Changes

A second study showed that a strain of ''S. cerevisiae'' was able to adapt and grow in a lab setting to increasing concentrations of lactic acid. After multiple generations and by slowly increasing the amount of lactic acid per generation, the researchers got the pH of the growth media (either raffinose or glucose plus lactic acid) all the way down to pH 2.8. At this low pH, the yeast began to use lactic acid as a food source. This might explain some anecdotal experiences by brewers who have seen the pH of kettle sour beers rise (more evidence is needed to confirm this hypothesis). The researchers found that the gene called ''ACE2'' is likely to be associated with the ability to adapt to low pH conditions. It is also a gene that controls the expression level of other genes, and is also responsible for forming "snowflake-like" structures (multicellular clumps of genetically identical cells that stick together after budding <ref>[https://www.quantamagazine.org/20151103-snowflake-yeast-multicellularity/ "Life’s Secrets Sought in a Snowflake". Emily Singer. Quantum Magazine. 11/03/2015. Retrieved 12/27/2016.]</ref>). The yeast strain began to form these "snowflake-like" clumps after being adapted to the low pH environment. Further work should be done to determine which strains of ''S. cerevisiae'' might be more easily adapted to low pH environments, or if possibly all strains of ''S. cerevisiae'' could be adapted to low pH environments over time <ref>[http://www.sciencedirect.com/science/article/pii/S1096717616301756 Evolutionary engineering reveals divergent paths when yeast is adapted to different acidic environments. Eugene Fletcher, Amir Feizi, Markus M.M. Bisschops, Björn M. Hallström, Sakda Khoomrung, Verena Siewers, Jens Nielsen. 2016.]</ref><ref>[http://www.nature.com/articles/ncomms7102 Origins of multicellular evolvability in snowflake yeast. William C. Ratcliff, Johnathon D. Fankhauser, David W. Rogers, Duncan Greig & Michael Travisano. 2015.]</ref>.

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