This sponsored post has been published in partnership with Hydrosome Labs, a Chicago-based firm specializing in the production of ultrafine bubbles.
Ultrafine bubbles—bubbles so small you can fit a trillion of them in a single Champagne bubble—exhibit radically different properties to bubbles visible to the human eye, unlocking an intriguing set of novel applications in everything from functional beverages to high-end cosmetics.
As for their potential to drive more efficient biomass and precision fermentation, meanwhile, we’re barely scratching the surface, says Chicago-based Hydrosome Labs, which has recently conducted RNA sequencing on E. coli strains that provides fresh insight into what is happening to cells exposed to its tiny bubbles.
It stands to reason that bubbles with neutral buoyancy (they don’t float), a strong negative surface charge that attracts nutrients, and a high surface area to volume ratio, can deliver more efficient gas and nutrient transfer to cells in a fermentation tank, says SVP and principal scientist Dr. Nick Jackowetz.
However, new RNA sequencing work on gene expression during the aerobic growth of E.coli exposed to Hydrosome Labs’ ultrafine bubbles in a 400-liter bioreactor further explains why companies that have tested them are seeing significantly faster doubling rates, increased peak cell biomass from the same amount of feedstock, reduced fermentation times, and higher titers, says Jackowetz.
“We found distinct genetic differences between cells exposed to ultrafine bubbles and the control, which suggests that the presence of ultrafine bubbles is causing E. coli to adapt its metabolism.”
Ultrafine bubbles help cells do more with less
Notably, says Jackowetz, the bacteria appear to be “shifting towards more efficient carbon utilization pathways,” which helps to explain why they can do more with less.
“Cells exposed to ultrafine bubbles exhibited genetic changes indicative of enhanced nutrient and oxygen availability, increased transport activity, and alterations in stress response pathways.”
Oxygen availability to cells is especially significant, he adds: “Typically in an aerobic fermentation, oxygen is a bottleneck; the cells are growing, but the limiting factor is oxygen. If you can nudge that in a positive direction [by upregulating genes involved in oxygen utilization and energy production with ultrafine bubbles], you can improve cellular metabolic efficiency and overall performance.”
That said, he stresses, “We’re still working on that mechanistic understanding, and it’s an open question in the field of ultrafine bubbles. But our understanding at this point is that we’re getting better mass transfer, better oxygen transfer, and that really drives a lot of what we see.”
While more research is needed to confirm these effects across different cell types and fermentation conditions, he cautions, the findings suggest ultrafine bubbles can optimize fermentation processes through meaningful improvements in metabolic efficiency in cells.
And this, says Hydrosome Labs president Bob Jacobs, is “pretty exciting,” given that most strategies to increase fermentation efficiency via strain engineering or improved downstream processing tend to deliver “only incremental improvements.”
“Ultrafine bubbles have a negative charge on the outside and they attract water soluble nutrients to their surface. As the surface area of these bubbles in solution is huge, that has an incredible compounding effect on the surface area that’s available to deliver nutrients to cells.
“When our bubbles [which are under 100 nanometers across] encounter a cell, the cell recognizes those nutrients that are outside the cell and brings them in. We believe that includes the gases that are inside the bubble as well, but there’s ongoing research to determine exactly what’s being transferred across the cell membrane.” Bob Jacobs, president, Hydrosome Labs
More efficient use of carbon
Testing with E.coli strains at the Integrated Bioprocessing Research Laboratory (IBRL) at the University of Illinois Urbana-Champaign has shown that substituting regular water with water containing ultrafine bubbles can boost cell doubling rates 2x, increase peak cell biomass 2x, and reduce fermentation time by 25%, which translates to higher yields and lower costs, says Jackowetz.
“But we’ve also seen great results with yeasts such as Pichia pastoris and Saccharomyces” and strains of filamentous fungi. The movement of carbon through the cell seems to be more directed at biomass production than making other secondary metabolites that would divert carbon away from biomass.”
