Correct! So where might we expect to find microbes that can digest lignin?
I don’t see that. Lignin can be digested… through slow, round-about means. It’s a very complex, interwoven and cross-linked material. If the energy were readily accessible in lignins then like other sources it would be extracted. Note that the cellulose in many plants is also slow to digest. In comparison, starch, a polymer with a slightly different linkage between glucose subunits compared to cellulose, is much easier to break down. Of course, starch and cellulose have very different physical properties…
On decaying plant matter or in the guts of wood eating insects. A ‘consortium’ (group of species working together) is probably required to break things all the way down. The lignin-digesting fungi probably also work in the presence of other species that contribute enzymes. It’s a extracellular digestion process, meaning the microbes have to dispense digestive enzymes out into the environment. I think some of the reactions require aerobic conditions so buried and swamp-covered plant material may take much longer to degrade. But lignin is tough, highly-crosslinked and provides difficult access. Sure there’s a lot of energy bound in the structure but it seems expensive and slow to access.
This is a very very good guess. But not correct (it seems), because termites cannot digest lignin, even with the help of their gut microbes. Bonus points to someone who can guess why this might be.
Correct.
Wait, I know! I have patients who claim they eat nothing but salads and yet gain weight! They must have lignin digesting symbiotic bacteria in their upper gut! Case solved.
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Seems the bacteria “SCF1 is capable of degrading 56% of the lignin under anaerobic conditions within 48 h, with increased cell abundance in lignin-amended compared to unamended growth (Figure 1).”
The bacteria is found in wet tropical soils, which “are attractive targets for discovery of bacterial lignin-degraders, which would be amenable to industrial engineering and efficient for removing lignin inhibitors to cellulose availability for biofuels.”
From the article Evidence supporting dissimilatory and assimilatory lignin degradation in Enterobacter lignolyticus SCF1
So, do I win the science fair??
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That’s an interesting paper, Jay! Different electron pathway flow.
No, not termites – That’s cellulose. But there are beetles where at least partial lignin degradation occurs. No idea why termites couldn’t if they managed to acquire the necessary symbionts. Are you alluding to the degradation of aromatics?
You know, my further reading on the subject suggests to me that while lignin degradation is slow (-ish), there is obviously still a whopping lot of turnover in the environment. Further, in established environments, net turnover has to be close to the rate of deposit. (D’oh! Should’ve seen that at first). The mass of microbes (including fungi) in the environment is huge. They don’t leave much to waste.
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I think this will do nicely… it was written by @TedDavis. Ted talks about God Guiding evolution - - and even says it is essentially the same discussion as Robin Collins’ !!!
[QUOTE:]
"Harvard botanist Asa Gray, shown here in 1868, was not only the first American Darwinian but also an early proponent of what he himself (in 1880) called “theistic evolution,” though he was probably not the first person to use that term.
Gray endorsed the explanatory power of natural selection, but he also believed that “variation has been led along certain beneficial lines” by the Creator, guiding the process of evolution. Followed by: Robin Collins’ conception of “theistically guided evolution” is similar in spirit. -
[END QUOTE]
Good find George. It’s pretty difficult to avoid this.
The view of evolution I propose is what I will call theistically guided evolution.
So this is all really good guys. I’ll make a few more scientific observations.
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Contra Axe, there are actually several organisms that can subsist on lignin. The bacteria @Jay313 mentions are one example, but I also found some really cool examples of synergism between enzymest of different species that allow them together to live of lignin alone Synergistic enzymatic and microbial lignin conversion - Green Chemistry (RSC Publishing). And also there are examples of microbial communities in coal beds!!! that subsist entirely on lignin, and also have several fungal-independent mechanisms of degrading lignin Metagenomic scaffolds enable combinatorial lignin transformation - PubMed.
