Since the rate of low-specificity lateral gene transfer in lower prokaryotes is comparable to that of an electron communication system, bacteria have been viewed as a planetary monoclonal community or a superorganism since 1983 [1]. The intensity of genetic exchanges increases in dense populations, which contributes to the survival of species under new and unfavorable ecological conditions.The discovery of chemical communication extended the notion of the social behavior in bacteria. This process involves extracellular metabolites, which are designated pheromones, alarmones, or sensors [2], and determine the adaptation of bacteria to stress factors.The interaction between bacteria mediated by exometabolites occurs under unfavorable conditions, stress, recovery of division capacity in resting cells, and death of bacteria [2][3][4][5]. Reactivating factors (RFs) were shown to act at the interspecies level [6][7][8].Our previous studies showed that Luteococcus japonicus subsp. casei cells secrete a protein factor, which exerts reactivation and protective effects on producer cells exposed to heat shock, oxidative shock, and UV irradiation.This work was designed to study the reactivation effect of lower eukaryotes ( Saccharomyces cerevisiae yeasts) and reactivation cross-effects of extracellular factors of adaptation in specimens of two domains (eukaryotes and prokaryotes).
MATERIALS AND METHODSGrowth of microorganisms and isolation of the sources of reactivating exometabolites. We studied Luteococcus casei bacteria and Saccharomyces cerevisiae yeasts. Bacteria were grown by a method described elsewhere [3]. The glucose-mineral medium contained 1.5% glucose, 0.3% (NH 4 ) 2 SO 4 , 0.1% KH 2 PO 4 , 0.2% Na 2 HPO 4 , 0.002% CaCl 2 , 0.002% MgSO 4 , 0.002% NaCl, 0.001% CoCl 2 · 6 H 2 O, 0.1% tryptone (Difco, USA), 0.05% yeast extract (Difco, USA), and distilled water (pH 6.8-7.0).The cells were isolated by centrifugation at 10000 g for 20 min, washed with 0.05 M sodium phosphate buffer (pH 7.4), and suspended in the same buffer. The cell suspension was used to study the effect of stress. The supernatant, or the culture liquid (CL), served as a source of RFs.Reactivation activity was localized to a protein exometabolite of the CL with a molecular weight of 9 kDa [9]. This exometabolite was isolated as described previously. S. cerevisiae yeasts were grown in four-ball mash. Cells in the logarithmic growth phase were isolated by centrifugation at 1500 g for 5 min, washed two times with 0.05 M phosphate buffer, and suspended in the same buffer. Experiments with the CL and cell suspension were performed as described above.Source of irradiation. UV irradiation (254 nm) was delivered using a BUV-30 bactericidal lamp. The sample was irradiated with 30 erg/(mm 2 s). The study culture suspension (4.5-5 ml) was put into flat glass petri dishes (diameter, 10 cm) and exposed to UV irradiation. A tenfold dilution was made before inoculation in solid media. Three independent suspensions were irradiated at each point. The sample from eac...
