Identification and characterization of a novel AA9-type lytic polysaccharide monooxygenase from a bagasse metagenome

Hyperthermophilic xylanase and thermophilicity analysis by molecular dynamic simulation with quantum mechanics

Thermophilic xylanases catalyzing the cleavage of β-1,4-glycosidic bonds in xylan have applications in food, feed, biorefinery, and pulp industries. In this study, a hyperthermophilic endo-xylanase was obtained by further enhancement of thermal tolerance of a thermophilic GH11 xylanase originated from metagenome of bagasse pile based on rational design. Introducing N13F and Q34L to the previously reported X11P enzyme shifted the optimal working temperature to 85 °C and led to 20.7-fold improvement in thermostability at 90 °C along with a marked increase in Tm to 93.3 °C. X11PNQ enzyme converted xylan to prebiotic xylooligosaccharides with high specificity on xylobiose to xylohexaose and high operational stability at 85 °C, resulting in 10.3-folds yield improvement compared to the parental enzyme. Molecular dynamic simulation and quantum mechanical analysis revealed improved H-bonding networks within GH11 xylanase principal domains and greater dynamic cross-correlations. A novel thermostabilization mechanism by π-amide interaction with slightly lower interaction energy than the native H-bond, but compensated by increased occurrence frequency was firstly demonstrated for thermophilic enzymes. The enzyme represents one of the most thermostable xylanases ever reported with biotechnological potential. KEY POINTS: • Hyperthemophilic xylanase X11PNQ was obtained by rational design engineering. • X11PNQ showed specificity to prebiotic xylooligosaccharides (XOS) at 85 °C with improved t1/2 at 90 °C. • Novel thermostabilization by π-amide interaction was demonstrated by MD/QM.

Enzymes and enzymatic mechanisms in enzymatic degradation of lignocellulosic biomass: A mini-review

Enzymatic hydrolysis is the key step limiting the efficiency of the biorefinery of lignocellulosic biomass. Enzymes involved in enzymatic hydrolysis and their interactions with biomass should be comprehended to form the basis for looking for strategies to improve process efficiency. This article updates the contemporary research on the properties of key enzymes in the lignocellulose biorefinery and their interactions with biomass, adsorption, and hydrolysis. The advanced analytical techniques to track the interactions for exploiting mechanisms are discussed. The challenges and prospects for future research are outlined.

Lytic polysaccharide monooxygenases (LPMOs) producing microbes: A novel approach for rapid recycling of agricultural wastes

Out of the huge quantity of agricultural wastes produced globally, rice straw is one of the most abundant ligno-cellulosic waste. For efficient utilization of these wastes, several cost-effective biological processes are available. The practice of field level in-situ or ex-situ decomposition of rice straw is having less degree of adoption due to its poor decomposition ability within a short time span between rice harvest and sowing of the next crop. Agricultural wastes including rice straw are in general utilized by using lignocellulose degrading microbes for industrial metabolite or compost production. However, bioconversion of crystalline cellulose and lignin present in the waste, into simple molecules is a challenging task. To resolve this issue, researchers have identified a novel new generation microbial enzyme i.e., lytic polysaccharide monooxygenases (LPMOs) and reported that the combination of LPMOs with other glycolytic enzymes are found efficient. This review explains the progress made in LPMOs and their role in lignocellulose bioconversion and the possibility of exploring LPMOs producers for rapid decomposition of agricultural wastes. Also, it provides insights to identify the knowledge gaps in improving the potential of the existing ligno-cellulolytic microbial consortium for efficient utilization of agricultural wastes at industrial and field levels.