Several studies suggest that microbes successfully consumed part of the oil.[59][162] By mid-September, other research claimed that microbes mainly digested natural gas rather than oil.[163][164] David L. Valentine, a professor of microbial geochemistry at UC Santa Barbara, said that the capability of microbes to break down the leaked oil had been greatly exaggerated.[165] However, biogeochemist Chris Reddy, said natural microorganisms are a big reason why the oil spill in the Gulf of Mexico was not far worse.[166][167]