We investigated biodegradation of technical nonylphenol (tNP) in Phragmites australis rhizosphere sediment by conducting degradation experiments using sediments spiked with tNP. Accelerated tNP removal was observed in P. australis rhizosphere sediment, whereas tNP persisted in unvegetated sediment without plants and in autoclaved sediment with sterile plants, suggesting that the accelerated tNP removal resulted largely from tNP biodegradation by rhizosphere bacteria. Three bacterial strains, Stenotrophomonas sp. strain IT-1 and Sphingobium spp. strains IT-4 and IT-5, isolated from the rhizosphere were capable of utilizing tNP and 4-tert-octylphenol as a sole carbon source via type II ipso-substitution. Oxygen from P. australis roots, by creating highly oxygenated conditions in the sediment, stimulated cell growth and the tNP-degrading activity of the three strains. Moreover, organic compounds from P. australis roots functioned as carbon and energy sources for two strains, IT-4 and IT-5, supporting cell growth and tNP-degrading activity. Thus, P. australis roots elevated the cell growth and tNP-degrading activity of the three bacterial strains, leading to accelerated tNP removal. These results demonstrate that rhizoremediation of tNP-contaminated sediments using P. australis can be an effective strategy.
"Microbial degradation mainly contributes to the removal of NP in polluted site, which can abate its ecotoxicological risk (De Weert et al., 2010). To date, bacterial degradation of NP under aerobic conditions has been well-documented (De Weert et al., 2010; Toyama et al., 2011). The characterized NP-degrading bacterial isolates are affiliated with Acidovorax (Watanabe et al., 2012), Pseudomonas (Soares et al., 2003; Yuan et al., 2004; Watanabe et al., 2012), Bacillus (Chang et al., 2008), Stenotrophomonas (Soares et al., 2003), Sphingomonas "
[Show abstract][Hide abstract] ABSTRACT: Nonylphenol (NP) is one of commonly detected contaminants in the environment. Biological degradation is mainly responsible for remediation of NP-contaminated site. Knowledge about the structure of NP-degrading microbial community is still very limited. Microcosms were constructed to investigate the structure of microbial community in NP-contaminated river sediment and its change with NP biodegradation. A high level of NP was significantly dissipated in 6-9 days. Bacteria and ammonia-oxidizing archaea (AOA) were more responsive to NP amendment compared to ammonia-oxidizing bacteria (AOB). Gammaproteobacteria, Alphaproteobacteria and Bacteroidetes were the largest bacterial groups in NP-degrading sediment. Microorganisms from bacterial genera Brevundimonas, Flavobacterium, Lysobacter and Rhodobacter might be involved in NP degradation in river sediment. This study provides some new insights towards NP biodegradation and microbial ecology in NP-contaminated environment.
"The community assembly of bacteria in rhizosphere exposed to organic pollutants is little understood. Most of the previous studies have reported efficiency of pollutant biodegradation (Kidd et al. 2008; Abhilash et al. 2009; Becerra-Castro et al. 2011; Toyama et al. 2011). However, the bacterial clades responsible for these biodegradations remain partially characterized. "
[Show abstract][Hide abstract] ABSTRACT: This study investigated the impacts of an organochlorine (OC, γ-hexachlorocyclohexane and chlorobenzenes) mixture on microbial communities associated to Phragmites australis rhizosphere. Seventy-eight distinct colony morphotypes were isolated, cultivated and analysed by 16S rDNA sequence analysis. Toxicity tests confirmed sensitivity (e.g. Hevizibacter, Acidovorax) or tolerance (e.g. Bacillus, Aeromonas, Pseudomonas, Sphingomonas) of isolates. Rhizosphere analysis by pyrosequencing showed the microbial adaptation induced by OC exposure. Among the most abundant molecular operational taxonomic units, 80 % appeared to be tolerant (55 % opportunist, 25 % unaffected) and 20 % sensitive. P. australis rhizosphere exposed to OCs was dominated by phylotypes related to α-, β- and γ-Proteobacteria. Specific genera were identified which were previously described as chlorinated organic pollutant degraders: Sphingomonas sp., Pseudomonas sp., Devosia sp. and Sphingobium sp. P. australis could be suitable plants to maintain their rhizosphere active microbial population which can tolerate OCs and potentially improve the OC remediation process in part by biodegradation.
Applied Microbiology and Biotechnology 02/2014; DOI:10.1007/s00253-014-5545-6 · 3.34 Impact Factor
"In our experimental system, similar effects can be assumed. However, while in Toyama et al. (2011) the rhizospheric microbial activity was actually considered as mainly responsible for contaminant depletion, our quantification of phenolics in plant tissues indicates P. australis as an important element in determining their depletion by absorption. Noteworthily, the phyto-based approach, besides determining the depletion of NPs, determined also the net decrease in the COD and the BOD 5 values (Table 1), and the positive effect of the Phr013 bioaugmentation was still evident, determining a higher depletion of the two parameters with reference to the sole P. australis and to the inoculation with NP001. "
[Show abstract][Hide abstract] ABSTRACT: In the present study, the quality of effluents from a conventional wastewater treatment plant in Italy has been analyzed. Residual level of contamination by 4-nnonylphenol, mono- and di-ethoxylated nonylphenols has
been recorded in the effluents that resulted to be also phytotoxic and genotoxic. The possibility of exploiting
phytoremediation as a sustainable tertiary treatment for the depletion of the priority pollutants and for the reduction in the residual toxicity has been verified at mesocosm scale. The phyto-based treatment has been performed by the exploitation of Phragmites australis by either a bacterialassisted and not assisted approach. In relation to the bacterial-assisted approach, two new bacterial strains, capable of using the nonylphenols as a sole carbon source, have been isolated. One was identified as a plant growth-promoting
rhizobacteria (PGPR) belonging to the Stenotrophomonas species, and the second one was classified as
a Sphingobium species strain. Both strains were independently bioaugmented in the P. australis rhizosphere. In relation to the not assisted approach, the phyto-based process determined 87, 70 and 87 % for 4-n-nonylphenol, mono-ethoxylated nonylphenols and di-ethoxylated nonylphenols, respectively. The toxicological assessment of the process evidenced the complete depletion of either the phytotoxicity or the genotoxicity of the treated effluents. With reference to the bacterial-assisted approach, the PGPR Stenotrophomonas species strain resulted to be capable of significantly increasing the efficiency of the
phyto-based process in nonylphenol depletion up to 88 % for the 4-n-nonylphenol, 84 % for the mono-ethoxylated nonylphenol and 71 % for the di-ethoxylated nonylphenol.
International journal of Environmental Science and Technology 01/2014; 12(4). DOI:10.1007/s13762-014-0522-2 · 2.19 Impact Factor
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