Abstract: A process is described for the growth of anaerobic thermophilic heterotrophic methanogens belonging to the species Pyrobaculum islandicum and Pyrococcus furiosus to high cell densities under steady state conditions.

Abstract: A machine for manufacturing piston rings from the metal strip (10). The machine comprises feeding means (12) for feeding the strip, shaping means (14, 16, 18, 20) for shaping successive portions of the strip into piston rings of a desired shape, and severing means (22) operable to sever the piston rings from the remainder of the strip. The machine also comprises displacing means (28) operable during each operation of the severing means (22) to move the severing means to substantially reduce the relative movement between the severing means and the point on the strip (10) at which the strip is severed. The severing means (22) is moved along a linear path which extends substantially tangentially to the path of said point.

Abstract: Glycerol dehydrogenase enzymes having exeptionally good thermal stability are produced by culturing novel strains of Bacillus stearothermophilus. Procedures for deriving and identifying suitable strains are described. The strains are grown in conventional culture media, preferably containing 0.05 to 4.0%, especially 0.1 to 1.0%, by weight of glycerol or a glycerol analogue at 40.degree.-65.degree. C. and pH 5 to 8. The enzyme is isolated by conventional cell disruption and separation techniques, and typically has a molcular weight of 240,000.+-.30,000, composed of four similar sub-units, and a specific activity of greater than 5 Units per mg protein at 30.degree. C. by the modified assay described. They may be stored as aqueous solutions or a freeze dried solids.The enzymes may be used for assay of serum triglycerides by conventional assay methods, but preferably by the nictotinamide adenine dinucleotide spectrophotometric assay at a pH of 7 to 8.8.