Is Endosymbiosis Supported by Evidence?

An experiment to
prove endosymbiosis
falls short

 

 

by Jerry Bergman, PhD

One of the largest (and most important) gaps in the fossil record is the gap between prokaryotes and eukaryotes (see illustration below). A eukaryotic cell, or a cell that contains membrane-bound structures, is the basis for every multicellular organism, including animals, plants, and humans as well as a few unicellular organisms such as protozoa. The prokaryote cells are all single celled organisms such as bacteria. The eukaryote cell is also from 100 to 10,000 times larger than prokaryotic cells.[1] As Christian Hallman stated, “evolution made a big leap towards complex life forms when eukaryotic cells appeared.”[2] The most widely accepted attempt to fill this large gap is the theory of endosymbiosis popularized by Lynn Margulis.

Endosymbiosis is the idea that organelles (in particular mitochondria, chloroplasts, and flagella) were once free-living bacteria that were engulfed by other bacteria. They then, the theory teaches, evolved inside of their host to take on specialized functions, including producing ATP as an energy source for the host.[3] Although endosymbiosis is the most widely accepted theory of the origin of eukaryotic organelles (largely because no better theory exists), the theory faces major lethal problems.[4] Among the many problems with endosymbiosis theory include

the first hurdle of host cell entry, a prospective endosymbiont must overcome challenges associated with immune responses, metabolism and growth synchronization [of its host]. Even if the combined metabolisms theoretically sustain growth in silico, unstable outcomes are the prevailing norm, failing to stabilize vertical transmission.[5]

The history of the attempts to prove endosymbiosis are littered with failure.[6] The newest research used a tiny hollow needle and an air pump to inject bacteria into a larger eukaryotic cell.[7] The end goal was to produce experimental evidence of endosymbiosis, which is what, the author admits, was “thought to be what sparked the evolution of complex life.”[8]

This experiment researched conditions in which a microbial partner could live within the cell of another organism. Even with their technical wizardry, the researcher’s initial pairings often failed. One reason was because the would-be symbiont divided too fast and killed its host. The team was finally successful when they recreated the natural symbiosis that normally occurs between certain strains of the fungal plant pathogen, Rhizopus microsporus, and the bacterium, Mycetohabitans rhizoxinica. The symbiotic relationship involves the bacteria producing a toxin that protects the fungus from predation. Specifically, they used their technique to artificially implant the bacterium Mycetohabitans rhizoxinica into Rhizopus microsporus. When the spores germinated, bacteria were present in the cells of the next fungi generation. This was evidence that the implanted bacteria could be passed on to its offspring.

The end goal of this research was to understand how certain cell organelles, specifically the mitochondria and chloroplasts, emerged in eukaryotes at a time of history that scientists assume was over a billion years ago. Note in the study explanation the frequent use of terms that illustrate how tentative these research findings are:

Biologists created a symbiotic system that hints at how cell features such as mitochondria and chloroplasts might have emerged a billion years ago. Scientists think that mitochondria, the organelles that are responsible for cells’ energy production, evolved when a bacterium took up residence inside an ancestor of eukaryotic cells…. A plant cell containing chloroplasts (dark green) — specialized organelles that scientists think evolved from endosymbionts.[9]

Problems with the research

The first concern is the common word that we use for what occurred is simply bacterial infection. In this case, the experimenters deliberately caused the infection. Bacteria are designed to infect and live inside of their host, such as E. coli that live in the human gut and produce many important vitamins, organic compounds, and the enzymes required to synthesize certain vitamins, including B1, B9, B12, and K.[10] Bacteria also naturally infect a wide variety of organisms, including fungi, without the help of researchers.[11] Some of the bacteria that infect cells are pathogenic, but most are not.

The many problems with researchers implanting bacteria into other life-forms include common problem of failure to infect, noting that

the germination success of the bacteria-containing spores was low. In a mixed population of spores (some with bacteria and some without), those with bacteria vanished after two generations. To see whether relations could be improved, the researchers used a fluorescent cell sorter to select spores containing bacteria — which had been labeled with a glowing protein — and propagated only these spores in future rounds of reproduction. By ten generations, the bacteria-containing spores germinated nearly as efficiently as those without bacteria. The basis of this adaptation isn’t clear. Genome sequencing identified a handful of mutations associated with improved germination success in the fungus — which was a strain of R. microsporus not known to carry endosymbionts naturally — and found no changes in the bacteria.[12]

Endosymbiotic relationships in which microbes live harmoniously within cells of another organism are found in numerous life-forms besides fungi and includes insects. This is not an esoteric field, but one of great importance to science:

Bacteria and fungi can form a range of physical associations that depend on various modes of molecular communication for their development and functioning. These bacterial-fungal interactions often result in changes to the pathogenicity or the nutritional influence of one or both partners toward plants or animals (including humans). They can also result in unique contributions to biogeochemical cycles and biotechnological processes. Thus, the interactions between bacteria and fungi are of central importance to numerous biological questions in agriculture, forestry, environmental science, food production, and medicine.[13]

The research methodology process used in injecting bacteria into fungi cells, although touted as important to understand endosymbiosis, is very different from that process proposed to have achieved endosymbiosis. The bacteria type that infects fungi is also very different from the bacteria type proposed to have infected other bacteria that eventually becomes an integral part of the bacteria as endosymbiosis claims.

