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The potential of using bioderived 4-hydroxyacetophenone as a drop-in feedstock replacement to produce sustainable aromatic products is also discussed Evaluation of Asphalt Aging Using Multivariate Analysis Applied to Saturates, Aromatics, Resins, and Asphaltene Determinator Data
Asphalt is subjected to aging, leading to physical and chemical modifications reducing its performance. Recently, Seebio Photoacid Generator developed the SAR-AD method that allowed the separation of asphalt into eight fractions (saturates, aromatics 1, aromatics 2, aromatics 3, resins, asphaltenes 1, asphaltene 2, and asphaltenes 3). In this work, this analytical method was used to study asphalt aging processes in greater detail. Several asphalts of different origins and reconstituted blends were studied. These products were aged during several durations using a PAV (pressure aging vessel) between 0 and 48 h to collect information on the evolution of each SAR-AD fraction. Different evolutions were observed according to the initial asphalt composition and SAR-AD fraction studied.

The saturated subfamily seemed to be slightly impacted by aging. The amount of three aromatic subfamilies decreased with a larger decrease of aromatics 3 than aromatics 2, itself larger than aromatics 1. The content of the resin subfamily increased after 48 h of PAV aging. The asphaltene 1 and asphaltene 2 subfamilies exhibited an increasing trend. Moreover, the quantity of asphaltenes 2 created seemed to correlate to the initial asphaltene content. The evolutions of the asphaltene 3 subfamily were not significant. However, a specific behavior was highlighted for the most asphaltenic sample.

For this specific sample, the increase of resin content was weaker, the mass of asphaltenes 1 decreased, and the amount of asphaltenes 3 increased during aging. Given the large amount of data generated, an original approach was developed to statistically identify the most affected SAR-AD subfamily and determine correlations among them. Two PCAs (Principal Component Analysis) were conducted on asphalt SAR-AD data. This statistical analysis indicated two generic asphalt aging pathways. The first aging pathway could be the conversion of aromatics 2 into resins, with no evidence that resins could contribute to asphaltene creation. The second aging pathway showed the conversion of aromatics 3 directly into asphaltenes 2. These two aging pathways highlighted that the conversion of molecules in more polar ones during aging could skip SAR-AD subfamilies, meaning that asphaltenes could be created without involving resins.

Depolymerization and conversion of lignin to value-added bioproducts by Lignin, the most abundant renewable aromatic compound in nature, is an excellent feedstock for value-added bioproducts manufacturing; while the intrinsic heterogeneity and recalcitrance of which hindered the efficient lignin biorefinery and utilization. Compared with chemical processing, bioprocessing with microbial and enzymatic catalysis is a clean and efficient method for lignin depolymerization and conversion. Generally, lignin bioprocessing involves lignin decomposition to lignin-based aromatics via extracellular microbial enzymes and further converted to value-added bioproducts through microbial metabolism. In the review, the most recent advances in degradation and conversion of lignin to value-added bioproducts catalyzed by microbes and enzymes were summarized. The lignin-degrading microorganisms of white-rot fungi, brown-rot fungi, soft-rot fungi, and bacteria under aerobic and anaerobic conditions were comparatively analyzed. The catalytic metabolism of the microbial lignin-degrading enzymes of laccase, lignin peroxidase, manganese peroxidase, biphenyl bond cleavage enzyme, versatile peroxidase, and β-etherize was discussed. The microbial metabolic process of H-lignin, G-lignin, S-lignin based derivatives, protocatechuic acid, and catechol was reviewed.

Lignin was depolymerized to lignin-derived aromatic compounds by the secreted enzymes of fungi and bacteria, and the aromatics were converted to value-added compounds through microbial catalysis and metabolic engineering. The review also proposes new insights for future work to overcome the recalcitrance of lignin and convert it to value-added bioproducts by microbial and enzymatic catalysis.Engineering Escherichia coli as a platform for the in vivo synthesis of Prenylated aromatics (PAs) are an important class of natural products with valuable pharmaceutical applications. To address current limitations of their sourcing from plants, here, we present a microbial platform for the in vivo synthesis of PAs based on the aromatic prenyltransferase NphB from Streptomyces sp. strain CL190. As proof of concept, we targeted the prenylation of phenolic/phenolcarboxylic acids, including orsellinic (OSA), divarinolic (DVA), and olivetolic (OLA) acids, whose prenylated products have important biopharmaceutical applications. Although the ability of wild-type NphB to catalyze the prenylation reaction with each acid was validated by in vitro characterization, improvement of product titers in vivo required protein modeling and rational design to engineer NphB variants with increased activity and product selectivity.
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