Modified Lysozymes as Novel Broad Spectrum Natural Antimicrobial Agents in Foods

Abstract

In recent years much attention and interest have been directed toward application of natural antimicrobial agents in foods. Some naturally occurring proteins such as lactoperoxidase, lactoferrin, and lysozyme have received considerable attention and are being considered as potential antimicrobial agents in foods. Lysozyme kills bacteria by hydrolyzing the peptidoglycan layer of the cell wall of certain bacterial species, hence its application as a natural antimicrobial agent has been suggested. However, limitations in the action of lysozyme against only Gram-positive bacteria have prompted scientists to extend the antimicrobial effects of lysozyme by several types of chemical modifications. During the last 2 decades extensive research has been directed toward modification of lysozyme in order to improve its antimicrobial properties. This review will report on the latest information available on lysozyme modifications and examine the applicability of the modified lysozymes in controlling growth of Gram-positive and Gram-negative bacteria in foods. The results of modifications of lysozyme using its conjugation with different small molecule, polysaccharides, as well as modifications using proteolytic enzymes will be reviewed. These types of modifications have not only increased the functional properties of lysozyme (such as solubility and heat stability) but also extended the antimicrobial activity of lysozyme. Many examples will be given to show that modification can decrease the count of Gram-negative bacteria in bacterial culture and in foods by as much as 5 log CFU/mL and in some cases essentially eliminated Escherichia coli. In conclusion this review demonstrates that modified lysozymes are excellent natural food preservatives, which can be used in food industry.

Susceptibility of Colistin-Resistant, Gram-Negative Bacteria to Antimicrobial Peptides and Ceragenins

“…Of particular concern are Gram-negative bacteria, because these organisms are inherently resistant to many antibiotics due to the permeability barrier provided by their outer membranes and the efflux pumps located therein (3, 4). To treat infections from Gram-negative bacteria, clinicians are increasingly using colistin, a member of the polymyxin family of antibiotics (5).…”

Cloning and Characterization of a Novel N-acetylglucosaminidase (AtlD) from Enterococcus faecalis

“…This result suggests that one or more of the rest of the enzymes with PGH activity visualized by zymography in that report could be responsible for the activity against gram-negative bacteria. Besides, it is possible that the recombinant AtlD do not show this lytic capacity because gram-negative bacteria possess an external lipopolysaccharide membrane that could protect them from exogenously added PGH, as in the case of lysozyme versus E. coli [Aminlari et al, 2014]. The difference in inhibition capacity among Gram-positive bacteria could be related to the different cell wall architecture in the strains assayed.…”

Lysozyme activity of the Ruminococcus champanellensis cellulosome

“…The enzyme is active at extremes of temperature and stable for long incubation periods at elevated temperatures. These characteristics could therefore render the ScaK enzyme a suitable candidate for industrial applications, for example, as an antimicrobial agent in the food industry (Datta et al ., ; Callewaert et al ., ; Aminlari et al ., ) and may also be considered as a therapeutic agent in humans (Pastagia et al ., ).…”

“…These characteristics could therefore render the ScaK enzyme a Similarly, the ScaG cohesin appears to be very selective in its binding to the ScaA dockerin, and fails to bind other Group 2 dockerins. suitable candidate for industrial applications, for example, as an antimicrobial agent in the food industry (Datta et al, 2008;Callewaert et al, 2011;Aminlari et al, 2014) and may also be considered as a therapeutic agent in humans (Pastagia et al, 2013).…”