“There is a shorter lag phase, so the fermentation gets started more quickly, and then once it gets going, we see a faster doubling time, and then at the peak phase, we see the biomass level is significantly higher, with the same amount of feedstock.” Dr. Nick Jackowetz, principal scientist, Hydrosome Labs
Cell-friendly bubble creation
So how does Hydrosome Labs’ tech compare to that of other players creating tiny bubbles such as Moleaer? And if the benefits are so clear in biomanufacturing, why isn’t the tech widespread?
According to Jacobs, two things stand out about Hydrosome Labs’ tech in this respect. First, its bubbles are smaller than other players’, increasing their stability and shelf-life. Second, its patented production method doesn’t damage cells.
“Some players in this space use higher shear forces to create their bubbles, which can damage the cells, whereas we use a gentler process called hydrodynamic cavitation,” he explains. “We’re essentially spinning the water and creating a vacuum inside of our unit [which would be leased to biomanufacturing companies]. When the water exits our device, that cavitation core vacuum is disrupted, and that’s what creates trillions of ultrafine bubbles.
“This means we can pass that liquid fermentation media, cells and all, right through our process and create the bubbles without damaging the cells.”
If companies are doing a fed batch fermentation and already recirculating their solution through some kind of a pump system and putting it back into the bioreactor, Hydrosome Labs’ technology can “easily hook up to that recirculation loop and add bubbles as that media is being recirculated in the tank,” he says.
“But we can also work with companies using batch fermentation processes. Here our technology can bolt on to the end of their reverse osmosis system [which purifies water before it’s used in the fermentation], feed bubbles into the water, and then into their batch. Basically, we’ve designed our technology in such a way that it can be retrofitted to just about any fermentation system out there. It’s plug and play.”
For proof-of-concept work, says Jackowetz: “We have internal microbiology capabilities, so we do things at bench scale in shaker flasks and in 100-liter bioreactors. We can also ship water to clients that has ultrafine bubbles in it so they can do some initial testing.”
According to Jacobs: “If they see good results with that, we have test units that we can ship to a partner, and they can hook it up to their fermenters and pilot it.”
Functional beverages, skincare, and a novel path to sugar reduction?
While other players in the nanobubbles space are focused on wastewater treatment and indoor agriculture, where tiny bubbles can deliver better nutrient absorption and higher yields, Hydrosome Labs is focused on “white spaces” where other companies have not yet ventured such as fermentation, functional beverages, and skincare.
It has already commercialized its tech in cosmetics via the Cindy Crawford ‘Meaningful Beauty’ range, in which its ultrafine bubbles are claimed to increase uptake of its bioactive ingredients, and is currently talking to several firms in the beverages space to explore how its tiny bubbles can deliver superior hydration and absorption of nutrients from collagen to vitamins, minerals, and electrolytes.
However, one of the most intriguing areas of exploration is sugar reduction, says Jackowetz.
“When we first started drinking water with ultrafine bubbles, we noticed it had a different taste; a slight cooling effect, so we sent the water to Ohio State University and had them do a sensory panel that backed this up. Then we thought, what if we don’t just load these bubbles with air, but with some other gas such as nitrous oxide [laughing gas]? What’s interesting about nitrous oxide [which is used in the food industry as a propellant in whipped creams] is that when it’s dissolved in water, it has a sweet taste.”
Unsurprisingly, given the intense focus on sugar reduction in beverages, he says, “there’s a lot of interest in using this to modulate sweetness. We’re also looking at the ability of ultrafine bubbles to impact the taste profile of some [high intensity] sweeteners to provide a more rounded taste profile, but we’ve really only scratched the surface at this point.”
The gut microbiome
Finally, one of the most exciting new areas of study for the company is the microbiome, says Jackowetz, citing a recent 12-week pre-clinical animal study [not yet published] indicating positive changes to the gut microbiome in mammals fed water with ultrafine bubbles vs a control, from increased production of beneficial short chain fatty acids such as butyrate to a decrease in inflammatory markers.
While this is just a preliminary piece of work and Hydrosome Labs doesn’t have the resources to engage in costly human clinical trials to validate it, it is hoping that through work like this, it can “generate a proof of concept or enough interest, and then hopefully we can find a partner,” says Jacobs.
