Hi, and thank you! All I know is that we provide our own
R. palustris to them (BW), and that our cultures make up a mere portion of the blend in that product. They declined my offer to assist in developing Purple M in favor of keeping its contents strictly secret (fair enough). That includes, by the way, all production and packaging procedures, which certainly are also important.
For example, the characteristic PNSB culture odors, which are for the most part derived from sulfides, may be removed through various abiotic treatments (least harmful of these to the PNSB is aeration, excluding a couple options that would be unfeasible in terms of production cost). There are some biotic means of odor mitigation that might serve that purpose, such as the use of antibiotics to specifically target sulfate-reducing bacteria hitchhikers in the inoculum. If they’ve developed a process to remove these and other malodorous compounds without compromising the efficacy of the PNSB or using any undesirable additives, I applaud the achievement. But I speculate along with the rest of you.
With respect to PO4 control, the overall best choice will be the product that provides the highest density of viable
polyphosphate accumulating bacteria (or, I guess, much larger doses of a low-density alternative). In all the products discussed here, this will be restricted practically to PNSB. Not all PNSB species perform polyphosphate accumulation (PA); all three PNSB species
listed in PNS ProBio can perform PA. One interesting aspect about density…Be cautious of the color you’re seeing. I’m admittedly only judging from a product image, but from the picture of one product made overseas, my reasonably well-trained eye suggests that it may have had dyes added (seriously! haha). More recently, two individuals I know, who are pretty familiar with PNSB, have both expressed similar suspicions to me about yet another product. Might sound crazy, but we’ve unfortunately seen worse in our hobby/industry before.
There may be some other considerations here. Think also about the contribution of rest media (i.e., the left over culture medium, including wastes). Imbalanced growth media can leave substantial quantities of undesirable substances behind in the finished product, including DOM, trace elements, and certainly nutrients. Phosphorus in particular is commonly overdosed in lab recipes in order to maximize cell density, without any regard for residual PO4. So, someone sourcing their live cultures from a lab supply to include in an aquarium product--especially one that is nominally formulated to control nutrients--is truly concocting a self-defeating potion haha. Same with anyone using excessively rich media to push cell density. But wait, there's more…
In addition to illuminated/anaerobic conditions and long incubation periods (stationary growth phase), phosphorus starvation is necessary to induce PA in PNSB. MEANING if you obtain a crap product from an inexperienced cultivator, you’re not only potentially adding PO4 to your system, but (perhaps even more importantly)
the capacity of those bacteria to sequester PO4 has gone from extraordinary to ordinary. That latter point is especially compelling when you consider that
R. palustris, for example, when grown under the appropriate conditions, can accumulate phosphorus up to 13%-15% of its cell dry weight (!).
In sum, the best microbial product for PO4 management in aquaria, in my opinion, is the one that:
- Contains PNSB species that are known to be capable of polyphosphate accumulation.
- Contains a multi-species consortium of PNSB (enhanced ability to occupy multiple niches within the aquarium environment), thereby enhancing/prolonging nutrient sequestration.
- Features the highest density of viable PNSB cells–more living cells remove more phosphate, dead cells remove no phosphate.
- Is optimized for health and viability of PNSB (e.g., rich in endogenous energy stores such as polyhydroxybutyrate)--more robust cells are more capable of surviving the abrupt transition to an aquarium environment, and more living cells remove more phosphate.
- Is produced under a specific set of conditions (e.g., phosphorus starvation) that together promote production of kinases responsible for triggering polyphosphate accumulation.
- Does NOT contain excess phosphorus in the rest medium.
These are points that I list as important, from my perspective, for this
specific application. They’re not meant to insinuate that any particular product is better than another. I’ll leave it to the consumer to draw their own conclusions after objectively evaluating the performance of our products alongside those of our collaborators, competitors and copycats.
But I do hope this leaves you feeling considerably better informed. Thanks for reaching out, and thanks again for your awesome support!
You're welcome! I'm really not in a position to say pigments are or aren't being used. I'm just posting my observations 
.
, and I plan on putting that under the scope as well. Who knows what I'll see.
