Isotopic Resonance Hypothesis: Experimental Verification by Escherichia coli Growth Measurements

Abstract

Isotopic composition of reactants affects the rates of chemical and biochemical reactions. As a rule, enrichment of heavy stable isotopes leads to progressively slower reactions. But the recent isotopic resonance hypothesis suggests that the dependence of the reaction rate upon the enrichment degree is not monotonous. Instead, at some “resonance” isotopic compositions, the kinetics increases, while at “off-resonance” compositions the same reactions progress slower. To test the predictions of this hypothesis for the elements C, H, N and O, we designed a precise (standard error ±0.05%) experiment that measures the parameters of bacterial growth in minimal media with varying isotopic composition. A number of predicted resonance conditions were tested, with significant enhancements in kinetics discovered at these conditions. The combined statistics extremely strongly supports the validity of the isotopic resonance phenomenon (p ≪ 10−15). This phenomenon has numerous implications for the origin of life studies and astrobiology, and possible applications in agriculture, biotechnology, medicine, chemistry and other areas.

On the Effect of Planetary Stable Isotope Compositions on Growth and Survival of Terrestrial Organisms

“…The temperature dependence of the effect magnitude (a significant effect at 25°C and hardly noticeable effect at 39°C) is also in agreement with the IsoRes theory and previous observations[32]. Since the impact of the isotopic resonance is somewhat similar to a temperature increase, the biological growth should accelerate more, in relative terms, when higher temperature leads to faster growth (for E .…”

“…As expected, the effect was even stronger for Venus’s composition (p<10 −6 and <10 −5 , respectively). The relative value of the effect was ≈1% for Mars and ≈2–3% for Venus; such effects are large compared to the precision of measurements (≈0.05% after statistical processing[32]). At 39°C, the temperature of the maximum growth of E .…”

“…Thus, another framework may be needed for rationalization of our results, such as the one provided by the isotopic resonance (IsoRes) phenomenon[32]. The IsoRes hypothesis suggests that the abundances of stable isotopes affect the rates of chemical and biochemical reactions in a nonlinear way, and that at certain isotopic compositions of elements the complexity of the molecules built of these elements decreases.…”

“…Slightly higher deuterium content may not be toxic per se , but could instead lead to faster kinetics of most biochemical processes involving proteins (IsoRes theory predicts a strong resonance at ≈300 ppm D[31,32]), which in turn means shorter lifespan. This phenomenon is likely to be responsible for the shorter lifetime at 600 ppm, while at 1200 ppm the general toxicity of deuterium may become the prime reason for the lifespan decline.…”

Shifts in rotifer life history in response to stable isotope enrichment: testing theories of isotope effects on organismal growth

“…This theory predicts that at certain abundances of the stable isotopes, the rates of chemical and biochemical reactions accelerate, affecting biological growth. For example, the resonance conditions are predicted to occur at 0.35% of 13 C, 3.5% of 15 N, 6.6% of 18 O and 0.03% of 2 H, and these predictions were confirmed using experiments with E. coli grown at varying isotopic composition [6]. Although these resonance isotopic concentrations are too high to occur naturally in any environment on Earth, they are within the range of concentrations applied in laboratory and field experiments with isotope-enriched substrates (e.g.…”