Degradation of 2,4-dichlorophenoxyacetic acid by haloalkaliphilic bacteria.
Three 2,4-dichlorophenoxyacetic acid (2,4-D)-degrading bacterial isolates were obtained from the highly saline and alkaline Alkali Lake site in southwestern Oregon contaminated with 2,4-D production wastes. While similar in most respects, the three isolates differed significantly in 2,4-D degradation rates, with the most active strain, I-18, demonstrating an ability to degrade up to 3000 mg 2,4-D I-1 in 3 d. This strain was well adapted to the extreme environment from which it was isolated, growing optimally on 2,4-D at pH 8.4-9.4 and at sodium ion concentrations of 0.6-1.0 M. According to its optimum salt concentration and pH for growth, this isolate was a moderately halophilic, alkaliphilic bacterium. The 16S RNA gene sequence (303 nt) was identical for all three isolates and most closely resembled those of the moderately halophilic eubacteria of the family Halomonadaceae (91% identity). Biochemical and genetic examination revealed strain I-18 utilizes the same 2,4-D degradation pathway as most of the 2,4-D-degrading bacteria from non-extreme environments. Hybridization data and comparison of the partial sequences of the tfdA gene from the Alkali Lake isolates with those of bacteria from non-extreme environments suggested a common genetic origin of the 2,4-D degradation pathway in the two groups of micro-organisms.
Maltseva
Olga
O
Center for Microbial Ecology and Department of Microbiology, Michigan State University, East Lansing, Michigan 48824, USA.
McGowan
Catherine
C
Center for Microbial Ecology and Department of Microbiology, Michigan State University, East Lansing, Michigan 48824, USA.
Fulthorpe
Roberta
R
Center for Microbial Ecology and Department of Microbiology, Michigan State University, East Lansing, Michigan 48824, USA.
Oriel
Patrick
P
Center for Microbial Ecology and Department of Microbiology, Michigan State University, East Lansing, Michigan 48824, USA.
D015084:2,4-Dichlorophenoxyacetic Acid / Q000378:metabolism*; D001483:Base Sequence; D001673:Biodegradation, Environmental; D002952:Citric Acid Cycle; D019143:Evolution, Molecular; D006088:Gram-Negative Aerobic Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D012329:RNA, Bacterial / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012964:Sodium / Q000032:analysis; D014874:Water Pollutants, Chemical / Q000378:metabolism*
D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S; D014874:Water Pollutants, Chemical; D015084:2,4-Dichlorophenoxyacetic Acid; D012964:Sodium