Impact of pH on succession of sourdough lactic acid bacteria communities and their fermentation properties

Abstract

30Sourdough, a traditional fermented dough, is made via natural fermentation by lactic 31 acid bacteria (LAB). Its pH changes from near neutral to acid during the subculture 32 process. However, the product quality of subcultured sourdough depends on the 33 unpredictable succession of LAB communities, the influential factors of which are still 34 unclear. To elucidate one end of the LAB community succession mechanism, we 35 evaluated the effect of pH by designing four subculture experiments using a model 36 medium adjusted to pH 6.7, 5.5, and 4.5, as well as a natural sourdough subculture. All 37 experiments began by inoculating a sourdough LAB mixture, and both bacterial 38 successions and fermentative properties were monitored until ten subculture steps. In 39 media subcultures, lactic acid production was higher in higher pH media. Three LAB 40 genera, Weissella, Pediococcus, and Lactobacillus, each represented by one operational 41 taxonomic unit (OTU), were successively detected in all subcultures. In later steps with 42 lower pH media, an OTU closely related to Lactobacillus brevis dominated, replacing 43 an OTU closely related to the Weissella cibaria-confusa group that was more dominant 44 than the L. brevis OTU in the near-neutral pH medium. In the sourdough subculture, the 45 three genera were also detected, while Lactobacillus was dominant in earlier steps due 46 4 to the emergence of an OTU closely related to Lactobacillus sanfranciscensis. These 157

Sourdough Microbiome Comparison and Benefits

“…Often, the optimum length of fermentation time is targeted in grasping the best outcome. However, Oshiro et al [ 82 ] summarised some of the obstacles, for instance, the uncontrollable succession of LAB due to spontaneous fermentation as well as the limitations of technology in quantifying them precisely and quickly. Despite that, the succession of microbes in sourdough starters during the fermentation period can still be described generally.…”

“…Despite that, the succession of microbes in sourdough starters during the fermentation period can still be described generally. The process of one species successively giving way to another species until the maturation of sourdough is divided into three phases [ 65 , 82 , 87 ]. Most studies tracked the microbial dynamics for ten days, for example, Ercolini et al [ 56 ] detected the high abundance of microbes which were naturally inherited from cereals [ 101 ], such as Acinetobacter , Pseudomonas , Sphingomonas and especially Enterobacter , during the first phase, followed by domination of Weissella spp.…”

Mechanistic Insight into Yeast Bloom in a Lactic Acid Bacteria Relaying-Community in the Start of Sourdough Microbiota Evolution

“…In vitro culture-based experiments provide mechanistic data that cannot be obtained using 16S rRNA amplicon sequencing ( 13 ). In several studies of fermented food microbiota, including sourdough, microbial interaction patterns were successfully verified by introducing a culture-based in vitro model that mimics the environment ( 14 – 17 ).…”

Effects of Dry Sourdough on Bread-Making Quality and Acrylamide Content

“…The decrease in pH value with the increased level of SD addition has been reported by various researchers [14,34]. These decreases are due to the lactic acid content of SD, which was obtained as a result of the fermentation of lactic acid bacteria in wheat flour [35]. During fermentation, the pH value slightly increased with the increase in the dough fermentation time.…”