Saving Our Bacon: Katie Summers, PhD
Bacon.
The word alone conjures up thoughts of strips sizzling in frying pans, the distinctive scent wafting to your nose, the satisfyingly salty crunch when you take a bite. Is your mouth watering? Bacon is delicious. And so are its porky cousins. From BBQ ribs and pulled pork to pork roasts and chops, pork is tasty.
But what if pork became a rarity and bacon was just a distant memory? Sadly, the pork supply is under threat. The world’s population is booming, and people love pork. As more people eat more pork, our livestock supplies are continuously pressured. On top of this, climate change is making agriculture harder and affecting livestock feed supplies, farms experience bouts of swine flu and other diseases, and the US and Europe are producing smaller pigs since their ban on the use of antibiotics in animal feed to prevent creating antibiotic resistance.
Katie Summers, PhD
Thankfully, while the challenges are real and serious, there are super-smart scientists diligently working to develop bigger, healthier pigs. Katie Summers is one of these researchers, and she recently talked to me about her work. Katie has a PhD in microbiology and immunology from the University of Michigan and is a scientist at the Animal Biosciences and Biotechnology Laboratory within the Agricultural Research Service at the US Department of Agriculture. While saving the world’s bacon supply may sound glamorous, Katie believes that the answer to the problem lies in a material that is decidedly less so.
Pig poop.
Yes, pig poop. More specifically, Katie studies this material because she is interested in the microbiota of pigs and how its composition can impact the health and growth of the animals. The ultimate goal for this research is to figure out ways to grow bigger pigs with fewer health issues and lower food intake.
Hints that the microbiota may be an important facet of growing healthier pigs arose when the US and the EU banned the use of antibiotics in animal feed. People noticed that the resulting pigs were smaller. This suggested that exposing animals to antibiotics had led to larger animals. But the connection between antibiotics and growth wasn’t clear. It is, however, known that antibiotics can impact the composition of the microbiota, suggesting a possible link between the microbiota and healthy animal growth.
Katie studies how a pig develops its microbiota. When pigs are born, they don’t have much of an immune system. They are almost totally dependent on colostrum and their mother’s antibodies. When they are 21 days old, piglets are weaned, and for the next 2 weeks, they are predisposed to infections and health issues, such as microbe-induced scours/diarrhea. The piglet’s immature immune system is strained during this time, due to dietary changes and stress. If the piglet gets sick during weaning, it won’t grow as fast, nor is it able to make it up. While this adds pressure on our food supply and costs the farmer money, it also indicates a potential connection between this early period of development and growth.
Katie and others have found that throughout early development, the piglet’s microbiome is in a state of flux. Like humans, in the first few days after a piglet’s birth, there is chaos in the gut as certain bacterial species are trying to colonize their preferred niches. These are called founder species, and they come in and adjust the microenvironment, paving the way for the arrival of anerobic bacteria. Once the core bacteria are established, the composition of the microbiome stays relatively constant until weaning. Then the bacteria in the microbiome change yet again.
But Katie found that this dynamism didn’t appear to exist with the gut’s fungal populations. Of particular interest was a fungus called Kazachstania slooffiae (K. slooffiae), a strain related to the fungus Candida albicans that causes thrush in humans. Katie found that K. slooffiae was the predominant fungal strain after the weaning process, and its dominance occurred across pig genetic lines used in industry, regardless of geography. But it doesn’t start out dominant. In fact, during the first few weeks of life, it’s barely present in the piglet’s gut. But once weaning starts, it quickly multiplies and then persists.
Could K. slooffiae be a key link between the microbiota and a pig’s growth and health? Katie has found that the fungus is still present in sick pigs, but the balance with bacteria is off. This led Katie to explore potential connections between K. slooffiae and different bacterial strains. She studied these relationships by looking at biofilms, amalgamations of different microorganisms that stick together and form a surface. The structure of a biofilm relies on a network of interactions between its components. For example, one microorganism may consume a specific compound, break it down, and release byproducts into the microenvironment. These byproducts may then be used as food by other microbial components of the biofilm.
Katie found that K. slooffiae produced biofilms that became increasingly complex when a certain Lactobacillus bacterial strain was present. In other words, the two species thrived when they were around each other, suggesting that they could have positive interactions in the gut. Conversely, when K. slooffiae was in the presence of Enterococcus bacteria, the biofilm broke down. This indicated that the two species could have a negative and antagonistic relationship in the gut.
Taken together, these findings provided clues that K. slooffiae could impact the bacterial composition of the gut microbiota. K. slooffiae and its fungal friends make up the “mycobiome,” a subset of the total gut microbiota. Some species of the mycobiome, such as K. slooffiae, may promote the growth of certain healthy bacteria, while preventing the expansion of pathogenic bacteria. In other words, K. slooffiae could help drive the piglet’s microbiota toward a more growth-promoting state while preventing disease-causing bacteria from colonizing the gut. This is an intriguing prospect that Katie and her team are now testing.
Katie is now experimenting with a K. slooffiae as a probiotic to see if supplementing the piglets’ mycobiome during weening can impact their growth. A beneficial probiotic strategy could be impactful because it represents a cheap preventative action to keep pigs healthy. For the livestock industry, this is key because farmers aren’t going to spend lots of money on costly treatments for sick pigs, since pigs aren’t worth as much as cattle. But a cheap and effective preventative approach could help ensure that more pigs remain healthy and reach market weight faster, without overburdening the farmer.
As Katie works on understanding the relationship between the microbiota and pig growth, other researchers have found links between microbiota alterations and susceptibility of pigs to disease, such as swine flu. The more often pigs develop swine flu, the more frequently these diseases will jump to humans. Collectively, the work that Katie and her colleagues do makes it clear that understanding the microbiota and the part it plays in animal health and growth is vital. Deciphering this puzzle could prevent the next flu pandemic, as well as ensure that you’ll have the B for your next BLT sandwich.
Special thanks to:
Katie Summers, PhD, Research Microbiologist, USDA Agricultural Research Service (katie.summers@usda.gov)
QIAGEN and Todd Festerling, PhD for sponsoring the blog