Reduction of biogenic amines formation by foodborne pathogens using postbiotics in lysine-decarboxylase broth.

Postbiotics is a novel term proposed to describe as a set of bioactive compounds obtained from beneficial microorganisms. In this work, postbiotics from four lactic acid bacteria (LAB) including Leuconostoc mesenteroides subsp. cremoris, Pediococcus acidilactici, Lactococcus lactis subsp. lactis and Streptococcus thermophilus were prepared in MRS broth. The antimicrobial properties and organic acids content of postbiotics were also investigated. Postbiotics were used to tentatively reduce the production of biogenic amines by foodborne pathogens (i.e., Salmonella paratyphi A and Escherichia coli) on lysine decarboxylase broth (LDB). Experimental data showed that acetic, propionic, and butyric acids were in the range of 387.51-709.21 mg/L, 0.00-1.28 mg/L, and 0.00-20.98 mg/L, respectively. The inhibition zone of postbiotics on E. coli and S. paratyphi A were 11.67, and 12.33 mm, respectively. Two different levels of postbiotics (25%, and 50%) were used in LDB to measure the diamines (cadaverine and putrescine), polyamines (agmatine, spermidine, and spermine, ammonia), and other biogenic amine formation by pathogens. E. coli produced cadaverine and putrescine with concentrations of 1072.21 and 1114.18 mg/L, respectively. The postbiotics reduced cadaverine formation by 67% in E. coli, and cadaverine production was mostly suppressed by postbiotics from P. acidilactici in E. coli (97%) and L. lactis subsp. lactis in S. paratyphi A (90%). Putrescine production by E. coli was reduced by 94% with postbiotics of P. acidilactici at a concentration of 25%, whereas putrescine production by S. paratyphi A has been decreased by 61% in the presence of postbiotics from L. lactis subsp. Lactis with a 25% concentration. The results revealed that an increase in postbiotics concentration (from 25% to 50%) in LDB may lead to synergistic effects, resulting from the production of biogenic amines by microbial pathogens. It was importantly concluded that postbiotics of LAB may degrade biogenic amines or prevent their formation by foodborne pathogens.

Postbiotics produced by lactic acid bacteria: The next frontier in food safety.

There are many critical challenges in the use of primary and secondary cultures and their biological compounds in food commodities. An alternative is the application of postbiotics from the starter and protective lactic acid bacteria (LAB). The concept of postbiotics is relatively new and there is still not a recognized definition for this term. The word "postbiotics" is currently used to refer to bioactive compounds, which did not fit to the traditional definitions of probiotics, prebiotics, and paraprobiotics. Therefore, the postbiotics may be presently defined as bioactive soluble factors (products or metabolic byproducts), produced by some food-grade microorganisms during the growth and fermentation in complex microbiological culture (in this case named cell-free supernatant), food, or gut, which exert some benefits to the food or the consumer. Many LAB are considered probiotic and their postbiotic compounds present similar or additional health benefits to the consumer; however, this review aimed to address the most recent applications of the postbiotics with food safety purposes. The potential applications of postbiotics in food biopreservation, food packaging, and biofilm control were reviewed. The current uses of postbiotics in the reduction and biodegradation of some food safety-related chemical contaminants (e.g., biogenic amines) were considered. We also discussed the safety aspects, the obstacles, and future perspectives of using postbiotics in the food industry. This work will open up new insights for food applications of postbiotics prepared from LAB.