Removal of benzo(a)pyrene by Lactobacillus strains under simulated starch conditions

Abstract:

[Objective] The performances of Lactobacillus acidophilus NCFM, Lactobacillus plantarum121 and Lactobacillus pentosus ML32 in removing benzo(a)pyrene [B(a)P] in simulated starch conditions were studied. To provide a novel way to reduce the potential risk of B(a)P to human, several factors which affect the binding of the 3 Lactobacillus strains to the chemical toxin were investigated in starch system. [Methods] The percentage of B(a)P bound by Lactobacillus strains was determined with HPLC after incubation at 37℃ for 4 h. The B(a)P-removing capabilities of Lactobacillus strains in various simulated starch systems were evaluated, including the concentrations, types and gelatinization of starch, incubation time, pH and starch-hydrolyzed products. [Results] The B(a)P-binding percentages of the Lactobacillus strains increased as starch concentrations were elevated from 2% to 10%. Starch types, either from corn, potato or sweet potato, had little effects on the ability of these bacterial cells to bind B(a)P. The gelatinization of starch favored Lactobacillus strains to bind more B(a)P. The percentage of these bacterial cells to bind B(a)P grew fast at 37℃ for the first 4 h-incubation time, and then slowly increased. The three Lactobacillus strains bound more B(a)P when starches were acidified to pH of 3 to 4 or alkalified to pH of 8 to 9. The viable cells of three Lactobacillus strains removed more B(a)P via their binding than their dead cells did. Moreover, both glucose and maltose, the end products after starch is hydrolyzed, improved significantly the performance of the 3 bacterial strains to remove B(a)P. [Conclusion] All of the three Lactobacillus strains perform good ability to bind B(a)P in the presences of starch. Their B(a)P-removing ability would be improved with an increased starch concentration, and the gelatinization of starch as well as the supplements of glucose and maltose. Thus, the selected Lactobacillus strains in our current work should be promising as a biological agent to reduce the occurrence of B(a)P in starch-based food products.