Lead biosorption of probiotic bacteria: effects of the intestinal content from laying hens

This study investigated the effects and the possible mechanisms of intestinal content (IC) from laying hens on in vitro lead (Pb²⁺) biosorption of four probiotic bacterial strains (Bifidobacterium longum BB79, Lactobacillus paracasei Kgl6, Lactobacillus pentosus ITA23, and Lactobacillus acidipiscis ITA44). The total Pb²⁺ removal capacity of the four probiotic strains, with and without capsule polysaccharides (CPSs), increased in the presence of IC compared to the control (without IC). SEM imaging revealed certain unidentified particles from the IC adhered on the surface of bacterial cells sorted out using flow cytometry. Follow-up experiment showed an overall trend of increase in the Pb²⁺ removal capacity of the sorted bacteria, but statistically significant for L. pentosus ITA23 and B. longum BB79 after incubation with IC, particularly with the suspended solid portion of the IC. In addition, the Fourier transform infrared spectrophotometer data showed that functional groups such as C-H, O-H, C=O, and C-O-C which possibly associated with Pb²⁺ binding were mainly presented in the suspended solid portion of IC. Putting the above together, we postulated that the enhanced Pb²⁺ binding capacity the probiotic bacteria incubated in IC is due to the adherence of the yet to be identified particles which could much exist in suspended solid portion of IC containing negatively charged functional groups which bind with the positive Pb²⁺ ions.