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Whenever lignin degradation happens, for a whole host physics and chemistry reasons, it is slow. Sure, there is a lot of energy stored up there, but it is very hard to get to. There are several strategies for degrading it, but frequently they rely on oxygen species, which is why it is a little rare for gut microbes to be able to degrade it (that is an anaerobic environment). Though some insects actually can eat lignin http://zeus.plmsc.psu.edu/~jimenez/PNAS08.pdf. Of course, the organisms that @Jay313 pointed out do not use an oxygen mechanism but an electron donation process (possibly to make radicals?).
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It turns out, also, that several people have been able to generate novel lignin degradation enzymes in the lab (see here Paper: Novel enzymes for lignin degradation generated with an easy chromosomal gene amplification method (2016 SIMB Annual Meeting and Exhibition)). This counts as enzymatic novelty, right?
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Perhaps more importantly in the ecosystem, lignin automatically is degraded by light http://www.pnas.org/content/early/2016/03/31/1516157113/F5.expansion.html. So ultimately, almost all of the lignin is ultimately accessed by microbes any way, after it is light degraded.
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So why is lignin hard to degrade any ways, from an evolutionary point of view? Well, “evolutionary warfare”. Plants are continually making new types of lignin for the purpose of protecting themselves. Microbes are evolving new ways to degrade it. At any given moment, some types of lignin are certainly resistant to some types of degradation. More importantly, once a tree dies, ultimately the degradation pathways win because light is the great equalizer.
From this we see a very different picture shaping up. It looks like lignin can be degraded by microbes and they do take advantage of that vast amount of resources. Even as they do this, this does not cause the biosphere to collapse, as one might fear. Instead, the degradation of lignin ends up being very important to the carbon cycle, and one reason why we are not producing coal in large quantities any more.
Of course the reason why many microbes do not eat lignan is because they have no reason to. LIgnin is very hard to digest, so they just focus on easy to digest things, and wait for light or fungi to start the process. The exception to this is places where lignin dominates the environment. In these places organisms can subsist largely on lignin.
So this is certainly a very interesting scientific puzzle, but hardly the puzzle to evolution it is made out to be. This certainly is not “proof of evolution” but it is a fun scientific study.
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Fine. Now explain why no organisms have evolved to use nuclear fusion as their metabolic energy source.
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Then I strongly recommend you find out what happened in the wager in that other thread… it has a bearing on your life’s work, @Eddie…
… and yet you walk away from it … what a hoot…
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Another good example is this.
If the image of God refers to our spiritual capacities, God could still have used the natural process of evolution to create our bodies and human abilities. God could have used a miraculous process to create our spiritual capacities, or used some combination of natural processes and divine revelation to develop these capacities. Either way, God is the creator of our whole selves, including both our physical and spiritual aspects.
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The sad thing is that a relative idiot like me (speaking scientifically) can find something to refute Axe in 5 min. on Google. I started to give him the benefit of the doubt, since the original article was written in 2012 and the article that I found in 2013, but then I noticed that the audio file you linked was created last year. Geez.
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Interestingly, the researchers in the work you referenced found that gene amplification followed by random mutation and DNA rearrangements created a novel chimeric protein that increased the ability of the bacteria to utilize lignin. This wasn’t an enzyme ‘creatively designed by humans’, but instead developed by via evolutionary mechanisms.
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You saw this video already, right?
Using movie technology developed in Hollywood, these scientists developed an impressive way to show how the environment (Hey! @Relates ! ) can induce rapid changes in the genetics of a bacteria population!
It is living proof that as a population becomes stressed and almost wiped out (in this case, just in the frontier region of a giant bacteria culture!) … small changes in chromosomes can quickly spread throughout the stressed region, and create a new genetic baseline for normalcy in the population.
The cyclical process repeats itself every time it bumps into a new concentration of toxic antibiotic chemicals in their environment.
No “intelligence” here … just the constant interplay between life form and environment!
You are right! No intelligence, but an “intelligent” God Who can create life and create the process of evolution whereby simple cells can create intelligent life.
All I hope that you read the original story at https://Harvard.edu/news/bugs-screen.
Evolution is not the survival of the fittest. It is adaption to a changing environment.
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