The catabolism of lignin-derived p-methoxylated aromatic compounds by Rhodococcus jostii RHA1.

Emergent strategies to valorize lignin, an abundant but underutilized aromatic biopolymer, include tandem processes that integrate chemical depolymerization and biological catalysis. To date, aromatic monomers from C-O bond cleavage of lignin have been converted to bioproducts, but the presence of recalcitrant C-C bonds in lignin limits the product yield. A promising chemocatalytic strategy that overcomes this limitation involves phenol methyl protection and autoxidation. Incorporating this into a tandem process requires microbial cell factories able to transform the p-methoxylated products in the resulting methylated lignin stream. In this study, we assessed the ability of Rhodococcus jostii RHA1 to catabolize the major aromatic products in a methylated lignin stream and elucidated the pathways responsible for this catabolism. RHA1 grew on a methylated pine lignin stream, catabolizing the major aromatic monomers: p-methoxybenzoate (p-MBA), veratrate, and veratraldehyde. Bioinformatic analyses suggested that a cytochrome P450, PbdA, and its cognate reductase, PbdB, are involved in p-MBA catabolism. Gene deletion studies established that both pbdA and pbdB are essential for growth on p-MBA and several derivatives. Furthermore, a deletion mutant of a candidate p-hydroxybenzoate (p-HBA) hydroxylase, ΔpobA, did not grow on p-HBA. Veratraldehyde and veratrate catabolism required both vanillin dehydrogenase (Vdh) and vanillate O-demethylase (VanAB), revealing previously unknown roles of these enzymes. Finally, a ΔpcaL strain grew on neither p-MBA nor veratrate, indicating they are catabolized through the ß-ketoadipate pathway. This study expands our understanding of the bacterial catabolism of aromatic compounds and facilitates the development of biocatalysts for lignin valorization.IMPORTANCELignin, an abundant aromatic polymer found in plant biomass, is a promising renewable replacement for fossil fuels as a feedstock for the chemical industry. Strategies for upgrading lignin include processes that couple the catalytic fractionation of biomass and biocatalytic transformation of the resulting aromatic compounds with a microbial cell factory. Engineering microbial cell factories for this biocatalysis requires characterization of bacterial pathways involved in catabolizing lignin-derived aromatic compounds. This study identifies new pathways for lignin-derived aromatic degradation in Rhodococcus, a genus of bacteria well suited for biocatalysis. Additionally, we describe previously unknown activities of characterized enzymes on lignin-derived compounds, expanding their utility. This work advances the development of strategies to replace fossil fuel-based feedstocks with sustainable alternatives.

Consensus Recommendations for the Use of Simulation in Therapeutic Patient Education.

INTRODUCTION: Simulation is rarely used to help individuals with chronic diseases develop skills. The aim of the study was to provide recommendations for the use of simulation in therapeutic patient education (S-TPE). METHODS: Expert consensus was achieved with the participation of the following 3 groups of experts: (a) expert patients and caregivers; (b) health professionals specialized in therapeutic patient education (TPE); and (c) simulation experts. Each expert received a list of questions by e-mail in 3 iterations. The synthesis of the 2 first questionnaires resulted in 34 first recommendations voted during the consensus conference meeting. Each recommendation was subject to an extensive literature review. The quality of the evidence and the strength of the recommendations were assessed through the evaluation, development, and evaluation criteria categories (GRADE criteria). The third questionnaire selected and illustrated recommendations more specific to the use of S-TPE. RESULTS: At the end of the process, the experts identified 26 recommendations specific to the use of S-TPE. They proposed examples of skills in different diseases and stressed the importance of adapting the conditions of use (location, equipment, time of the care) to the circumstances of the patient learner and skills to be developed. Experts should exercise great caution as this technique presents ethical considerations related to patient care. CONCLUSIONS: These recommendations underline the fact that simulation could bring added value to TPE. They provide a framework and examples for the experimental use of simulation in TPE. Research into feasibility and acceptability is needed.