Experimental evidence for the role of natural radioactivity in influencing viability of commensal microorganisms

The role of natural radioactivity in influencing viability of commensal microorganisms, with particular reference to those pertaining to the human microbiota, has not been investigated in detail. The results of experiments culturing a diversified array of microorganims - probiotics - in naturally radioactive mineral water or deuterium-depleted water are here described. Culturing microorganisms in naturally radioactive mineral water yielded one order of magnitude more live microbial cells in comparison with culturing in deuterium-depleted water. Based on these experimental results, a method for co-culturing prebiotic microorganisms (cyanobacteria) that are extremely resistant to the harmful effects of radiations, together with the probiotics mentioned above, is described. The goal of this co-culture in naturally radioactive mineral water is to transfer the information from the radiation-resistant microorganisms to the probiotics whose viability is enhanced by natural radioactivity. Expression of DNA repair genes in cyanobacteria is induced by co-culturing in a medium of carbonated mineral water naturally containing the radioactive isotopes 228U and 226Ra. The culture medium, in addition to naturally radioactive water, contains silica from vegetal origin to enhance horizontal gene transfer. Finally, it is described the transfer of resistance to the harmful effects of radiations to human cells through a Lactococcus phage-encoded protein, ORF252, that is the evolutionary precursor of human proteins involved in DNA repair and cancer protection.