Changes

In general, most of the cultures of kveik that have been analyzed contain more than one strain of ''S. cerevisiae''. The exact number of strains that is present in a given kveik culture is difficult to analyze; generally labs with better equipment and more time can identify more strains than others. Some kveik cultures contain multiple strains of closely related strains of ''S. cerevisiae'', while others contain a more diverse group of strains <ref name="garshol_preiss_mbaa" />. The kveik cultures with closely related strains defy what a "strain" isolate is; Richard Preiss describes these kveik cultures as being "heterogenous but related communities", meaning that there can be a lot of genetic overlap between subpopulations in a kveik culture and where one strain begins and another ends is not possible to define <ref name="preiss_strains" />. Strains within cultures probably arose due to mutations during cell division, as well as sporulation which kveik is more capable of than other domesticated yeast strains <ref>[https://www.facebook.com/groups/MilkTheFunk/posts/6929359520425536/?comment_id=6929468623747959&reply_comment_id=6933491356679019 Richard Preisse. Milk The Funk Facebook group thread about landrace yeast and sporulation. 05/16/2023.]</ref>. ''S. cerevisiae'' was the only species in all of the kveik cultures analyzed by Preiss et al. (2018). Of the 9 kveik cultures analyzed by Preiss et al. (2018), only Muri (which has since been found to be commercially available Bavarian Weizen yeast and not a landrace farmhouse yeast at all; see [[Landrace Yeast]]), Simonaitis, and Stranda contained only one strain of ''S. cerevisiae'', while all of the others contained more than one strain of ''S. cerevisiae'' up to 9 strains in the case of Granvin (see [https://www.frontiersin.org/files/Articles/409253/fmicb-09-02137-HTML-r1/image_m/fmicb-09-02137-t001.jpg this table from the paper]). A Master's Thesis by [https://nmbu.brage.unit.no/nmbu-xmlui/handle/11250/2681970?show=full Nadia Marlen Aasen from Norwegian University of Life Sciences] isolated 4-10 strains from 4 different kveik cultures: Ørjasæter, Otterdal, Gausemel and Gamlegrua. As with Preiss (2018), the only species of yeast found was ''S. cerevisiae''. While only yeast was found in Otterdal and Ørjasæter, the Gausemel also had two bacteria species, ''Acetobacter malorum'' and ''Lactobacillus plantarum'', and the Gamlegrua also had ''L. plantarum'' <ref name="Aasen">[https://nmbu.brage.unit.no/nmbu-xmlui/handle/11250/2681970?show=full Nadia Marlen Aasen. Growth, metabolism and beer brewing with kveik. Master's Thesis. Norwegian University of Life Sciences. 2020.]</ref>.