Internalization and accumulation of model lignin breakdown products in bacteria and fungi.

Autor: Barnhart-Dailey MC; 1Department of Bioenergy and Defense Technologies, Sandia National Laboratories, Albuquerque, NM 87123 USA., Ye D; 3Department of Nanobiology, Sandia National Laboratories, Albuquerque, NM 87123 USA., Hayes DC; 2Department of Nano and Bio-Sensors, Sandia National Laboratories, Albuquerque, NM 87123 USA., Maes D; 1Department of Bioenergy and Defense Technologies, Sandia National Laboratories, Albuquerque, NM 87123 USA., Simoes CT; 3Department of Nanobiology, Sandia National Laboratories, Albuquerque, NM 87123 USA., Appelhans L; 4Department of Organic Materials Science, Sandia National Laboratories, Albuquerque, NM 87123 USA., Carroll-Portillo A; 1Department of Bioenergy and Defense Technologies, Sandia National Laboratories, Albuquerque, NM 87123 USA.; 5Present Address: Section of Gastroenterology, New Mexico VA Health Care System, Albuquerque, NM 87108 USA., Kent MS; 3Department of Nanobiology, Sandia National Laboratories, Albuquerque, NM 87123 USA., Timlin JA; 1Department of Bioenergy and Defense Technologies, Sandia National Laboratories, Albuquerque, NM 87123 USA.
Jazyk: angličtina
Zdroj: Biotechnology for biofuels [Biotechnol Biofuels] 2019 Jul 03; Vol. 12, pp. 175. Date of Electronic Publication: 2019 Jul 03 (Print Publication: 2019).
DOI: 10.1186/s13068-019-1494-8
Abstrakt: Background: Valorization of lignin has the potential to significantly improve the economics of lignocellulosic biorefineries. However, its complex structure makes conversion to useful products elusive. One promising approach is depolymerization of lignin and subsequent bioconversion of breakdown products into value-added compounds. Optimizing transport of these depolymerization products into one or more organism(s) for biological conversion is important to maximize carbon utilization and minimize toxicity. Current methods assess internalization of depolymerization products indirectly-for example, growth on, or toxicity of, a substrate. Furthermore, no method has been shown to provide visualization of depolymerization products in individual cells.
Results: We applied mass spectrometry to provide direct measurements of relative internalized concentrations of several lignin depolymerization compounds and single-cell microscopy methods to visualize cell-to-cell differences in internalized amounts of two lignin depolymerization compounds. We characterized internalization of 4-hydroxybenzoic acid, vanillic acid, p -coumaric acid, syringic acid, and the model dimer guaiacylglycerol-beta-guaiacyl ether (GGE) in the lignolytic organisms Phanerochaete chrysosporium and Enterobacter lignolyticus and in the non-lignolytic but genetically tractable organisms Saccharomyces cerevisiae and Escherichia coli . The results show varying degrees of internalization in all organisms for all the tested compounds, including the model dimer, GGE. Phanerochaete chrysosporium internalizes all compounds in non-lignolytic and lignolytic conditions at comparable levels, indicating that the transporters for these compounds are not specific to the lignolytic secondary metabolic system. Single-cell microscopy shows that internalization of vanillic acid and 4-hydroxybenzoic acid analogs varies greatly among individual fungal and bacterial cells in a given population. Glucose starvation and chemical inhibition of ATP hydrolysis during internalization significantly reduced the internalized amount of vanillic acid in bacteria.
Conclusions: Mass spectrometry and single-cell microscopy methods were developed to establish a toolset for providing direct measurement and visualization of relative internal concentrations of mono- and di-aryl compounds in microbes. Utilizing these methods, we observed broad variation in intracellular concentration between organisms and within populations and this may have important consequences for the efficiency and productivity of an industrial process for bioconversion. Subsequent application of this toolset will be useful in identifying and characterizing specific transporters for lignin-derived mono- and di-aryl compounds.
Competing Interests: Competing interestsThe authors declare that they have no competing interests.
Databáze: MEDLINE
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