Observation of Evolution in Bacteria

In a recent paper in Nature Genetics,1 scientists have reported observing the evolution of Escherichia coli bacteria in a matter of days. An initial response might be to ask what they evolved into. The answer would be mutant bacteria with a loss of pre-existing genetic information. The next question might be about what the authors’ definition of evolution is. The answer would be mutation and natural selection acting over millions of years to bring about complex life forms from simpler ones. The final question might be: “Then did they really observe evolution?” The answer would be: “No!”

Equivocation of terms

Equivocation is the logical fallacy of changing the meaning of a word in the middle of an argument. The authors of the paper make it clear that they believe evolution means molecules-to-man over millions of years. Senior author Bernhard Palsson states, “Paleontologists look at the fossil record to study how evolution of dinosaurs and other animals occurred over millions of years, but in the case of E. coli bacterium, new technology has given us the ability to observe evolution as it is occurring over a matter of days.”2 From the paper3 it is obvious that the authors believe the mechanisms driving evolution are mutation and natural selection. However, as has been shown time and again (see “Evolution or Adaptation?”), mutation and natural selection lead to a loss of genetic information, not the gain of information needed for molecules-to-man evolution. So they are equivocating the term evolution. Evolution can’t mean both a gain of and a loss of genetic information. The authors are either unaware of this apparent fallacy, or are deliberately trying to deceive the public. Christopher Herring, another author of the paper4 makes it clear, “Opinion surveys indicate that many people don’t believe that evolution occurs but if skeptics could witness evolution actually occurring, as we did, I think they’d be more likely to believe that it’s not just a theory.”5

Experimental evolution

Scientists used the MG1655 strain of E. coli K-12 bacteria that has been cultured in the lab environment for approximately 80 years. This strain has adapted well to the lab setting of growing on rich media full of carbon sources (unlike that found in natural environments). MG1655 was grown in a minimal medium containing the sole carbon source glycerol for a period of 44 days. The strain already has the pathway to catabolize (breakdown) glycerol so the “evolution” that occurred did not originate the pathway to utilize glycerol. MG1655 did not utilize glycerol well initially (as evidenced by a slow growth rate) but it was found that mutant strains developed that could utilize glycerol better (faster growth rate) than the original strain over time. The entire genome (all the DNA) from these strains was sequenced to observe mutations that led to the better utilization of glycerol. Do these mutations provide evidence that the bacteria evolved?

One strain had a mutation in a gene for the enzyme glycerol kinase which is important in the first step of glycerol breakdown. This mutation reduced the ability of glycerol kinase to be inhibited by fructose-1,6-bisphosphate (FBP). FBP is important in limiting the rate at which glycerol is catabolized. This is important since a side reaction during glycerol breakdown results in the production of a metabolite which is toxic at high concentrations. No gain of information took place as required by evolution, only loss leading to dysregulation of this pathway. In the wild, versus the rather comfy lab environment, this could be extremely detrimental.

No gain of information took place as required by evolution—only an alteration in the regulation of specific pathways that give the bacteria an advantage in their current environment.

Another strain had mutations in the gene for the enzyme RNA polymerase. This enzyme is important for making temporary copies of the DNA in the form of RNA that are then translated into proteins. These mutations seem to lead to better overall transcription of DNA into RNA (thus more proteins) for genes in several categories involved in protein processing and cell growth. This appears to be either dysregulation or upregulation of specific pathways in the cell. Again, no gain of information took place as required by evolution—only an alteration in the regulation of specific pathways that give the bacteria an advantage in their current environment.

What is occurring with these bacteria is analogous to what is observed with the development of antibiotic resistant bacteria. Mutations occur in the DNA leading to bacterial proteins that cannot interact with the antibiotic and the bacteria survive. Although they survive well in this environment, it has come at a cost. The altered protein is less efficient in performing its normal function. In an environment without antibiotics, the non-mutant bacteria are more likely to survive because the mutant bacteria cannot compete as well. It is not known how these mutant strains of MG1655 would perform in the wild; however, dysregulation of important cellular pathways would most likely lead to bacteria that cannot compete well.

Conclusion

The authors conclude their paper with this: “A full appreciation of the plasticity of genomes and the capacity of bacteria to rapidly adapt to new environments will emerge as genome-scale technologies such as CGS are applied to study experimental evolution.”6 Again, we have an equivocation of terms. Adaptation is the result of the processes of mutation and natural selection leading to a loss of genetic information—but an organism more suited for a particular environment. Evolution requires the gain of genetic information to go from molecules-to-man. Adaptation and evolution are not the same thing. Bacteria are not evolving. Instead they are a testimony to God’s wonderful design, master adapters and survivors in a sin-cursed world.