Antimicrobial Action of Hydrolyzed Chitosan against Spoilage Yeasts and Lactic Acid Bacteria of Fermented Vegetables

Abstract

The antimicrobial properties of various chitosan-lactate polymers (ranging from 0.5 to 1.2 MDa in molecular weight) against two yeasts isolated from fermented vegetables and against three lactic acid bacteria from a mixed starter for sauerkraut on methylene blue agar (MBA) and in vegetable juice medium (VJM) were investigated. Chitosan-lactate reduced the growth of all microorganisms in solid (MBA) as well as in liquid (VJM) medium. In MBA, a concentration of 5 g/liter was needed to inhibit the growth of Saccharomyces bayanus, while 1 g/liter was sufficient to inhibit the growth of Saccharomyces unisporus. Lactic acid bacteria were also inhibited in this range of concentrations. The low-molecular-weight chitosan-lactate DP3 (0.5 kDa) was most efficient in solid medium (MBA), and inhibitory activities decreased with increasing hydrolysate lengths. In liquid medium (VJM), 0.5 g of chitosan-lactate per liter reduced the growth rates for both yeasts, but 10 g/liter was insufficient to prevent yeast growth. Intermediate-molecular-weight chitosan-lactate (5 kDa) was more efficient than chitosan of low molecular weight. Native chitosan (1.2 MDa) showed no inhibition in either medium. Microscopic examination of S. unisporus Y-42 after treatment with chitosan-lactate DP25 showed agglutination of a refractive substance on the entire cell wall, suggesting an interaction between chitosan and the cell wall. When chitosanase was added to the culture media containing chitosan-lactate, refractive substances could not be observed.

Fate of <i>Escherichia coli</i> O157 Cells Inoculated into Lightly Pickled Chinese Cabbage during Processing, Storage and Incubation in Artificial Gastric Juice

“…This conclusion is able to adapt to all of tested commercially purchased items including those using food additive s to control undesirable overgrowth of microorganisms Table 2 . Chitosan, mustard extract and other food additives have been used commercially and some of them are reported to be effective for control the over growth of yeast and lactic acid bacteria in fermented vegetables to keep good quality longer Miyao, 1997Savard et al, 2002 No meaningful effectiveness of food additives to reduce the population of contaminated E. coli O157 during storage at 10 was observed in this study however. Enterohemorrhagic E. coli is reported to grow under condition at pH4.4, water activity 0.95 and 7-8 FSC, 2010 .…”

Dehydrated pork manure by-product: effect of a chitosan amendment on bacterial community and common scab incidence

“…This slight decrease might be attributed to the antimicrobial activity of chitosan. This polymer has been shown to be generally more toxic on fungi than on bacteria (Savard et al 2002). The decrease in anaerobic bacteria population might confer an advantage to biosolid PC in agricultural practices.…”

Biomedical-Grade Chitosan in Wound Management and Its Biocompatibility In Vitro

“…For example, the fungicidal effects of N-carboxymethyl chitosan (NCMC) are different in vegetable and graminea hosts. The antimicrobial activity is more immediate on fungi and algae than on bacteria (Savard et al, 2002). Furthermore, in the presence of more than 0.025% chitosan, the growth of Excherichia coli, Fusarium, Alternaria and Helminthosporium is inhibited (Hirano, 1995).…”