Dataset Information

Assessment of the Mutagenicity of Sediments from Yangtze River Estuary Using Salmonella Typhimurium/Microsome Assay.

ABSTRACT: Sediments in estuaries are of important environmental concern because they may act as pollution sinks and sources to the overlying water body. These sediments can be accumulated by benthic organisms. This study assessed the mutagenic potential of sediment extracts from the Yangtze River estuary by using the Ames fluctuation assay with the Salmonella typhimurium his (-) strain TA98 (frameshift mutagen indicator) and TA100 (baseshift mutagen indicator). Most of the sediment samples were mutagenic to the strain TA98, regardless of the presence or absence of exogenous metabolic activation (S9 induction by ?-naphthoflavone/phenobarbital). However, none of the samples were mutagenic to the strain TA100. Thus, the mutagenicity pattern was mainly frameshift mutation, and the responsible toxicants were both direct (without S9 mix) and indirect (with S9 mix) mutagens. The mutagenicity of the sediment extracts increased when S9 was added. Chemical analysis showed a poor correlation between the content of priority polycyclic aromatic hydrocarbons and the detected mutagenicity in each sample. The concept of effect-directed analysis was used to analyze possible compounds responsible for the detected mutagenic effects. With regard to the mutagenicity of sediment fractions, non-polar compounds as well as weakly and moderately polar compounds played a main role. Further investigations should be conducted to identify the responsible components.

SUBMITTER: Liu L

PROVIDER: S-EPMC4659643 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Assessment of the Mutagenicity of Sediments from Yangtze River Estuary Using Salmonella Typhimurium/Microsome Assay.

Liu Li L Chen Ling L Floehr Tilman T Xiao Hongxia H Bluhm Kerstin K Hollert Henner H Wu Lingling L

PloS one 20151125 11

Sediments in estuaries are of important environmental concern because they may act as pollution sinks and sources to the overlying water body. These sediments can be accumulated by benthic organisms. This study assessed the mutagenic potential of sediment extracts from the Yangtze River estuary by using the Ames fluctuation assay with the Salmonella typhimurium his (-) strain TA98 (frameshift mutagen indicator) and TA100 (baseshift mutagen indicator). Most of the sediment samples were mutagenic ...[more]

PMID: 26606056

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Project description:The newly discovered complete ammonia-oxidizing (comammox) Nitrospira has been identified in different environments, including coastal environments, where salinity is one of the most important factors for the abundance and activity of nitrifiers. Here, we demonstrate the effect of salinity on comammox Nitrospira, canonical ammonia-oxidizing bacteria (AOB), and ammonia-oxidizing archaea (AOA) in the intertidal sediments of the Yangtze River estuary based on microcosm experiments, DNA stable-isotope probing (DNA-SIP), and potential ammonium-oxidation rate (PAR) tests for different groups of ammonia oxidizers with selective inhibitors. During microcosm incubations, the abundance of comammox Nitrospira was more sensitive to increased salinity than that of other ammonia oxidizers. The results obtained with DNA-SIP heavy fractions showed that the dominant phylotype in clade A.2 (containing genes involved in the adaptation to haloalkaline environments) had high proportions in comammox Nitrospira community under both freshwater (0.06% salinity) and highly saline water (3% salinity) conditions. In contrast, another phylotype of clade A.2 (which lacks these genes) was dominant only under freshwater conditions. The PARs confirmed that comammox Nitrospira presented greater contributions to nitrification under freshwater conditions with a PAR of 4.37 ± 0.53 mg N·day-1·kg soil-1 (54%) than under saline water conditions with a PAR of 0.60 ± 0.94 mg N·day-1·kg soil-1 (18%). Moreover, AOA were specific to saline water conditions, whereas AOB were common under both freshwater and saline water conditions (44% and 52%, respectively). The present study provided evidence that salinity markedly affects the activity of comammox Nitrospira, and that the salt sensitivity of different phylotypes varies. IMPORTANCE Complete ammonia oxidation (comammox) is a newly discovered type of nitrification through which ammonia is oxidized to nitrate in an organism. Comammox Nitrospira were abundantly found in coastal ecosystems and demonstrated high community diversity. Changes in salinity are considered one of the most important factors to comammox Nitrospira in coastal ecosystems; however, reports on the correlation between them remain inconsistent. Therefore, it is critical to experimentally determine the influence of salinity on comammox Nitrospira in the coastal ecosystem. This study demonstrated a clear effect of salinity on the abundance, activity, and relative contribution of different ammonia oxidizers, especially for comammox Nitrospira. To the best of our knowledge, this is the first study demonstrating comammox Nitrospira activity at seawater salinities, implying the existence of a salt-tolerant type comammox Nitrospira, despite its activity being much lower than in freshwater conditions. The indicated correlation between the activity of specific comammox Nitrospira and salinity is anticipated to provide insights into the distribution of comammox Nitrospira and their potential contributions in estuaries and coastal ecosystems.

Dataset Information

Assessment of the Mutagenicity of Sediments from Yangtze River Estuary Using Salmonella Typhimurium/Microsome Assay.

Publications

Assessment of the Mutagenicity of Sediments from Yangtze River Estuary Using Salmonella Typhimurium/Microsome Assay.

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