# How much does light effect the growth of "beneficial" bacteria?



## castle (26 Aug 2022)

Assume the  aquarium has a substrate of sand/gravel/botanicals. No plants, as the light may not be required 😉


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## Ria95 (27 Aug 2022)

This topic has been discussed here: Dr Timothy Hovanec's comments about Bacterial supplements
In my opinion, it's one of those things  that gets way overblown in theory with little application to actual aquarium keeping. Aquarium lights are of a reduced spectrum compared to sunlight ( most lack significant UV radiation) and have a  reduced intensity. If there really is no shade, biofilms will create some.


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## dw1305 (27 Aug 2022)

Hi all, 


Ria95 said:


> In my opinion, it's one of those things that gets way overblown in theory with little application to actual aquarium keeping. Aquarium lights are of a reduced spectrum compared to sunlight ( most lack significant UV radiation) and have a reduced intensity. If there really is no shade, biofilms will create some.


<"Same for me"> .

cheers Darrel


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## castle (27 Aug 2022)

Great, I’ll read the thread. 

 I’m looking at reducing light on my tanks down to something like a 2w led, I don’t expect to be able to grow any plants, and with that I’m trying to understand how I can best support these tanks stability. I don’t for example expect duckweed to grow 😅


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## John q (27 Aug 2022)

Bacteria will grow without light,  it will also grow with light. Not really sure what you're asking. 🤫


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## castle (27 Aug 2022)

thanks, yes, I know bacteria grows with or without light, I’m asking whether “it” grows better with light.


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## castle (27 Aug 2022)

So I don’t seem so silly, I appreciate there are probabaly billions of types of bacteria, and some will obviously be excellent with or without light. 

I guess this question is too vague, I don’t know what bacteria are good, nor could I grow them even if I wanted too 😂 what I wondered is whether there could be some that could help with aquarium stability and high grow better with some light than not. 

I’m going to guess light makes little difference in aquarium microbiome, thanks for helping me get to that conclusion.

I’m starting to willing to bet, some aquariums  probabaly have very different bacteria in them depending on their local water/owners etc.

Tbh, I’m not even sure these bacteria colonies are that stable anyway


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## Simon Cole (27 Aug 2022)

Yes, it will. In a biofilm, algae are the producers, and they provide organic molecules to consumers (bacteria and other microbes). They also remove nutrients from the water column. The biofilm provides a matrix (e.g. polysaccharides) supporting the microbial assemblage, allowing it to attach to hard surfaces. Sponge filters do trap flocculants, but they do not tend to form very much biofilm - perhaps because they are too dark to support algae (linked here).


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## Tim Harrison (27 Aug 2022)

Autotrophic Bacteria: Definition, Types, Examples and Importance
					

Autotrophic bacteria synthesize their own food using energy from light or inorganic chemical compounds. Learn about different types of Autotrophic Bacteria, at BYJU’S.




					byjus.com


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## dw1305 (28 Aug 2022)

Hi all, 


John q said:


> Bacteria will grow without light, it will also grow with light. Not really sure what you're asking.


The suggestion is that the bacteria involved in nitrification are light sensitive  and <"photoinhibition can limit nitrification">. You mention this in <"algae and algae spores in filter?">

It has been used as an argument for why only the filter bacteria count in nitrification, because the filter is the only place that is dark. 

It would be fair to say that I'm less than convinced by this as an argument, but unfortunately I've had a lot of correspondence (<"much of it fairly abusive">) telling me that it is one of the (many) reasons why plants are obviously irrelevant to nitrification and that they actually limit nitrification because plants need light and having a light inhibits bacterial nitrification.


castle said:


> I guess this question is too vague, I don’t know what bacteria are good, nor could I grow them even if I wanted too 😂 what I wondered is whether there could be some that could help with aquarium stability and high grow better with some light than not.





Simon Cole said:


> In a biofilm, algae are the producers, and they provide organic molecules to consumers (bacteria and other microbes). They also remove nutrients from the water column, and function to provide a matrix of polysaccharides supporting the microbial assemblage, allowing it to attach to hard surfaces.


