The latest discovery made by a student and I involves the bacterium Rhodobacter sphaeroides. Compared to the original ‘wild type’ strain (top), a mutant (bottom) seems to be producing a lot more PHB (which appears red after being stained with the PHB binding dye Nile Red). We have not yet quantified the level of PHB, but upon our preliminary investigations, it appears to be at least 5-fold more than in the wild type. Compared to the wild type, which produces varying levels from cell to cell, accumulation in the mutant is very high in virtually every cell. We are looking at publishing the data soon. Also of great interest is whether this mutant of R. sphaeroides can use cheap fermentation sources such as agricultural waste products to produce PHB. Here, the strains were grown using a combination of acetate and malate as carbon sources.