Wild probiotic consortia of microorganisms (bacteria and yeasts) associated in the artisanal cultures’ microbiota (milk kefir grains, water kefir grains and kombucha) are considered valuable promoters for metabiotics (prebiotics, probiotics, postbiotics and paraprobiotics) production. The beneficial effects of the fermented products obtained with the artisanal cultures on human well-being are described by centuries and the interest for them is continuously increasing. The wild origin and microbial diversity of these above-mentioned consortia give them extraordinary protection capacity against microbiological contaminants in unusual physico-chemical conditions and unique fermentative behaviour. This review summarizes the state of the art for the wild artisanal cultures (milk and water kefir grains, respectively, kombucha—SCOBY), their symbiotic functionality, and the ability to ferment unconventional substrates in order to obtain valuable bioactive compounds with in vitro and in vivo beneficial functional properties. Due to the necessity of the bioactives production and their use as metabiotics in the modern consumer’s life, artisanal cultures are the perfect sources able to biosynthesize complex functional metabolites (bioactive peptides, antimicrobials, polysaccharides, enzymes, vitamins, cell wall components). Depending on the purposes of the biotechnological fermentation processes, artisanal cultures can be used as starters on different substrates. Current studies show that the microbial synergy between bacteria—yeast and/or bacteria—offers new perspectives to develop functional products (food, feeds, and ingredients) with a great impact on life quality.

Wild artisanal cultures, such as a symbiotic culture of bacteria and yeasts (SCOBY) and water kefir grains (WKG), represent a complex microorganism consortia that is composed of yeasts and lactic and acetic acid bacteria, with large strains of diversity and abundance. The fermented products (FPs) obtained by the microbiome’s contribution can be included in functional products due to their meta-biotics (pre-, pro-, post-, and paraprobiotics) as a result of complex and synergistic associations as well as due to the metabolic functionality. In this study, consortia of both SCOBY and WKG were involved in the co-fermentation of a newly formulated substrate that was further analysed, aiming at increasing the postbiotic composition of the FPs. Plackett–Burman (PBD) and Response Surface Methodology (RSM) techniques were employed for the experimental designs to select and optimise several parameters that have an influence on the lyophilised starter cultures of SCOBY and WKG activity as a multiple inoculum. Tea concentration (1–3%), sugar concentration (5–10%), raisins concentration (3–6%), SCOBY lyophilised culture concentration (0.2–0.5%), WKG lyophilised culture concentration (0.2–0.5%), and fermentation time (5–7 days) were considered the independent variables for mathematical analysis and fermentation conditions’ optimisation. Antimicrobial activity against Bacillus subtilis MIUG B1, Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, and Aspergillus niger MIUG M5, antioxidant capacity (DPPH), pH and the total acidity (TA) were evaluated as responses. The rich postbiotic bioactive composition of the FP obtained in optimised biotechnological conditions highlighted the usefulness of the artisanal co-cultures, through their symbiotic metabolic interactions for the improvement of bioactive potential.

Kombucha culture (named SCOBY-Symbiotic Culture of Bacteria and Yeasts) and milk kefir grains represent multiple consortia of wild microorganisms that include lactic acid bacteria, acetic acid bacteria and yeasts with valuable functional properties. Their fermentative potential provides a wide range of derivate metabiotics (prebiotics, probiotics, postbiotics and paraprobiotics) with valuable in vitro and in vivo benefits. This study targeted the evaluation of the functionality of a co-culture of SCOBY-based membranes and milk kefir grains, used as freeze-dried starter cultures, for the fermentation of a newly formulated medium based on black tea infusion, supplemented with bovine colostrum and sugar, in order to produce bioactive compounds with functional properties. The design and optimization of the biotechnological process were achieved by using the Plackett–Burman experimental design (six factorial points, three center points) and the response surface methodology and central composite design (three factorial points, six axial points and two center points in axial) tools. The statistical analysis and the mathematical modelling of the responses such as the pH, titratable acidity, antioxidant activity and antimicrobial activity (against Bacillus subtilis, Escherichia coli, Staphylococcus aureus and Aspergillus niger) were investigated. Further, the composition of organic acids, polyphenols and flavonoids of the fermented product obtained under the optimized fermentation conditions was also analyzed. The fermentation of the medium containing 6.27% (w/v) bovine colostrum powder, 1.64% (w/v) black tea, 7.5% (w/w) sugar, pH 6.7, with an inoculum based of 0.36% (w/v) milk kefir grains powder and 0.5% (w/v) SCOBY-based membrane (both as freeze-dried culture), at 30 °C, for 5 days, in an aerobic stationary system, revealed an antifungal activity between 80 and 100% against Aspergillus niger, an antibacterial activity of 8–22 mm against Escherichia coli and Bacillus spp. And a titratable acidity of 445 °Th. The chemical composition of the obtained product had a positive impact on the functional properties of the fermented products in terms of the antimicrobial and antioxidant properties.

Due to the increasing interest in probiotic components to improve quality of life, this study aimed to investigate the bioactive potential of a paraprobiotic derived from a selected strain of probiotic lactic acid bacteria (Lacticaseibacillus paracasei MIUG BL80) on Saccharomyces cerevisiae MIUG D129, used as a cellular model organism. The paraprobiotics (inactivated cells) were obtained through a combination of ultrasonic and conventional heat treatments. It was observed that adding more than 10 % of the paraprobiotic suspension to the cultivation medium of yeast had a positive influence on the metabolic activity of the starter culture (S. cerevisiae). The specific growth rate increased from 0.227 in the control sample to 0.507 in the sample with 15% paraprobiotic supplementation (S3), while the generation time decreased from 4.403 h to 1.972 h. This suggests that adding probiotics to the cultivation medium enhances the metabolic performance of S. cerevisiae cells. Additionally, an improvement in yeast cell viability during wet biomass storage (from 48 h to 14 days at 4 °C) was observed.

In recent years, there has been an increasing interest among food industry producers for functional foods. In this context, the study aims to isolate new lactic acid bacteria strains with probiotic potential that could further be used to obtain valuable metabiotics with good technological potential and health benefits. In the current study, twenty-nine newly LAB strains were isolated from various natural sources, including artisanal cultures (like, kefir grains and kombucha membrane), and selected through fermentation potential on unconventional plant-base substrates, consisting red lentils flour, red potato peel powder, and okara. The strains identified using 16S rDNA sequencing, as Lacticaseibacillus paracasei (encoded BL13, BL80, BL87) and Lactiplantibacillus plantarum (encoded BL21) were further screened considering their in vitro probiotic properties. The safety assessment evaluation highlighted that Lacticaseibacillus paracasei (BL13) and Lactiplantibacillus plantarum (BL21) selected as performant strains have antimicrobial potential against Escherichia coli and Staphylococcus aureus, being also susceptible to tetracycline, chloramphenicol and ampicillin. Furthermore, Lactiplantibacillus plantarum (encoded BL21) proved good adhesion properties on the HT-29 cell line. These strains are new promising probiotic starter cultures candidates with approachable potential to be used for obtaining functional food and ingredients through fermentation processes, that could offer health benefits.