Effects of agave bagasse and Lactococcus lactis addition on microbial communities and metabolite profiles of Mexican wheat sourdough

Abstract

In Mexico, the tequila industry is an important source of agro-industrial by-products, such as agave bagasse (AB). A second use of this high-fiber material may be accomplished by its incorporation into sourdough fermentation. This study evaluated the impact on the microbial communities in wheat sourdough added with AB and Lactococcus lactis NRRL B-50307. Five treatments were evaluated, B1: wheat flour; BI2: B1 inoculated with L. lactis (10⁶ CFU/mL); C10: B1 + AB (10 % w/w); T5: BI2 + AB (5 % w/w); and T10: BI2 + AB (10 % w/w). Sourdough was produced after a 6-day fermentation at 25 °C, with daily evaluation of the fermentation quotient (FQ), fermentation curves (FC), and organic acid production. Acidification kinetics revealed that treatment T10 was the most stable during fermentation, with lactic acid as the primary metabolite produced, being significantly higher (p < 0.05) for treatments T10 and BI2 (11.5–12.2 mg/kg). From high-throughput sequencing, the addition of L. lactis exhibited increased dominance and population diversity in treatment T10. Diversity analysis revealed that Bacillota was the predominant bacterial phylum in most treatments. Saccharomyces cerevisiae was by far the dominant yeast species in all treatments, associated with the sourdoughs' acidification. From HPLC and GC–MS sugars (e.g., fructose and lactose) and volatile organic content (e.g., pentanoic acid, 2,3-dimethylpentane) varied depending on the sourdough treatment. AB may be utilized as a fiber source for sourdough production. Concurrently, the interaction between AB and L. lactis promoted an early stabilization of the sourdough acidification process, bacterial community modulation, and a different volatile compounds profile.