The oxidative stress facing fish during intensive production brings about diseases and mortalities that negatively influence their performance. Along with that, the increased awareness of omega-3 polyunsaturated fatty acids (omega-3-PUFAs) health benefits has been triggered the introduction of alternative additives in aqua feed that cause not only modulation in fish immune response but also fortification of their fillet. In this context, the role of microalgae mix (NSS) containing Nannochloropsis oculate and Schizochytrium and Spirulina species, which were enriched with bioactive molecules, especially EPA and DHA, was assessed on Nile tilapia’s performance, fillet antioxidant stability, immune response, and disease resistance. Varying levels of NSS (0.75%, 1.5%, and 3%) were added to Nile tilapia’s diet for 12 weeks and then a challenge of fish with virulent Aeromonas hydrophila (A. hydrophila) was carried out. Results showed that groups fed NSS, especially at higher levels, showed an improved WG and FCR, which corresponded with enhanced digestive enzymes’ activities. Higher T-AOC was detected in muscle tissues of NSS_3.0% fed fish with remarkable reduction in ROS, H₂O₂, and MDA contents, which came in parallel with upregulation of GSH-Px, CAT, and SOD genes. Notably, the contents of EPA and DHA in fillet were significantly increased with increasing the NSS levels. The mean log₁₀ counts of pathogenic Vibrio and Staphylococcus species were reduced, and conversely, the populations of beneficial Lactobacillus and Bacillus species were increased more eminent after supplementation of NSS_3.0% and NSS_1.5%. Moreover, regulation of the immune response (lysozyme, IgM, ACH50, NO, and MPO), upregulation of IL-10, TGF-β, and IgM, and downregulation of IL-1β, TNF-α, HSP70, and COX-2 were observed following dietary higher NSS levels. After challenge, reduction in A. hydrophila counts was more prominent, especially in NSS_3.0% supplemented group. Taken together, the current study encourages the incorporation of such microalgae mix in Nile tilapia’s diet for targeting maximum performance, superior fillet quality, and protection against A. hydrophila.

Malachite green (MG) dye is a common environmental pollutant that threatens human health and the integrity of the Earth’s ecosystem. The aim of this study was to investigate the potential biodegradation of MG dye by actinomycetes species isolated from planted soil near an industrial water effluent in Cairo, Egypt. The Streptomyces isolate St 45 was selected according to its high efficiency for laccase production. It was identified as S. exfoliatus based on phenotype and 16S rRNA molecular analysis and was deposited in the NCBI GenBank with the gene accession number OL720220. Its growth kinetics were studied during an incubation time of 144 h, during which the growth rate was 0.4232 (µ/h), the duplication time (td) was 1.64 d, and multiplication rate (MR) was 0.61 h, with an MG decolorization value of 96% after 120 h of incubation at 25 °C. Eleven physical and nutritional factors (mannitol, frying oil waste, MgSO₄, NH₄NO₃, NH₄Cl, dye concentration, pH, agitation, temperature, inoculum size, and incubation time) were screened for significance in the biodegradation of MG by S. exfoliatus using PBD. Out of the eleven factors screened in PBD, five (dye concentration, frying oil waste, MgSO₄, inoculum size, and pH) were shown to be significant in the decolorization process. Central composite design (CCD) was applied to optimize the biodegradation of MG. Maximum decolorization was attained using the following optimal conditions: food oil waste, 7.5 mL/L; MgSO₄, 0.35 g/L; dye concentration, 0.04 g/L; pH, 4.0; and inoculum size, 12.5%. The products from the degradation of MG by S. exfoliatus were characterized using high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS). The results revealed the presence of several compounds, including leuco-malachite green, di(tert-butyl)(2-phenylethoxy) silane, 1,3-benzenedicarboxylic acid, bis(2-ethylhexyl) ester, 1,4-benzenedicarboxylic acid, bis(2-ethylhexyl) ester, 1,2-benzenedicarboxylic acid, di-n-octyl phthalate, and 1,2-benzenedicarboxylic acid, dioctyl ester. Moreover, the phytotoxicity, microbial toxicity, and cytotoxicity tests confirmed that the byproducts of MG degradation were not toxic to plants, microbes, or human cells. The results of this work implicate S. exfoliatus as a novel strain for MG biodegradation in different environments.

A critical milestone in nano-biotechnology is establishing reliable and ecological friendly methods for fabricating metal oxide NPs. Because of their great biodegradable, electrical, mechanical, and optical qualities, zirconia NPs (ZrO2NPs) attract much interest among all zirconia NPs (ZrO2NPs). Zirconium oxide (ZrO2) has piqued the interest of researchers throughout the world, particularly since the development of methods for the manufacture of nano-sized particles. An extensive study into the creation of nanoparticles utilizing various synthetic techniques and their potential uses has been stimulated by their high luminous efficiency, wide bandgap, and high exciton binding energy. Zirconium dioxide nanoparticles may be used as antimicrobial and anticancer agents in food packaging. In response to the growing interest in nano ZrO2, researchers invented and developed methods for synthesizing nanoparticles. ZrO2 nanocomposites with various morphologies have recently been created using biological (green chemistry) methods. Microbes and plants both contribute to the production of zirconia in the laboratory. Capping and stabilizing agents are provided by the biomolecules found in plant extracts, whereas microorganisms provide enzymes as capping and stabilizing agents (intracellular or extracellular). It is possible to analyze the nanoparticles produced using a variety of analytical approaches, including ultraviolet-visible spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FT-IR). When applied to bacteria (both Gram-positive and Gram-negative) and fungi, ZrO2NPs show promising antibacterial capabilities. Normal and malignant cells are sensitive to ZrO2 nanoparticles, which can be explained by the generation of reactive oxygen (ROS). This work discusses and describes many ways of producing ZrO2 nanoparticles, their properties, and various application possibilities.

Fusarium oxysporum is one of the most harmful soil-borne pathogens that cause root rot, damping-off, and wilt disease in many plant species. Management of Fusarium oxysporum diseases is often by using many harmful and expensive chemical fungicides which have many harmful effects on the environment and human health. The current study was conducted to identify the chemical constituents of black cumin seeds’ methanolic extract and investigate the ability of the major constituents to inhibit the Fusarium oxysporum trypsin-like serine protease, which play an important role in F. oxysporun pathogenicity. The HPLC-MS analysis of black cumin seeds’ methanolic extract revealed the presence of seven major compounds: amentoflavone, Procyanidin C2, Quercetin3-O-sophoroside-7-O-rhamnoside, 5,7-Dihydroxy-3,4-dimethoxyflavone, Borapetoside A, tetrahydroxy-urs-12-en-28-O-[b-D-glucopyranosyl (1-2)-b-D-glucopyranosyl] ester, and kudzusapongenol A-hexA-pen. The results of molecular docking between these compounds and the active site of Fusarium oxysporium trypsin showed that only four compounds were able to bind to the active site of F. oxysporum trypsin. Amentoflavone, 5,7-Dihydroxy-3,4-dimethoxyflavone, and Quercetin3-O-sophoroside-7-O-rhamnoside have the highest binding energy, −6.4, −6.5, and −6.5 Kcal/mol, respectively. In addition, the results clarify that 5,7-Dihydroxy-3,4-dimethoxyflavone was the only compound to form a hydrogen bond with Asp189 (the residue responsible for substrate specificity). The results of the study strongly indicate that flavonoids of black cumin seeds’ methanolic extract could be used as effective inhibitors for the F. oxysporum trypsin-like serine protease.