Photoheterotrophic growth of purple nonsulfur bacteria, a kind of photosynthetic
bacteria, brings about high conversion rates of dissolved organic matter into their cell
materials and little emission of carbon dioxide. From this point of view, wastewater
treatment using purple nonsulfur bacteria under light and anaerobic conditions is
expected to produce a large amount of useful biomass with little carbon dioxide, one
of the major green-house gases (Figure 1). The biomass of these bacteria can be
utilized for agricultural and industrial uses such as a feed for fish and animals,
fertilizers [1] and source of PHAs (polyhydroxyalkanoates) [2].
Polyhydroxyalkanoates are well known to be stored intracellularly by various
bacteria under imbalanced nutrient conditions and is commercially produced into a
biodegradable plastic.