102
|
Morris JJ, Johnson ZI, Szul MJ, Keller M, Zinser ER. Dependence of the cyanobacterium Prochlorococcus on hydrogen peroxide scavenging microbes for growth at the ocean's surface. PLoS One 2011; 6:e16805. [PMID: 21304826 PMCID: PMC3033426 DOI: 10.1371/journal.pone.0016805] [Citation(s) in RCA: 179] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2010] [Accepted: 12/31/2010] [Indexed: 01/08/2023] Open
Abstract
The phytoplankton community in the oligotrophic open ocean is numerically dominated by the cyanobacterium Prochlorococcus, accounting for approximately half of all photosynthesis. In the illuminated euphotic zone where Prochlorococcus grows, reactive oxygen species are continuously generated via photochemical reactions with dissolved organic matter. However, Prochlorococcus genomes lack catalase and additional protective mechanisms common in other aerobes, and this genus is highly susceptible to oxidative damage from hydrogen peroxide (HOOH). In this study we showed that the extant microbial community plays a vital, previously unrecognized role in cross-protecting Prochlorococcus from oxidative damage in the surface mixed layer of the oligotrophic ocean. Microbes are the primary HOOH sink in marine systems, and in the absence of the microbial community, surface waters in the Atlantic and Pacific Ocean accumulated HOOH to concentrations that were lethal for Prochlorococcus cultures. In laboratory experiments with the marine heterotroph Alteromonas sp., serving as a proxy for the natural community of HOOH-degrading microbes, bacterial depletion of HOOH from the extracellular milieu prevented oxidative damage to the cell envelope and photosystems of co-cultured Prochlorococcus, and facilitated the growth of Prochlorococcus at ecologically-relevant cell concentrations. Curiously, the more recently evolved lineages of Prochlorococcus that exploit the surface mixed layer niche were also the most sensitive to HOOH. The genomic streamlining of these evolved lineages during adaptation to the high-light exposed upper euphotic zone thus appears to be coincident with an acquired dependency on the extant HOOH-consuming community. These results underscore the importance of (indirect) biotic interactions in establishing niche boundaries, and highlight the impacts that community-level responses to stress may have in the ecological and evolutionary outcomes for co-existing species.
Collapse
Affiliation(s)
- J. Jeffrey Morris
- Department of Microbiology, University of Tennessee, Knoxville, Tennessee, United States of America
| | - Zackary I. Johnson
- Nicholas School of the Environment, Duke University Marine Laboratory, Beaufort, North Carolina, United States of America
| | - Martin J. Szul
- Department of Microbiology, University of Tennessee, Knoxville, Tennessee, United States of America
| | - Martin Keller
- Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States of America
| | - Erik R. Zinser
- Department of Microbiology, University of Tennessee, Knoxville, Tennessee, United States of America
- * E-mail:
| |
Collapse
|
103
|
de-Bashan LE, Hernandez JP, Nelson KN, Bashan Y, Maier RM. Growth of quailbush in acidic, metalliferous desert mine tailings: effect of Azospirillum brasilense Sp6 on biomass production and rhizosphere community structure. MICROBIAL ECOLOGY 2010; 60:915-27. [PMID: 20632001 PMCID: PMC2974781 DOI: 10.1007/s00248-010-9713-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2010] [Accepted: 06/20/2010] [Indexed: 05/18/2023]
Abstract
Mine tailing deposits in semiarid and arid environments frequently remain devoid of vegetation due to the toxicity of the substrate and the absence of a diverse soil microbial community capable of supporting seed germination and plant growth. The contribution of the plant growth promoting bacterium (PGPB) Azospirillum brasilense Sp6 to the growth of quailbush in compost-amended, moderately acidic, high-metal content mine tailings using an irrigation-based reclamation strategy was examined along with its influence on the rhizosphere bacterial community. Sp6 inoculation resulted in a significant (2.2-fold) increase in plant biomass production. The data suggest that the inoculum successfully colonized the root surface and persisted throughout the 60-day experiment in both the rhizosphere, as demonstrated by excision and sequencing of the appropriate denaturing gradient gel electrophoresis (DGGE) band, and the rhizoplane, as indicated by fluorescent in situ hybridization of root surfaces. Changes in rhizosphere community structure in response to Sp6 inoculation were evaluated after 15, 30, and 60 days using DGGE analysis of 16S rRNA polymerase chain reaction amplicons. A comparison of DGGE profiles using canonical correspondence analysis revealed a significant treatment effect (Sp6-inoculated vs. uninoculated plants vs. unplanted) on bacterial community structure at 15, 30, and 60 days (p < 0.05). These data indicate that in an extremely stressed environment such as acid mine tailings, an inoculated plant growth promoting bacterium not only can persist and stimulate plant growth but also can directly or indirectly influence rhizobacterial community development.
