Production of carotenoids from aromatics and pretreated lignocellulosic biomass by Novosphingobium aromaticivorans

Journal Article · Thu Dec 21 00:00:00 UTC 2023 · Applied and Environmental Microbiology

DOI: https://doi.org/10.1128/aem.01268-23 · OSTI ID:2222551

Hall, Benjamin W.  ^[1]; Kontur, Wayne S. ^[2]; Neri, Jeanette C. ^[2]; Gille, Derek M. ^[2]; Noguera, Daniel R.  ^[3]; Donohue, Timothy J.  ^[4]; Zhou, ed., Ning-Yi

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1. DOE Great Lakes Bioenergy Research Center, University of Wisconsin, Madison, Wisconsin, USA, Wisconsin Energy Institute, University of Wisconsin, Madison, Wisconsin, USA, Laboratory of Genetics, University of Wisconsin, Madison, Wisconsin, USA
2. DOE Great Lakes Bioenergy Research Center, University of Wisconsin, Madison, Wisconsin, USA, Wisconsin Energy Institute, University of Wisconsin, Madison, Wisconsin, USA
3. DOE Great Lakes Bioenergy Research Center, University of Wisconsin, Madison, Wisconsin, USA, Wisconsin Energy Institute, University of Wisconsin, Madison, Wisconsin, USA, Department of Civil and Environmental Engineering, University of Wisconsin, Madison, Wisconsin, USA
4. DOE Great Lakes Bioenergy Research Center, University of Wisconsin, Madison, Wisconsin, USA, Wisconsin Energy Institute, University of Wisconsin, Madison, Wisconsin, USA, Department of Bacteriology, University of Wisconsin, Madison, Wisconsin, USA

ABSTRACT Carotenoids are lipophilic compounds found in the membranes of various organisms. Individual carotenoids are also commodity chemicals, produced industrially for use as food additives, nutritional supplements, cosmetics, and pharmaceuticals. The alphaproteobacterium Novosphingobium aromaticivorans has previously been established as a potential platform microbe for converting aromatic compounds derived from lignocellulosic plant biomass into valuable extracellular products. Here, we show that N. aromaticivorans DSM 12444 cells naturally produce the carotenoid nostoxanthin, and we construct a set of gene deletion mutants that accumulate β-carotene, lycopene, or zeaxanthin, which are predicted intermediates in nostoxanthin biosynthesis as well as commodity chemicals. We also show that a mutant strain heterologously expressing a CrtW protein accumulates the carotenoid astaxanthin. When grown on vanillate as the carbon source, we find that the levels of carotenoids are not significantly affected by O ₂ concentration in the tested range of 5% to 21% O ₂ . We also show that these carotenoids are produced at comparable levels when strains are grown in liquor from alkaline pretreated sorghum biomass [sorghum alkaline pretreatment liquor (APL)], which contains a mixture of aromatics. Finally, we construct strains that produce zeaxanthin, β-carotene, or astaxanthin concurrently with 2-pyrone-4,6-dicarboxylic acid, a potential building block for biodegradable polymers, when grown in sorghum APL. Combined, our results show that N. aromaticivorans can simultaneously produce valuable intracellular and extracellular commodities when grown in the presence of either pure aromatics or pretreated lignocellulosic biomass. IMPORTANCE There is economic and environmental interest in generating commodity chemicals from renewable resources, such as lignocellulosic biomass, that can substitute for chemicals derived from fossil fuels. The bacterium Novosphingobium aromaticivorans is a promising microbial platform for producing commodity chemicals from lignocellulosic biomass because it can produce these from compounds in pretreated lignocellulosic biomass, which many industrial microbial catalysts cannot metabolize. Here, we show that N. aromaticivorans can be engineered to produce several valuable carotenoids. We also show that engineered N. aromaticivorans strains can produce these lipophilic chemicals concurrently with the extracellular commodity chemical 2-pyrone-4,6-dicarboxylic acid when grown in a complex liquor obtained from alkaline pretreated lignocellulosic biomass. Concurrent microbial production of valuable intra- and extracellular products can increase the economic value generated from the conversion of lignocellulosic biomass-derived compounds into commodity chemicals and facilitate the separation of water- and membrane-soluble products.

• Research Organization: Great Lakes Bioenergy Research Center (GLBRC), Madison, WI (United States); Univ. of Wisconsin, Madison, WI (United States)
• Sponsoring Organization: National Institutes of Health (NIH); USDOE; USDOE Office of Science (SC)
• Grant/Contract Number: SC0018409
• OSTI ID: 2222551
• Journal Information: Applied and Environmental Microbiology, Journal Name: Applied and Environmental Microbiology Journal Issue: 12 Vol. 89; ISSN 0099-2240
• Publisher: American Society for MicrobiologyCopyright Statement
• Country of Publication: United States
• Language: English