CHARACTERIZATION AND GENOMIC ANALYSIS OF TWO ESCHERICHIA COLI O157:H7 BACTERIOPHAGES ISOLATED FROM PIGEONS

Enterohemorrhagic Escherichia coli, also known as EHEC, is a subset of Shiga toxin-producing E. coli (STEC), and it has recently been identified as one of the principal foodborne pathogens. E. coli O157:H7 is the most important serotype of STEC for its role in causing foodborne illnesses. E. coli O157:H7 could cause various gastroenteritis symptoms such as diarrhea, hemolytic uremic syndrome, hemorrhagic colitis, and thrombotic thrombocytopenic purpura and may cause death. Elimination of E. coli O157:H7 during food processing and storage is a possible solution. Bacteriophages have a significant impact on bacterial populations in nature due to their ability to lyse their bacterial host. All E. coli O157:H7 phages that have been previously announced were found in ruminants or swine. Here, I studied the characterization and genomic analysis of two lytic E. coli O157:H7 bacteriophages isolated from feaces of wild pigeon; UAE MI- 01 and Ec_MI-02. This is the first time to report E. coli O157:H7 phages from birds feaces. UAE_MI-01 belonged to the family Siphoviridae in order Caudovirales. UAE_MI-01 had a with a burst size of almost 100 plaque-forming units (PFU) per host cell after a latent period of 20 min and an adsorption rate constant (K) of 1.25 × 10−7 mL/min. UAE_MI-01 was found stable at a wide range of temperature, pH and some of the common laboratory disinfectants. The 44,281 bp-long genomes of the phage had an average GC content of 54.7%. On the other hand, Ec_MI-02 belonged to genus Tequatrovirus in the order Caudovirales. The K value of Ec_MI-02 was found to be 1.55 × 10−8 mL/min. The latent period was almost 50 min with burst size of almost 10 PFU /host cell. Ec_MI-02 was stable at a wide range of pH, and temperature and was resistant to ethanol 70%. Its genome was made of 266 genes with total 165454 bp and average GC content of 35.5%. It is worthy of note that wherever the phage is present, the host cell must be present. Thus, if the bacteriophage of E. coli O157:H7 is present in the feaces of a wild bird, then the E. coli O157:H7, is most probably present in wild birds. The current study provides additional evidence that wild birds could also be a good natural reservoir for bacteriophages and could be good candidates for phage therapy. Studying the genetic makeup of bacteriophages that infect human pathogens is crucial for ensuring their safe usage in the food industry

Data_Sheet_1_Green nanotechnology for controlling bacterial load and heavy metal accumulation in Nile tilapia fish using biological selenium nanoparticles biosynthesized by Bacillus subtilis AS12.pdf

Heavy metal accumulation and pathogenic bacteria cause adverse effects on aquaculture. The active surface of selenium (Se) nanoparticles can mitigate these effects. The present study used Se-resistant Bacillus subtilis AS12 to fabricate biological Se nanoparticles (Bio-SeNPs). The double-edged Bio-SeNPs were tested for their ability to reduce the harmful effects of heavy metals and bacterial load in Nile tilapia (Oreochromis niloticus) and their respective influences on fish growth, behavior, and health. The Bio-SeNPs have a spherical shape with an average size of 77 nm and high flavonoids and phenolic content (0.7 and 1.9 g g−1 quercetin and gallic acid equivalents, respectively), resulting in considerable antioxidant and antibacterial activity. The Bio-SeNPs (3–5 μg ml−1) in the current study resolved two serious issues facing the aquaculture industry, firstly, the population of pathogenic bacteria, especially Aeromonas hydrophilia, which was reduced by 28–45% in fish organs. Secondly, heavy metals (Cd and Hg) at two levels (1 and 2 μg ml−1) were reduced by 50–87% and 57–73% in response to Bio-SeNPs (3–5 μg ml−1). Thus, liver function parameters were reduced, and inner immunity was enhanced. The application of Bio-SeNPs (3–5 μg ml−1) improved fish gut health, growth, and behavior, resulting in fish higher weight gain by 36–52% and a 40% specific growth rate, compared to controls. Furthermore, feeding and arousal times increased by 20–22% and 28–53%, respectively, while aggression time decreased by 78% compared to the control by the same treatment. In conclusion, Bio-SeNPs can mitigate the accumulation of heavy metals and reduce the bacterial load in a concentration-dependent manner, either in the fish media or fish organs.</p