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Auxiliary activity family 9 (AA9) lytic polysaccharide monooxygenases (LPMOs) show significant synergism with cellulase in cellulose degradation. In recent years, there have been many reports on AA9 LPMOs; however, the identification of efficient and thermostable AA9 LPMOs with broad potential for industrial applications remains necessary. In this study, a new AA9 LPMO from Talaromyces cellulolyticus, named TcAA9A, was identified. An analysis of the oxidation products of phosphoric acid-swollen cellulose categorized TcAA9A as a type 3 AA9 LPMO, and TcAA9A exhibited a better synergistic effect with cellulase from Trichoderma reesei than what is seen with TaAA9A, a well-studied AA9 LPMO from Thermoascus aurantiacus. Two AA9 LPMOs were successfully expressed in T. reesei, and the transformants were named TrTcAA9A and TrTaAA9A. The activities and thermostabilities of the AA9 LPMOs in TrTcAA9A were higher than those of the AA9 LPMOs in TrTaAA9A or the parent. The enzyme solution of TrTcAA9A was more efficient than that of the parent or TrTaAA9A for the degradation of Avicel and delignified corncob residue. Thus, TcAA9A showed a better performance than TaAA9A in T. reesei cellulase cocktails. This study may offer an innovative solution for improving enzyme cocktail activity for lignocellulosic degradation. [ABSTRACT FROM AUTHOR]

Lignocellulosic biohydrogen is a promising renewable energy source that could be a potential alternative to the unsustainable fossil fuel-based energy. Biohydrogen production could be performed by Clostridium thermocellum that is the fastest known cellulose-degrading bacterium. Previous investigations have shown that the co-culture of C. thermocellum JN4 and a non-cellulolytic bacterium Thermoanaerobacterium thermosaccharolyticum GD17 produces more hydrogen than the C. thermocellum JN4 mono-culture, but the mechanism of this improvement is unknown. In this work, we carried out genomic and evolutionary analysis of hydrogenase-coding genes in C. thermocellum and T. thermosaccharolyticum, identifying one Ech-type [NiFe] hydrogenase complex in each species, and, respectively, five and four monomeric or multimeric [FeFe] hydrogenases in the two species. Further transcriptional analysis showed hydrogenase-coding genes in C. thermocellum are regulated by carbon sources, while hydrogenase-coding genes in T. thermosaccharolyticum are not. However, comparison between transcriptional abundance of hydrogenase-coding genes in mono- and co-cultures showed the co-culturing condition leads to transcriptional changes of hydrogenase-coding genes in T. thermosaccharolyticum but not C. thermocellum. Further metabolic analysis showed T. thermosaccharolyticum produces H at a rate 4-12-fold higher than C. thermocellum. These findings lead to the suggestion that the improvement of H production in the co-culture over mono-culture should be attributed to changes in T. thermosaccharolyticum but not C. thermocellum. Further suggestions can be made that C. thermocellum and T. thermosaccharolyticum perform highly specialized tasks in the co-culture, and optimization of the co-culture for more lignocellulosic biohydrogen production should be focused on the improvement of the non-cellulolytic bacterium. [ABSTRACT FROM AUTHOR]