The role of flour type and feeding schedule on the sourdough microbiome

Sep 29, 2026

Upload by Ben

Sourdough starters are spontaneous fermentations shaped by environmental inputs and host-associated microbes, yet only a limited set of bacterial and yeast species typically dominate. Using a meta-barcoding approach, the study tests whether baking flour types (all-purpose, bread, whole wheat) and feeding frequency (backslopping) alter starter communities over one month. Results show the yeast genus Kazachstania rapidly dominates across all treatments, whereas flour type significantly shifts bacterial composition. Flour thus influences sourdough microbiota and may affect functional traits.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages12

Reading Time30 min

AccessFree to download

Abstract

Methods

Key findings

Conclusions

Importance

Ecological context

Practical implications

| Food Microbiology | Research Article The role of flour type and feeding schedule on the sourdough microbiome Sima Taheri,1,2 Enrique Schwarzkopf,3 Hanna L. Berman,2 Nathan Brandt,3 Jessica McNeill,3 Nico Sevier,3 Margot Ruffieux,3 Robert R. Dunn,2 Caiti Smukowski Heil3 AUTHOR AFFILIATIONS See affiliation list on p. 9. ABSTRACT Sourdough starters are fermentations of various grains by bacteria andyeast and are of worldwide economic and cultural importance. Sourdoughs are sometimes spontaneously inoculated, and their resident microbial communities are in part shaped by environmental factors, potentially including flour, water, air, human microbiota, equipment, geography, and temperature. The number of different genera of bacteria and yeast found in sourdoughs is large; however, only a handful of species typically dominate an individual sourdough starter. Understanding how and why certain species form a mature climax community in a particular environment is a key question in microbial ecology. To investigate this question, we used a meta-barcoding approach and tested whether different baking flours (all-purpose, bread, and whole wheat) and frequency of feeding, also known as backslopping, shape the sourdough starter microbial community over the course of one month. We found that the yeast genus Kazachstania rapidly rose in frequency and became the most abundant yeast in all starters, regardless of flour type or feeding schedule. In contrast, flour type did affect the bacterial community. Mature sourdoughs all contained the bacterial genera Companilactobacillus, Levilactobacillus, Lactiplantibacillus, Furfurilactobacillus, and Acetobacter, with Companilactobacillus detected at higher relative abundance in whole wheat flour and Levilactobacillus detected at higher relative abundance in bread flour. We conclude that flour can shape the microbial community of sourdough and has potential implications for functional traits. IMPORTANCE How organisms disperse and colonize new environments is central to our understanding of biodiversity. Sourdough, the often spontaneously inoculated fermentation of grains by bacteria and yeast, represents a great system to test and observe how microorganisms come to inhabit a particular niche. In our study, we investigate how environmental parameters such as flour type and feeding frequency influence the microbial community. We find that the common sourdough yeast genus Kazachstania is most abundant in all starters regardless of treatment, but we also find a significant effect of flour type on the lactic acid bacteria composition of the sourdough starters. This work shows how the environment can impact the presence and abundance of particular microorganisms and prompts future studies to test how particular lactic acid bacteria species can specialize on certain resources. KEYWORDS sourdough, flour, 16S, ITS, microbial ecology, Kazachstania, lactic acid bacteria S ourdough describes the fermentation of grains and water by a mixture of yeasts and bacteria for the production of bread and related products. This type of fermentation is an ancient practice, with the earliest evidence of yeast and bacteria in sourdough from China and Egypt in the first and second millennia BC (1, 2), though Editor Jeffrey A. Gralnick, University of Minnesota Twin Cities, St. Paul, Minnesota, USA Address correspondence to Caiti Smukowski Heil, [cheil@ncsu.edu](cheil@ncsu.edu). authors declare conflict of interest earlier archaeobotanical remains suggest a more ancient origin for breadmaking and the processing of vegetal materials for consumption (3–7) . Sourdoughs are maintained through “backslopping,” which entails discarding a portion of the sourdough starter and providing new grains and water (8–10) . There are many variations on this process across culture, geography, time, and scale of production (11–14) . Various forms of sourdough are produced by cultures across the globe, and leavened bread serves

FAQs

How did the researchers test the effects of flour type and feeding schedule?

They used a meta-barcoding approach and monitored starter communities over one month under different flour types (all-purpose, bread, whole wheat) and different feeding frequencies (backslopping).

What yeast genus became most abundant in the sourdough starters?

Kazachstania rapidly increased in frequency and became the most abundant yeast in all starters, regardless of flour type or feeding schedule.

Did flour type affect both yeast and bacterial communities?

Flour type did not change the dominant yeast trend, but it significantly affected the bacterial community, including higher relative abundance of Companilactobacillus in whole wheat and higher Levilactobacillus in bread flour.

Sep 29, 2026

Upload by Ben