Abstract
The quest for the use of natural ingredients as preservatives and antimicrobial agents is rising. Polysaccharide gums are usually used as emulsifying agents and as preservatives. The objective of this study was to investigate the combined effect of five different polysaccharide gums and antimicrobial agents on growth, susceptibility and protein expression of select pathogenic microorganisms in milk. Antimicrobial susceptibility and protein concentration were determined by disc diffusion and Pierce BCA assay, respectively. The proteome pattern and the number of protein spots were determined by two-dimensional gel electrophoresis. The results showed that xanthan (6.68±0.02 Log CFU/mL) caused the most growth inhibition of Salmonella enterica, compared to the control. Inclusion of pectin led to a significant (P<0.0001) 2-log reduction of Salmonella enterica during a 2-day refrigerated storage (4 oC). The highest inhibition zones (20.50±0.70) was observed in E. coli O157:H7 exposed to carrageenan-maltodextrin-cefixime. The proteome pattern was impacted by the gums with protein band of size 30kDa being the most prominent band. The highest number of protein spots (35) were obtained in locust bean treated samples. These findings indicated that tested gums affected microbial protein expression and were effective in inhibitory activity against tested pathogens specifically Escherichia coli O157:H7, thus gums hold great promise as some antimicrobial agents. Further characterization of protein targets is warranted.
Highlights
There are increasing concerns about issues of food safety and antimicrobial resistance. These concerns come from growing occurrence of new and emerging foodborne disease outbreaks caused by pathogenic microorganisms including Salmonella spp, Escherichia coli, Listeria monocytogenes, Staphylococcus aureus, Bacillus spp. amongst others (Tajkarimi, Ibrahim & Cliver, 2010)
Apart from pectin, all tested gum slightly inhibited the growth of S. enterica, with the addition of xanthan (6.68±0.02 Log CFU/mL, P
The results of this study showed that xanthan caused the most growth inhibition of Salmonella enterica, compared to the control
Summary
There are increasing concerns about issues of food safety and antimicrobial resistance. These concerns come from growing occurrence of new and emerging foodborne disease outbreaks caused by pathogenic microorganisms including Salmonella spp, Escherichia coli, Listeria monocytogenes, Staphylococcus aureus, Bacillus spp. amongst others (Tajkarimi, Ibrahim & Cliver, 2010). The benefits of natural antimicrobials include controlling microbial contamination in food, inhibiting pathogenic bacteria, extending shelf life and reducing antibiotic resistance by pathogenic microorganisms (Nazef, Belguesmia, Tani, Pre- vost, & Drider, 2008; Abou-taleb & Kawai, 2008). Antimicrobial resistance remains a critical food safety issue globally as demonstrated by reports on the clinical and public health consequences of drug resistance in E. coli and other foodborne microorganisms. Polysaccharides gums, referred to hydrocolloids, produced from http://jfr.ccsenet.org
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