Gerbino Esteban, Carasi Paula, Tymczyszyn E Elizabeth, Gómez-Zavaglia Andrea
Center for Research and Development in Food Cryotechnology,CCT-CONICET La Plata, RA-1900,Argentina.
Laboratorio de Microbiología, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas,Universidad Nacional de La Plata,Argentina.
J Dairy Res. 2014 Aug;81(3):280-7. doi: 10.1017/S0022029914000314. Epub 2014 Jun 24.
The aim of this work was to evaluate the capacity of Lactobacillus kefir strains to remove cadmium cations and protect eukaryotic cells from cadmium toxicity. Lb. kefir CIDCA 8348 and JCM 5818 were grown in a 1/2 dilution of MRS broth supplemented with Cd(NO3)2 ranging 0 to 1 mM. Growth kinetics were followed during 76 h at 30 °C by registering optical density at 600 nm every 4-10 h. The accumulated concentration of cadmium was determined on cultures in the stationary phase by atomic absorption. The viability of a human hepatoma cell line (HepG2) upon exposure to (a) free cadmium and (b) cadmium previously incubated with Lb. kefir strains was evaluated by determining the mitochondrial dehydrogenase activity. Lb. kefir strains were able to grow and tolerate concentrations of cadmium cations up to 1 mM. The addition of cadmium to the culture medium increased the lag time in all the concentrations used. However, a decrease of the total biomass (maximum Absorbance) was observed only at concentrations above 0.0012 and 0.0011 mM for strains CIDCA 8348 and JCM 5818, respectively. Shorter and rounder lactobacilli were observed in both strains upon microscopic observations. Moreover, dark precipitates compatible with intracellular precipitation of cadmium were observed in the cytoplasm of both strains. The ability of Lb. kefir to protect eukaryotic cells cultures from cadmium toxicity was analysed using HepG2 cells lines. Concentrations of cadmium greater than 3×10(-3) mM strongly decreased the viability of HepG2 cells. However, when the eukaryotic cells were exposed to cadmium pre-incubated 1 h with Lb. kefir the toxicity of cadmium was considerably lower, Lb. kefir JCM 5818 being more efficient. The high tolerance and binding capacity of Lb. kefir strains to cadmium concentrations largely exceeding the tolerated weekly intake (TWI) of cadmium for food (2.5 μg per kg of body weight) and water (3 μg/l) addressed to human consumption, is an important added value when thinking in health-related applications.
这项工作的目的是评估开菲尔乳杆菌菌株去除镉阳离子以及保护真核细胞免受镉毒性影响的能力。开菲尔乳杆菌CIDCA 8348和JCM 5818在添加了浓度范围为0至1 mM硝酸镉的1/2稀释MRS肉汤中培养。在30℃下培养76小时期间，每4 - 10小时记录600 nm处的光密度，跟踪生长动力学。通过原子吸收法测定稳定期培养物中镉的累积浓度。通过测定线粒体脱氢酶活性来评估人肝癌细胞系（HepG2）在暴露于（a）游离镉和（b）先前与开菲尔乳杆菌菌株孵育过的镉时的活力。开菲尔乳杆菌菌株能够生长并耐受高达1 mM的镉阳离子浓度。向培养基中添加镉增加了所有使用浓度下的延迟期。然而，仅在CIDCA 8348菌株浓度高于0.0012 mM以及JCM 5818菌株浓度高于0.0011 mM时，才观察到总生物量（最大吸光度）下降。显微镜观察发现，两种菌株中的乳杆菌都更短更圆。此外，在两种菌株的细胞质中都观察到了与镉细胞内沉淀相符的深色沉淀物。使用HepG2细胞系分析了开菲尔乳杆菌保护真核细胞培养物免受镉毒性影响的能力。大于3×10(-3) mM的镉浓度会显著降低HepG2细胞的活力。然而，当真核细胞暴露于先前与开菲尔乳杆菌孵育1小时的镉时，镉的毒性要低得多，开菲尔乳杆菌JCM 5818的效果更显著。开菲尔乳杆菌菌株对大大超过人类食用食品（每千克体重2.5微克）和水（3微克/升）中镉的每周耐受摄入量（TWI）的镉浓度具有高耐受性和结合能力，这在考虑与健康相关的应用时是一项重要的附加价值。
