics and to have genomic similarities with propionic acid bacteria. The anaerobic corynebacteria have been reclassified as P. acnes, P. avidum, P. granulosum and P. lymphophilum and are called cutaneous propionibacteria now. 

Cutaneous propionibacteria can be considered as a biological defense for their human host and as a useful natural microflora in the rumen of ruminants. They stimulate the immune system in humans, have beneficial effects on farm animals and poultry, and therefore may find application as components of medical and preventive preparations. However, further investigations are needed before propionibacteria can be used in medicine. 

Greenmail J, Holland KT and Cunliffe WJ (1981) Effects of glucose concentration on biomass, maximum specific growth rate and extracellular enzyme production by three species of cutaneous propionibacteria grown in continuous culture. J Gen Microbiol 127 371-376... 

Holland KT, Greenman J and Cunhffe WJ (1979) Growth of cutaneous propionibacteria on synthetic medium growth yields and exoenzyme production. J Appl Bacteriol 47 383-394 Holland KT, Ingham E and Cunhffe WJ (1981) The microbiology of acne. J Appl Bacteriol 51 195-215... 

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