Functional metaproteome analysis of protein extracts from contaminated soil and groundwater

• Published in: The ISME Journal 2007-07, Vol.1 (3), p.224-234
• Main Authors: Benndorf, Dirk, Balcke, Gerd U, Harms, Hauke, von Bergen, Martin
• Format: Article
• Language: English
• Subjects: 2,4-D; Acetic acid; Amino Acid Sequence; Aquifers; Bacterial Proteins - analysis; Bacterial Proteins - isolation & purification; Biodegradation; Chlorobenzene; Chlorophenoxy acids; Dioxygenases - analysis; Dioxygenases - isolation & purification; Electrophoresis; Electrophoresis, Gel, Two-Dimensional; Electrophoresis, Polyacrylamide Gel; Groundwater; Humic acids; Ionization; Liquid chromatography; Mass spectrometry; Microbial activity; Microorganisms; Minerals; Molecular Sequence Data; Organic constituents; Organic matter; Peptide Elongation Factor Tu - analysis; Peptide Elongation Factor Tu - isolation & purification; Phenols; Proteins; Proteome - analysis; Proteome - isolation & purification; Sodium hydroxide; Soil - analysis; Soil contamination; Soil Microbiology; Spectrometry, Mass, Electrospray Ionization; Sulfates; Water analysis; Water sampling
• ISSN: 1751-7362; 1751-7370
• DOI: 10.1038/ismej.2007.39

Using proteins from soil or groundwater as functional biomarkers requires efficient extraction. We developed an extraction method in which the separation of proteins from the inorganic and organic constituents of the soil matrix was achieved by a combination of 0.1 M NaOH treatment and phenol extraction. Incubation with NaOH released humic acids and proteins from soil minerals, and simultaneously, disrupted microorganisms. The subsequent phenol extraction separated the proteins from the humic organic matter. Protein extracts were applied to sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and 2D-electrophoresis (2-DE). Spots and bands were excised and individual proteins identified by liquid chromatography online linked to mass spectrometry (MS) via electrospray ionization source (LC-ESI-MS). To assess the suitability of the method for the functional analysis of environmental metaproteomes, it was applied to soil that had been enriched in chlorophenoxy acid-degrading bacteria by incubation with 2,4-dichlorophenoxy acetic acid (2,4-D) for 22 days. The method was also used to analyze groundwater from the aquifer of a chlorobenzene-contaminated site. The identification of enzymes such as chlorocatechol dioxygenases was consistent with bacterial metabolic pathways expected to be expressed in these samples. The protocol enabled thus the analysis of the metaproteome of soil and groundwater samples. It thereby provides a means to study the diversity of environmental microbial communities while addressing functional aspects more directly than metagenome or even metatranscriptome analysis.