1. Field of the Invention
The present invention relates to an inhibitor against bio-film formation of Listeria monocytogenes on abiotic or biotic surfaces.
2. Description of the Related Art
Microorganisms can attach to various surfaces and produce a biofilm, which is an aggregate of microorganisms in which cells adhere to each other and/or to an abiotic or biotic surface. Numerous studies have reported that biofilms include a complex multicellular structure; the mass of microcolonies in a single layer or with vertical and horizontal channels allows liquid flow and dispersion of nutrients and waste components.
According to the World Health Organization (2000), Listeria monocytogenes is one of the major food-related microorganisms causing foodborne diseases. This bacterium can adhere to the inert surfaces found in the food-processing environment. Its bio-film is a potential, chronic source of microbial contamination, which may compromise the food quality and pose a significant health hazard. Therefore, greater understanding of the interaction between microorganisms and food-processing surfaces is required.
The adhesion of L. monocytogenes to food-processing surfaces influences the hydrophobic interactions between the surface material and the outer surface components of the bacterium, rather than being a specific ligand-receptor process. Several researchers have suggested that flagella play a major role in the initial adhesion of higher numbers of L. monocytogenes cells to glass and stainless steel compared with nonmotile cells. In L. monocytogenes, flagella biosynthesis is dependent on temperature and regulated by a distinctly different mechanism from the well-described hierarchical regulation of gram-negative bacteria. Thus, at the mammalian host physiologic temperature of 37° C., most L. monocytogenes strains do not produce flagella and are nonmotile, because of MogR-induced repression of flagellar gene transcription at this temperature. In contrast, at 30° C. and below, the bacterium is motile because MogR is inhibited by its antirepressor, GmaR, permitting flagellar gene transcription. Therefore, L. monocytogenes strains have variable abilities to produce biofilms depending on their growth conditions.
As one of the methods for inhibiting bio-film formation, pretreatment of surfaces with protein has been shown to result in lower numbers of adhering microorganisms. Over the past decade, several strategies for preventing microorganism adhesion and biofilm formation on surfaces have been proposed. Most of them focus on surface modification to inhibit adhesion by adsorption of antimicrobial proteins or compounds such as nisin, lysozyme, benzalkonium chloride, silver, or chlorhexidine.
Moreover, L. monocytogenes causes commonly called listeriosis, serious illness, including meningitis, septicemia and stillbirth, with a mortality rate of up to 30%. Listeriosis generally affects the elderly, neonates, pregnant and immune-compromised people. This microorganism often found in food elsewhere in nature having been isolated from a variety of sources including soil, vegetation, silage, fecal material, sewage, water, and in the intestines of healthy animals, including humans. Four serotypes (4b, ½a, ½b, and ½c) among 13 known serotypes have been isolated from a wide range of foods. Three of these serotypes (4b, ½a, and ½b) are associated with the majority of human listeriosis. Recently, numerous outbreaks of febrile gastroenteritis have also been reported in healthy persons who ingested L. monocytogenes contaminated cheese or delicatessen meat. Symptoms of the febrile gastroenteritis are diarrhea, fever, headache, stomach cramps, and vomiting. However, patho/physiological features or the factors that influence the infectious dose and the occurrence and course of infection still need to be clarified.