Collagen is one of the most widely used biomaterials in health-related sectors. The industrial production of collagen mostly relies on its extraction from mammals, but several issues limited its use. In the last two decades, marine organisms attracted interest as safe, abundant, and alternative source for collagen extraction. In particular, the possibility to valorize the huge quantity of fish industry waste and byproducts as collagen source reinforced perception of fish collagen as eco-friendlier and particularly attractive in terms of profitability and cost-effectiveness. Especially fish byproducts from eco-sustainable aquaponics production allow for fish biomass with additional added value and controlled properties over time. Among fish species, Oreochromis niloticus is one of the most widely bred fish in large-scale aquaculture and aquaponics systems. In this work, type I collagen was extracted from aquaponics-raised Tilapia skin and characterized from a chemical, physical, mechanical, and biological point of view in comparison with a commercially available analog. Performed analysis confirmed that the proprietary process optimized for type I collagen extraction allowed to isolate pure native collagen and to preserve its native conformational structure. Preliminary cellular studies performed with mouse fibroblasts indicated its optimal biocompatibility. All data confirmed the eligibility of the extracted Tilapia-derived native type I collagen as a biomaterial for healthcare applications.

In the last two decades, fisheries and fish industries by-products have started to be recovered for the extraction of type I collagen because of issues related to the extraction of traditional mammalian tissues. In this work, special attention has been paid to by-products from fish bred in aquaponic plants. The valorization of aquaponic fish wastes as sources of biopolymers would make the derived materials eco-friendlier and attractive in terms of profitability and cost effectiveness. Among fish species, Nile Tilapia is the second-most farmed species in the world and its skin is commonly chosen as a collagen extraction source. However, to the best of our knowledge, no studies have been carried out to investigate, in depth, the age-related differences in fish skin with the final aim of selecting the most advantageous fish size for collagen extraction. In this work, the impact of age on the structural and compositional properties of Tilapia skin was evaluated with the aim of selecting the condition that best lends itself to the extraction of type I collagen for biomedical applications, based on the known fact that the properties of the original tissue have a significant impact on those of the final product. Performed analysis showed statistically significant age-related differences. In particular, an increase in skin thickness (+110 µm) and of wavy-like collagen fiber bundle diameter (+3 µm) besides their organization variation was observed with age. Additionally, a preferred collagen molecule orientation along two specific directions was revealed, with a higher fiber orientation degree according to age. Thermal analysis registered a shift of the endothermic peak (+1.7 °C) and an increase in the enthalpy (+3.3 J/g), while mechanical properties were found to be anisotropic, with an age-dependent brittle behavior. Water (+13%) and ash (+0.6%) contents were found to be directly proportional with age, as opposed to protein (−8%) and lipid (−10%) contents. The amino acid composition revealed a decrease in the valine, leucine, isoleucine, and threonine content and an increase in proline and hydroxyproline. Lastly, fatty acids C14:0, C15:0, C16:1, C18:2n6c, C18:3n6, C18:0, C20:3n3, and C23:0 were revealed to be upregulated, while C18:1n9c was downregulated with age.

In recent years, there has been a growing interest in the use of probiotics in aquaculture, due to their effectiveness on production, safety, and environmental friendliness. Probiotics, used as feed additives and as an alternative to antibiotics for disease prevention, have been shown to be active as growth promoters, improving survival and health of farmed fish. In this study, we have investigated the ability of the strain Bacillus velezensis MT9, as potential probiotic, to modulate the intestinal microbiota of the Nile tilapia (Oreochromis niloticus) fed with the Bacillus velezensis-supplemented feed in an experimental aquaculture plant. The analysis of the microbial community of the Nile tilapia by culture-based and 16S rRNA gene metabarcoding approaches demonstrated that B. velezensis MT9 reshapes the fish intestinal microbiota by reducing the amounts of opportunistic Gram-negative bacterial pathogens belonging to the phylum of Proteobacterium (Pseudomonadota) and increasing the amounts of beneficial bacteria belonging to the phyla Firmicutes (Bacillota) and Actinobacteria (Actinomycetota). Specifically, dietary supplementation of Nile tilapia with B. velezensis MT9 resulted in an increase in the relative abundance of bacteria of the genus Romboutsia, which has a well-documented probiotic activity, and a decrease in the relative abundance of Gammaproteobacteria of the genera Aeromonas and Vibrio, which include opportunistic pathogens for fish, and Escherichia/Shigella, which may pose a risk to consumers. The whole genome sequence of B. velezensis MT9 was then determined. Genome analysis revealed several peculiarities of B. velezensis MT9 compared to other B. velezensis reference strains including specific metabolic traits, differences in two-component and quorum sensing systems as well as the potential ability to produce a distinct array of secondary metabolites, which could explain the strong ability of this strain to modulate the intestinal microbiota of the Nile tilapia.

Inert media such as plastic, ceramic or zeolite are conventionally used for wastewater biofiltration. They all need microbial activation and are essentially chosen for their surface/mass ratio, since biofiltration is entirely performed within the surface biofilm. Using biodegradable media may enhance the sustainability of the system, but it should not produce decomposition-related pollutants. Due to their surface extension, peculiar microbiota and structural resistance, aquatic moss appears to be a very good support for biofilters. Thus, in this study, we evaluated aquatic moss mats as an alternative medium for biofiltration of aquaculture or aquaponic effluents. Two moss species, Taxiphyllum barbieri and Leptodictyum riparium, were tested, also for their contribution on nitrogen metabolism and potential negative effects on hydroponic plants cultivation, due to competition for nutrients. Our proof-of-concept research demonstrates equivalence in real conditions, as inert and moss media exhibited comparable rates; however, the amount of moss required can be several times lower than that of any competing media. Preliminary results suggest the possibility to integrate moss-based biofilters in aquaculture and aquaponics technologies.

The use of marine collagen for regenerative applications is rapidly expanding. Tilapia ( Oreochromis niloticus ) skin is an emerging byproduct of food industry and a valuable biomaterial known for its pro‐regenerative properties. Enhancing its intrinsic composition through nutritional strategies could further improve its clinical potential. This study investigates the impact of a hydrolyzed collagen‐enriched diet on the skin properties of aquaponically farmed Tilapia, with the aim of enhancing collagen content while preserving tissue homeostasis. The results showed a modulation of key amino acids and fatty acids, suggesting a favorable shift toward anti‐inflammatory and pro‐regenerative properties. A measurable increase in skin thickness and hydration was registered, as well as an ECM remodeling. No detrimental effects on mineral content or mechanical integrity were observed. These findings demonstrate that dietary supplementation with collagen can be an effective, non‐invasive, approach to improving the biomedical quality of fish‐derived skin products.