Phosphate starvation-independent 2-aminoethylphosphonic acid biodegradation in a newly isolated strain of Pseudomonas putida, NG2

A strain of Pseudomonas putida that utilized the biogenic organophosphonate 2-aminoethylphosphonic acid as sole carbon and energy, nitrogen and phosphorus source contained 2-aminoethylphosphonic acid: pyruvate aminotransferase and phosphonoacetaldehyde hydrolase (phosphonatase) activities which were inducible by the presence of 2-aminoethylphosphonic acid in the culture medium, regardless of the phosphate status of the cells. Neither of these activities were induced in either phosphate-free or phosphate-replete medium in the absence of 2-aminoethylphosphonic acid. Alkaline phosphatase activity was induced in phosphate limited medium, however, indicating a phosphate-starvation inducible response. In Enterobacter aerogenes IFO 12010, 2-aminoethylphosphonate : pyruvate aminotransferase and phosphonatase activities were induced only when cells were both phosphate limited and supplied with 2-aminoethylphosphonic acid as sole phosphorus source for growth. Neither enzyme activity was induced in phosphate-replete medium, or in medium where both 2-aminoethylphosphonic acid and inorganic phosphate were supplied as sources of phosphorus. The results point to the presence of a substrate inducible 2-aminoethylphosphonic acid biodegradation pathway in the isolated strain of Pseudomonas putida. Uniquely, therefore, the pathway is not under pho regulon control in this strain.