Annually, the wine industry produces high amounts of waste that can be toxic if disposed of without pretreatment. Vermicomposting is an efficient and low-cost method of decomposing organic matter using earthworms under controlled conditions. The organic substrate used in the vermicomposting process affects microbial populations and reflects the dynamics of enzymatic activity, decomposition of organic matter, and nitrogen transformations. However, the microbiome associations during the whole process are still unexplored. Thus, the aim of the present study was to investigate physicochemical, enzymatic, microbial, and microbiome activities during vermicomposting of winery waste. In this vein, a rectangular vermireactor with Eisenia andrei and Eisenia fetida earthworms, loaded with winery waste, was used. At the end of the process, the carbon/nitrogen (C/N) ratio was decreased, the total nitrogen was increased, the pH was neutralized and excess enzymatic activities were recorded. The bacterial and fungal phyla detected by next-generation sequencing analysis identified Armatimonadetes, Bacteriodetes, Candidatus saccharibacteria, Chloroflexi, Cyanobacteria, Planctomycetes, and Proteobacteria and Ascomycota, Basidiomycota, Chytridiomycota, Entomophthoromycota, Glomeromycota, and Mucoromycota, respectively. Physicochemical and microbial changes occurring during vermicomposting of winery waste, along with the microbiome diversity at the beginning and end of the process, may lead to a better understanding of winery-waste biotransformation into effective biofertilizer.

Plant extracts contain valuable sources of biologically active molecules and, lately, have attracted scientific and industrial interest as inhibitors of food-borne pathogens and growth stimulators of beneficial microbes. In this vein, the aim of this study was to explore and exploit the effect of Aloysia citrodora extracts as potent functional regulators of food microbiota by stimulating the growth of probiotic strains and by suppressing the evolution of common food-spoilage and pathogenic bacteria. Aqueous and ethanolic extracts of A. citrodora, rich in polyphenols, were prepared and their phytochemical composition was unveiled by LC-triple quadruple and LC-QToF mass spectrometry. The growth stimulatory activity of a wild-type Lacticaseibacillus rhamnosus strain, along with L. rhamnosus GG, used as a control, was assessed by monitoring cell growth in the presence of sodium chloride, bile salts, thermal stress, and alcohol. We found that the aqueous extract stimulated the growth of probiotic strains at 0.5 mg/mL. At the same concentration, stimulatory activity was observed for the wild-type L. rhamnosus in the presence of bile salts and alcohol and for L. rhamnosus GG in the presence of NaCl and under thermal stress. The ethanolic extract of A. citrodora exhibited prebiotic activity at 0.25 mg/mL, but did not promote the growth of the strains under the stress conditions tested. In addition, minimum inhibitory (MIC) and minimum bactericidal concentrations (MBC) against food-spoilage and pathogenic microbes were determined. The strongest growth inhibitory activity of foodborne pathogens was noted by the A. citrodora ethanolic extract, while the aqueous A. citrodora extract had no effect against Escherichia coli. Importantly, the spoilage and pathogenic microbes tested were more sensitive to the extracts than the probiotic strains, indicating a significant contribution to the functional regulation of food microbiota, provided that they are used at the optimum concentration.