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MacKellar D, Lieber L, Norman JS, Bolger A, Tobin C, Murray JW, Oksaksin M, Chang RL, Ford TJ, Nguyen PQ, Woodward J, Permingeat HR, Joshi NS, Silver PA, Usadel B, Rutherford AW, Friesen ML, Prell J. Streptomyces thermoautotrophicus does not fix nitrogen. Sci Rep 2016; 6:20086. [PMID: 26833023 PMCID: PMC4735515 DOI: 10.1038/srep20086] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 12/07/2015] [Indexed: 11/09/2022] Open
Abstract
Streptomyces thermoautotrophicus UBT1 has been described as a moderately thermophilic chemolithoautotroph with a novel nitrogenase enzyme that is oxygen-insensitive. We have cultured the UBT1 strain, and have isolated two new strains (H1 and P1-2) of very similar phenotypic and genetic characters. These strains show minimal growth on ammonium-free media, and fail to incorporate isotopically labeled N2 gas into biomass in multiple independent assays. The sdn genes previously published as the putative nitrogenase of S. thermoautotrophicus have little similarity to anything found in draft genome sequences, published here, for strains H1 and UBT1, but share >99% nucleotide identity with genes from Hydrogenibacillus schlegelii, a draft genome for which is also presented here. H. schlegelii similarly lacks nitrogenase genes and is a non-diazotroph. We propose reclassification of the species containing strains UBT1, H1, and P1-2 as a non-Streptomycete, non-diazotrophic, facultative chemolithoautotroph and conclude that the existence of the previously proposed oxygen-tolerant nitrogenase is extremely unlikely.
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Affiliation(s)
- Drew MacKellar
- Harvard Medical School, 200 Longwood Ave, Boston MA 02130
- Wyss Institute, 3 Blackfan Cir, Boston MA 02115
| | - Lucas Lieber
- Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Zavalla S2125ZAA, Santa Fe, Argentina
- Dept. Life Sciences, Imperial College, London, SW7 2AZ, UK
| | - Jeffrey S. Norman
- Department of Plant Biology, Michigan State University, 612 Wilson Rd, East Lansing, MI USA 48824
| | - Anthony Bolger
- Institute for Biology I, BioSC, RWTH Aachen University, Worringer Weg 3, 52074 Aachen, Germany
| | - Cory Tobin
- TheLab Inc, 1340 E. 6th Street Suite 603, Los Angeles, CA USA 90021
| | | | - Mehtap Oksaksin
- Institute for Biology I, BioSC, RWTH Aachen University, Worringer Weg 3, 52074 Aachen, Germany
| | - Roger L. Chang
- Harvard Medical School, 200 Longwood Ave, Boston MA 02130
| | - Tyler J. Ford
- Harvard Medical School, 200 Longwood Ave, Boston MA 02130
| | | | - Jimmy Woodward
- Department of Plant Biology, Michigan State University, 612 Wilson Rd, East Lansing, MI USA 48824
| | - Hugo R. Permingeat
- Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Zavalla S2125ZAA, Santa Fe, Argentina
| | | | - Pamela A. Silver
- Harvard Medical School, 200 Longwood Ave, Boston MA 02130
- Wyss Institute, 3 Blackfan Cir, Boston MA 02115
| | - Björn Usadel
- Institute for Biology I, BioSC, RWTH Aachen University, Worringer Weg 3, 52074 Aachen, Germany
| | | | - Maren L. Friesen
- Department of Plant Biology, Michigan State University, 612 Wilson Rd, East Lansing, MI USA 48824
| | - Jürgen Prell
- Institute for Biology I, BioSC, RWTH Aachen University, Worringer Weg 3, 52074 Aachen, Germany
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Bashan Y, De-Bashan LE. Protection of tomato seedlings against infection by Pseudomonas syringae pv. tomato by using the plant growth-promoting bacterium Azospirillum brasilense. Appl Environ Microbiol 2002; 68:2637-43. [PMID: 12039714 PMCID: PMC123946 DOI: 10.1128/aem.68.6.2637-2643.2002] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2001] [Accepted: 02/27/2002] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas syringae pv. tomato, the causal agent of bacterial speck of tomato, and the plant growth-promoting bacterium Azospirillum brasilense were inoculated onto tomato plants, either alone, as a mixed culture, or consecutively. The population dynamics in the rhizosphere and foliage, the development of bacterial speck disease, and their effects on plant growth were monitored. When inoculated onto separate plants, the A. brasilense population in the rhizosphere of tomato plants was 2 orders of magnitude greater than the population of P. syringae pv. tomato (10(7) versus 10(5) CFU/g [dry weight] of root). Under mist chamber conditions, the leaf population of P. syringae pv. tomato was 1 order of magnitude greater than that of A. brasilense (10(7) versus 10(6) CFU/g [dry weight] of leaf). Inoculation of seeds with a mixed culture of the two bacterial strains resulted in a reduction of the pathogen population in the rhizosphere, an increase in the A. brasilense population, the prevention of bacterial speck disease development, and improved plant growth. Inoculation of leaves with the mixed bacterial culture under mist conditions significantly reduced the P. syringae pv. tomato population and significantly decreased disease severity. Challenge with P. syringae pv. tomato after A. brasilense was established in the leaves further reduced both the population of P. syringae pv. tomato and disease severity and significantly enhanced plant development. Both bacteria maintained a large population in the rhizosphere for 45 days when each was inoculated separately onto tomato seeds (10(5) to 10(6) CFU/g [dry weight] of root). However, P. syringae pv. tomato did not survive in the rhizosphere in the presence of A. brasilense. Foliar inoculation of A. brasilense after P. syringae pv. tomato was established on the leaves did not alleviate bacterial speck disease, and A. brasilense did not survive well in the phyllosphere under these conditions, even in a mist chamber. Several applications of a low concentration of buffered malic acid significantly enhanced the leaf population of A. brasilense (>10(8) CFU/g [dry weight] of leaf), decreased the population of P. syringae pv. tomato to almost undetectable levels, almost eliminated disease development, and improved plant growth to the level of uninoculated healthy control plants. Based on our results, we propose that A. brasilense be used in prevention programs to combat the foliar bacterial speck disease caused by P. syringae pv. tomato.
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Affiliation(s)
- Yoav Bashan
- Environmental Microbiology, The Center for Biological Research of the Northwest, La Paz, Mexico
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