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Title: Oxygen-­dependent regulation of bacterial lipid production

Understanding the mechanisms of lipid accumulation in microorganisms is important for several reasons. In addition to providing insight into assembly of biological membranes, lipid accumulation has important applications in the production of renewable fuels and chemicals. The photosynthetic bacterium Rhodobacter sphaeroides is an attractive organism to study lipid accumulation, as it has the somewhat unique ability to increase membrane production at low O₂ tensions. Under these conditions, R. sphaeroides develops invaginations of the cytoplasmic membrane to increase its membrane surface area for housing of the membrane-bound components of its photosynthetic apparatus. Here we use fatty acid levels as a reporter of membrane lipid content. We show that, under low-O₂ and anaerobic conditions, the total fatty acid content per cell increases 3-fold. We also find that the increases in the amount of fatty acid and photosynthetic pigment per cell are correlated as O₂ tensions or light intensity are changed. To ask if lipid and pigment accumulation were genetically separable, we analyzed strains with mutations in known photosynthetic regulatory pathways. While a strain lacking AppA failed to induce photosynthetic pigment-protein complex accumulation, it increased fatty acid content under low O2 conditions. We also found that an intact PrrBA pathway is required formore » low O2-induced fatty acid accumulation. In conclusion, our findings suggest a previously unknown role of R. sphaeroides transcriptional regulators in increasing fatty acid and phospholipid accumulation in response to decreased O₂ tension.« less
Authors:
 [1] ;  [2] ;  [1] ;  [1]
  1. Univ. of Wisconsin, Madison, WI (United States)
  2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Publication Date:
OSTI Identifier:
1208744
Report Number(s):
PNNL-SA--106866
Journal ID: ISSN 0021-9193; 48544; 48815; KP1704020
Grant/Contract Number:
AC05-76RL01830; FC02-07ER64494
Type:
Accepted Manuscript
Journal Name:
Journal of Bacteriology
Additional Journal Information:
Journal Volume: 197; Journal Issue: 9; Journal ID: ISSN 0021-9193
Publisher:
American Society for Microbiology
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (United States). Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES Environmental Molecular Sciences Laboratory