Abstract
The characterization of microbiota of a large number of industrial and artisanal sourdoughs has greatly promoted our understanding of the microbial ecology of sourdoughs [1–3]; (Chaps. 6 and 7). Currently, reliable information for several hundred sourdoughs that are used for bread production are available (Chap. 6), in addition, hundreds of sourdoughs that were propagated in laboratories provide additional information on ecological principles governing community assembly in sourdoughs. The lactic microbiota of back-slopped sourdoughs are dependent on the technological aim of the fermentation, which dictates the fermentation parameters. Organisms in back-slopped sourdoughs are markedly different from the microbiota of spontaneously fermenting sourdoughs or the raw materials, excluding the raw materials as a significant source of most lactic acid bacteria associated with sourdough. The congruency of lifestyles, phylogeny, and taxonomy that the current taxonomic framework provides for genera of the Lactobacillaceae clearly indicates the origin of many sourdough microbes [3–5]. For example, Lactobacillus and Limosilactobacillus species that dominate in many Type II sourdoughs are vertebrate host adapted. Several sourdough isolates of Lm. reuteri colonize mice, one of the hallmarks of host adaptation in the species [6, 7]. Fructilactobacillus sanfranciscensis is likely of insect origin, although evidence for an insect origin of the species remains culture-independent or indirect [8, 9]. Conversely, fermentation microbes in spontaneous sourdoughs are free-living or nomadic organisms that are associated with plants. Genome sequence data for isolates from spontaneous fermentations allows source tracking of fermentation microbes with strain-specific PCR [10]. Analysis of mahewu, a spontaneously fermented cereal beverage produced in the South of Africa demonstrated that strains of Lactiplantibacillus plantarum were present as very minor components of the microbiota of millet malt, one of the ingredients [10].