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This content will become publicly available on March 3, 2017

Title: Establishment of stable synthetic mutualism without co-evolution between microalgae and bacteria demonstrated by mutual transfer of metabolites (NanoSIMS isotopic imaging) and persistent physical association (Fluorescent in situ hybridization)

The demonstration of a mutualistic interaction requires evidence of benefits for both partners as well as stability of the association over multiple generations. A synthetic mutualism between the freshwater microalga Chlorella sorokiniana and the soil-derived plant growth-promoting bacterium (PGPB) Azospirillum brasilense was created when both microorganisms were co-immobilized in alginate beads. Using stable isotope enrichment experiments followed by high-resolution secondary ion mass spectrometry (SIMS) imaging of single cells, we demonstrated transfer of carbon and nitrogen compounds between the two partners. Further, using fluorescent in situ hybridization (FISH), mechanical disruption and scanning electron microscopy, we demonstrated the stability of their physical association for a period of 10 days after the aggregated cells were released from the beads. The bacteria significantly enhanced the growth of the microalgae while the microalgae supported growth of the bacteria in a medium where it could not otherwise grow. In conclusion, we propose that this microalga-bacterium association is a true synthetic mutualism independent of co-evolution. (155 words).
Authors:
 [1] ;  [2] ;  [3] ;  [2] ;  [4] ;  [5] ;  [6] ;  [1]
  1. The Bashan Institute of Science, Auburn, AL (United States); Auburn Univ., AL (United States); Environmental Microbiology Group, Northwestern center for Biological Research, La Paz (Mexico)
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  3. NASA Ames Research Center (ARC), Moffett Field, Mountain View, CA (United States)
  4. NASA Ames Research Center (ARC), Moffett Field, Mountain View, CA (United States); Bay Area Environmental Research Inst. Petaluma, CA (United States)
  5. The Bashan Institute of Science, Auburn, AL (United States); Environmental Microbiology Group, Northwestern center for Biological Research, La Paz (Mexico)
  6. The Bashan Institute of Science, Auburn, AL (United States)
Publication Date:
OSTI Identifier:
1241994
Report Number(s):
LLNL-JRNL--675179
Journal ID: ISSN 2211-9264
Grant/Contract Number:
AC52-07NA27344
Type:
Accepted Manuscript
Journal Name:
Algal Research
Additional Journal Information:
Journal Volume: 15; Journal Issue: C; Journal ID: ISSN 2211-9264
Publisher:
Elsevier
Research Org:
Lawrence Livermore National Laboratory (LLNL), Livermore, CA
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES microalgae; NanoSIMS; plant growth-promoting bacteria; synthetic mutualism