# Skin microbes on frogs prevent morbidity and mortality caused by a lethal skin fungus



## rozdaboff (Feb 27, 2005)

_*Skin microbes on frogs prevent morbidity and mortality caused by a lethal skin fungus*

Harris RN, Brucker RM, Walke JB, Becker MH, Schwantes CR, Flaherty DC, Lam BA, Woodhams DC, Briggs CJ, Vredenburg VT, Minbiole KP.

Department of Biology, James Madison University, MSC 7801, Harrisonburg, VA, USA.

ISME J. 2009 Mar 26. [Epub ahead of print]

Emerging infectious diseases threaten human and wildlife populations. Altered ecological interactions between mutualistic microbes and hosts can result in disease, but an understanding of interactions between host, microbes and disease-causing organisms may lead to management strategies to affect disease outcomes. Many amphibian species in relatively pristine habitats are experiencing dramatic population declines and extinctions due to the skin disease chytridiomycosis, which is caused by the chytrid fungus Batrachochytrium dendrobatidis. Using a randomized, replicated experiment, we show that adding an antifungal bacterial species, Janthinobacterium lividum, found on several species of amphibians to the skins of the frog Rana muscosa prevented morbidity and mortality caused by the pathogen. The bacterial species produces the anti-chytrid metabolite violacein, which was found in much higher concentrations on frog skins in the treatments where J. lividum was added. Our results show that cutaneous microbes are a part of amphibians' innate immune system, the microbial community structure on frog skins is a determinant of disease outcome and altering microbial interactions on frog skins can prevent a lethal disease outcome. A bioaugmentation strategy may be an effective management tool to control chytridiomycosis in amphibian survival assurance colonies and in nature.The ISME Journal advance online publication, 26 March 2009; doi:10.1038/ismej.2009.27.

PMID: 19322245 [PubMed - as supplied by publisher]_

(If you are interested in the PDF and don't have access to the journal, send me a PM with your email)


----------



## melas (Oct 24, 2007)

So do you think this could be a glimmer of hope in the fight against chytrid?


----------



## MonarchzMan (Oct 23, 2006)

melas said:


> So do you think this could be a glimmer of hope in the fight against chytrid?


Unfortunately, I don't think so. It's a nice possible cure, but it works at the individual level, not the population level where differences could actually be made against chytrid.

I wonder if this is the same microbe found on salamanders that helps prevent infection.


----------



## dom (Sep 23, 2007)

really good article..

a concern of mine would be that if we did mass treatments with the microbial baths would and could chytrid adapt to the bacteria. And no longer be affected by it. Therefore just evolving to another level of devistation.


----------



## atlfrog (Dec 31, 2006)

dom said:


> really good article..
> 
> a concern of mine would be that if we did mass treatments with the microbial baths would and could chytrid adapt to the bacteria. And no longer be affected by it. Therefore just evolving to another level of devistation.


Could this be administered by air, like dropping it from a plane over large areas? Like pesticides or water? I might be naive or might be new to this, not chytrid, but this article in general. Cool article though.


----------



## dom (Sep 23, 2007)

atlfrog said:


> Could this be administered by air, like dropping it from a plane over large areas? Like pesticides or water? I might be naive or might be new to this, not chytrid, but this article in general. Cool article though.


i dont know if that would work but that might, i was refering to just bathing alot of frogs in a given area, would chytrid evolve to survive?


----------



## atlfrog (Dec 31, 2006)

dom said:


> i dont know if that would work but that might, i was refering to just bathing alot of frogs in a given area, would chytrid evolve to survive?


According to "Save Your Frogs" Chytrid Fungus They say that Chytrid can evolve to fight bacterial threats but at what rate I don't know.


----------



## dom (Sep 23, 2007)

atlfrog said:


> According to "Save Your Frogs" Chytrid Fungus They say that Chytrid can evolve to fight bacterial threats but at what rate I don't know.


i wonder if anyone is doing any research on chytrid adaptions to enviromental changes? could be something important to lookinto. If chytrid starts adapting to warm temperatures this could effect alot more places.


