A method is disclosed relating to the treatment of a hydrocarbon well, which method comprises administering down a bore hole thermophilic microorganisms capable of generating a well treatment chemical, in particular wherein the bore hole is a producer bore hole and the well treatment chemical is a peptide such as polyAsp; further aspects include thermophilic microorganisms which have been genetically engineered to produce a well treatment chemical and bioreactors in which microorganisms generate well treatment chemicals for application to a down hole environment.