Antimicrobial activity of a porcine myeloperoxidase against plant pathogenic bacteria and fungi

Abstract

SO N . 1999. Porcine myeloperoxidase was evaluated for its antimicrobial activity against plant pathogenic bacteria and fungi. The results indicated that the enzyme, in the presence of a small amount of hydrogen peroxide, was effective against a broad spectrum of plant pathogens. The growth of seven bacterial species, including nine pathovars, from the genera Erwinia, Pseudomonas and Xanthomonas, was significantly inhibited by the enzyme at a concentration as low as 0·4 U ml, while 4·0 U ml −1 was lethal to all plant pathogenic bacteria examined. Myeloperoxidase, at 40 U ml −1 , was lethal to germinating spores from three isolates of the fungal plant pathogen Fusarium solani and two isolates from each of Colletotrichum gloeosporioides and C. malvarum. The enzyme's antifungal effects on the rice blast pathogen Magnaporthe grisea were studied both in vitro and on host plants. The enzyme significantly inhibited spore germination of two isolates of M. grisea races IC17 and IB49 at concentrations over 16 U ml −1 , and disintegration of fungal spore walls was caused by 80 U ml −1 . The enzyme was even more effective in reducing disease incidence of blast on young rice plants treated with 0·5 U ml −1 , while 2·5 U ml −1 resulted in complete inhibition of infection. These results support and further extend the suggestion that myeloperoxidase could be used as a broad-spectrum biocontrol agent or as a transgenically expressed protein to combat diseases caused by plant pathogenic bacteria and fungi.

Antimicrobial Property of Extracts of Indian Lichen against Human Pathogenic Bacteria

“…The reason for different sensitivity of bacteria can be found in different transparency of the cell wall [22]. The cell wall of the gram-positive bacteria consists of peptidoglycan (mureins) and teichoic acids; the cell wall of the gram-negative cells consists of lipopolysaccharides and lipoproteins [23, 24].…”

Enhanced Killing of Acanthamoeba Cysts with a Plant Peroxidase-Hydrogen Peroxide-Halide Antimicrobial System

“…This resulted in an increased rate of cysticidal activity and total killing of the cyst inocula by 2 h with 3% H 2 O 2 and by 4 h with 2% H 2 O 2 . The system also enabled a sublethal H 2 O 2 concentration (1%) to produce 3-log killing within 6 h. Furthermore, this finding indicates that the previously observed in vitro activity of the peroxidase-peroxide-halide system against pathogenic viruses, bacteria, fungi, and the helminth S. mansoni can be extended to include the pathogenic protozoan Acanthamoeba (10,11,13,15,16,24,28).…”

“…The primary agent involved is hypohalous acid, which destroys cells by halogenation and oxidation of cell surface components (14,17,23,28). It has been suggested that the peroxidase-peroxidehalide system acts preferentially against pathogenic rather than nonpathogenic organisms through binding to the cell surface; the target-bound peroxidase then catalyzes halide oxidation and facilitates the disproportionation of peroxide to singlet molecular oxygen at the surface of the target microbe (1, 2, 3).…”

“…Subsequently, it was demonstrated that this mechanism can be reproduced in vitro to obtain enhanced hydrogen peroxide killing of a variety of pathogenic microbes, including bacteria (10,13,15,24,25), fungi (28), human immunodeficiency virus type 1 (16), and the parasitic helminth Schistosoma mansoni (11). Peroxidases other than myeloperoxidase have been used, including eosinophil peroxidase (27), lactoperoxidase, horseradish peroxidase (HRP), and catalase (2,3,9,24).…”

“…In neutrophils, at least, the process is further enhanced by the action of a myeloperoxidase that forms hypochlorous acid (HOCl) from chloride ions and H 2 O 2 (17). The combination of H 2 O 2 and HOCl is a potent antimicrobial combination that destroys cells by halogenation and oxidation of cell surface components (14,17,23,28).…”