Title: Mutations That Alter the Bacterial Cell Envelope Increase Lipid Production

Abstract

ABSTRACT Lipids from microbes offer a promising source of renewable alternatives to petroleum-derived compounds. In particular, oleaginous microbes are of interest because they accumulate a large fraction of their biomass as lipids. In this study, we analyzed genetic changes that alter lipid accumulation in Rhodobacter sphaeroides . By screening an R. sphaeroides Tn 5 mutant library for insertions that increased fatty acid content, we identified 10 high-lipid (HL) mutants for further characterization. These HL mutants exhibited increased sensitivity to drugs that target the bacterial cell envelope and changes in shape, and some had the ability to secrete lipids, with two HL mutants accumulating ~60% of their total lipids extracellularly. When one of the highest-lipid-secreting strains was grown in a fed-batch bioreactor, its lipid content was comparable to that of oleaginous microbes, with the majority of the lipids secreted into the medium. Based on the properties of these HL mutants, we conclude that alterations of the cell envelope are a previously unreported approach to increase microbial lipid production. We also propose that this approach may be combined with knowledge about biosynthetic pathways, in this or other microbes, to increase production of lipids and other chemicals. IMPORTANCE This paper reports on experiments tomore » understand how to increase microbial lipid production. Microbial lipids are often cited as one renewable replacement for petroleum-based fuels and chemicals, but strategies to increase the yield of these compounds are needed to achieve this goal. While lipid biosynthesis is often well understood, increasing yields of these compounds to industrially relevant levels is a challenge, especially since genetic, synthetic biology, or engineering approaches are not feasible in many microbes. We show that altering the bacterial cell envelope can be used to increase microbial lipid production. We also find that the utility of some of these alterations can be enhanced by growing cells in bioreactor configurations that can be used industrially. We propose that our findings can inform current and future efforts to increase production of microbial lipids, other fuels, or chemicals that are currently derived from petroleum.« less

Authors:

Lemmer, Kimberly C. ^[1]; Zhang, Weiping ^[2]; Langer, Samantha J. ^[1]; Dohnalkova, Alice C. ^[3]; Hu, Dehong ^[3]; Lemke, Rachelle A. ^[4]; Piotrowski, Jeff S. ^[1]; Orr, Galya ^[3]; Noguera, Daniel R. ^[2]; Donohue, Timothy J.  ^[5];

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Ruby, ed., Edward G.; Harwood, Caroline; McEwan, Alastair

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+ Show Author Affiliations

1. DOE Great Lakes Bioenergy Research Center, University of Wisconsin—Madison, Madison, Wisconsin, USA
2. DOE Great Lakes Bioenergy Research Center, University of Wisconsin—Madison, Madison, Wisconsin, USA, Department of Civil and Environmental Engineering, University of Wisconsin—Madison, Madison, Wisconsin, USA
3. Pacific Northwest National Laboratory, Environmental Molecular Sciences Laboratory, Richland, Washington, USA
4. Department of Bacteriology, University of Wisconsin—Madison, Madison, Wisconsin, USA
5. DOE Great Lakes Bioenergy Research Center, University of Wisconsin—Madison, Madison, Wisconsin, USA, Department of Bacteriology, University of Wisconsin—Madison, Madison, Wisconsin, USA

Publication Date:

Wed Jul 05 00:00:00 EDT 2017

Research Org.:

Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)

Sponsoring Org.:

USDOE

OSTI Identifier:

1786911

Alternate Identifier(s):

OSTI ID: 1372975

Report Number(s):

PNNL-SA-125854
Journal ID: ISSN 2161-2129; e00513-17

Grant/Contract Number:  

AC05-76RL01830

Resource Type:

Published Article

Journal Name:

mBio

Additional Journal Information:

Journal Name: mBio Journal Volume: 8 Journal Issue: 3; Journal ID: ISSN 2161-2129

Publisher:

American Society for Microbiology

Country of Publication:

United States

Language:

English

Subject:

59 BASIC BIOLOGICAL SCIENCES; Environmental Molecular Sciences Laboratory