Sourdough starters are mystical, inexplicable… but one must attempt many impossible things for science! This, my dear listeners, is our sole mission. Welcome to Sourdough Center… (Cue music, ominous or calm).
Firstly, allow me to introduce you to the subjects of our time today: the starters themselves. These curious little habitats are simply environments of liquid, flour and yeast. Now, I did mention that these are habitats, and you may be wondering: What are these concoctions actually hosting? Small, super tiny, (possibly really cute) organisms called microbes. Microbes exist to help the sourdough bread rise and maintain its scrumptious taste!
For this podcast, we will be examining, analyzing, and confronting the harsh realities of one experimental venture into sourdough starters: my own venture, actually! The overall question of this experiment was to discover how the genetic composition of these microbial organisms (our baby, darling microbes…. Awwww, they’re just so cute that I can’t stop thinking about them!!!) changed various physical and sensory elements of the starters, such as smell and texture. I was in a class full of fellow science enthusiasts who all ran their own experiments along these same lines, using different fruits to obtain different microbes. My own experiment... (cue funeral-esque music) went poorly, to say the least. I used mango and banana (both delicious fruits when combined or alone), but I was unfortunately unable to feed them at regular intervals due to a family issue. My starters (God rest their inanimate souls) are now hopefully thriving in a celestial, Sourdough sauna in bread heaven...hopefulllyyy.
In order to actually examine and make conclusions about these microbes’ effects on the starters, we had to sequence the DNA of the starters. For my less educated listeners, there is absolutely no reason to be scared of this idea! It simply involves the reading of DNA fragments to create a map of sorts, and thereby develop more of an idea as to what the genetics of an organism actually does. See? Super easy concept, right? For our purposes, this sequencing allows us to fully examine the genetic makeup of these microbes. There are two different types of sequencing commonly used, Sanger sequencing and NGS, but we used NGS, mainly for it’s cool name! Just kidding, we used NGS due to its ability to map out much larger chunks than Sanger. (think millions of units in comparison to Sanger’s, i dunno, ten units?) As far as what we are actually sequencing, the subject is the 16s rRNA gene, a piece of the organelle in a cell called the ribosome. The funky “16s” refers to the location on the ribosome of the rRNA genes we are sequencing, but all this enables us to do is more easily find significant results in our data.
My own research question was one of utmost importance: does the status of the fruits (whether they are bought canned or fresh) determine what microbes are found in the starters! Unfortunately, we can not actually answer this question due to delays in sequencing processes. Instead of that, I have chosen two samples from the Fall 2020 semester data set to analyze and research.
The fruit I chose from the sample data was the blueberry! These samples are similar to my research question in the way that they can still be investigated under the question of whether the fruit is fresh or canned. Yay!!!!
When analyzing samples 55 (control) and 57 (blueberry), I found that one unique microbe found in the blueberry starter (but not the control starter) was Pediococcus pentosaceus. This microbe is used to ferment foods and release flavor compounds, as well as boost probiotic potential (such as in blueberries). The microbe holds a gene that, when placed into other organisms via genetic engineering, may help preserve the food as a substitute for salting or other artificial preservative methods. Overall, a superbly useful microbe!
In the same vein, we received back our Spring 2021 data, and, listeners, I have some disappointing news. My initial hope was that I would find a certain bacteria, P. Pentosaceus, in fruits commonly used in fermentation of foods. To limit the amount of data I had to cover, I chose two fruits I knew were commonly utilized in fermentation, pineapple and grapes from two separate individuals. To my chagrin and scientific surprise, the bacteria was not to be found in either sample. Alas! My hypothesis was rejected, but not all is lost! There are plenty more scientific avenues to walk in this life, even within this project itself! All of this being taken in stride, I do believe that this bacteria is neither beneficial nor harmful to the sourdough, as both Fall 2020 and Spring 2021 sets seemed to grow regardless of its presence.
Should I ever be given the opportunity to work with such samples in an actual laboratory setting, I would love to investigate the effect that external temperature has on the microbes that appear at the submission period. Certain bacterias thrive in extreme temperatures, high or low, and I would be most interested in discovering any of these bacteria living off of the sourdough while also existing in such a seemingly cruel environment. Anyways, this sets the scene for so many more scientific inquiries. Signing off, loyal listeners, your respectful and eager host, Joseph Lewis.
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