Mahmoud Saleh Mahmoud Mohamed

Fish products are essential sources of animal proteins and numerous nutrients required for healthy human nutrition worldwide. However, some types of low-priced fish may look very similar to some other expensive types, and usually, it is not easy to differentiate between them for inexperienced customers. Moreover, in some markets, adulterating such high-priced fish types through its substitution by cheaper ones or mixing with bacterially spoiled ones, mostly when sold as fish fillets, is sometimes common. Certainly, fish microbial contamination in open markets represents serious hazards for people’s public health. Accordingly, seeking easy and fast fish fraud detection methods and their microbial contamination disclosure is crucial. Currently, available techniques are costly, time-consuming, and requiring special laboratories. In the present work, laser-induced fluorescence (LIF), as a spectrochemical analytical technique and diffuse optical measurements, has been used to discriminate between fillets of low-priced Tilapia and expensive Nile Perch and disclose microbial contamination in any. The experimental data have been analyzed and evaluated using the principal component analysis (PCA), partial least square regression (PLSR), and receiver operatic characteristic (ROC) methods. The results demonstrated the high advantages of optical and spectrochemical techniques in the fast and accurate discrimination between the two fish species. Moreover, LIF spectral band obtained at 490 nm showed a difference in microbial load between both species. © 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.

The search for effective and bioactive antimicrobial molecules to  encounter the medical need for new antibiotics is an encouraging area of research. Plant defensins are small cationic, cysteine-rich peptides with a stabilized tertiary structure by disulfide-bridges and characterized by a wide range of biological functions. The heterologous expression of Egyptian maize defensin (MzDef) in Escherichia coli and subsequent purification by glutathione affinity chromatography yielded 2 mg/L of recombinant defensin peptide. The glutathione-S-transferase (GST)-tagged MzDef of approximately 30 kDa in size (26 KDa GST +  ~ 4 KDa MzDef peptide) was immunodetected with anti-GST antibodies. The GST-tag was successfully cleaved from the MzDef peptide by thrombin, and the removal was validated by the Tris-Tricine gel electrophoresis. The MzDef induced strong growth inhibition of Rhizoctonia solani, Fusarium verticillioides, and Aspergillus niger by 94.23%, 93.34%, and 86.25%, respectively, whereas relatively weak growth inhibitory activity of 35.42% against Fusarium solani was recorded. Moreover, strong antibacterial activities were demonstrated against E. coli and Bacillus cereus and the moderate activities against Salmonella enterica and Staphylococcus aureus at all tested concentrations (0.1, 0.2, 0.4, 0.8, 1.6, and 3.2 µM). Furthermore, the in vitro MTT assay exhibited promising anticancer activity against all tested cell lines (hepatocellular carcinoma, mammary gland breast cancer, and colorectal carcinoma colon cancer) with IC50 values ranging from 14.85 to 29.85 µg/mL. These results suggest that the recombinant peptide MzDef may serve as a potential alternative antimicrobial and anticancer agent to be used in medicinal application.