Lactobacillus plantarum-Mediated Regulation of Dietary Aluminum Induces Changes in the Human Gut Microbiota: an In Vitro Colonic Fermentation Study

The gut microbiota has been identified as a target of toxic metals and a potentially crucial mediator of the bioavailability and toxicity of these metals. In this study, we show that aluminum (Al) exposure, even at low dose, affected the growth of representative strains from the human intestine via pure culture experiments. In vitro,Lactobacillus plantarumCCFM639 could bind Al on its cell surface as shown by electron microscopy and energy dispersive X-ray analysis. The potential ofL. plantarumCCFM639 to reverse changes in human intestine microbiota induced by low-dose dietary Al exposure was investigated using an in vitro colonic fermentation model. Batch fermenters were inoculated with fresh stool samples from healthy adult donors and supplemented with 86 mg/L Al and/or 10(9) CFU ofL. plantarumCCFM639. Al exposure significantly increased the relative abundances of Bacteroidetes (Prevotella), Proteobacteria (Escherichia), Actinobacteria (Collinsella), Euryarchaeota (Methanobrevibacter), and Verrucomicrobiaceae and decreased Firmicutes (Streptococcus,Roseburia,Ruminococcus,Dialister,Coprobacillus). Some changes were reversed by the inclusion ofL. plantarumCCFM639. Alterations in gut microbiota induced by Al andL. plantarumCCFM639 inevitably led to changes in metabolite levels. The short-chain fatty acid (SCFAs) contents were reduced after Al exposure, butL. plantarumCCFM639 could elevate their levels. SCFAs had positive correlations with beneficial bacteria, such asDialister,Streptococcus,Roseburia, and negative correlations withErwinia,Escherichia, andSerratia. Therefore, dietary Al exposure altered the composition and structure of the human gut microbiota, and this was partially mitigated byL. plantarumCCFM639. This probiotic supplementation is potentially a promising and safe approach to alleviate the harmful effects of dietary Al exposure.