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doi:10.2204/iodp.proc.331.106.2011 MicrobiologyCultivation of thermophilesGrowth of Thermococcales (e.g., Thermococcus) at 80°C and Aquificales (e.g., Persephonella) and thermophilic Epsilonproteobacteria (e.g., Nitratiruptor) at 55°C was examined onboard for Section 331-C0016B 1L-1, which was a “Kuroko” type of massive sulfide deposit. It was predicted that indigenous (hyper)thermophilic microorganisms would most likely occur in the vein structures of the massive sulfide deposits. However, no growth of any kind of microorganisms was observed. Contamination testsDrilling mud that adhered to the outer surface of core from Hole C0016B was collected for perfluorocarbon tracer (PFT) testing (Table T6) as a positive control on PFT concentration in drill mud used. Two of these core surface mud samples yielded PFT concentrations of 1.08 and 1.34 ppm/g. Mud water Samples C0016B-1LMW and 2LMW from the onboard mixing tank used for drilling operations in Hole C0016B had PFT concentrations of 1.43 and 0.09 ppm/g, respectively. The type of mud fluid in Sample C0016B-1LMW was the most commonly used during drilling operations (see Table T8 in Expedition 331 Scientists, 2011b) and is regarded as the most representative sample. Comparison of PFT concentrations in predrilling (1.43 ppm) and postdrilling (1.08 and 1.34 ppm) mud samples indicates that the PFT concentration was essentially preserved in the drilling mud from mixing through drilling to core recovery. This suggests that external contamination can be estimated by directly comparing the concentrations of PFT in the core sample with that of the mud fluid prepared onboard. |
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