Tellurium (Te) is a metalloid that is growing as a challenge since its increasing environmental presence, as a result of mining activity and improper disposal of high-tech devices, leads to an increasing selective pressure against living organisms. How microorganims adapt to the presence of increasing concentrations of metalloids, such as Te, could increase the know-how to solve Te contamination problems. Two mining isolates, Bacillus sp. and Paenibacillus sp, were able to grow in high concentrations of Te(IV) and were able to reduce Te(IV) to Te(0) so the effects of growth in the presence of Te(IV) was determined, at the level of total protein expression, for this strains. It was determined that growth of these strains in the presence of Te(IV) affected the general protein expression pattern, and hence the metabolism.