Cell envelope of Nitrosocystis oceanus

Abstract

The cell envelope of Nitrosocystis oceanus , a marine nitrifying bacterium, has been shown to be composed of seven distinct layers including an outer fibrous slime layer, a hexagonal layer comprised of 50 Å subunits, a double-tracked layer consisting of 40 Å subunits, two globular layers which are separated by a mucopeptide layer, and a plasma membrane. These studies show that N. oceanus cell envelopes differ from those found in Escherichia coli and other Gramnegative bacteria and illustrate the value of combining freeze-etching with other electron microscopic techniques for the study of bacterial cell envelopes.