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Purple non-sulfur bacteria can evolve molecular H2 catalyzed by nitrogenase under nitrogen-deficient conditions using light energy and reduced compounds (Xu 207).  Magnetospirillum (Aquaspirillum) is an exciting member of the purple nonsulfur bacteria, as it is the first magnetic bacterium discovered. Professor Richard Blakemore at the University of New Hampshire USA collected and purified the bacterium in culture, and to the amazement of students has demonstrated the rapid movement of populations in a glass flask in response to a bar magnet. Magnetosomes (nanochips) of iron-rich magnetite (FeO4) within the bacterioplasm form one or more chains that responds to geomagnetism that enable cells to migrate downward in freshwater columns. The polarity is opposite in the north and south hemispheres. The magnetic polarity can be reversed by single, magnetic pulses of high field strength (1-2 µs, 300-600 G). Magnetosomes are separated from each other by a small gap of 6.8 nm, and each one is surrounded by a trilaminate membrane containing proteins and lipids. Two of the proteins are unique to the magnetosome membranes, and may have a 'specific role' in microsome production, perhaps contributing to iron accumulation, iron oxidation, or development of magnetite. (Gorby at al. 1988). Magnetite sediments from two billion years ago have crystals similar to the bacterial geomagnetic nanocrystals, and likely were produced by bacteria (Vali and Kirschvink 1990). Blakemore, Richard (1975). "Magnetotactic bacteria". Science. 190 (4212): 377–379. Blakemore, R.B., R.B. Frankel and Ad.I. Kalmijn 1980. South-seeking magnetotactic bacteria in the Southern Hemisphere Nature 286(5771):384-385. Gorby, Y.A., T.J. Beveridge and R.P. Blakemore 1988. Characterizatio of the bacterial manetosome membrane. Journal of Bacteriology 170(2):834-841. Vali, x, and y Kirschvink 1990. Observations of magnetosome organization, surface structure and iron biomineralization of undescribed magnetic bacteria: Evolutionary speculations. In: Biominerals (Frankel, R.B. and R.P. Blakemore), Plenum Press, New York:97-115. Xu, Z.2007. Biological Production of Hydrogen from Renewable Resources. In: Bioprocessing for Value-Added Products from Renewable Resources:527-557. Rhodospirillaceae
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