inducer, the amount of protein in the space experiment was lower than in ground conditions,
while the opposite picture was observed when lactose was used. The maximum yield of
Escherichia coli TGl (pPR-TGATG-hIL-1rα) biomass observed in microgravity conditions with
induction by lactose was higher than in ground conditions. The result obtained can
demonstrate the positive effect of microgravity on culture growth and on the high sensitivity of
the culture to the nature of the inducer in these conditions.
In samples with lactose induction under microgravity conditions, a significant drop in the
number of viable cells (CFU) was observed, which could be caused by both spaceflight factors
and the oversaturation of cells by the target protein. This finding was confirmed in microscope
observations and electrophoretic analysis.
The amount obtained in the space experiment of medication containing various forms of
recombinant protein did not differ from that obtained under ground conditions. In the
conditions of this experiment, most indicative were the initial cultivation doses of 107 and 109
cells/ml, at which the lowest degree of plasmid elimination was observed, and thus better
synthesis of target protein by the cells of these cultures both on the ISS and on the ground.
In the Aryl-2 investigation, plasmid elimination in Escherichia coli BL21(DE3) (pAYC-ET-(hIFN-
α2b)-lacI) strain cells was absent or minimal both on the ISS and in ground control samples,
which distinguishes this strain from the Escherichia coli TG1 (pPR-TGATG-hIL-1rα) previously
used.
The clones selected from the flight sample during ISS Expedition 29 demonstrated varying levels
of target protein production, ranging from hyper production to almost complete absence.
Based on studying the growth pattern and microscopic picture, it can be stated that the
addition to the culture medium of supernatant from the stationary growth phase of the
Escherichia coli BL21(DE3) [pAYC-ET-(hIFN-α2b)-lacI] culture positively impacts survival in space
conditions.
In order to clarify the mechanism of action of the supernatant, in subsequent experiments it
would make sense to study the effect of a simulated mixture of compounds as the additive to
reproduce the content of supernatant from the stationary phase of culture development
(system of biologically active components of Aktoflor culture broth).
This investigation is ongoing and additional results are pending publication.