The content of thiamine in germfree plants and biosynthesis of thiamine in vivo in germfree leaves under gnotobiotic conditions

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Abstract
The thiamine content and growth of radish and Bashona plants by hydroculture were investigated under both gnotobiotic and conventional conditions. The fresh weight of germfree plants at the period of 20 days growth after transplanting was larger than that of conventional plants, and the fresh weight of Hashona was much larger than that of radish plants in either conventional or germfree conditions at 20th day after transplanting. The thiamine content in a Bashona plant under gnotobiotic conditions was equal to that under conventional conditions, but concentration of thiamine in green leaves of radish plants under conventional conditions was twice as much as that under germfree conditions. This experiment suggests that thiamine content of radish under conventional conditions was increased by coexisting microorganisms. The thiamine content in roots for both type of plants was of the order of 15% or less compared with that in green leaves under both conditions. Biosynthesis of thiamine by thiamine precursors in vivo in germfree green leaves of both type of plants was clearly demonstrated with vacuum infiltration. Green leaves of Hashona plants grown for 28 days produced more thiamine than did those of radish plants under germfree conditions. Biosynthesis of thiamine from precursors in the absence of ATP in both type of plants was confirmed under the given light conditions. These results indicate that thiamine is synthesized from the plant itself and that thiamine content in some plants is affected by the presence of microorganisms.

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