[Development of hydrogen bacteria on hard surfaces]

A simple model system stimulating the physical conditions of hydrogen bacterial growth in soil and loose rocks was studied. Hydrogen bacterial cells grown under the autotrophic conditions were applied to the surface of coarse-grained silica gel, crushed brick and peat, and constantly supplied with a mixture of H2:O2:CO2 (7:2:1). It was shown that Nocardia opaca Z-766, when cultivated on well-developed solid surfaces with a small quantity of mineral medium, produced an active bacterial film at the whole surface and was capable of oxidizing hydrogen over 100 days. The rate of gas consumption had a maximum and then sharply decreased to a level of one-third--one-fifth of the maximal rate. The same was true of Pseudomonas carboxydoflava Z-352 and Nocardia autotrophica Z-1046; apparently, this is a common characteristic of all organisms growing on solid surfaces and fed with gases. The results suggest that microorganisms oxidizing hydrogen can grow on solid surfaces for a long period of time, serving as a bacterial filter which effectively removes a gaseous substrate.