Formation in radiation-resistant

Pseudomonas radiora was isolated primarily as a radiation-resistant bacteria during the work on the radiation conservation of rice and was put forward as a new species belonging to the genus Pseudomonas by IIZUKA and ITO (1, 2). We further reported that the intracellular red-pigments of a strain RP-C of P. radiora were carotenoids, in which bacterioruberin (3) was the main component. We also found the formation of bacteriochlorophyll (Bchl) in six strains of this species. To date only a few papers have dealt with Bchl formation in non-photosynthetic bacteria: those by SATO and SFIIMIZU (4, 5) for Protaminobacter ruber and Pseudornonas AM-I and by HARASHIMA et at. (h) and SHIVA ct at. (7, 8) for marine bacteria. The strains of P. radiora tested are as follows: 0-1 (the type strain, lA 12098), RP-C (IAM 12099), RPA-C, 0-2 and T7-2 isolated from rice. K12-3 from Kamaboko (fish cake), MD-1 from sewage sludge and C I42 from animal feed by IIZUKA and ITO (1, 2, 9), respectively. The cultivation of these organisms was carried out at 30° in potato-peptoneglucose medium (extract from 200 g of potato, polypeptone 10 g, glucose 10 g per liter, pH 7.0) using a reciprocal shaker. The culture flasks were illuminated for the first 24 hr and then kept in the dark for the following 48 hr. The pigments were extracted with chloroform-methanol (1: 1, v/v) from the whole cells harvested by centrifugation. After eliminating the cell debris by filtration, the pigments were concentrated to dryness under reduced pressure. The crude pigment thus obtained was dissolved in a small volume of chloroform, and subjected to chromatography on a column of silica gel (28-200 mesh). Elution was carried out with chloroform and the fraction containing Bchl was evaporated. The residue obtained was applied to thin-layer chromatography with silica gel using chloroform as developing solvent. After development, the lowest greenish band was scraped off from the plate and the pigment was eluted with diethylether. A part of the