健康新生儿粪便中耐铅菌株的分离鉴定及铅吸附实验

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

目的分离、鉴定具备重金属铅抗性、铅吸附性的乳酸菌,为成为具有排铅功能的新型保健食品提供新的菌源。方法利用乳酸菌选择性培养基MRS,从30份健康、足月新生儿粪便分离耐铅菌,通过形态特征,16S rRNA测序,构建系统发育树;利用《伯杰氏系统细菌学手册》进行生理生化、药敏检测和耐酸耐胆盐试验;进一步通过ICP-OES法检测分离菌对铅离子的吸附能力。结果分离得到3株可耐受500 mg/L铅离子浓度的干酪乳杆菌,均对青霉素、头孢曲松敏感。耐酸耐胆盐试验显示p H 2.0人工胃液培养3 h,细菌数保持相同数量级,0.3%的胆盐环境8 h存活率可达62.5%。吸附实验表明对低浓度(1 mg/L)铅离子的吸附率高达90.4%,对高浓度(50 mg/L)铅离子的吸附率可达86.27%。结论从新生儿粪便中分离到3株具备铅抗性、铅吸附性、耐酸耐胆盐的干酪乳杆菌,为利用益生菌膳食策略缓解铅中毒效应开辟新的途径和解决方案。

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 16 S r RNA 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（p H 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.