Purple Non Sulphur Bacteria - PNSB

[Eatfrenchfries]

Going 1000x smaller  into the culture expansion has been quite the ride. Every success met with several failures as the purple bacteria is slow to culture leaving it prone to contamination despite all the hoops in place. 

What is Purple Non Sulphur Bacteria?

Bacteria that use light to convert carbon sources into food. PNSB differ from nitrifying bacteria that inhabit live rock and DSB since they can use photosynthesis. Purple/green bacteria uses hydrogen and sulfide to convert carbon while PNSB prefers not to use O2 if there is a choice . Often associated with detritus or sludge eating bacteria. 

Why PNSB?

-metabolically diverse (chemoheterotroph, photoheterotroph, photoautotroph) enables them to function in places where others may not

-a form of organic carbon dosing that sources organic compounds already built up within aquaria 

 -improve water quality by uptake nitrite, nitrate, ammonia and organic compounds which can accelerate the cycling process 

-food for bacterivores (coral, NPS, zooplankton)  coming in between 600 - 1000 nanometers ( 0.6 - 1 micron)

-depending on growth condition can be influenced to be rich in red pigments (aerobic vs anaerobic)  

-used in waste water treatment, improving soil quality, large scale aquaculture (shrimp)

-compounds consumed and secreted fuel plant growth 

 

Why do you culture PNSB?

Simply put. I enjoy culture work. But in truth it has to do with keeping macroalgae long term. Maintaining a reef tank is no simple task and it can vary greatly on what the goal is. Not to get into all the problems of growing macro but the worst has to be Old Tank Syndrome (OTS) regarding built up organics (indigestible plant matter, yellowing from terpenes, plants going through seasons, residual traces).  Regular cleaning maintenance + propagating smaller cuttings only goes so far without having to sterilize the tank every so often to reset the balance in maintaining #s. Organics can be hard to keep track of long term and an imbalance could be the reason cyanobacteria/dinoflagellates smothers all your photosynthetics. 

PNSB methodology

-These bacteria are quite special in marine aquaria since their ideal environment involves low dissolved oxygen but high light. This would place it deep enough in the layers of sand without O2 but shallow to still receive light. A perfect spot to tackle organic waste in built up as mulm but also close to other microbes (good or bad) leading to competition for organics (good). Some of these other microbes can produce harmful substances such as hydrogen sulfide. 

-PNSB need light but will shy away from oxygen to maintain their ideal mode of fixation. They need to adapt to drastic lighting changes because of this naturally in the water column, The bacteria contain special pigments called bacteriochlorophyll that can operate at higher wave lengths of 740 - 925nm versus plant chlorophyll which absorbs 660 - 680nm. Able to handle fast lighting changes. 

-the organic carbon gets tackled PNSB in a much more pleasant way without depleting O2 like heterotrophs. This keeps tank inhabitants healthy and a steady supply of nutrients to fuel algae growth (coral, macro, cryptic) 

What PNSB strains do you work with?

-Rhodobacter capsulatus: found in muddy, stagnant, nutrient rich waters. Primarily in freshwater but does have some tolerance in saltwater. One of the first strains to be cultivated and produced on a larger scale for study. In the absence of oxygen it will be brown in culture but in aquaria it can appear red in the water column. 

-Rhodospirillum rubrum: found in rivers, streams, marshes, stagnant, and used in waste treatment facilities. Its tolerance to salt is related to its method of nitrogen fixation. It will grow in a tropical environment shying away from oxygen but maintain contact with light. If dissolved oxygen is high then it will produce at a reduced rate to keep from building O2 and appear colorless. The red pigments will build in low O2. 

-Rhodobacter sphaeroides: found in deep lakes and stagnant waters. Compounds sequestered are believed to be essential in plant growing hormones.  Produced largely for use in waste water treatment. It doesn't really have a preference and loves to tackle any situation.

*will provide more details after getting some testing done and maybe some more expansion work. Time is the limiting factor for me. 

.......................

