In Vitro PAH-Binding Ability of Lactobacillus Brevis TD4

Recently, there has been a growing attention in utilizing microorganisms, particularly, lactic acid bacteria and probiotics in reduction of various toxic compounds such as heterocyclic amines, polycyclic aromatic hydrocarbons, acrylamide, heavy metals and mycotoxins. Therefore, this study was aimed to evaluate detoxification ability of Lactobacillus brevis TD4 in removal of four PAHs (PAH4), namely, Benzo(a)anthracene (BaA), Benzo(a)pyrene (BaP), Benzo(b)fluoranthene (BbF) and Chrysene (Chr) from artificially contaminated phosphate buffer saline (PBS). In this regard, response surface methodology (RSM) in combination with Box-Behnken design was applied to investigate the effect of incubation time (1-24 h), PAH concentration (5-15 ppm), pH (3-7) and bacterial population (7-9 log CFU/mL) at three levels on binding rate of BaA, BaP, BbF and Chr as a response. The results showed that L. brevis TD4 was able to remove PAH4 from PBS and this removal was entirely toxin-specific. The results also showed that pH, bacterial population, initial concentration of each PAH and time were the variables that significantly affected BaA, BbF, BaP and Chr binding rate by L. brevis TD4 in linear and quadratic manners. Furthermore, there was an interaction between initial concentration of each PAH and time in removal of BaA, BbF, BaP and Chr. In this respect, the highest binding rate of each PAH occurred at pH near 5, initial concentration of 10 ppm, bacterial population of 10(9) CFU/mL and after 24 h incubation. It can be generally concluded that according to the PAH type and concentration, there is a definite incubation time, pH and bacterial population to obtain maximum binding rate of BaA, BaP, BbF and Chr.