Hydrolysis of xylans by enzyme systems from solid cultures of Trichoderma harzianum strains

Xylanase activity was isolated from crude extracts of Trichoderma harzianum strains C and 4 grown at 28oC in a solid medium containing wheat bran as the carbon source. Enzyme activity was demonstrable in the permeate after ultrafiltration of the crude extracts using an Amicon system. The hydrolysis patterns of different xylans and paper pulps by xylanase activity ranged from xylose, xylobiose and xylotriose to higher xylooligosaccharides. A purified ß-xylosidase from the Trichoderma harzianum strain released xylose, xylobiose and xylotriose from seaweed, deacetylated, oat spelt and birchwood xylans. The purified enzyme was not active against acetylated xylan and catalyzed the hydrolysis of xylooligosaccharides, including xylotriose, xylotetraose and xylopentaose. However, the enzyme was not able to degrade xylohexaose. Xylanase pretreatment was effective for hardwood kraft pulp bleaching. Hardwood kraft pulp bleached in the XEOP sequence had its kappa number reduced from 13.2 to 8.9 and a viscosity of 20.45 cp. The efficiency of delignification was 33%

Scenario modelling of biomass usage in the Australian electricity grid

Responding to the global crises - Covid19 and climate change - governments around the world are formulating green recovery plans to stimulate economic growth, boost clean energy technologies and cut emissions. Potential transition pathways for low carbon energy systems, however, remain as open questions. Generally, the simulation of biomass in the grid models is limited in their tempo-spatial resolution, transition pathways description, and/or biomass feedstock supply representation. This study aims to provide spatio-temporal highly resolved grid configurations featuring disaggregated biomass feedstocks, to assess Australia's potential energy transition pathways and 100% renewable electricity supply scenarios under various biomass bidding strategies and cost assumptions. We find that, as carbon prices increase, bioelectricity will prove to be a cost-effective flexible option compared to other low-carbon (such as CSP) and fossil-based flexible options (e.g. coal and gas), with its generation share reaching _9%-12% at higher carbon price scenarios. Biomass power plants can be well suited for operating in gap-filling mode to provide flexible power generation and to facilitate grid stability and load balancing. In light of the high biomass resource potential in Australia, keeping bioelectricity in the generation mix is beneficial for reducing system capacity and cost by 32% and 21%, respectively, under a future renewable-dominated Australian grid system