Nutritional interdependence betweenThermoanaerobacter thermohydrosulfuricus andClostridium thermocellum

Thermoanaerobacter thermohydrosulfuricus strain YM3 andClostridium thermocellum strain YM4, obtained originally as a stable coculture, required yeast extract to grow separately. Cell-free broths ofT. thermohydrosulfuricus strain YM3 andC. thermocellum strain YM4 monocultures replaced yeast extract in supporting the growth of strains YM4 and YM3, respectively.T. thermohydrosulfuricus strain YM3 produced vitamin B6, B12 analog(s),p-aminobenzoic acid and folic acid, which were required byC. thermocellum strain, YM4. Likewise, strain YM4 produced niacin-active compound(s), thiamine, and methionine required by strain YM3.