Project description:The study is first to describe the temporal and differential transcriptional expression of two lytic polysaccharide monooxygenase (LPMO) genes of Rasamsonia emersonii in response to various carbon sources. The mass spectrometry based expression of carbohydrate active enzymes (CAZymes) on different carbon sources showed varying levels of LPMOs (AA9), AA3, AA7, catalase, and superoxide dismutase pointing to the redox interplay between the LPMOs and auxiliary enzymes. Moreover, it was observed that cello-oligosaccharides have a negative impact on the expression of LPMOs, which has not been highlighted in any previous research. The LPMO1 (30 kDa) and LPMO2 (47 kDa), cloned and expressed in Pichia pastoris were catalytically active with (Kcat/Km) of 6.6 × 10-2 mg-1 ml min-1 and 1.8 × 10-2 mg-1 ml min-1 against Avicel, respectively. The mass spectrometry of hydrolysis products of Avicel/CMC showed presence of C1/C4 oxidized oligosaccharides indicating them to be type 3 LPMOs. The 3D structural analysis of LPMO1 and LPMO2 revealed distinct arrangement of conserved catalytic residues. Furthermore, the developed enzyme cocktails consisting of cellulase from R. emersonii mutant M36 supplemented with recombinant LPMO1/LPMO2 resulted in significantly enhanced saccharification of steam/acid pretreated unwashed rice straw slurry from PRAJ industries (Pune, India). The current work indicates that LPMO1 and LPMO2 are catalytically efficient and have a high degree of thermostability, emphasising their usefulness in improving benchmark enzyme cocktail performance.
