Cheese whey, the major by-product of the dairy industry, poses an environmental challenge due to its high organic load but simultaneously represents a nutrient-dense matrix suitable for biotechnological valorization. This review synthesizes recent advances positioning whey as (i) a fermentation substrate for lactic acid bacteria, yeasts/fungi, and microalgae, enabling the production of functional biomass, organic acids, bioethanol, exopolysaccharides, enzymes, and wastewater bioremediation; (ii) a platform for postbiotic generation, supporting cell-free preparations with functional activities; and (iii) a food-grade encapsulating material, particularly through whey proteins (β-lactoglobulin, α-lactalbumin), which can form emulsions, gels, and films that protect biotics and bioactive compounds during processing, storage, and gastrointestinal transit. We analyze key operational variables (whey type and pretreatment, supplementation strategies, batch and continuous cultivation modes), encapsulation routes (spray drying, freeze-drying, and hybrid protein–polysaccharide systems), and performance trade-offs relevant to industrial scale-up. Finally, we outline future directions, including precision fermentation, mixed-culture processes with in situ lactase activity, microfluidics-enabled encapsulation, and life-cycle assessment, to integrate product yields with environmental performance. Collectively, these strategies reframe whey from a high-impact waste into a circular bioeconomy resource for the food, nutraceutical, and environmental sectors.

This study demonstrated the biodegradation of two different brands of cigarette butts (CBs), which are primarily composed of cellulose acetate, by four distinct microorganisms. These included the white rot fungus Pleurotus ostreatus, the brown rot fungus Lentinus lepideus, and the bacteria Bacillus cereus and Pseudomonas putida. After 31 days of treatment, weight loss measurements revealed a mass loss of 24–34%, where B. cereus exhibited the greatest efficacy in terms of mass loss for both brands of CBs. Fourier-Transform Infrared Spectroscopy (FTIR), confocal microscopy, and scanning electron microscopy (SEM) confirmed changes in the surface of the CBs, attributable to structural wear and material breakdown, indicating effective biodegradation by the evaluated microorganisms. Furthermore, the analyses confirmed changes in the surface of the CBs, attributable to structural wear and material breakdown, indicating effective biodegradation by the evaluated microorganisms.

Kefiran is a bioactive exopolysaccharide produced by kefir grains, whose synthesis is strongly influenced by culture medium composition. In this study, cheese whey was evaluated as an alternative fermentation substrate for kefiran production, and the effect of supplementation with fermentable sugars (glucose, galactose, and lactose) and casein was assessed under controlled conditions. Kefir grains were cultivated in whey- and milk-based media, and kefiran production was quantified using an anthrone-based method, while grain growth and carbohydrate consumption were monitored. Supplementation with sugars and casein reduced kefiran production by up to 34.6% and did not improve yield, whereas unsupplemented whey supported the highest kefiran concentration (86.9 ± 3.7 mg/L), comparable to that obtained in semi-skimmed milk (84.0 ± 3.0 mg/L). The recovered polysaccharide was characterized by Fourier-transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance spectroscopy (¹H NMR), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC), showing structural and physicochemical properties comparable to kefiran obtained from semi-skimmed milk. These results indicate that whey constitutes a feasible and simple fermentation medium for kefiran production, and that increased medium complexity does not necessarily improve process performance.