Mohamed H. El-Sayed, Abd El-Nasser A. Kobisi, Islam A. Elsehemy, and Mohamed A. El-Sakhawy. J. Microbiol. Biotechnol. 2023;33:607-20. https://doi.org/10.4014/jmb.2301.01001

Biosciences, Biotechnology Research Asia is an international, open access, peer reviewed research journal covering all aspects of Biosciences and Biotechnology field.

For a long time, nanoparticle biosynthetic discipline is still under development and is known to have a big impact on numerous manufactures. Synthesis of nanoparticles by green methods with antimicrobial properties is of great researchers concern in the explored of new pharmaceutical and biomedical products. In this study, synthesis of silver nanoparticles (AgNPs) have been carried out using aqueous extract of lemon peel (Citrus limon), which acts as encapsulating cage for the silver nanoparticles. Synthesized AgNPs was monitored by formation of brown color, confirmed by UV/VIS spectra, which showed appearance of a surface plasmon resonance (SPR) band. FT-IR analysis of the bioextract afterthe addition of silver solution showed strong bands at 1021, 1443, 1634 and 3428 cm−1. Transmission electron microscopy examination of the solution containing AgNPs demonstrated spherical particles within nanoranged from 9.3 nm to 20.3 nm with the main diameter of 15.76 nm. The biologically synthesized AgNPs showed a promising antimicrobial activity, where the maximal growth inhibition was recorded for both Pseudomonas (P.) aeruginosa and Escherichia (E.) coli – 21.5 ± 1.3 and 19.0 ± 0.20 mm, respectively. While the minimum growth inhibition was recorded for Gram positive bacteria Bacillus subtilis (B.) and Staphylococcus (S.) aureus – 15.0 ± 0.20 and 16.5 ± 1.50 mm, respectively. At the same time weak antifungal activity was observed for both Aspergillus (A.) flavus and Candida (C.) albicans – 14.0 ± 0.15 and 12.5 ± 0.45 mm, respectively.

Antimicrobial resistance is a subject of great concern in the public health. The prevalence of antimicrobial resistance among food pathogens has increased during recent decades. Studying the incidence and antibiotic resistance pattern of bacterial species isolated from fish and vended street fruits. Eleven fish swabs and thirteen sliced fruit samples were collected and prepared for isolation of bacterial species through inoculation onto selective and non-selective nutrient media. The grown colonies were purified through subculturing on nutrient agar plates then identified by morphological and biochemical methods. The obtained pure cultures were then kept on nutrient agar slants. Testing antibiotic resistance of the isolated bacterial strains was studied by Kirby-Bauer disk diffusion method on Mueller Hinton agar using ten antibiotics belonging to different classes. The resultant inhibition zone was interpreted according to Clinical Laboratory Standard Institute. Twenty-eight bacterial cultures were isolated from the collected food samples. The conventional identification using morphological and biochemical methods of these cultures revealed presence of three Gram positive species; Staphylococcus aureus, Streptococcus sp. and Bacillus subtilis in addition to four Gram negative; Escherichia coli, Brucella sp., Enterococcus faecalis and Proteus mirabilis. The incidence of the obtained bacterial species was arranged as 29.16% for both S. aureus and E. faecalis followed by Brucella sp. 16.66%; B. subtilis & E. coli 12.5% then Streptococcus sp. and P. mirabilis with an incidence of 8.33% each. Testing antibiotic resistance pattern of seven bacterial species against ten antibiotics showed that, among three Gram positive bacterial species, only one (33.33%) strain S. aureus exhibited resistance to six antibiotics; amoxicillin, erythromycin, ciprofloxacin, ceftriaxone, fluconazole and dicloxacillin. Among four Gram negative bacterial strains only one (25.0%) strain Enterococcus faecalis exhibited resistance to eight antibiotics; amoxicillin, streptomycin, chloramphenicol, cotrimoxazole, ciprofloxacin, ofloxacin, sparfloxacin and cloxacillin. Occurrence of multi-drug resistant bacteria in fish and vended street fruits poses not only risk of disease to the foods but public health hazard to food handlers and consumers in general. Also the result of this study recommended augmentin and cephazolin as good choice antibiotics for treatment of infection in the study area.