Analytical Py-GC/MS of Genetically Modified Poplar for the Increased Production of Bio-aromatics

Abstract

Genetic engineering is a powerful tool to steer bio-oil composition towards the production of speciality chemicals such as guaiacols, syringols, phenols, and vanillin through well-defined biomass feedstocks. Our previous work demonstrated the effects of lignin biosynthesis gene modification on the pyrolysis vapour compositions obtained from wood derived from greenhouse-grown poplars. In this study, field-grown poplars downregulated in the genes encoding CINNAMYL ALCOHOL DEHYDROGENASE ( CAD ), CAFFEIC ACID O-METHYLTRANSFERASE ( COMT ) and CAFFEOYL-CoA O-METHYLTRANSFERASE ( CCoAOMT ), and their corresponding wild type were pyrolysed in a Py-GC/MS. This work aims at capturing the effects of downregulation of the three enzymes on bio-oil composition using principal component analysis (PCA). 3,5-methoxytoluene, vanillin, coniferyl alcohol, 4-vinyl guaiacol, syringol, syringaldehyde, and guaiacol are the determining factors in the PCA analysis that are the substantially affected by COMT , CAD and CCoAOMT enzyme downregulation. COMT and CAD downregulated transgenic lines proved to be statistically different from the wild type because of a substantial difference in S and G lignin units. The s CAD line lead to a significant drop (nearly 51%) in S-lignin derived compounds, while CCoAOMT downregulation affected the least (7–11%). Further, removal of extractives via pretreatment enhanced the statistical differences among the CAD transgenic lines and its wild type. On the other hand, COMT downregulation caused 2-fold reduction in S-derived compounds compared to G-derived compounds. This study manifests the applicability of PCA analysis in tracking the biological changes in biomass (poplar in this case) and their effects on pyrolysis-oil compositions.

Experimental and Kinetic Modeling Study on the Gas-Phase Pyrolysis of Hydroxycinnamaldehyde Model Compounds

“…CoA was also reported as a major product in experiments studying the pyrolysis of coniferyl alcohol. , In addition, p -coumaraldehyde (PA) and CoA, as the precursors of monolignols, can be largely incorporated into the lignin structure via genetic engineering . Recent studies performed in our group have demonstrated that this technology can be used as a potential tool to control the lignin composition of biomass, which allows us to increase the production of high-value chemicals via fast pyrolysis. − Therefore, it is essential to study the pyrolysis products and mechanisms of PA and CoA.…”

Identification of Extractives from Various Poplar Species

“…It was detected repeatedly in hardwood smoke [32,33]. Its presence was confirmed in bio-oil obtained by pyrolysis of genetically modified poplar varieties [34,35]. Zarzy ński [36] confirms the occurrence of an isomeric compound-2-methoxy-6-vinylphenol-in the wood of, among others, European aspen (Populustremula) and brittle willow (Salix fragilis), but the author's identification may be questionable as he does not state which library he used and the compound does not appear in the most widely used NIST database.…”

State of the Art and Perspectives in Catalytic Conversion Mechanism of Biomass to Bio-aromatics

“…In addition, biomass typically has a high moisture content, which may interfere with its direct application in the production of most bio-products, and a predrying process is recommended. Currently, many scholars have studied the influence of the type of biomass on the bio-aromatics preparation. − Mihalcik et al investigated the catalytic cracking of oak, corn cob, willow twigs, and corn stalks, etc. The study found that, except for switch, the main product of biomass raw materials after catalytic cracking is xylene, of which oak has the highest yield.…”