Bactericidal Action of Egg Yolk Phosvitin against Escherichia coli under Thermal Stress

• Published in: Journal of agricultural and food chemistry Vol. 48; no. 5; pp. 1503 - 1506
• Main Authors: Sattar Khan, M. A, Nakamura, Soichiro, Ogawa, Masahiro, Akita, Emmanuel, Azakami, Hiroyuki, Kato, Akio
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.05.2000
• Subjects: Animal, plant, fungal and microbial proteins, edible seaweeds and food yeasts; Biological and medical sciences; Food industries; Fundamental and applied biological sciences. Psychology; Egg yolk; Temperature; Escherichia coli; Emulsifier; External membrane; Biological activity; Phosvitin; Animal protein; Chelation; Surface properties; Bacteria; Antibacterial agent; Mechanism of action; Enterobacteriaceae
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf990700r

Chicken egg yolk phosvitin showed a remarkable antibacterial effect against Escherichia coli under thermal stress at 50 °C. E. coli cells (106/mL) completely disappeared in 1 mL of L-broth coexisting with 0.l mg/mL phosvitin when incubated at 50 °C for 20 min, whereas a considerable amount of cells (105/mL) survived at the same thermal stress without phosvitin. Blocking of the chelating effect of phosvitin by the addition of Ca2+ ion displayed a protective effect against the bactericidal activity at 50 °C. In addition, the antibacterial activity of phosvitin was dramatically reduced by treatment with α-chymotrypsin, although the chelating effect remained. The surface properties, such as interfacial tension and emulsifying properties of phosvitin, which are an index of the affinity with the outer membrane, were greatly reduced by the α-chymotrypsin digestion. This indicates that the α-chymotrypsin-digested membrane-penetrating hydrophobic domains at the N- and C-terminal regions play an important role in antibacterial activity. These results suggest that a significant part of the bactericidal activity of phosvitin against E. coli resides in the synergistic effect of the high metal-chelating ability and the high surface activity under the influence of thermal stress. Keywords: Egg yolk phosvitin; bactericidal effect; Escherichia coli; emulsifying activity; metal chelating effect