[Stability of genetic markers in methane-oxidizing bacteria].

A number of Methylococcus thermophilus 111p clones have been obtained which have acquired resistance to tetracycline. The stability of maintenance of marker resistance in these clones and also in already designed Methylomonas rubra 15sh mutants has been investigated. Chromosomal markers resistance to antibiotics or formaldehyde were maintained in the marked strains Methylococcus thermophilus 111p and Methylomonas rubra 15sh after storage in nonselective conditions. The markers of resistance to antibiotics, which were coded by plasmids (pAS8-121 and pULB113), were not always preserved in Methylomonas rubra and Methylococcus thermophilus. The stability of maintenance of chromosomal markers in the investigated methane oxidizing bacteria testifies to the fact that they can be used in laboratory and industrial practice for testing the marked bacteria on selective media. The collection of the marked bacteria-mutants Methylomonas rubra 15sh and Methylococcus thermophilus 111p has been created. These strains stably support the marker resistance to various antibiotics or formaldehyde in unselective conditions.