Proteomic Insights into Cadmium Resistance of a Novel Levilactobacillus brevis Isolate for Bioremediation Application

This study aimed to evaluate the cadmium-removal capacity of lactic acid bacteria (LAB) and highlight their potential role in environmental detoxification. LAB strains resistant to cadmium were screened using MRS broth supplemented with cadmium at an initial concentration of 30 mg/L. Out of 50 isolates tested, ten were selected based on their strong growth in the presence of cadmium and their ability to form biofilms. These isolates were identified through 16S rRNA gene sequencing. The isolate N4, identified as Levilactobacillus brevis, exhibited the highest minimum inhibitory concentration (MIC) for cadmium at 600 mg/L and showed effective cadmium removal after 72 h, achieving a removal rate of 36.94% and a cadmium uptake (qe) of 35.415 mg/g. Proteomic analysis of N4 using LC-MS Triple TOF chromatography revealed 1094 proteins. Among these, 65 were unique to the control group, 655 were unique to the cadmium-treated group, and 294 were shared. The differentially abundant proteins were primarily involved in energy metabolism, cell wall synthesis, amino acid and lipid metabolism, and substance transport. These findings enhance our understanding of the molecular mechanisms by which Levilactobacillus brevis binds and removes cadmium, supporting its potential application in mitigating heavy metal pollution.