Abstract
Human dietary habits and food compositions are key factors in the composition of the human gut microbiota, but, inevitably, unmapped for many dietary components, which are poorly studied individually. Fermented foods and beverages consist of a large portion of the human diet. Among them, sourdough bread represents a key component of the human diet. We have industrially produced bread made with baker’s yeast (BYB) and sourdough (SB30), which have been used to power the Twin Mucosal-SHIME system (Simulator of Human Intestinal Microbial Ecosystem - SHIME®) a scientifically verified gastrointestinal simulator worldwide. Bread feeding not affected the microbiota structure at phylum and family level of both donors in all sections of the colon Twin M-SHIME and in the lumen and mucosal compartments. The genus core microbiota displayed few significant fluctuations, which affected the relative abundances of Lactobacillus and Leuconostoc according to feeding with BYB and SB30, respectively. The content of all short-chain fatty acids (SCFA), and isovaleric and 2-methylbutyric acids increased significantly (p<0.05) with SB30 feeding. The same was found for the content of some amino acids such as Asp, Thr, Glu, GABA, and Orn. Here we believe that we have used the most efficient approach to investigate a key component of diet, excluding the interference of other dietary factors, reaching the conclusion that healthy colonic microbiota metabolism improves with daily consumption of sourdough bread.
Linked to dietary habits, the study of the microbiota and of the gastrointestinal microbiome is reversibly correlated to the state of human health under different disease conditions. In fact, like the intestine, also the skin has its own microbiome where multiple bacterial species reside and may sometimes provide protection by acting as a barrier against potential pathogens. Because of the close relationship between these two environments, we cannot exclude that some skin diseases (e.g., psoriasis, atopic dermatitis) are related to a state of dysbiosis of the microbiota, disturbing its balance and the host health. We conducted an observational study recruiting a cohort of 26 patients with alopecia aerata (AA) and a court of 18 healthy controls. A decrease in alpha-diversity was found in patients with autoimmune disorders. At the genus level Lactococcus and Eubacterium ventriosum group, both considered possible markers of other autoimmune diseases, were identified as more present in AA patients. At the metabolic level, it seems that AA patients have a more dysregulated function in the production of certain metabolites such as pentanoic, butanoic and 2-methylbutyric acid, which may be related to a state of dysbiosis.
The Mediterranean diet is characterized by a high consumption of vegetables, fruits and whole grains that are rich in different beneficial polyphenols. Nowadays, as well as the consumption of health-promoting foods, is growing the necessity to exploit food wastes, especially those rich in bioactive and nutraceutical 3 compounds such as plant-based Mediterranean foods by-product. Apple by-products are one of the most abundant food wastes that can be recycled by exploiting the inherent beneficial phenolics compounds. During the work, other studies were conducted to recovery and recycle apple by-products and validate a production protocol for developing nutraceutical foods. In this regard, tailored fermentation may promote the release of bond plant cell phenolic acids and increase the antioxidant properties of apple by-products, which in turn make this substrate a suitable dietary supplement.
Moreover, we demonstrated that the lactic acid fermentation is a powerful tool to valorise also other plant-derived by products as a dietary supplement. Relatedly, a novel phenomics’ understanding was brought to characterize the metabolic derivation of Lactiplantibacillus plantarum and Leuconostoc pseudomesenteroides caused by a lignocellulosic by-product, such as brewers' spent grain (BSG). We observed increased metabolic activity for gentiobiose, cellobiose, and β-glucoside conjugates of phenolic compounds during BSG fermentation. Through gene expression analysis, it confirmed the importance of cellobiose metabolism, while a release of lignin-derived aglycones was found during BSG fermentation. We have thereby afforded a complete overview of the important role played by LAB 6-phospho-β-glucosidases and the major metabolic pathways that are undertaken during plant-based fermentations.
All these studies have allowed to identify and validate some fermented foods and/or dietary supplements typical of the Mediterranean diet that might have positive repercussions on the intestinal and scalp microbiome and metabolome.