For those of you who have been helping me test this. I appreciate your contributions greatly. Your feedback is critical in further understanding PNSB use in marine aquaria. 

-a couple people have told me it got rid of their cyano problems

-skimmers having increased output

-one reefer had success administering PNSB to fuel xenia growth enough to export for phosphate. (no baseline here so hard to say what happened but they were happy with the result so I'll take it)

-several have mentioned steady deductions in nutrient values but this could also be from them upping efforts in other areas. 

-adding phyto and PNSB seems to reduce time between glass cleaning (personal observation in my tanks)

-adding PNSB to zooplankton cultures is ill advised if they do not have access to substantial light to trigger the bacteria. If not the bloom will be too dense among the detritus reducing space for pods to grow, capping their population/growth size. 

-No more yellow water in water changes 

Edited June 11, 2023 by Eatfrenchfries

[Lexinverts]

I'm one of those people trying out PNS bacteria dosing on my tanks. It's too early to tell if it doing anything, but I am excited about the possibilities. Thanks, Sharokh!

[obrien.david.j]

I'm also one of those people trying out PNS.   I'm a believer in diversity.   Still too early for me to judge, but a few corals are sprouting when they hadn't for the past few months.   Causation or Correlation, can't tell.

 

 

[LadAShark]

I have two cultures both a mix of rhodobacter spheroides and rhodopsuedomonas palustris. I've had some success with them when I was dosing more regularly, but time will tell. Sps was growing really well and stopped and took a turn a while after I stopped dosing, so I do wonder if there is a correlation. 
 

Something that I do with my cultures and also my reef is I supplement B vitamins. Rhodopsuedomonas (and maybe other pnsb) are limited by various B vitamins and it seems to help keep them going. 
 

P.s: have been meaning to ask about acquiring some cultures and some macro from you, but haven't had the time. Will shoot you a pm when I do. 

Edited June 12, 2023 by LadAShark

[Eatfrenchfries]

Day 14/28 for Rhodobacter s. 

-yellow is the color of the enrichment media with b vitamins, microalgae trace, pasteurized copepod molts (chitin) + phytoplankton cells (cellulose)

 

Day 22/28

-8 days for the bacteria to consume and fill the entire culture vessel. 

-greenish white snot is a layer of dead Phyto/Pods in my bulk grow out

-rusty film strip on the right is a PNSB film that developed roughly around the same time I was due to clean the container out

-reduced turbidity could be from the bacteria taking it into the biofilm 

-pods fed a mixture of PNSB + Phyto

-no worry about disturbing the anoxic mulm layer because the PNSB won't suck the remaining oxygen out of the water while still recycling the mulm for future pod food 

-terrible picture of PNSB colonizing glass in a refugium lit by T5s 

-biofilm established on glass because I lack a sand bed. It will find a niche to survive or create it's own. 

-the film does not spread onto living organisms. It will only take unoccupied real estate and can be eaten by CUC

-biofilm is important as it represents not just PNSB colonization but the archaea that come with it. 

[Eatfrenchfries]

(picture of nematodes because the actual video makes me squeamish)

Sifting through established PNSB mats in my tank has shown an unusually high amount of nematodes. My zooplankton culture vessels show some nematodes but surprisingly dileptus in number as well. Dileptus are cool predators but indiscriminate of prey. 

*personal observation* copepods prey on motile daughter cells, nematodes remain amongst nonmotile mother cells. Snails consume, Fish that are detritivores (lawnmower, ctenochaetus), Cucumber actively eats bacteria. 

It seems the consistency of dosing micro fauna (bacteria) has "brought forth" my meiofauna community. The nematodes feed on bacteria/detritus and oxygenate the microbiome. Organic matter is either recycled by the benthos to be used again or buried to be worked on over various cycles. 

 

*skimmerless systems appear to form biofilm. Manual removal required. Highly advised to use skimmer for ease of maintenance *

 

(PNSB concentrated in dropper form. estimated to treat 3000gallons. currently running trials.)