Screening Of Bifidobacterium Strains To Detoxify Benzo[a]pyrene Under Food Stress Factors

Contaminations of benzo[a]pyrene(B[a]p)in food is the main source of B[a]p exposure to human.B[a]p as one of the most studied polycyclic aromatic hydrocarbon(PAH)omnipresent in environment and food.Nowlactic acid bacteria(LAB)strains as renowned bacteria in probiotic related food have been used to confront carcinogenic contaminants of food.Some of the LAB strains potentially show anti-carcinogenic ability to certain carcinogenic compounds and eliminate them via stable physical binding.This present study was designed to investigate the potential of Bifidobacterium strains to adsorb B[a]p,especially their B[a]p-binding possibility under food stress factors.The following are main results obtained.1.In the first part of this study,the mechanism of' physical binding of LAB strains to remove B[a]p was reviewed.The data from published work showed that the binding of LAB strains with B[a]p take place by physical binding.The cell wall peptidoglycan was the key binding site and this binding was effective by certain factors mainly by LAB strains and pH.The strains of genera Lactobacillus,Bifidobacterium,Pecliococcus and Streptococcus were found effective in B[a]p binding and removal,not only in-vitro from aqueous medium but also in-vivo animal models,gastrointestinal models,and food system.A critical comparison of B[a]p removal by non-LABs vs LABs was also conducted.It was concluded that LAB strains were highly efficient in the removal of B[a]p also having no toxic effects and potential adverse health effects.However,few studies have been done to evaluate the potential of bifidobacteria strains in removing B[a]p.2.In the second part of this study,Bifidobacterium strains were tested for their ability to binding with B[a]p.Bifidobacterium lactis strains BI04,HN019,and Bifidobacteriumlongumsubsp.infantisBY12 showed highest binding rate with B[a]p.Moreover,the effect of different food processing stress factors(acid,detergent,oxidative,base,enzymatic,osmotic,and heat)was also evaluated on the bindingrate of B[a]p.Positive correlations were observed for simulated gastric condition,and TCA(Trichloracetic acid)stress.While,heat stress showed that the viability of bacteria cells was not significant for binding.The mechanisms behind the effect of each stress factor on binding ability were also discussed.3.In the other part of study the component of the Bifidobacterium cell wall more particularly the functional groups from peptidoglycan involved in the mechanism of binding with Benzo[a]pyrene were determined.The effect of different food stress factors(acid,heat,base,oxidative,osmotic,enzymatic,and detergent factors)on the functional group and the overall binding mechanism of Bifidobacterium with B[a]p were also evaluated.Fourier transform infrared spectroscopic(FTIR)were used to explain the binding mechanism of bifidobacterial strains with B[a]p along with HPLC(high-performance liquid chromatography).The peptidoglycan-B[a]p complexes were highly stable after benzene washing.Peptidoglycan from Bifidobacterium infantisBY12 showed highest binding rate with B[a]p.FTIR spectrum showed that the main functional groups involved in B[a]p binding were C-O,OH and/or NH.FTIR spectra as a function of different food stress factors(acid,base,heat,oxidative,osmotic,detergent,and enzymatic factors)revealed that the stress factors act on the C-O functional group induce the binding with B[a]p.In conclusions,technologically the improvement of cell resistance towards various stresses would be useful for the more B[a]p-binding of bifidobacterial strains,as different factors could significantly affect the performance of the probiotic strains.It was concluded from our data that Bifidobacteriumlongumsubsp.infantisBY12 may be employed as a biological detoxification agent for the elimination of B[a]p from human diet and animal feed in the future due to its high binding with the chemical.