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Cultivation of different bacterial spp. on lignin

Nöbel, Matthias LU (2017) KETM01 20171
Chemical Engineering (M.Sc.Eng.)
Abstract
Lignin accounts for 15 – 30 % of plant biomass, but is till today remarkably underutilized, mainly due to its heterogeneity and recalcitrance towards depolymerization. The bacterial conversion of lignin into value added chemicals is a highly promising approach to overcome this underutilization and can help to improve the economic competitiveness of the biorefinery concept.
In the current study, 10 different bacterial strains were examined in their growth on plates containing depolymerized lignin or lignin model compounds vanillin and guaiacol as the only carbon source. Rhodococcus opacus, Pseudomonas fluorescens and Pseudomonas putida EM42 showed the best growth and were selected for further experiments in liquid cultures. Two different... (More)
Lignin accounts for 15 – 30 % of plant biomass, but is till today remarkably underutilized, mainly due to its heterogeneity and recalcitrance towards depolymerization. The bacterial conversion of lignin into value added chemicals is a highly promising approach to overcome this underutilization and can help to improve the economic competitiveness of the biorefinery concept.
In the current study, 10 different bacterial strains were examined in their growth on plates containing depolymerized lignin or lignin model compounds vanillin and guaiacol as the only carbon source. Rhodococcus opacus, Pseudomonas fluorescens and Pseudomonas putida EM42 showed the best growth and were selected for further experiments in liquid cultures. Two different sets of experiments were performed, using either a lignin model compounds mixture (3 mM each of 4-hydroxybenzoic acid, vanillin and guaiacol) or 1 g/L depolymerized lignin as sole carbon sources. R. opacus was the only organism able to rapidly take up guaiacol. When grown on guaiacol only, R. opacus reached a specific growth and uptake rate of 0.2 h^-1 and 2.4 mmol (gCDW*h)^-1 , respectively. Also, R. opacus showed the highest biomass formation on depolymerized lignin with an optical density (OD) of 0.15 and was the only organism able to catabolize low molecular weight lignin to a large extend. UHPLC analysis emphasizes a strong correlation between the conversion of guaiacol and uptake of low molecular weight lignin. Furthermore, P. fluorescens showed a substantial reduction of high molecular weight lignin and simultaneous uptake of breakdown products, leading to the highest overall conversion of depolymerized lignin.
In conclusion, R. opacus and P. fluorescens were identified as two promising species with very different ways of metabolizing depolymerized lignin. Both organisms may have the potential to eventually close the gap towards a complete utilization of lignin. (Less)
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author
Nöbel, Matthias LU
supervisor
organization
course
KETM01 20171
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
8912047
date added to LUP
2017-06-16 11:39:12
date last changed
2017-06-16 11:39:12
@misc{8912047,
  abstract     = {Lignin accounts for 15 – 30 % of plant biomass, but is till today remarkably underutilized, mainly due to its heterogeneity and recalcitrance towards depolymerization. The bacterial conversion of lignin into value added chemicals is a highly promising approach to overcome this underutilization and can help to improve the economic competitiveness of the biorefinery concept. 
In the current study, 10 different bacterial strains were examined in their growth on plates containing depolymerized lignin or lignin model compounds vanillin and guaiacol as the only carbon source. Rhodococcus opacus, Pseudomonas fluorescens and Pseudomonas putida EM42 showed the best growth and were selected for further experiments in liquid cultures. Two different sets of experiments were performed, using either a lignin model compounds mixture (3 mM each of 4-hydroxybenzoic acid, vanillin and guaiacol) or 1 g/L depolymerized lignin as sole carbon sources. R. opacus was the only organism able to rapidly take up guaiacol. When grown on guaiacol only, R. opacus reached a specific growth and uptake rate of 0.2 h^-1 and 2.4 mmol (gCDW*h)^-1 , respectively. Also, R. opacus showed the highest biomass formation on depolymerized lignin with an optical density (OD) of 0.15 and was the only organism able to catabolize low molecular weight lignin to a large extend. UHPLC analysis emphasizes a strong correlation between the conversion of guaiacol and uptake of low molecular weight lignin. Furthermore, P. fluorescens showed a substantial reduction of high molecular weight lignin and simultaneous uptake of breakdown products, leading to the highest overall conversion of depolymerized lignin.
In conclusion, R. opacus and P. fluorescens were identified as two promising species with very different ways of metabolizing depolymerized lignin. Both organisms may have the potential to eventually close the gap towards a complete utilization of lignin.},
  author       = {Nöbel, Matthias},
  language     = {eng},
  note         = {Student Paper},
  title        = {Cultivation of different bacterial spp. on lignin},
  year         = {2017},
}