[Adaptation of a Bacillus subtilis strain, containing a recombinant plasmid with a human interferon-alpha2 gene, to...

Adaptation of the Bacillus subtilis strain 2335/105 (Km Inf+) containing a recombinant plasmid encoding the extracellular human interferon alpha 2 was studied under various conditions. Stability of the plasmid in the population of B. subtilis 2335/105 was estimated under nonselective conditions. The plasmid-free cells and cells with a low number of plasmid copies were found to accumulate progressively, constituting 80% of the population after 10 culture passages, indicating the poor competitiveness of cells carrying a high number of plasmid copies. The behavior of vegetative cells of the recombinant strain introduced into aquatic microcosms differing in trophic chain length was studied. Within the first 10 days, the lysis of vegetative cells of B. subtilis 2335/105 occurred; the number of viable spores was very low but remained constant for half a year.