----------



## atlfrog (Dec 31, 2006)

dom said:


> i wonder if anyone is doing any research on chytrid adaptions to enviromental changes? could be something important to lookinto. If chytrid starts adapting to warm temperatures this could effect alot more places.


http://www.jcu.edu.au/school/phtm/PHTM/frogs/adms/attach7.pdf

This talks about it to some degree. I believe that they have plenty of researchers out there studying this but I do not have access or money to get the reports. LOL


----------



## Rain_Frog (Apr 27, 2004)

> Unfortunately, I don't think so. It's a nice possible cure, but it works at the individual level, not the population level where differences could actually be made against chytrid.
> 
> I wonder if this is the same microbe found on salamanders that helps prevent infection.


The only populations of mountain yellow legged frogs unaffected by the infection had healthy level of these microbes present BEFORE treatment-- this is an old article.

It sounds very much like there is a "trigger" allowing chytrid to invade populations-- more like amphibian immune systems are compromised.


----------



## atlfrog (Dec 31, 2006)

Rain_Frog said:


> The only populations of mountain yellow legged frogs unaffected by the infection had healthy level of these microbes present BEFORE treatment-- this is an old article.
> 
> It sounds very much like there is a "trigger" allowing chytrid to invade populations-- more like amphibian immune systems are compromised.


That's actually quite fascinating to me. I will have to do some research and see what I can come up with to verify anything on this.


----------



## Rain_Frog (Apr 27, 2004)

Bacteria Found to Fight the Killer Fungus - The frogs' salvation? - Softpedia

About chytrid becoming resistant to heat-- while I believe Ed K. pointed out that chytrid is sexually reproducing, the genetic variation of chytrid strains are very similar. This point further illustrates its recent origin from Xenopus laevis, but also makes one less fearful that it will mutate rapidly.

Honestly, like some have pointed out, the underlying cause could be pollutants and endocrine disruptors making frogs more susceptible to the disease-- not forgetting to mention climate change. Remember the article about latex being toxic to tadpoles?


----------



## dom (Sep 23, 2007)

Rain_Frog said:


> Honestly, like some have pointed out, the underlying cause could be pollutants and endocrine disruptors making frogs more susceptible to the disease-- not forgetting to mention climate change. Remember the article about latex being toxic to tadpoles?


I wish i had a lab so many ideas, what if testing the bacteria to see if it is affected by the pollutants and if the pollutants are killing of the bacteria right off the amphibians themselves. Or then again it could be because of the global warming like you mentioned

haha so i posted before i read the article!! i wonder if there team is doing any research with it and i hope they are


----------



## atlfrog (Dec 31, 2006)

dom said:


> I wish i had a lab so many ideas, what if testing the bacteria to see if it is affected by the pollutants and if the pollutants are killing of the bacteria right off the amphibians themselves. Or then again it could be because of the global warming like you mentioned
> 
> haha so i posted before i read the article!! i wonder if there team is doing any research with it and i hope they are


I bet you Ed would have some ideas on this. I haven't come up with much but i haven't been home much today.


----------



## MonarchzMan (Oct 23, 2006)

It's probably global warming that's the primary cause of its spread. Think of Atelopus zeteki. Many of these animals occur is relatively pristine habitats, but still decline. Pollutants have been largely considered insignificant to the losses seen in rainforest regions. It's possible in temperate regions, though, but I don't believe that there has been research on how them might affect the bacteria since it's relatively new.


----------



## Ed (Sep 19, 2004)

There are several thoughts about montane and pristine habitats being so severely affected.. cultivation, climate change, nitrification of the habit have all been demonstrated 

see http://www.jcu.com.au/school/phtm/PHTM/frogs/papers/mendelson-2004.pdf

ScienceDirect - Geoforum : The hydrological significance of cloud forests in the Sierra de las Minas Biosphere Reserve, Guatemala


There is also thought about long term persistance of pesticides and herbicides drifting further than projected in the atmosphere (see ScienceDirect - Chemosphere : Pesticides in rain for a reference) 

The greater problem is probably due to immunosuppression as even some skin peptides in some frogs have been shown to have antifungal activity against chytrid (see ScienceDirect - Developmental & Comparative Immunology : Activity of antimicrobial skin peptides from ranid frogs against Batrachochytrium dendrobatidis, the chytrid fungus associated with global amphibian declines) yet chytrid still can kill these frogs.... 


Ed


----------



## atlfrog (Dec 31, 2006)

Ed said:


> There are several thoughts about montane and pristine habitats being so severely affected.. cultivation, climate change, nitrification of the habit have all been demonstrated
> 
> see http://www.jcu.com.au/school/phtm/PHTM/frogs/papers/mendelson-2004.pdf
> 
> ...


