Physiological peculiarities of propionibacteria--present facts and prospective applications

The genus Propionibacterium includes dairy and cutaneous propionibacteria; they differ principally by their natural habitats: in milks, cheeses and on human skin and in the rumen ruminants respectively. Using modern methods of molecular biology a new composition of the genus, containing at present 10 species was established. These bacteria generate energy by fermentation, which is linked with a short anaerobic respiration chain yielding more ATP than in any other bacterial fermentation. Propionibacteria contain the apparatus for the aerobic lifestyle including antioxidative defense systems consisting of SOD, catalase and peroxidase. The metabolism of "anaerobic" species of propionic acid bacteria (PAB) is tuned to the use of a high level of vitamin B12, which participates not only in fermentation, but in a number of vital anabolic reactions too. In the absence of vitamin B12, PAB switch to a B12-independent way of existence, which is, however, less effective than the B12-dependent one. Cells, culture liquids (CL) and cell extracts possess antimutagenic (AM) activity. AM activity of CL is linked with an extracellular protein(s). The proteinaceous cytosolic fraction of propionibacteria exerts reactivative activity on pro- and eukaryotic organisms subjected to different and unrelated stresses. The physiological peculiarities of PAB open up new areas of their practical applications: the possibility of creation of medical and prophylactic preparations with AM and antistress properties, preparations with antioxidative properties, SOD and of human probiotics that may be useful in the biotechnology of environmental health.