The effort expended in injecting bacteria into fungi cells was also enormous, as indicated by a team led by microbiologist Julia Vorholt, at the Swiss Federal Institute of Technology in Zurich. The research team has spent the past few years engineering endosymbiosis in the laboratory before finally achieving success.  The researchers admitted from their several years of effort that

The emergence of new endosymbiosis remains a challenge to observe and study. We have developed an experimental system that allows real-time investigation of the initial steps in the association of a fungal host with an intracellular bacterium. Such encounters are thought to occur frequently in nature, but will be predominantly unstable and transient.[14]

Summary

Evolutionists postulate that mitochondria, the organelles that are responsible for cells’ energy production, evolved from a bacterium that took up residence inside an ancestor of eukaryotic cells. After millions of years, the bacterial cell supposedly evolved into a very different type of cell called an organelle. Chloroplasts likewise emerged when an ancestor of plants swallowed a photosynthetic microorganism.

Both of these proposals involve very different circumstances than injecting a bacterium into a fungus. They are even more different because they used a natural symbiosis that normally occurs between certain strains of a fungal plant pathogen, Rhizopus microsporus, and the bacterium, Mycetohabitans rhizoxinica. The attempt to connect the two events to evolution is obvious by the fact that the Nature article mentioned the word ‘evolution’ 55 times, even though the research had little directly to do with evolution.

References

[1] Tarantino, Corinne. 2022. Eukaryote cells. https://www.osmosis.org/answers/eukaryotic-cell

[2] Hallmann, C., “Eukaryotes: A new timetable of evolution,” Max-Planck Gesellschaft. https://www.mpg.de/9256248/eukaryotes-evolution, 2015.

[3] Palmer, J., “The mitochondrion that time forgot,” Nature 387:454-455.

[4] Bergman, J., “Origin of eukaryotes: Still wishing and hoping endosymbiosis is true. Subsequent to the origin of life, the origin of eukaryotic cells is admittedly the next most serious problem for evolutionists.” https://crev.info/2022/10/eukaryogenesis/, 2022.

[5] Giger, G.H., et al., “Inducing novel endosymbiosis by implanting bacteria in fungi,” Nature. https://doi.org/10.1038/s41586-024-08010-x, 2024.

[6] Bergman, J., “Research has overturned endosymbiosis: The unbridgeable gap between prokaryotes and eukaryotes remains,” Journal of Creation 35(1):38–47, April 2021.

[7] Giger, et al., 2024.

[8] Hallmann, 2015; emphasis added.

[9] Callaway, E., “Is this how complex life evolved? Experiment that put bacteria inside fungi offers clues,” Nature. https://www.nature.com/articles/d41586-024-03224-5, 3 October 2024; emphasis added.

[10] Khan, S., “Gut microbiome: Meet E. coli – the infamous bacteria with an unfair reputation.” https://theconversation.com/gut-microbiome-meet-e-coli-the-infamous-bacteria-with-an-unfair-reputation-213626#, 2024.

[11] Frey-Klett, P., et al., “Bacterial-fungal interactions: Hyphens between agricultural, clinical, environmental, and food microbiologists,” Microbiology and Molecular Biology Reviews 75(4):583–609,

doi: 10.1128/MMBR.00020-11, December 2011.

[12] Callaway, 2024.

[13] Frey-Klett, et al., 2011.

[14] Giger, G.H., et al., 2024.

[15] Tarantino, Corinne. 2022. https://www.osmosis.org/answers/eukaryotic-cell

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Dr. Jerry Bergman has taught biology, genetics, chemistry, biochemistry, anthropology, geology, and microbiology for over 40 years at several colleges and universities including Bowling Green State University, Medical College of Ohio where he was a research associate in experimental pathology, and The University of Toledo. He is a graduate of the Medical College of Ohio, Wayne State University in Detroit, the University of Toledo, and Bowling Green State University. He has over 1,900 publications in 14 languages and 40 books and monographs. His books and textbooks that include chapters that he authored are in over 1,800 college libraries in 27 countries. So far over 80,000 copies of the 60 books and monographs that he has authored or co-authored are in print. For more articles by Dr Bergman, see his Author Profile.