Thanks for coming in on this subject. I knew if I place the "Bat" Signal up you would come. LOL Just kidding. I appreciate the input, this is all educational to me.


----------



## Ed (Sep 19, 2004)

I actually almost didn't see it. It was actually an accident when I hit the link and saw the posts... 

Ed


----------



## Rain_Frog (Apr 27, 2004)

> There are several thoughts about montane and pristine habitats being so severely affected.. cultivation, climate change, nitrification of the habit have all been demonstrated


I agree Ed. Nobody cultivates crops in the arctic or antarctic ocean, but many marine mammals-- especially polar bears-- absorb many toxins. According to this article (many related articles), these flame retardants are commonly used in plastics and furniture:

Flame retardants are yet another toxic threat to polar bears | Grist | Daily Grist | 09 Jan 2006

From reading, chytrid zoospores are not killed by UV light. Is it possible that over UV exposure could be responsible too?


----------



## MonarchzMan (Oct 23, 2006)

Rain_Frog said:


> From reading, chytrid zoospores are not killed by UV light. Is it possible that over UV exposure could be responsible too?


For some species, possibly (i.e. species exposed to sun often), but those under the shade of a canopy for most of their lives, unlikely.


----------



## atlfrog (Dec 31, 2006)

Ed said:


> I actually almost didn't see it. It was actually an accident when I hit the link and saw the posts...
> 
> Ed


Well thanks anyway, regardless.


----------



## Rain_Frog (Apr 27, 2004)

I'd like to see Ed's input on UV exposure. Many of South America's frog species are from the highlands-- and I believe UV exposure is higher.

Plus, remember, someone posted long ago about the loss of leaf litter on the forest floor from climate change-- also affecting many lizard species:

Lizards Join Frogs in Rapid Decline | Environmental Research Foundation


----------



## MonarchzMan (Oct 23, 2006)

Rain_Frog said:


> I'd like to see Ed's input on UV exposure. Many of South America's frog species are from the highlands-- and I believe UV exposure is higher.
> 
> Plus, remember, someone posted long ago about the loss of leaf litter on the forest floor from climate change-- also affecting many lizard species:
> 
> Lizards Join Frogs in Rapid Decline | Environmental Research Foundation


You're right, but that's only really applicable to species that are not understory forest species (the Cascades Frog, for example). Just doing a quick search, there is some experimental/observational evidence to suggest that at least some rainforest species are not drastically affected like montane species:

Pumilio and auratus avoid UV
http://www3.interscience.wiley.com.proxy2.cl.msu.edu/journal/118501516/abstract?CRETRY=1&SRETRY=0

Unfortunately, I couldn't find a link for the full paper, but the citation for it is:

Garcia TS , Romansic JM, and Blaustein AR. 2006. Survival of three species of anuran metamorphs exposed to UV-B radiation and the pathogenic fungus Batrachochytrium dendrobatidis. DISEASES OF AQUATIC ORGANISMS 72: 163-169.

These guys tested UV-B exposure and chytrid and looked at synergistic effects and found that there was no interaction effect between the two in the three species they looked at (which I'll admit is somewhat surprising).

Most papers done on UV exposure deal with amphibians that lay eggs in shallow, open water where the larvae are exposed to UVB and cannot escape it easily (especially during egg development), whereas adults can. Montane populations certainly could be exposed to increased levels of UVB if they breed in open water (and some hylids could possibly be in that group, although many species lay eggs under leaves), but in my experience, most tropical amphibians avoid the large bodies of open water that would be exposed to UVB in some fashion.

I would think that there could be synergistic effects, but it would seem that, unless Ed knows of something, that there isn't an interaction between UVB and chytrid (perhaps because UVB primarily affects larval amphibains and Chytrid primarily affects adult amphibians?).


----------



## Ed (Sep 19, 2004)

It depends on what you mean by affects.. chytrid does infect tadpoles and is reported to cause high mortality in metamorphs (see Froglife - latest information on Chytridiomycosis) but keep in mind that at least some species of anurans that bask (like American Bullfrogs) can be resistant to chytrid so I wouldn't link UV exposure to chytrid mortality unless its species specific and has been shown to be linked (and I think this is the text for the UVB pumilio/auratus article (http://oregonstate.edu/~blaustea/news articles/Frogs avoid damaging UV-B radiation.pdf) 

Ed


----------

