At the J. Craig Venter institute In La Jolla, California scientist have created a “minimal cell” named JCVI-syn3.0. This created cell, based on the Bacterium Mycoplasma mycoides, has a synthetic genome with just 473 genes. While there was worry that stripping down a cell to it's bare essentials would leave it defenseless the JCVI-syn3.0 seems to be thriving in it's given environment. The notion of this minimal cell was discussed at the first international meeting on synthetic biology at Massachusetts.
They developed methods for chopping up the bacterium's genome and removing segments piece by piece, allowing them to get just the essentials of the cell. The starting point for this minimal cell was an earlier synthetic cell, JCVI-syn1.0. With techniques like this they hope to be able to redesign bacteria and other relatively simple organisms so that they generate useful chemicals and materials. For more information on the minimal cell here and here.