Biodegradation of dibutyl phthalate and di-(2-ethylhexyl) phthalate and microbial community changes in mangrove sediment

In this study, we investigated the microbial degradation of the phthalate esters (PAEs) dibutyl phthalate (DBP) and di-(2-ethylhexyl) phthalate (DEHP), and change in microbial communities in mangrove sediment collected from 5 sampling sites along the Tanshui River in Taiwan. Aerobic degradation half-lives (t(1/2)) of DBP and DEHP ranged from 1.6 to 2.9 d and 5.0 to 8.3 d, respectively. The addition of yeast extract (5 mg/L), hydrogen peroxide (1 mg/L), brij 35 (91 mu M), humic acid (0.5 g/L), cellulose (0.96 mg/L), and sodium chloride (1%) enhanced PAE aerobic degradation. Sediment samples were separated into fractions with various particle size ranges from 0.1-0.45 to 500-2000 mu m. Sediment fractions with smaller particle sizes demonstrated higher PAE biodegradation rates. Of the microorganism strains isolated from the mangrove sediment, strains J2, J4, and J8 (all identified as Bacillus sp.) expressed the best biodegrading ability. Our results showed that Bacillus sp. was the dominant bacteria in the process of PAE aerobic degradation in the mangrove sediments. (C) 2010 Elsevier B.V. All rights reserved.