Identification of two organohalide-respiring Dehalococcoidia associated to different dechlorination activities in PCB-impacted marine sedimentsReport as inadecuate




Identification of two organohalide-respiring Dehalococcoidia associated to different dechlorination activities in PCB-impacted marine sediments - Download this document for free, or read online. Document in PDF available to download.

Microbial Cell Factories

, 16:127

First Online: 24 July 2017Received: 23 November 2016Accepted: 14 July 2017

Abstract

BackgroundMicrobial reductive dechlorination of polychlorinated biphenyls PCBs plays a major role in detoxifying anoxic contaminated freshwater and marine sediments from PCBs. Known members of the phylum Chloroflexi are typically responsible for this activity in freshwater sediments, whereas less is known about the microorganisms responsible for this activity in marine sediments. PCB-respiring activities were detected in PCB-impacted marine sediments of the Venice Lagoon. The aim of this work was to identify the indigenous organohalide-respiring microorganisms in such environments and assess their dechlorination specificity against spiked Aroclor™ 1254 PCBs under laboratory conditions resembling the in situ biogeochemistry.

ResultsHigh PCB dechlorination activities from 150 ± 7 to 380 ± 44 μmol of chlorine removed kg week were detected in three out of six sediments sampled from different locations of the lagoon. An uncultured non-Dehalococcoides phylotype of the class Dehalococcoidia closely related to Dehalobium chlorocoercia DF-1, namely phylotype VLD-1, was detected and enriched up to 10 16S rRNA gene copies per gram of sediment where dechlorination activities were higher and 25-4-24-4 and 25-2-24-2-4-4 chlorobiphenyls CB accumulated as the main tri-dichlorinated products. Conversely, a different phylotype closely related to the SF1-m-1 clade, namely VLD-2, also enriched highly where lower dechlorination activity and the accumulation of 25-3 CB as main tri-chlorinated product occurred, albeit in the simultaneous presence of VLD-1. Both phylotypes showed growth yields higher or comparable to known organohalide respirers and neither phylotypes enriched in sediment cultures not exhibiting dechlorination.

ConclusionsThese findings confirm the presence of different PCB-respiring microorganisms in the indigenous microbial communities of Venice Lagoon sediments and relate two non-Dehalococcoides phylotypes of the class Dehalococcoidia to different PCB dechlorination rates and specificities.

KeywordsPolychlorinated biphenyls Microbial reductive dechlorination Organohalide respiration Marine sediments Dehalococcoidia Electronic supplementary materialThe online version of this article doi:10.1186-s12934-017-0743-4 contains supplementary material, which is available to authorized users.

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Author: Andrea Nuzzo - Andrea Negroni - Giulio Zanaroli - Fabio Fava

Source: https://link.springer.com/



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