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mimzy

True colonisation vs mycelial exploration

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I recently conducted an experiment to determine whether some strains I had would colonise a novel substrate. I inoculated the the substrate with a small agar plug and happily watched as the mycelium spread out through substrate. I am now concerned however that the mycelial expansion is not true colonisation, and the organism is just using the agar plug nutrients to expand through the substrate. Some mycelia has is quite fluffy, and remains sparse... not the dense colonisation you see on something like grain.

So the questions is; how can you tell which is which.. true colonisation vs spreading?

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not sure if I fully understand the question.

A change to fluffy myc for some species is a sign of nutrient status change, usually low.

(Low nutrients can also lead to faster genetic change/degradation from the original clone as an aside.)

I'd be looking for signs of metabolised substrate. "True Colonisation" I am presuming you mean it is actively metabolising it?

EDIT - another thought....some substrates can be grown upon but offer limited to no "food", usually the myc has to be in a source or bridge into a substrate it can metabolise.

Some materials cant be metabolised or even grown upon.

Your novel substrate can only be used by fungi that possess the ability to metabolise it.

Like hydrocarbons, not all can do it, some do it and then die in their own metabolites, others can thrive on it.

dunno if that helps...

Edited by waterboy 2.0

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Yes by true colonisation I am referring to active production of carbohyrases and lignin peroxidases and active growth. What I suspect is happening is that the fungi are merely savaging free dissolved sugars and simple polysaccharides for exploratory growth, or still using the agar plug. My point is that is difficult to tell from a morphologically, whether the substrate is being metabolised or not... at least at this point in time.

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Yes by true colonisation I am referring to active production of carbohyrases and lignin peroxidases and active growth. What I suspect is happening is that the fungi are merely savaging free dissolved sugars and simple polysaccharides for exploratory growth, or still using the agar plug. My point is that is difficult to tell from a morphologically, whether the substrate is being metabolised or not... at least at this point in time.

I've experienced this in experiments as well.

Best thing you can do is wait, especially if it's a small plug + a large amount of substrate. The inoculated plug will lose it's resources and the mycelium won't find food elsewhere

You can also run the experiment backwards just to be thorough- add some identical sterile substrate to a colonised agar plate and see if the growth pattern is the same

Also run controls, just in case there is something weird with the substrate. It happens.

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All good advice DL. Thanks!

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Do you want to mention what the substrate is Mimzy? :wink:

lol...I like novel things

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I've been optimising substrates derived from various plant parts by removing particular components, sometimes adding them back in at different growth stages... the aim is to grow some of our more fastidious fungal friends. I would love to say more, but this is the internet and once its gone, it's gone forever. Exciting times though :)

Edit: grammar

Edited by mimzy
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If the substrate is white when broken up it would be safe to say its colonised. How much nutrients the mycelium is extracting from the substrate is probably impossible to measure other than by health of colonised mycelium/speed of colonisation.

i find that king stropharia sometimes on things like compost or coir tends to throw rhizos through but it never all goes white weirdly. I get the feeling this is because its searching for more preferred substrates/mediums.

I guess unless the species in question it mycorrhizal if the substrate contains some nutrients then it will probably colonise it

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Well I guess a fruiting body would be conclusive evidence of nutrient utilisation right? :)

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Not necessarily- I've found sometimes a small fruiting form from the original mycelial inoc point when the new substrate is inappropriate.

Is like species goes into panic mode cos it can't send out vegetative growth too well, so opts for sending out spores.

But I guess we aren't talking about the same species :)

I hope you got a win!

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Just guessing about the species from some of your recent posts Mimzy.

Do you think it could be an adaptive mechanism the mycelium uses until it encounters root exudates from the host it needs ?

Like an exploritory growth habit until it finds the host it's evolved to form a symbiosis with. It would be a waste of energy for it expend too much energy in active growth until it finds a host.

Edited by Sally

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Haha no secrets about the organisms I'm working on Sally. You're cluey though, I'd love to hear about interests.

Bad news in this case unfortunately. I have both an L. shimeji saprobic mutant and the wildtype mycorrhizal in my library. Looking at my notes I suspect I have innoculated with the saprobic mutant instead of the mycorrhizal, sigh. The nutrient source was so poor, it was behaving like a mycorrhizal and didn't notice.

I've read a few mycorrhizal studies that used a liquid media containing root exudates from host trees grown hydroponically. The effect on mycelial branching (a proxy for ECM sheath development) was striking. What would be interesting would be to see how the mycelial behaves in a media with a gradient of root exudate, dangling the carrot so to speak. Perhaps rhizomorph morphology could be induced? I might give it a go.

DL - It's been too long between chats. I've been in the trenches with lab work, but I'm on the other side with a few good ideas I'd love to chat about :)

Edited by mimzy

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Haha no secrets about the organisms I'm working on Sally. You're cluey though, I'd love to hear about interests.

A few people have said that I seem cluey over the years - until they get to know me.

I'm more of an idiot savant, with a heavy bias towards idiot :wink:

Edited by Sally
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Bad news in this case unfortunately. I have both an L. shimeji saprobic mutant and the wildtype mycorrhizal in my library. Looking at my notes I suspect I have innoculated with the saprobic mutant instead of the mycorrhizal, sigh. The nutrient source was so poor, it was behaving like a mycorrhizal and didn't notice.

I hate it when that happens. Has happened to me too in the past :/

DL - It's been too long between chats. I've been in the trenches with lab work, but I'm on the other side with a few good ideas I'd love to chat about :)

Yes please, would be lovely to catch up. I'll SMS you tonight

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