Food waste-based pellets for feeding grass carp (Ctenopharyngodon idellus): Adding baker's yeast and enzymes to enhance growth and immunity

The application of protease in aquaculture: Prospects for enhancing the aquafeed industry

Low-fishmeal and protein-saving diets are two prominent nutritional strategies utilized to address challenges related to the scarcity and sustainability of protein sources in aquaculture. However, these diets have been associated with adverse effects on the growth performance, feed utilization, and disease resistance of aquatic animals. To mitigate these challenges, exogenous protease has been applied to enhance the quality of diets with lower protein contents or fishmeal alternatives, thereby improving the bioavailability of nutritional ingredients. Additionally, protease preparations were also used to enzymatically hydrolyze fishmeal alternatives, thus enhancing their nutritional utilization. The present review aims to consolidate recent research progress on the use of protease in aquaculture and conclude the benefits and limitations of its application, thereby providing a comprehensive understanding of the subject and identifying opportunities for future research.

Debaryomyces hansenii supplementation in low fish meal diets promotes growth, modulates microbiota and enhances intestinal condition in juvenile marine fish

BACKGROUND

The development of a sustainable business model with social acceptance, makes necessary to develop new strategies to guarantee the growth, health, and well-being of farmed animals. Debaryomyces hansenii is a yeast species that can be used as a probiotic in aquaculture due to its capacity to i) promote cell proliferation and differentiation, ii) have immunostimulatory effects, iii) modulate gut microbiota, and/or iv) enhance the digestive function. To provide inside into the effects of D. hansenii on juveniles of gilthead seabream (Sparus aurata) condition, we integrated the evaluation of the main key performance indicators coupled with the integrative analysis of the intestine condition, through histological and microbiota state, and its transcriptomic profiling.

RESULTS

After 70 days of a nutritional trial in which a diet with low levels of fishmeal (7%) was supplemented with 1.1% of D. hansenii (17.2 × 10⁵ CFU), an increase of ca. 12% in somatic growth was observed together with an improvement in feed conversion in fish fed a yeast-supplemented diet. In terms of intestinal condition, this probiotic modulated gut microbiota without affecting the intestine cell organization, whereas an increase in the staining intensity of mucins rich in carboxylated and weakly sulphated glycoconjugates coupled with changes in the affinity for certain lectins were noted in goblet cells. Changes in microbiota were characterized by the reduction in abundance of several groups of Proteobacteria, especially those characterized as opportunistic groups. The microarrays-based transcriptomic analysis found 232 differential expressed genes in the anterior-mid intestine of S. aurata, that were mostly related to metabolic, antioxidant, immune, and symbiotic processes.

CONCLUSIONS

Dietary administration of D. hansenii enhanced somatic growth and improved feed efficiency parameters, results that were coupled to an improvement of intestinal condition as histochemical and transcriptomic tools indicated. This probiotic yeast stimulated host-microbiota interactions without altering the intestinal cell organization nor generating dysbiosis, which demonstrated its safety as a feed additive. At the transcriptomic level, D. hansenii promoted metabolic pathways, mainly protein-related, sphingolipid, and thymidylate pathways, in addition to enhance antioxidant-related intestinal mechanisms, and to regulate sentinel immune processes, potentiating the defensive capacity meanwhile maintaining the homeostatic status of the intestine.

Growth Performance, Feed Utilisation, Endogenous Digestive Enzymes, Intestinal Morphology, and Antimicrobial Effect of Pacific White Shrimp (Litopenaeus vannamei) Fed with Feed Supplemented with Pineapple Waste Crude Extract as a Functional Feed Additive

This study used pineapple waste crude extract (PWCE) to increase the potential of Pacific white shrimp (Litopenaeus vannamei) production for food sustainability and stability. The objective was to investigate the appropriate technique to increase the yield production and quality of shrimp and decrease waste from shrimp culture. Pacific white shrimp (average body size: 0.51 g) were fed with commercial feed supplemented with PWCE at various concentrations of 0 (control), 90, 170, and 250 ppt. Shrimp were fed five times per day for 80 days. At the end of the trial, the results showed that shrimp fed with the PWCE 250 ppt supplementation provided the highest growth rate and the best feed utilisation and yield (P < 0.05). The protein content of whole shrimp in all shrimp fed with the PWCE supplementation diet was higher than that in the control group (P < 0.05). On the contrary, the variation of endogenous digestive enzymes, including protease, trypsin, and the T/C ratio, was significantly lower in shrimp fed a diet supplemented with PWCE 250 ppt (P < 0.05). While in this group, the number of microorganisms on thiosulfate-citrate-bile salt-sucrose (TCBS), blood agar, and trypticase soy agar (TSA) was lowest (P < 0.05). Furthermore, the dietary PWCE at 250 ppt increased the volume of microvilli in the hindgut of shrimp, but the supplementation at 170 ppt improved the number of F-cells in the epithelial cells of the hepatopancreas. Nevertheless, the supplementation of PWCE in the diet did not affect the water quality (P > 0.05). Therefore, pineapple waste crude extract supplementation improves both quantitative and qualitative yields and tends to reduce waste.

