Tantalum has no known biological function. Escherichia coli cells can preferentially accumulate tantalum ions and leave niobium ions in solution (Fisel et al, 1971).

For more information:

Search Medline for tantalum AND bacteria

Fisel S, Topala N, Tintaru V. Concentration and separation with microbiological collectors. Niobium and tantalum separation with Escherichia coli. Lucr Conf Nat Chim Anal., 3rd. 1971;4:425-30.