Removal of cadmium by Lactobacillus kefir as a protective tool against toxicity

Abstract

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.

Analysis of Health Benefits Conferred by Lactobacillus Species from Kefir

“…It also was reported to have an ability to remove cadmium, a toxic heavy metal, from its surrounding environment. This, in turn, could reduce its cytotoxic effects on cells in the surrounding environmental, such as HepG2 cells [63].…”

Mechanisms and therapeutic effectiveness of lactobacilli

“…88 In this regard, two L. kefir strains, CIDCA 8348 and JCM 5818, can remove cadmium cations when cocultured with a human hepatoma cell line, HepG2. 89 Particularly, L. kefir JCM 5818 is more efficient in protecting cells from cadmium toxicity. Therefore, since consumption of harmful metals is a growing medical issue, the regular administration of formulations containing the above mentioned strains might be useful to prevent toxin compound-induced lipid peroxidation and free radical production.…”

Protective Effects of Lactobacillus plantarum CCFM8246 against Copper Toxicity in Mice

“…However, chelators usually have some unavoidable side effects including renal toxicity and the loss of essential trace elements[ 10 ]. Previous reports have suggested that some lactobacilli can bind and remove heavy metals such as cadmium, lead, and copper in vitro [ 11 – 14 ]. Besides their copper binding capacity, the known antioxidative properties of lactobacilli may also be important [ 15 , 16 ].…”