Valorization of Food Waste to Produce Value-Added Products Based on Its Bioactive Compounds

The rapid growth of the global population and changes in lifestyle have led to a significant increase in food waste from various industrial, agricultural, and household sources. Nearly one-third of the food produced annually is wasted, resulting in severe resource depletion. Food waste contains rich organic matter, which, if not managed properly, can pose a serious threat to the environment and human health, making the proper disposal of food waste an urgent global issue. However, various types of food waste, such as waste from fruit, vegetables, grains, and other food production and processing, contain important bioactive compounds, such as polyphenols, dietary fiber, proteins, lipids, vitamins, organic acids, and minerals, some of which are found in greater quantities in the discarded parts than in the parts accepted by the market. These bioactive compounds offer the potential to convert food waste into value-added products, and fields including nutritional foods, bioplastics, bioenergy, biosurfactants, biofertilizers, and single cell proteins have welcomed food waste as a novel source. This review reveals the latest insights into the various sources of food waste and the potential of utilizing bioactive compounds to convert it into value-added products, thus enhancing people’s confidence in better utilizing and managing food waste.

Can Agri-Food Waste Be a Sustainable Alternative in Aquaculture? A Bibliometric and Meta-Analytic Study on Growth Performance, Innate Immune System, and Antioxidant Defenses

The agri-food industry generates a large amount of waste every year, which is both an environmental and economic problem, especially for the countries in charge of its disposal. Over the years, there has been a growing interest especially in plant waste, since they are rich in compounds with high nutritional and nutraceutical value. As a result, several scientific disciplines are investigating their alternative use in the formulation of dietary supplements for human or animal use, or as biostimulants for agricultural purposes. In this review, using a meta-analytical approach, we summarize the main and most recent findings related to the use of plant waste as potential ingredients in dietary supplementation for fish grown under controlled experimental conditions. In particular, in this review, it has been highlighted that plant waste may have not only positive effects on growth performance, but also beneficial effects on modulation of the innate immune system and antioxidant defenses. Finally, the bibliometric study and a mapping provide an overview of the recent publications, showing the research strength across the country, the number of potential collaborations among institutions, and the main research focus, demonstrating how this topic is growing in interest, especially in Europe.

CQDs/ZnO composites based on waste rice noodles: preparation and photocatalytic capability

To provide a low-cost photocatalyst and new methodology for the utilization of waste rice noodle (WRN), a carbon quantum dots/zinc oxide (CQDs/ZnO) composite using WRN as the raw material was synthesized and characterized. The CQDs/ZnO composite based on WRN exhibited a highly efficient photocatalytic degradation effect on various organic pollutants and could be a good alternative for commercial ZnO. For methylene blue, the CQDs/ZnO composite showed a good degradation rate of 99.58% within 40 min, a high degradation rate constant of 0.2630 min⁻¹, and could be recycled and reused for ten photocatalytic cycles without an appreciable decrease in the degradation effect, which was much better than that of commercial ZnO. The resulting CQDs/ZnO composite also displayed a nice photocatalytic degradation effect on other common organic pollutants, such as malachite green, methyl violet, basic fuchsin, rhodamine B, aniline and tetracycline. In particular, it could achieve excellent photocatalytic degradation on malachite green with an extremely high degradation rate constant of 1.9260 min⁻¹. Besides, the CQDs/ZnO composite could also be used to control the pollution of tetracycline or aniline. The introduction of CQDs based on WRN to ZnO resulted in efficient electron–hole pair separation and enabled more photogenerated electrons to reduce O₂ and more photogenerated holes to oxidize H₂O, which caused stronger abilities in producing radicals (such as O₂˙⁻ and ˙OH) and a better photocatalytic degradation effect to organic pollutants.

A CQDs/ZnO composite based on waste rice noodles displayed a highly efficient photocatalytic degradation effect on various organic pollutants.

Nano-scale applications in aquaculture: Opportunities for improved production and disease control

Aquaculture is the fastest growing food-production sector and is vital to food security, habitat restoration and endangered species conservation. One of the continued challenges to the industry is our ability to manage aquatic disease agents that can rapidly decimate operations and are a constant threat to sustainability. Such threats also evolve as microbes acquire resistance and/or new pathogens emerge. The advent of nanotechnology has transformed our approach to fisheries disease management with advances in water disinfection, food conversion, fish health and management systems. In this review, several nano-enabled technology successes will be discussed as they relate to the challenges associated with disease management in the aquaculture sector, with a particular focus on fishes. Future perspectives on how nanotechnology can offer functional approaches for improving disinfection and innovating at the practical space of early warning systems will be discussed. Finally, the importance of "safety by design" approaches to the development of novel commercial nano-enabled products will be emphasized.