Bacterial degradation of arsenobetaine via dimethylarsinoylacetate.
Microorganisms from Mytilus edulis (marine mussel) degraded arsenobetaine, with the formation of trimethylarsine oxide, dimethylarsinate and methylarsonate. Four bacterial isolates from these mixed-cultures were shown by HPLC/hydride generation-atomic fluorescence spectroscopy (HPLC/HG-AFS) analysis to degrade arsenobetaine to dimethylarsinate in pure culture; there was no evidence of trimethylarsine oxide formation. Two of the isolates ( Paenibacillussp. strain 13943 and Pseudomonas sp. strain 13944) were shown by HPLC/inductively coupled plasma-mass spectrometry (HPLC/ICPMS) analysis to degrade arsenobetaine by initial cleavage of a methyl-arsenic bond to form dimethylarsinoylacetate, with subsequent cleavage of the carboxymethyl-arsenic bond to yield dimethylarsinate. Arsenobetaine biodegradation by pure cultures was biphasic, with dimethylarsinoylacetate accumulating in culture supernatants during the culture growth phase and its removal accompanying dimethylarsinate formation during a carbon-limited stationary phase. The Paenibacillus sp. also converted exogenously supplied dimethylarsinoylacetate to dimethylarsinate only under carbon-limited conditions. Lysed-cell extracts of the Paenibacillus sp. showed constitutive expression of enzyme(s) capable of arsenobetaine degradation through methyl-arsenic and carboxymethyl-arsenic bond cleavage. The work establishes the capability of particular bacteria to cleave both types of arsenic-carbon bonds of arsenobetaine and demonstrates that mixed-community functioning is not an obligate requirement for arsenobetaine biodegradation.
Jenkins
Richard O
RO
School of Molecular Science, De Montfort University, The Gateway, LE1 9BH, Leicester, UK. roj@dmu.ac.uk
Ritchie
Alisdair W
AW
Edmonds
John S
JS
Goessler
Walter
W
Molenat
Nathalie
N
Kuehnelt
Doris
D
Harrington
Christopher F
CF
Sutton
Peter G
PG
D000085:Acetates / Q000378:metabolism*; D000333:Aeromonas / Q000302:isolation & purification; D000818:Animals; D001152:Arsenicals / Q000378:metabolism*; D001419:Bacteria / Q000254:growth & development / Q000302:isolation & purification* / Q000378:metabolism*; D001673:Biodegradation, Environmental; D049872:Bivalvia / Q000382:microbiology; D002101:Cacodylic Acid / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D013058:Mass Spectrometry; D011549:Pseudomonas / Q000302:isolation & purification / Q000378:metabolism
D000085:Acetates; D001152:Arsenicals; C477455:dimethylarsinoylacetic acid; D002101:Cacodylic Acid; C038992:arsenobetaine