The Survivor: Lactobacillus plantarum
Lactobacillus plantarum is a survivor. It is the "Navy SEAL" of the lactic acid bacteria. It is found everywhere: in sauerkraut, pickles, kimchi, olive brines, and—crucially—in the most robust sourdough starters.
The Peacemaker: Levilactobacillus brevis
While other microbes are busy fighting for sugar, L. brevis is quietly performing a chemical conversion that has profound implications for the human brain. It takes Glutamate—an excitatory molecule—and transforms it into GABA, the molecule of calm.
The Dead Starter: Pathogen Takeover in Neglected Jars
There is a point of no return. A moment when a neglected starter stops being a culture of beneficial microbes and becomes a Petri dish for pathogens. This transition is chemical. It is driven by a single variable: pH.
Microbial Ecology: The Lifecycle of Your Starter (And Why It Smells)
When you mix flour and water for the first time, you are not just making dough; you are terraforming a new world. You are initiating a biological sequence known as Ecological Succession. This process is violent, chaotic, and predictable. It involves a war for resources, a "Great Extinction" event, and finally, the establishment of a stable civilization.
The Handshake: The Baker's Skin Microbiome
Your hands are not sterile tools. They are a thriving ecosystem, a landscape of ridges and valleys populated by millions of bacterial residents. When you knead a loaf, you are not just shaping structure; you are performing a biological handshake. You are introducing your own microbial signature to the dough.
Meet Your Baker: F. sanfranciscensis.
Meet the rod-shaped bacterium with a name that barely fits on a label: Fructilactobacillus sanfranciscensis. This organism is the engine of the sourdough ecosystem. And its history is stranger than you think.