Survival of pathogenic bacteria in crude oil

The survival of three strains of Staphylococcus aureus and one strain each of Pseudomonas aeruginosa, Bacillus subtilis and Clostridium sporogenes has been investigated in samples of seven different crude oils obtained from Alberta oil fields. One strain each of Staphylococcus aureus, Pseudomonas aeruginosa, Clostridium sporogenes and Bacillus subtilis survived for longer than three years in three of the seven crude oils tested. The majority (four out of six) of the species of test micro-organisms remained viable for over two years in six out of the seven crude oils tested. Paraffinic or asphaltic-naphthenic base crude oils were better suited for the survival of the bacteria employed in these tests than were naphthenic-paraffinic or aromatic-paraffinic base oils. Only Clostridium sporogenes survived longer than three days in one of the crude oils (No. 7) which contained considerably more aromatic material than any of the other oils tested. The public health implications of the experimental results are discussed.