Collapse
Affiliation(s)
- Luz E. de-Bashan
- Department of Soil, Water and Environmental Science, University of Arizona, 429 Shantz Bldg. #38, 1177 E. Fourth Street, Tucson, AZ 85721-0038, USA. Environmental Microbiology Group, Northwestern Center for Biological Research (CIBNOR), La Paz, B.C.S., Mexico
| | - Juan-Pablo Hernandez
- Environmental Microbiology Group, Northwestern Center for Biological Research (CIBNOR), La Paz, B.C.S., Mexico
| | - Karis N. Nelson
- Department of Soil, Water and Environmental Science, University of Arizona, 429 Shantz Bldg. #38, 1177 E. Fourth Street, Tucson, AZ 85721-0038, USA
| | - Yoav Bashan
- Department of Soil, Water and Environmental Science, University of Arizona, 429 Shantz Bldg. #38, 1177 E. Fourth Street, Tucson, AZ 85721-0038, USA. Environmental Microbiology Group, Northwestern Center for Biological Research (CIBNOR), La Paz, B.C.S., Mexico
| | - Raina M. Maier
- Department of Soil, Water and Environmental Science, University of Arizona, 429 Shantz Bldg. #38, 1177 E. Fourth Street, Tucson, AZ 85721-0038, USA
| |
Collapse
|
105
|
Blanc G, Duncan G, Agarkova I, Borodovsky M, Gurnon J, Kuo A, Lindquist E, Lucas S, Pangilinan J, Polle J, Salamov A, Terry A, Yamada T, Dunigan DD, Grigoriev IV, Claverie JM, Van Etten JL. The Chlorella variabilis NC64A genome reveals adaptation to photosymbiosis, coevolution with viruses, and cryptic sex. THE PLANT CELL 2010; 22:2943-55. [PMID: 20852019 PMCID: PMC2965543 DOI: 10.1105/tpc.110.076406] [Citation(s) in RCA: 337] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2010] [Revised: 07/15/2010] [Accepted: 09/01/2010] [Indexed: 05/18/2023]
Abstract
Chlorella variabilis NC64A, a unicellular photosynthetic green alga (Trebouxiophyceae), is an intracellular photobiont of Paramecium bursaria and a model system for studying virus/algal interactions. We sequenced its 46-Mb nuclear genome, revealing an expansion of protein families that could have participated in adaptation to symbiosis. NC64A exhibits variations in GC content across its genome that correlate with global expression level, average intron size, and codon usage bias. Although Chlorella species have been assumed to be asexual and nonmotile, the NC64A genome encodes all the known meiosis-specific proteins and a subset of proteins found in flagella. We hypothesize that Chlorella might have retained a flagella-derived structure that could be involved in sexual reproduction. Furthermore, a survey of phytohormone pathways in chlorophyte algae identified algal orthologs of Arabidopsis thaliana genes involved in hormone biosynthesis and signaling, suggesting that these functions were established prior to the evolution of land plants. We show that the ability of Chlorella to produce chitinous cell walls likely resulted from the capture of metabolic genes by horizontal gene transfer from algal viruses, prokaryotes, or fungi. Analysis of the NC64A genome substantially advances our understanding of the green lineage evolution, including the genomic interplay with viruses and symbiosis between eukaryotes.
Collapse
Affiliation(s)
- Guillaume Blanc
- Centre National de la Recherche Scientifique, Laboratoire Information Génomique et Structurale UPR2589, Aix-Marseille Université, Institut de Microbiologie de la Méditerranée, 13009 Marseille, France.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
107
|
De-Bashan LE, Magallon P, Antoun H, Bashan Y. ROLE OF GLUTAMATE DEHYDROGENASE AND GLUTAMINE SYNTHETASE IN CHLORELLA VULGARIS DURING ASSIMILATION OF AMMONIUM WHEN JOINTLY IMMOBILIZED WITH THE MICROALGAE-GROWTH-PROMOTING BACTERIUM AZOSPIRILLUM BRASILENSE(1). JOURNAL OF PHYCOLOGY 2008; 44:1188-1196. [PMID: 27041715 DOI: 10.1111/j.1529-8817.2008.00572.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Enzymatic activities of glutamate dehydrogenase (GDH) and glutamine synthetase (GS) participating in the nitrogen metabolism and related ammonium absorption were assayed after the microalga Chlorella vulgaris Beij. was jointly immobilized with the microalgae-growth-promoting bacterium Azospirillum brasilense. At initial concentrations of 3, 6, and 10 mg · L(-1) NH4 (+) , joint immobilization enhances growth of C. vulgaris but does not affect ammonium absorption capacity of the microalga. However, at 8 mg · L(-1) NH4 (+) , joint immobilization enhanced ammonium absorption by the microalga without affecting the growth of the microalgal population. Correlations between absorption of ammonium per cell and per culture showed direct (negative and positive) linear correlations between these parameters and microalga populations at 3, 6, and 10 mg · L(-1) NH4 (+) , but not at 8 mg · L(-1) NH4 (+) , where the highest absorption of ammonium occurred. In all cultures, immobilized and jointly immobilized, having the four initial ammonium concentrations, enzymatic activities of Chlorella are affected by A. brasilense. Regardless of the initial concentration of ammonium, GS activity in C. vulgaris was always higher when jointly immobilized and determined on a per-cell basis. When jointly immobilized, only at an initial concentration of 8 mg · L(-1) NH4 (+) was GDH activity per cell higher.