What @Simon Cole says. I'd guess that you get a much more varied microbial community with added light, and as fair as I'm concerned <"diversity brings stability">. 

cheers Darrel


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## plantnoobdude (28 Aug 2022)

dw1305 said:


> Hi all,
> 
> The suggestion is that the bacteria involved in nitrification are light sensitive  and <"photoinhibition can limit nitrification">. You mention this in <"algae and algae spores in filter?">
> 
> ...


Obviously plants are relevant to nitrification. As for the light argument, wouldn’t much of the substrate not be exposed to any light… some people are a bit ridiculous😂


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## dw1305 (28 Aug 2022)

Hi all,





plantnoobdude said:


> Obviously plants are relevant to nitrification. As for the light argument, wouldn’t much of the substrate not be exposed to any light… some people are a bit ridiculous😂


You would be amazed, a lot of traditional  "fish keepers" are still very ill disposed towards plants.

Cheers Darrel


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## _Maq_ (28 Aug 2022)

Simon Cole said:


> In a biofilm, algae are the producers, and they provide organic molecules to consumers (bacteria and other microbes). They also remove nutrients from the water column, and function to provide a matrix of polysaccharides supporting the microbial assemblage, allowing it to attach to hard surfaces.


Actually, it's the other way round.
(1) First step - so called _conditioning film_. Organic substances with a tendency to seek phase interfaces (hard surfaces).
(2) Second step - solely bacterial _biofilm_. Bacteria create the polysaccharide matrix.
(3) Only after that benthic algae can develop. They have no roots to penetrate the surface. Naturally, not only algae but fungi, protozoa, etc. assemble in the biofilm and then contribute to its development.
[Learned from _Sigee - Freshwater microbiology_.]


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## FrankR (28 Aug 2022)

dw1305 said:


> Hi all,
> 
> The suggestion is that the bacteria involved in nitrification are light sensitive  and <"photoinhibition can limit nitrification">. You mention this in <"algae and algae spores in filter?">
> 
> ...


I've been reading about bacteria a few days ago. I might be wrong, but I thought the main reason that nitrifying bacteria grow faster in the filter is because of the filter media (porous media=more surface area). 
I also thought that nitrifying bacteria can be found everywhere in an aquarium system (rock, substrate, etc.). That's why the most important thing in a SW aquarium is the live rock. Because of all the bacteria and microorganisms on it.
Nitrifying bacteria are autotrophs, so it doesn't matter if there's light or not, right?


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## Simon Cole (29 Aug 2022)

Check out <this article> because it talks a bit about the impact of light on nitrifying bacteria and it was only published two months ago!


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## oreo57 (29 Aug 2022)

FrankR said:


> Nitrifying bacteria are autotrophs, so it doesn't matter if there's light or not, right?


Well it sort of matters.
Thing is it is actually quite complicated.
Even " which" nitrifiers one is referring to.
Marine or fw or soil..
Species ect.









						Light-Mediated Nitrite Accumulation during Denitrification by Pseudomonas sp. Strain JR12
					

The effect of light on the denitrifying characteristics of a nonphotosynthetic denitrifier, Pseudomonas sp. strain JR12, was examined. Already at low light intensities, nitrite accumulated as a result of light inhibition of nitrite but not of nitrate ...




					www.ncbi.nlm.nih.gov
				





			https://www.int-res.com/articles/ame/13/a013p233.pdf
		



			https://www.researchgate.net/publication/240303708_Photoinhibition_and_recovery_of_NH4-oxidizing_bacteria_and_NO2--oxidizing_bacteria
		


Rough draft.. more just fyi's

Fun calculator..


			Environmental Growth Chambers


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## dw1305 (29 Aug 2022)

Hi all,


Simon Cole said:


> Check out <this article> because it talks a bit about the impact of light on nitrifying bacteria and it was only published two months ago





> ........_The consortium of microalgae and nitrifying bacteria has attracted attention owing to its advantages, such as energy- and cost-efficiency in terms of using only light irradiation without aeration._ .......


That is an interesting paper. Forced aeration is one of the <"major costs in waste water treatment">, so there are financial benefits if you can just use light and microalgae <"to supply your oxygen">.


