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===Biological Explanations===
====Bryan Heit's of Sui Generis Blog Biology Explanation====
"This is what I would have expected - those claims of complete attenuation always rubbed me the wrong way, and from a scientific point of view, appeared impossible. pH will (eventually) inhibit even the most acid-tolerant of bacteria. Even if the bug is capable of protecting itself from the degradative nature of acids (which many can), at some point the concentration of protons (acid "atoms") will block the bacteria's proton motive force, which is used to "pump" molecules into bacteria (and in the case of some bacteria, to generate energy). Once the proton motive force is gone, the bacteria is effectively dead.
Bacteria setup a proton motive force by pumping protons out of their cytosol, into the extracellular space. This acidifies the extracellular space and alkinalyzes the cytosol. The energy of this gradient can then be used to "force" other molecules into the cell - e.g. ''Lactobacillus'' uses this to collect amino acids and DNA for growth and replication. However, the more acidic the environment, the more energy is required to pump additional protons out of the cell. The ability of cells to do this is finite; the theoretical maximum "pump force" that can be exerted is equal to the energy of hydrolysis of one ATP (energy molecule); roughly -31 kJ/mol. The theoretical max acidity that will work against is 1.2, but in reality these pumps are generally less than 30% efficient, so for most species pumps fail at pH's above 3.0. Most ''Lactobacillus'' crap out somewhere around 3.2 to 3.0. The pH of a fully attenuated 1.040 wort would be between 1.9 and 2.4 (ignoring buffering effects), depending on whether the ''Lactobacillus'' was homo or heterofermentive. So the claim that ''Lactobacillus'' can completely ferment wort doesn't seem to be biologically plausible." - Comments by [http://suigenerisbrewing.blogspot.com/ Bryan Heit of Sui Generis Blog] <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1114207325274147/?comment_id=1114540208574192&offset=0&total_comments=81&comment_tracking=%7B%22tn%22%3A%22R9%22%7D Conversation with Bryan Heit of Sui Generis Blog on 100% lacto fermentation. 7/22/2015.]</ref>
====Elke Arendt====