Collapse
Affiliation(s)
- Luz E De-Bashan
- Environmental Microbiology Group, Northwestern Center for Biological Research (CIBNOR), La Paz, B.C.S., Mexico Département des Sols et de Génie Agroalimentaire, Université Laval, Québec City, Québec, Canada Department of Soil, Water and Environmental Science, University of Arizona, Tucson, Arizona, USAEnvironmental Microbiology Group, Northwestern Center for Biological Research (CIBNOR), La Paz, B.C.S., MexicoDépartement des Sols et de Génie Agroalimentaire, Université Laval, Québec City, Québec, Canada Environmental Microbiology Group, Northwestern Center for Biological Research (CIBNOR), La Paz, B.C.S., Mexico Département des Sols et de Génie Agroalimentaire, Université Laval, Québec City, Québec, Canada Department of Soil, Water and Environmental Science, University of Arizona, Tucson, Arizona, USA
| | - Paola Magallon
- Environmental Microbiology Group, Northwestern Center for Biological Research (CIBNOR), La Paz, B.C.S., Mexico Département des Sols et de Génie Agroalimentaire, Université Laval, Québec City, Québec, Canada Department of Soil, Water and Environmental Science, University of Arizona, Tucson, Arizona, USAEnvironmental Microbiology Group, Northwestern Center for Biological Research (CIBNOR), La Paz, B.C.S., MexicoDépartement des Sols et de Génie Agroalimentaire, Université Laval, Québec City, Québec, Canada Environmental Microbiology Group, Northwestern Center for Biological Research (CIBNOR), La Paz, B.C.S., Mexico Département des Sols et de Génie Agroalimentaire, Université Laval, Québec City, Québec, Canada Department of Soil, Water and Environmental Science, University of Arizona, Tucson, Arizona, USA
| | - Hani Antoun
- Environmental Microbiology Group, Northwestern Center for Biological Research (CIBNOR), La Paz, B.C.S., Mexico Département des Sols et de Génie Agroalimentaire, Université Laval, Québec City, Québec, Canada Department of Soil, Water and Environmental Science, University of Arizona, Tucson, Arizona, USAEnvironmental Microbiology Group, Northwestern Center for Biological Research (CIBNOR), La Paz, B.C.S., MexicoDépartement des Sols et de Génie Agroalimentaire, Université Laval, Québec City, Québec, Canada Environmental Microbiology Group, Northwestern Center for Biological Research (CIBNOR), La Paz, B.C.S., Mexico Département des Sols et de Génie Agroalimentaire, Université Laval, Québec City, Québec, Canada Department of Soil, Water and Environmental Science, University of Arizona, Tucson, Arizona, USA
| | - Yoav Bashan
- Environmental Microbiology Group, Northwestern Center for Biological Research (CIBNOR), La Paz, B.C.S., Mexico Département des Sols et de Génie Agroalimentaire, Université Laval, Québec City, Québec, Canada Department of Soil, Water and Environmental Science, University of Arizona, Tucson, Arizona, USAEnvironmental Microbiology Group, Northwestern Center for Biological Research (CIBNOR), La Paz, B.C.S., MexicoDépartement des Sols et de Génie Agroalimentaire, Université Laval, Québec City, Québec, Canada Environmental Microbiology Group, Northwestern Center for Biological Research (CIBNOR), La Paz, B.C.S., Mexico Département des Sols et de Génie Agroalimentaire, Université Laval, Québec City, Québec, Canada Department of Soil, Water and Environmental Science, University of Arizona, Tucson, Arizona, USA
| |
Collapse
|