> The prime metric in nitrification isn't actually the ammonia concentration, it is the dissolved oxygen level. As you have water with greater amounts of organic pollution its Biochemical Oxygen Demand (BOD) increases, BOD values range from clean water at below 5 mg/l dissolved oxygen up to about 600 mg/L in raw sewage. Water is fully saturated with oxygen at about 10 mg/L, so you can see that you would need to continually add oxygen for nitrification to occur. Sewage works do this via the <"Activated Sludge"> process (below).


In nitrification <"dissolved oxygen is the parameter that really matters">, but it doesn't really matter <"how you top it up">.


FrankR said:


> I might be wrong, but I thought the main reason that nitrifying bacteria grow faster in the filter is because of the filter media (porous media=more surface area).


A bit of both really, a suitable environment and a constant flow of oxygen (and potentially ammonia) rich water. In nearly all cases microbial nitrification isn't restricted <"by lack of surface area">, it is restricted by lack of oxygen.


FrankR said:


> I also thought that nitrifying bacteria can be found everywhere in an aquarium system (rock, substrate, etc.). That's why the most important thing in a SW aquarium is the live rock. Because of all the bacteria and microorganisms on it.


They can. In a planted tank you have the rhizosphere, <"a zone of fluctuating REDOX values"> surrounding the growing root.  Roots are <"leaky structures">, sloughing off carbon rich cells and leaking oxygen and organic  compounds into the root zone.

Because we now know <"that nitrification"> (and I'd <"guess denitrification">) is carried out by a <"much greater range of organisms"> than the <"traditional view">.  I'm willing to bet that <"any established planted tank"> contains multiple sites where nitrification (and denitrification) occur, with the <"microbial assemblage fine tuned"> to the prevailing oxygen and fixed nitrogen supply.

I'd also wager that that the <"microbial assemblage"> will show a relatively quick response to changes in oxygen and ammonia levels.

cheers Darrel


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## _Maq_ (29 Aug 2022)

dw1305 said:


> I'm willing to bet that <"any established planted tank"> contains multiple sites where nitrification (and denitrification) occur, with the <"microbial assemblage fine tuned"> to the prevailing oxygen and fixed nitrogen supply.


Several years ago I conducted an experiment. It showed that nitrification initiated and run invariably with or without any filtration, just in silica sand. Now I'm running all my tanks without filtration (just with pumps to make water flowing and venturi to increase/maintain O2 and CO2 content) and I can clearly detect nitrification by measuring nitrogen directly or by pH move in response to dosing either ammonium (pH drop) or nitrates (pH rise).


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## towneeulalia (15 Oct 2022)

Light is not necessary for the growth of beneficial bacteria, as light can limit the growth of bacteria.


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## dw1305 (15 Oct 2022)

Hi all,


towneeulalia said:


> Light is not necessary for the growth of beneficial bacteria, as light can limit the growth of bacteria.


It depends how you define "beneficial", personally <"I'm keen on cyanobacteria">, but I understand that view isn't universal.

In terms of the organisms that <"actually oxidise ammonia">? <"I'd guess"> that they aren't all inhibited by light, and even if they are? It still doesn't matter, because they are going to be effectively shielded by the <"biofilms surrounding them">.

Cheers Darrel


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## MichaelJ (15 Oct 2022)

Our filters are mostly not exposed to any light and that seems to work out very well for the so-called beneficial bacteria. Same goes for the (same) bacteria that live in our substrate.  In nature by far most bacteria live in soil. That seems to suggest that light is definitely not a prerequisite.

Cheers,
Michael


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## jaypeecee (26 Nov 2022)

Hi @castle 

I'm not sure that I fully understand what is behind your question. But, it has been known for a long time that nitrifying bacteria are affected by light and this is spectrum-dependent. A good many papers address this topic. Here's one for starters:



			https://www.researchgate.net/publication/342483070_Influence_of_photoinhibition_on_nitrification_by_ammonia-oxidizing_microorganisms_in_aquatic_ecosystems
		


JPC


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## jaypeecee (26 Nov 2022)

castle said:


> I know bacteria grows with or without light, I’m asking whether “it” grows better with light.


Hi @castle 

OK, reading your posts again, you're obviously referring to nitrifying bacteria. So, the paper that I attached is applicable - not only to AOB* but also AOA**

*AOB = Ammonia-Oxidizing Bacteria

**AOA = Ammonia-Oxidizing Archaea

JPC


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