DE4326617C1 - Use of enzymatically active proteins, specific for cell wall lysis of Listeria - Google Patents

Abstract

Enzymatically active proteins, causing cell wall lysis, formed by bacteriophages of the genus Listeria during expression of late genes (phagolysine) are used for the selective control/decontamination of pathogenic bacteria of genus KListeria (Listeria monocytogenes) in and on food during prepn. and storage. The phagolysine compsn. contg. one or more phagolysines, is applied during or after the prodn. or in the food prodn. plant.

Description

1. Name of the invention

Selective control procedures Listeria monocytogenes in food Phagolysins from Listeriaphagen

2. Field of the Invention

A well-known problem of food hygiene is that Infestation of various foods with the human pathogenic Listeria monocytogenes bacterium. If immunodeficient People (sick or elderly, pregnant women) serious diseases can result in death result result.

3. State of the art

As a countermeasure, it has been suggested the food Chicken egg lysozyme (magazine "Applied and Environ mental microbiology ", year 55, 1989, pages 631-638) or bacteriocins produced by other bacteria (magazine "Applied and Environmental Microbiology", year 54, 1988, Pages 2349-2353) for the control or inhibition of Listeria to use in food. All previously proposed However, procedures have failed because of the additives biological or chemical nature have the disadvantage that not only Listeria, but also many or even everyone else Bacteria in the treated products are damaged or killed become. This is particularly disadvantageous when using starter cultures manufactured foods such as cheese or permeate; but these are particularly vulnerable to Listeria. That in The following described method does not have these disadvantages on.

4. Description of the invention

In total, numerous Listeriaphagen have been described, including numerous own isolates, especially the only one  virulent Listeriaphage A511 with extraordinarily wide host area from my laboratory. Listeriaphagen inject their DNA into Listeria host cells. To complete the infection after the infection to release the newly formed Listeriaphagen to the host cell as the final gene product during the expression of the late Phage genes formed a cell wall lytic enzyme (phagolysin). The Listeriaphagen phagolysins are specifically active against Cell walls of bacteria of the genus Listeria, as in ent speaking experiments has been demonstrated. Even the external one Add purified lysozyme in very low concentrations Listeria leads to their lysis and thus to cell death (bacterio zide effect). The preparation on which these experiments are based ration and characterization of phagolysin from Listeriaphagen as well as the started characterization of the associated Listeriaphagengenome has not been published anywhere.

By adding, adding, surface treatment to, in and of food as well as in food production was by means of the specifically effective phagolysins achieve selective elimination of listeria without to affect other (desired) organisms. Furthermore may have another effect / activity of lysine in any Way to be excluded. So that phagolysins are as life qualified additives. The phagolysin can be in one standardized form in the raw materials of endangered food introduced before or during given production steps Food or plant added, the finished end product added or applied to contaminate the dispensed food with human pathogenic listeria fight.

5. Production of the phagolysin preparations

The biochemical isolation was through to purity led and the phagolysin in o.a. Way tested. Off with Listeria cells infected with Listeria can be diagnosed with the method tested to obtain phagolysin. You can also use this process phagolysin from recombinant, the phagolysin Genes containing Escherichia coli strains can be prepared. For this purpose, the genes encoding the phagolysin from the genomes of Listeriaphagen isolated and in expression vectors in the Escherichia coli bacterium subcloned. The Synthesis of proteins using such expression vectors can be found in high yield in E. coli.  

6. Commercial use

Production and sale of phagolysin preparations Food manufacturers. So far there is no alternative to this procedure for selective control of Listeria in Food.

7th embodiment

For the production of soft cheese of the type "red smear cheese ", which is often contaminated with listeria Kettle milk for lactic acid formation and thickening with Acidification cultures offset. Because of the already happening here The addition of phagolysins can already in the milk or the Starter culture existing listeria can be removed. in the A further course of cheese making is repeated Surface red smear culture applied to the cheese, which may be contaminated with listeria. A simultaneous Application of the phagolysins is prevented at this time effective the development of pathogenic organisms. Frequently the contamination is also due to poor storage and ripening conditions, with listeria getting on the cheese. The presence of phagolysins on the cheese surfaces would counteract this recontamination. Since the Enzymes a very specific, only against Listeria have a directed activity spectrum and no foreign have activities is the development of the desired red smear flora not hindered. The uptake of phagolysins by eating the cheese is therefore also complete harmless.

Claims (1)

Use of cell wall lytic, enzymatically active Proteins, which are caused by bacteriophages of the genus Listeria are formed during expression of the late genes (Phagolysins), for the selective control / decontamination of pathogenic bacteria of the genus Listeria (Listeria monocytogenes) in and on foods during their Manufacturing and storage, the Phagolysin preparations containing one or more phagolysins may contain the food during or after the Manufactured added or in the food production plant be introduced.