The Return of (Vastly Improved!) PNS ProBio™

Updated: Mar 19

Not so long ago, when Hydrospace first opened for business, we proudly declared that we “continuously strive to increase the quality, rather than sheer size, of our product line.” Our flagship product, PNS ProBio™, which may be used in both freshwater and marine aquarium/aquaponic systems, was most popular from the start. Reports from users have been quite satisfactory. However, our users did indeed bring to attention one unmistakable aspect of the original product (as well as its companion product PNS YelloSno™); it stunk to high hell.


These decidedly bad smells largely came from decomposed yeast extract lurking within. Yeast extract is routinely included in culture media for purple nonsulfur bacteria (PNSB), as it is rich in certain “biofactors” (primarily B vitamins) that are required by, but not synthesized by, the microbes. For a dedicated microbiologist in a laboratory, these odors might just be an easily tolerable part of sciencing. For the average home aquarist, on the other hand, they seem to cause some discomfort to say the least.



Now, we can say that we warned you (remember the cautionary description of this stench as a “combination of flatulence and death?”). Though it lingered for a spell, it generally dissipated fairly quickly. But hey, straight from the shoulder, it was pretty nasty. One of our testers reported that after accidentally adding “a crapload” to her home aquarium system she had to leave the house for some time, adding somewhat jokingly that she had “never experienced anything quite like it.”  


She was only the second tester to get chased out of their home by our original formula.


All jokes aside (for now), the odor issue became much more pressing to us after reviewing some third-party customer feedback. On one prominent reef aquarium forum, a YelloSno™ user submitted that while the product did indeed appear to improve the condition of his SPS corals, he described our warning May cause strong odors! as the “understatement of the century.” We took a hard second look--even ceased production of both PNS products--and immediately began searching for a less abominable alternative.


Turns out the solution had been right under our noses all along.



Since 2017, we have involved ourselves (alongside City of Boulder Open Spaces & Mountain Parks) in efforts to eradicate the invasive Eurasian watermilfoil (Myriophyllum spicatum) from heavily infested sites along locally beloved Boulder Creek. One of our primary interests in this endeavor has always been to discover and develop agricultural uses for the harvested material (as opposed to throwing it in the local landfill).


From the beginning, we were particularly interested in the plant’s exceptionally high content of allelopathic polyphenolics. Seriously… This plant makes crazy amounts of the stuff. Like up to 10% of its dry weight sort of crazy. Of these substances, the most abundant and notable is Tellimagrandin II (TGII). This somewhat rare tannin (also found in cloves (Syzygium aromaticum)) is quite versatile in its noxiousness. Undoubtedly, EWM owes much of its invasiveness to the copious production of TGII, which not only deters herbivory but also inhibits the growth of competing unicellular photoautotrophs (especially cyanobacteria).


Initially, we were interested in studying the algicidal properties of TGII. Let’s just say that we have lots of interests. But we only have so much time. For us, in this case, it meant a few bottles of EWM-TGII extract abandoned amidst a mess of items on the table. For days, maybe weeks, those bottles just sat there. Within reach of the Sun’s intense afternoon rays... Eventually, the samples bottled at room temperature (i.e. not pasteurized) began to change wonderfully. The fluid, once greenish-yellow like a light herbal tea, quite suddenly became peachy pink in color. A very likely purple bacterium!


As subsequent research would reveal, PNSB absolutely love living as epiphytes on aquatic plants. Specifically, they consume organic waste products that are secreted by the plant. And the plants love them back. Proficient diazotrophs, PNSB fertilize host plants with their surpluses of fixed nitrogen (much like they do for zooxanthellate corals).


So, it wasn’t all that surprising to have inadvertently cultured a probable purple bacterium in this way--maybe even R. palustris, which is known to grow epiphytically on M. spicatum. But we had little means of conclusively identifying the microbe, at least in the instant. We continued to culture the unidentified species, which consistently grew well on 100% pure wildcrafted EWM tea. That is, without the addition of biofactors!



Our initial assumption was that the organism subsisted in the absence of exogenous growth factors--something only a couple PNSB species are capable of! However, as we played with the mystery microbe, we came to suspect that the plant’s extracts might actually contain all of the microbe’s requisite building blocks, including requisite biofactors (B vitamins). And if good for growth of this species, then maybe also for the purple bacterium in ProBio™ and YelloSno™, Rhodopseudomonas palustris


A bit of googling revealed that M. spicatum does indeed contain considerable amounts of both B1 and B2; in fact, studies suggest that all growth factors of the vitamin "B complex" of the B and G adsorbates are normally present in this plant.

Duh, right? To our credit, we did test growth of R. palustris on EWM extract months earlier. We got none. Ever. Because we did not yet understand the impact of pH/carbonate hardness on this species’ productivity (particularly with this medium), our early investigations yielded only poor results.


But you know what they say about necessity and invention. And we needed to improve the smell of the PNS products in a big way. With some (a lot of) trials and tinkering, we were eventually growing R. palustris exclusively on EWM extracts--and growing it like never before! Cultures were of an even higher quality, cell-dense and rich in carotenoids.


You might be wondering about harmful residues--stuff left over from the Tellimagrandin II. No worries! As yet more research revealed (we like researching things), R. palustris eats polyphenols for breakfast. In actual fact, it is regarded by bioengineers as a model among the few organisms that consume these compounds. In testing, we applied quadruple overdoses of the new ProBio™ without a whisper of complaint from fish, shrimp, SPS and LPS corals, soft corals and zoanthids (if anything, the corals seemed to like it). Sweet!


And the odor? Surprisingly tolerable! Light, earthy and just slightly tart, it is a far cry from the powerful, stomach-turning stink of the original formula. Now, if any odors are even evident after normal use, they disappear almost immediately. Truthfully, we are more excited about and proud of this product than ever before. And not just because it is rich and gorgeous.


We estimate that every 16.9 fluid ounce bottle of the new-and-infinitely-improved PNS ProBio™ calls for the annihilation of half a kilo of live, wild, non-native, totally evil Eurasian watermilfoil. In other words, this product can now boast of a significant net-positive environmental impact!



PNS YelloSno™ has recently undergone a similar redevelopment.



But what of the mystery microbe? An ID is still pending. Sample cultures are in the process of being purified, analyzed and ultimately identified at the University of Hyderabad, India under the direction of a rock star in the world of microbiology, Dr. (Mrs.). Ch. Sasikala of the Bacterial Discovery Laboratory. Once ID'd, will this bacterium (our very own strain!) find itself in a new Hydrospace product? Probable. Right now, we’re just taking a breather from the ongoing task of improving PNS ProBio™ in particular and our small product line in general. Our nostrils certainly are enjoying the respite!