Gram positive vs. gram negative bacteria

[plyr58]

It has been explained to me that using Maracyn is an effective means to control undesireable bacteria in a reef tank because the erythromyacin in Maracyn targets gram negative bacteria (such as Cyanobacteria) but not the gram positive nitirifying bacterias in the tank will not be affected. Putting aside the whole "don't put anything in the reef" mantra, is this an accurate statement? Are denitrifying bacterias gram positive or gram negative?

 

[plyr58]

no takers?

 

[bertoni]

I don't think we know which bacterial species are involved, and it's likely to be a guild that varies somewhat from tank to tank. That said, Maracyn isn't going to harm a biological filter. I still wouldn't use it in a reef tank, personally, because it might affect other organisms. The preferred way to dose is a hospital tank with a sponge or HOB filter.

 

[toaster77]

I believe there are many species of bacteria that can reduce nitrates under anaerobic environments both gram negative and gram positive. The question is, what species are present in your tank? A quick glance shows that many denitrificans species are actually gram-negative - however my hunch is that there are some gram positive species that can do denitrification as well, but it all depends on which species are in your tank and that is tough to figure out.

 

[yraveh]

Erythro in human is anti gram positive like strep group a (S. pyogenes)

 

[MCsaxmaster]

Erythromycin has fairly broad effects. It kills most gram-positive and some gram-negative bacteria. Some gram-positive (e.g., Micrococcus denitrificans) and gram-negative (e.g., Pseudomonas) have been implicated in dentrification.

Keep in mind, however, that only a very few kinds of bacteria can perform denitrification. Most bacteria do not and cannot perform denitrification, regardless of environment, just as a hammer cannot be used to do word processing. The metabolic pathways simply aren't there to be used. Some denitrifying bacteria may be relatively immune to erythromycin while others are likely sensitive to it.

 

[billsreef]

Bad idea for several reasons. One is the possiblity of making antibiotic resistant strains. The other is, it is like using a 12ga shotgun to kill a mouse in your kitchen. There is going to be undesirable collateral damage.

 

[Icefire]

I used Erythromicin for cyano and it was very effective with no cycle whatso ever.

It kill most positive and some negative but not the good one in low dose.

 

[plyr58]

Other than the possible negative affect on any gram negative nitrifying or de-nitrifying bacteria in the system, what other effect could a broad spectrum antibiotic have on a reef tank? I can't really see it having a negative impact on coral health, etc. I am just wondering here. I understand not using antibiotics if you don't have to from a drug resistant bacteria perspective, but this seems highly unlikely to have a large impact on a closed system like an aquarium.

 

[MCsaxmaster]

<a href=showthread.php?s=&postid=14185060#post14185060 target=_blank>Originally posted</a> by plyr58
Other than the possible negative affect on any gram negative nitrifying or de-nitrifying bacteria in the system, what other effect could a broad spectrum antibiotic have on a reef tank? I can't really see it having a negative impact on coral health, etc. I am just wondering here. I understand not using antibiotics if you don't have to from a drug resistant bacteria perspective, but this seems highly unlikely to have a large impact on a closed system like an aquarium.

In the last several years we have started to become accutely aware that the microbial flora on coral surface layers is absolutely critical to their good health. Healthy corals have very particular (perhaps species specific) guilds of microbes, and those guilds change in diseased corals. We haven't even begun to scratch the surface of other microbially mediated interactions on reefs.

Haphazard use of antibiotics in a reef tank is a bit like indiscriminate spraying of herbicides to kill a weed in the middle of a rose garden. There very well may be collateral damage associated with that

 

[billsreef]

Antibiotics, erythomyacin or otherwise, just can't distinguish between good and bad bacteria. The best they can distinguish is between gram positive and gram negative, and that differential has absolutely nothing to do with good and bad, just cell wall structure.

 

[OwenInAZ]

<a href=showthread.php?s=&postid=14190301#post14190301 target=_blank>Originally posted</a> by billsreef
Antibiotics, erythomyacin or otherwise, just can't distinguish between good and bad bacteria. The best they can distinguish is between gram positive and gram negative, and that differential has absolutely nothing to do with good and bad, just cell wall structure.

While this is a little broad, it points more or less in the right direction.

Think of each antibiotic as targeting a specific cellular function. For example, Erythromycin binds to the bacterial ribosome and prevents protein production, regardless of species. The difference in sensitivity lies in the antibiotic's ability to penetrate through the envelope and into the cytosol of the bacterium. I'm not convinced the structure of the cell wall itself has much to do with resistance, since on a molecular scale it has huge gaps to allow proteins to pass through. The discerning factor is, IMO, going to be the composition of the cell membrane, and the presence/abscence of any efflux machinery capable of pumping the antibiotic back out. That's not the thrust of your question though, it seems to me.

The very health of a reef tank, much like the health of a human body, depends entirely on the health of its microbial population. A broad spectrum antibiotic is likely to kill off more than just what we don't want, i.e. cyano. A better solution to that sort of problem is to attack the conditions which allowed it to thrive in the first place -- excess nutrients, insufficient flow, poor lighting, etc.

 

[toaster77]

<a href=showthread.php?s=&postid=14190915#post14190915 target=_blank>Originally posted</a> by OwenInAZ
While this is a little broad, it points more or less in the right direction.

Think of each antibiotic as targeting a specific cellular function. For example, Erythromycin binds to the bacterial ribosome and prevents protein production, regardless of species. The difference in sensitivity lies in the antibiotic's ability to penetrate through the envelope and into the cytosol of the bacterium. I'm not convinced the structure of the cell wall itself has much to do with resistance, since on a molecular scale it has huge gaps to allow proteins to pass through. The discerning factor is, IMO, going to be the composition of the cell membrane, and the presence/abscence of any efflux machinery capable of pumping the antibiotic back out. That's not the thrust of your question though, it seems to me.

The very health of a reef tank, much like the health of a human body, depends entirely on the health of its microbial population. A broad spectrum antibiotic is likely to kill off more than just what we don't want, i.e. cyano. A better solution to that sort of problem is to attack the conditions which allowed it to thrive in the first place -- excess nutrients, insufficient flow, poor lighting, etc.

well put!

 

[billsreef]

Now your really getting into the nitty gritty

 

[plyr58]

Thanks for the explanations guys. It was exactly what I was looking for. I (luckily) have never had a cyano problem in one of my tanks. I also tend towards the thrust of Owens postin all such issues of pest algaes/bacterias, in that the proper answer is fixing the conditions that led to the problem rather than temporarily removing the symptom. I have heard that erythromyacin was an effective treatment for cyano that had no negative effects on the system as a whole and wanted to find out from those of you who are infinitely more schooled about biology at a cellular level than I. Thanks for the information!

 

[OwenInAZ]

<a href=showthread.php?s=&postid=14191995#post14191995 target=_blank>Originally posted</a> by billsreef
Now your really getting into the nitty gritty

LOL that's sort of my jorb I passed my comps a while back, hopefully I haven't lost too much since then, because I'll have to defend sooner or later

Glad I and others could be of help!