[Isolation, identification and lead adsorption study of lead-resistant Lactobacillus casei strains from feces of healthy newborns].

ABSTRACT

OBJECTIVE: To isolate and identify lead-resistant Lactobacillus casei strains with lead adsorption ability from the stool of healthy newborns as a new source of bacteria for developing lead-eliminating food products. METHODS: MRS was used to isolate lead-resistant bacteria from the feces of 30 healthy and full-term neonates. A phylogenetic tree was constructed based on the morphological characteristics and 16S rRNA sequences of the isolated bacteria. Physiological and biochemical characterizations of the bacteria were performed according to the Berger's Systematic Bacteriology Handbook, followed by antimicrobial susceptibility test and acid-tolerant bile salt test. The adsorption capacity of Pb2+ of the bacteria was determined by inductively coupled plasma-optical emission spectroscopy (ICP-OES). RESULTS: Three strains of Lactobacillus casei were isolated, which were resistant to penicillin and ceftriaxone and could tolerate the exposure to 500 mg/L Pb2+. Acid-tolerant bile salt test showed that the bacteria were resistant to culture in the presence of artificial gastric juice (pH 2.0) for 3 h, and their survival rate reached 62.5% following exposure to 0.3% bile salt for 8 h. The bacteria showed a Pb2+ adsorption rate of 90.4% at a low Pb2+ concentration (1 mg/L) and of 86.27% at a high Pb2+ concentration (50 mg/L). CONCLUSION: Three Lactobacillus casei strains lead adsorption ability were isolated from the feces of newborns. These bacterial strains provide a new solution to alleviate lead poisoning by probiotic dietary.