In vitro assessment of histamine and lactate production by a multi-strain synbiotic

Abstract

Recent studies suggest histamine and d-lactate may negatively impact host health. As excess histamine is deleterious to the host, the identification of bacterial producers has contributed to concerns over the consumption of probiotics or live microorganisms in fermented food items. Some probiotic products have been suspected of inducing d-lactic-acidosis; an illness associated with neurocognitive symptoms such as ataxia. The goals of the present study were to test the in vitro production of histamine and d-lactate by a 24-strain daily synbiotic and to outline methods that others can use to test for their production. Using enzymatic based assays, no significant production of histamine was observed compared to controls (P > 0.05), while d-lactate production was comparable to a commercially available probiotic with no associated health risk. These assays provide a means to add to the safety profile of synbiotic and probiotic products.

Keywords: Food Safety; Histamine; Lactate; Probiotic; Synbiotic.

Fig. 1

The microbial biomolecules (a) histamine and b d-lactate can be deleterious to multiple organ systems

Fig. 2

In vitro production of histamine by L. reuteri ATCC 23,272 and Seed synbiotic grown aerobically and anaerobically in MRS. Statistical significance was determined by comparing each test group to the uninoculated control. Significance is indicated by asterisk (**** = p < 0.0001) or by lettering (ns = p > 0.05)

Fig. 3

In vitro production of a l-lactate and b D-lactate after 1 h and c l-lactate and d d-lactate after 24 h by two probiotic products and Lactobacillus strains in a relevant buffer solution. Statistical significance was determined by comparing each Seed synbiotic test group to a relevant probiotic mixture (Renew) and single strain controls. Significance is indicated by asterisk (* = p < 0.05) or by lettering (ns = not significant, p > 0.05)

Fig. 4

The proportion of D-lactate from the total lactate produced in vitro after a 1 h and b 24 h by two probiotic products and Lactobacillus strains in a relevant buffer solution. Statistical significance was determined by comparing each Seed synbiotic test group to a relevant probiotic mixture (Renew) and single strain controls. Significance is indicated by asterisk (* = p < 0.05 and **** = p < 0.0001) or by lettering (ns = not significant, p > 0.05)