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Atypical psychrophilic Aeromonas salmonicida isolates were obtained from farmed and wild fish in Northeastern North America. These bacteria were isolated between 1992 and 2001 and carried tetracycline resistance (Tc(r)) plasmids of approximately 58 kb. The nine isolates had plasmids which could be divided into four groups based on the specific tetracycline resistance (tet) gene carried [tet(A) or tet(B)], incompatibility of the plasmid [IncU or other], whether the plasmid carried the IS6100 sequences, the sul1 gene, coding for sulfonamide resistance, the dfrA16 gene, coding for trimethoprim resistance, and/or carried a complete Tn1721, and their ability to transfer their Tc(r) plasmids to an Escherichia coli recipient at 15 degrees C. Five of the isolates, with genetically related Tc(r) plasmids, were able to transfer their plasmids to an E. coli recipient at frequencies ranging from 5.7x10(-4) to 2.8x10(-6) per recipient. The 1992 isolate carried a genetically distinct plasmid, which transferred at a slightly higher rate. The three remaining isolates carried one of two genetically different plasmids, which were unable to transfer to an E. coli recipient. Conjugal transfer at 15 degrees C is the lowest temperature that has been documented in bacteria.

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The majority of the oil and gas production infrastructure in the UK sector of the North Sea was installed in the 1980's and 1990's. Typically these installations were designed with a lifespan of 15–25 years, and many of them are now at or beyond their original design life. With higher prevailing oil prices, and continued development via subsea field tie-backs, the economic lifespan of these installations look set to exceed design lives by a considerable margin. In addition, many installations are now processing very different fluids and rates as they enter the mature phases of production. This paper describes in more detail how the life extension challenge is being managed in Shell UK. It covers the overall process being adopted for managing facilities beyond their design life, as well as describing some of the methods and techniques being used to make key decisions. The key learning's that can be applied in other mature fields includes:Dealing with more stringent environmental legislation than was applied when the facility was built;What detailed structural reviews are carried out to extend the design life;When to apply retrospective design standards;Managing the obsolescence of critical systems in particular the control and automation hardware;How to undertake major projects on an operating asset and dealing with the limited accommodation for the construction teams. A number of Shell facilities in the North Sea are currently going through this process with the learning being applied in more assets in the coming years.