Metabolism and Preferential Utilization of Phenylacetic acid and 4-Hydroxyphenylacetic Acid in Pseudomonas putida CSV86

Abstract

Metabolic pathways for phenylaceticacid (PA) and 4-hydroxyphenylacetic acid (4-HPA) from Pseudomonas putida CSV86 were elucidated. PA grown strain CSV86 cells showed higher oxygen-uptake on PA as compared to hydroxyphenylacetic acids. Detection of phenylacetyl-CoA ligase and absence of 4-hydroxyphenylacetic acid hydroxylase (4HPAH) and 3,4-dihydroxyphenylacetic acid-dioxygenase (3,4-DHPADO) activity supports this observation. 4-HPA grown cells showed oxygen-uptake on 4-HPA and 3,4-dihydroxyphenylacetic acid (3,4-DHPA) but showed significantly lower respiration rates on 2,5-dihydroxyphenylacetic acid and PA. Detection of 4HPAH and 3,4-DHPADO activities support the respiration data. Metabolic studies indicate that strain CSV86 metabolizes PA via phenylacetyl-CoA while 4-HPA via 3,4-DHPA pathway. Glucose grown cells showed lower activity of enzymes and respiration on PA, 4-HPA and 3,4-DHPA, suggesting that pathways are inducible. When grown on double carbon sources such as PA or 4-HPA plus glucose, CSV86 cells showed diauxic growth pattern with oxygen uptake on PA, 4-HPA and 3,4-DHPA in the first log-phase which was reduced during the second log-phase with increase in the respiration rate on glucose. This observation was supported by detection of high 4HPAH and 3,4-DHPADO activity in the first log-phase and glucose-6-phosphate dehydrogenase activity in the second log-phase. These results suggest that strain CSV86 utilizes PA and 4-HPA preferentially over glucose.