Bacterial diversity and reductive dehalogenase redundancy in a 1,2-dichloroethane-degrading bacterial consortium enriched from a contaminated aquifer.
BACKGROUND
Bacteria possess a reservoir of metabolic functionalities ready to be exploited for multiple purposes. The use of microorganisms to clean up xenobiotics from polluted ecosystems (e.g. soil and water) represents an eco-sustainable and powerful alternative to traditional remediation processes. Recent developments in molecular-biology-based techniques have led to rapid and accurate strategies for monitoring and identification of bacteria and catabolic genes involved in the degradation of xenobiotics, key processes to follow up the activities in situ.


RESULTS
We report the characterization of the response of an enriched bacterial community of a 1,2-dichloroethane (1,2-DCA) contaminated aquifer to the spiking with 5 mM lactate as electron donor in microcosm studies. After 15 days of incubation, the microbial community structure was analyzed. The bacterial 16S rRNA gene clone library showed that the most represented phylogenetic group within the consortium was affiliated with the phylum Firmicutes. Among them, known degraders of chlorinated compounds were identified. A reductive dehalogenase genes clone library showed that the community held four phylogenetically-distinct catalytic enzymes, all conserving signature residues previously shown to be linked to 1,2-DCA dehalogenation.


CONCLUSIONS
The overall data indicate that the enriched bacterial consortium shares the metabolic functionality between different members of the microbial community and is characterized by a high functional redundancy. These are fundamental features for the maintenance of the community's functionality, especially under stress conditions and suggest the feasibility of a bioremediation treatment with a potential prompt dehalogenation and a process stability over time.
Marzorati
Massimo
M
DISTAM, Dipartimento di Scienze e Tecnologie alimentari e Microbiologiche, Università degli Studi di Milano, 20133 Milan, Italy.
Balloi
Annalisa
A
de Ferra
Francesca
F
Corallo
Lorenzo
L
Carpani
Giovanna
G
Wittebolle
Lieven
L
Verstraete
Willy
W
Daffonchio
Daniele
D
D000595:Amino Acid Sequence; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D001673:Biodegradation, Environmental; D044822:Biodiversity; D005025:Ethylene Dichlorides / Q000378:metabolism*; D006867:Hydrolases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D016415:Sequence Alignment; D014871:Water Microbiology
D001426:Bacterial Proteins; D005025:Ethylene Dichlorides; C024565:ethylene dichloride; D006867:Hydrolases