Preliminary Study on Screening and Genetic Characterization of Lactic Acid Bacteria Strains with Cadmium, Lead, and Chromium Removal Potentials

Due to industrial development, heavy metal pollution has become a severe global health hazard. The bioadsorption method represented by the adsorption of lactic acid bacteria (LAB) has been widely employed. The purpose of this study is to screen LAB strains that can remove cadmium, lead, and chromium. Through the heavy metal resistance tests, four strains with significant growth inhibition rate were identified. After 16S rDNA sequencing, these resistant strains were identified by Lactobacillus helveticus KD-3 (Cd2+ removal rate 37.54 ± 0.85%), Limosilactobacillus fermentum B27 (Pb2+ removal rate 69.41 ± 0.19%), Lacticaseibacillus rhamnosus 7469 (Cr6+ removal rate 71.13 ± 0.97%), and Lb. helveticus K5. Three encoding genes were identified in our screen strains, namely resistance gene czcD, chromium resistance gene chrA, and lead resistance gene pbrT. L.helveticus KD-3 exhibited the best comprehensive performance. Given the diverse types of heavy metal pollution at present, the current research mainly focuses on the removal of a single heavy metal by one strain. The four strains enrich the absorption resources of LAB for heavy metals, paving a new way for the biosorption of various heavy metals in food by LABs.