Molecular Characterization and Evaluation of The Antimicrobial Activity of Phenoloxidase Purified from Spodoptera littoralis against Different Array of Pathogenic Bacteria

Document Type : Original Article


1 Department of Entomology, Faculty of Science, Ain Shams University, Cairo11566, Egypt

2 Ain Shams University Specialized Hospital. Infectious Control Unit, Cairo, Egypt

3 Molecular Biology Department, Genetic Engineering and Biotechnology Research Institute, Sadat City University, Sadat City, Egypt, 32897 - Genetics Department, Faculty of Agriculture, Beni-Suef University, Beni-Suef, Egypt, 62511


Phenoloxidase (PO) is an important enzyme for various insect processes, such as defensive encapsulation and melanization of foreign organisms as well as wound healing. Here, we characterize phenoloxidase extracted from the hemolymph of the cotton leaf worm, Spodoptera littoralis, for the first time. We obtained a cDNA sequence of 600 bp as a new record, which has elevated homology with known PO sequences of other lepidopterous insects. Moreover, we evaluated the antibacterial activity of PO induced by synthesized antimicrobial peptides (AMPs) against Gram-positive Staphylococcus aureus and Enterococci,and Gram-negative Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii, and Klebsiella pneumonia. Standardized concentrations (0.5 McFarland) of bacterial suspensions were used. The highest antibacterial activity expressed as the “growth-inhibition zone,” was 2.0 ± 0.2 Cm observed against Staphylococcus. For the Gram-negative bacteria, a growth-inhibition zone (1.5 ± 0.15 Cm) was observed only for E. coli. Based on these results, future studies evaluating the effect of AMPs compared with existing antibiotics are warranted.