The Carini lab at The University of Arizona is focused on understanding how microbes help make Earth habitable for humans. This view leads us to diverse questions in both terrestrial and aquatic environments with the goal of understanding how microbial communities transform important nutrients, remove pollutants, affect soil fertility and influence aquatic productivity. By studying the growth of microbial cultures, their genome sequences and their environmental distributions, we design experiments that help uncover new and unusual biogeochemical cycles and provide hypothesis-based explanations for long standing geochemical observations.