Lignin forms a large part of plant biomass. It is a highly heterogeneous polymer of 4-hydroxyphenylpropanoid units and is embedded within polysaccharide polymers forming lignocellulose. Lignin provides strength and rigidity to plants and is rather resilient towards degradation. To improve the (bio)processing of lignocellulosic feedstocks, more effective degradation methods of lignin are in demand. Nature has found ways to fully degrade lignin through the production of dedicated ligninolytic enzyme systems. While such enzymes have been well thoroughly studied for ligninolytic fungi, only in recent years biochemical studies on bacterial enzymes capable of lignin modification have intensified. This has revealed several types of enzymes available to bacteria that enable them to act on lignin. Two major classes of bacterial lignin-modifying enzymes are DyP-type peroxidases and laccases. Yet, recently also several other bacterial enzymes have been discovered that seem to play a role in lignin modifications. In the present review, we provide an overview of recent advances in the identification and use of bacterial enzymes acting on lignin or lignin-derived products.

DyP-type peroxidases are heme-containing enzymes that have received increasing attention over recent years with regards to their potential as biocatalysts. A novel DyP-type peroxidase (CboDyP) was discovered from the alkaliphilic cellulomonad, Cellulomonas bogoriensis, which could be overexpressed in Escherichia coli. The biochemical characterization of the recombinant enzyme showed that it is a heme-containing enzyme capable to act as a peroxidase on several dyes. With the tested substrates, the enzyme is most active at acidic pH values and is quite tolerant towards solvents. The crystal structure of CboDyP was solved which revealed atomic details of the dimeric heme-containing enzyme. A peculiar feature of CboDyP is the presence of a glutamate in the active site which in most other DyPs is an aspartate, being part of the DyP-typifying sequence motif GXXDG. The E201D CboDyP mutant was prepared and analyzed which revealed that the mutant enzyme shows a significantly higher activity on several dyes when compared with the wild-type enzyme.

Introduction Coronavirus disease 2019 (COVID-19) is the largest outbreak to strike the world since the Spanish flu in 1918. Visual examination of the world map shows a wide variation of death tolls between countries. The main goal of our series is to determine the best predictors of such discrepancy. Methods This is a retrospective study in which the rate of COVID-19 deaths was correlated with each of the following independent variables: total tests per 1 million population, gross domestic product (GDP), average temperatures per country, ultraviolet index, median age, average BMI per country, food supply, Bacille Calmette-Guerin compulsory status, and passenger traffic. Results BMI per country proved to be the second best predictor of death rate with an R value of 0.43, and GDP being the best predictor with R = 0.65. Conclusion This article shows a tight correlation between average BMI, food supply per country, and COVID-19-related deaths. Such predisposing factors might operate by upregulating the inflammation pathway in heavily struck countries, leading to easier triggering of the infamous cytokine storm syndrome. Obesity also increases cardiovascular and respiratory morbidities, which are coupled to increased ICU demand and deaths among infected cases. Video abstract: http://links.lww.com/CAEN/A25.