The biodegradation of tributyl phosphate by naturally occurring microbial isolates

The biodegradation of tributyl phosphate by a mixed culture of Pseudomonads was demonstrated. Growth and the rate of tributyl phosphate consumption were variable and divisible into rapid and slow rates. Rapidly growing, rapidly tributyl phosphate-utilising cultures contained a 22-24 kb DNA fragment isolated by two methods, which was not visible in the cultures growing slowly. The mixed culture gave five periods of rapid growth interspersed with periods of poor growth during 7 months of weekly subculture, with the 22-24 kb DNA fragment detectable during the rapidly growing periods only. Seven Pseudomonads isolated from the culture grew at the expense of tributyl phosphate as the sole phosphorus source but spontaneously and irreversibly lost this ability after eight serial subcultures.