LB 10-109 - The Effect of Substrate and Environment on the Microbiome of Sour Dough Bread Starter Cultures.

Background/Question/Methods:

Microbial communities are complex dynamic systems that can be influenced by a variety of environmental conditions and other mechanisms. A microbial community of note can be found within sourdough bread starter cultures. These cultures are used in the production of sour dough bread, originating from the local environment, containing primarily yeasts, pollens, and native bacteria. The purpose of this study is to better understand the diversity of this dynamic community and to determine what factors influence its formation. It is hypothesized that substrate and surrounding community will influence the microbial community found within starters. Starter cultures were produced during the Summer of 2021 and created using flour from two grain types, wheat, or barley. After sourdough starters were created, triplicates of each starter were incubated in one of two environments. An indoor environment, a kitchen, or an outdoor environment, a green roof found on a local library. DNA was extracted from all 12 samples and quantified. Starter cultures were incubated and maintained in each environment for 14 days. DNA was sent to be analyzed through Illimuna sequencing of the 16s rRNA gene for bacteria and ITS (Internal Transcribed Spacer) region for fungi.

Results/Conclusions:

Unique microbial communities were found in each sourdough starter sample, with higher diversity being detected within samples incubated in outdoor environments. Bacterial communities were overall dominated by bacteria from the phylum Firmicutes and from the genus Lactobacillus. Fungal communities were dominated by Ascomycete yeasts, mainly from families Phaffomycetaceae and Saccharomycetaceae. Bacterial community composition was strongly impacted by both incubation location (outdoors vs indoors) and substrate type. Results were much less clear regarding fungal community data. No clear pattern could be ascertained from the data related to fungal community composition, with more analyses needed.