Separation and Characterization of Pollutant-degrading Microbes Separated from Surface Seawater

Microbes capable of degrading pollutant such as 1,4-dioxane were selected from the seawater samples of four coastal areas of Okinawa located in the most southern islands of Japan using the developed method and a seawater-charcoal perfusion apparatus. Specifically, aerobic culture in the apparatus led to the selection of candidate 1,4-dioxane degraders. Among these, strain RM-31 and KY-3 exhibited the strongest 1,4-dioxane degradation ability. 16S rDNA sequencing and the similarity analysis of strain RM-31 and KY-3 suggested that this organism was most closely related to Pseudonocardia carboxydivorans and Rhodococcus erythropolis respectively. These species are similar to Pseudonocardia and Rhodococcus spp. which has previously been reported as a 1,4-dioxane degrader. However, it was probably first bacteria from the seawater that can exert a strong degrading ability. The biodegradation rate of 1,4-dioxane by these strains at 25°C in broth medium with 3% NaCl was almost 20% faster than that without NaCl. PCR amplification test indicated that isolated strains had the SDIMO (soluble di-iron monooxygenase) ɑ-subunit gene. Key-Words: 1,4-dioxane, degrading microbe, seawater-charcoal perfusion apparatus, Psedonocardia, Rhodococcus, hydrophilic interaction chromatography, soluble di-iron monooxygenase