Impact of elevated nitrate on sulfate-reducing bacteria: a comparative Study of Desulfovibrio vulgaris

• Published in: The ISME Journal Vol. 4; no. 11; pp. 1386 - 1397
• Main Authors: He, Qiang, He, Zhili, Joyner, Dominique C, Joachimiak, Marcin, Price, Morgan N, Yang, Zamin K, Yen, Huei-Che Bill, Hemme, Christopher L, Chen, Wenqiong, Fields, Matthew M, Stahl, David A, Keasling, Jay D, Keller, Martin, Arkin, Adam P, Hazen, Terry C, Wall, Judy D, Zhou, Jizhong
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.11.2010; Nature Publishing Group
• Subjects: 631/208/191; 631/326/252/58; 631/326/41; 631/553; Bacteria; Betaine; Biomedical and Life Sciences; Bioremediation; Comparative studies; Competition; Desulfovibrio vulgaris; Desulfovibrio vulgaris - growth & development; Desulfovibrio vulgaris - metabolism; Desulfovibrio vulgaris - physiology; Detoxification; Ecology; Energy metabolism; Evolutionary Biology; Gene Expression Profiling; Genomic analysis; Glycine; Heavy metals; Hybrids; Inhibition; Life Sciences; Microbial Ecology; Microbial Genetics and Genomics; Microbiology; Nitrate; Nitrate reduction; Nitrate-reducing bacteria; Nitrates - metabolism; Nitrite; original-article; osmoprotectants; Osmotic Pressure; Osmotic stress; Oxidation-Reduction; Oxidative stress; Sodium chloride; Sodium Chloride - metabolism; Stress, Physiological; Sulfate reduction; Sulfate-reducing bacteria; Sulfates; Sulfates - metabolism; Survival; systems biology; sulfate-reducing bacteria; functional genomics; stress response; nitrate
• ISSN: 1751-7362; 1751-7370
• DOI: 10.1038/ismej.2010.59

Sulfate-reducing bacteria have been extensively studied for their potential in heavy-metal bioremediation. However, the occurrence of elevated nitrate in contaminated environments has been shown to inhibit sulfate reduction activity. Although the inhibition has been suggested to result from the competition with nitrate-reducing bacteria, the possibility of direct inhibition of sulfate reducers by elevated nitrate needs to be explored. Using Desulfovibrio vulgaris as a model sulfate-reducing bacterium, functional genomics analysis reveals that osmotic stress contributed to growth inhibition by nitrate as shown by the upregulation of the glycine/betaine transporter genes and the relief of nitrate inhibition by osmoprotectants. The observation that significant growth inhibition was effected by 70 m M NaNO 3 but not by 70 m M NaCl suggests the presence of inhibitory mechanisms in addition to osmotic stress. The differential expression of genes characteristic of nitrite stress responses, such as the hybrid cluster protein gene, under nitrate stress condition further indicates that nitrate stress response by D. vulgaris was linked to components of both osmotic and nitrite stress responses. The involvement of the oxidative stress response pathway, however, might be the result of a more general stress response. Given the low similarities between the response profiles to nitrate and other stresses, less-defined stress response pathways could also be important in nitrate stress, which might involve the shift in energy metabolism. The involvement of nitrite stress response upon exposure to nitrate may provide detoxification mechanisms for nitrite, which is inhibitory to sulfate-reducing bacteria, produced by microbial nitrate reduction as a metabolic intermediate and may enhance the survival of sulfate-reducing bacteria in environments with elevated nitrate level.