We know the process has been very successful in reservoirs from the low twenties and above. We have documented successful treatments from 16ºAPI to 42ºAPI. To date, not enough work has been done in the field with lower API gravity oils to be absolutely definitive on the lower limit. Lower gravity crudes have generally been seen to have fewer communities of microbes available, possible due to geologic heating of the oil. However, some recent testing has given some indication of more active microbial communities in heavy oil reservoirs. Only laboratory analysis can determine if the appropriate microbes are present in sufficient numbers. Titan continues to push the limits of API gravity. In some reservoirs, we have found unexpected microbes to be present due to natural adaptation.