Anaerobic Digester & Cynobacteria

[Subsea]

As a marine engineering student in 1970, a favorite technical elective was Oceaneering, with a focus on “dynamic equilibrium”. It was during these early years that I started my first marine tank as I collected in the Galveston Bay estuaries.

How Does Anaerobic Digestion Work? | US EPA

Describes the anaerobic digestion process and the benefits of anaerobic digestion. Anaerobic digestion is the process through which bacteria break down organic matter without oxygen.

www.epa.gov

Many years later, as a municipal waste water superintendent, I witnessed the power of reduction chemistry microbes in an anaerobic digester.

As I thought on these things, I realized that a cynobacteria mat does these things and I recalled an article written by @Randy Holmes-Farley on how cynobacteria create the chemistry to dissolve bound phosphate in sediments by using a feedback loop to monitor the chemistry. At that time, I was an instrumentation engineer in deep water drilling and I thought that it was marvelous that bacteria could adjust the environment around them
(gene expression).

Some years later, at a lull in reefkeeping maintenance, a severe Cynobacteria mat covered everything. While reversing the process on a yellow ball sponge that was completely covered in dark burgundy, I peeled off thick mat to reveal the bright yellow of a Yellow Ball sponge. However, it was less than 50% of its original size.

My takeaway from this was that Cynobacteria mats generate chemistry that assimilates inorganic phosphate and organic sponge biomass.

 

[Rocks reef]

This is very intriguing. I would like to hear what Randy has to say about this. Also, @Lasse will probably have some interesting discussion to add.

 

[Subsea]

Yes, Lassie & I both have municipal waste water backgrounds. We have discussed other things, but not this, yet.

AI says:
many species of cyanobacteria can assimilate both inorganic and organic compounds to support their growth, depending on environmental conditions.

Inorganic Assimilation
As photoautotrophs, cyanobacteria primarily use light energy to assimilate inorganic carbon, specifically carbon dioxide (CO2) and bicarbonate(HCO3−), through photosynthesis. This process converts low-energy inorganic molecules into high-energy organic compounds (carbohydrates) for cellular growth. They also assimilate inorganic nitrogen sources like ammonium (NH4+), nitrate (NO3−), and nitrite (NO2−), and some species can even fix atmospheric nitrogen gas (N2) into usable forms. Inorganic phosphorus, primarily phosphate (Pi), is also actively taken up.

Organic Assimilation
Under certain conditions, such as nutrient limitation or in darkness, many cyanobacteria can utilize organic compounds. This metabolic flexibility is known as mixotrophy or heterotrophy.

• Carbon sources: Common organic carbon sources include simple sugars like glucose, fructose, and sucrose, as well as glycerol.
• Nitrogen sources: They can assimilate simple organic nitrogen compounds like amino acids and urea.
• Phosphorus sources: When inorganic phosphate is scarce, cyanobacteria can produce extracellular and intracellular enzymes (like alkaline phosphatases) to break down dissolved organic phosphorus (DOP) compounds, such as phosphoesters and phosphonates, to acquire essential phosphorus.

This metabolic adaptability allows cyanobacteria to thrive in a wide range of diverse environments, from pristine oligotrophic oceans to nutrient-rich freshwater systems.

 

[Randy Holmes-Farley]

I have no doubt the sponge suffered greatly in terms of filtering seawater and thus getting food when covered with cyano. I'm sure that when it slowly died back, the cyano was happy to get the nutrients released under it. :)

 

[Subsea]

I have no doubt the sponge suffered greatly in terms of filtering seawater and thus getting food when covered with cyano. I'm sure that when it slowly died back, the cyano was happy to get the nutrients released under it. :)

To that sponges credit, it survived and grew back and that was 2 years ago.

 

[Subsea]

“This metabolic adaptability allows cyanobacteria to thrive in a wide range of diverse environments, from pristine oligotrophic oceans to nutrient-rich freshwater systems.”

After reading many recent threads on cyano invasion, hobbiest should understand how adaptable Cynobacteria is. If it were not for blue/green cynobacteria, Earths early athmosphere of methane & sulfur would have never evolved to 21% O2.

Even in a pristine reef tank, Cyanobacteria can thrive.

“Cyanobacteria are a group of autotrophic gram-negative bacteria of the phylum Cyanobacteriota that can obtain biological energy via oxygenic photosynthesis. The name "cyanobacteria" refers to their bluish green color, which forms the basis of cyanobacteria's informal common name, blue-green algae. Wikipedia
Scientific name: Cyanobacteriota
Rank: Phylum”