In this paper, we estimate the impacts of product market competition and skill shortages on the productivity level performance of Canadian manufacturing firms. We use firms' perceptions of their competitive environment from the Statistics Canada 1999 Survey of Innovation to measure product market competition and skill shortages. We argue in the paper that such perceptions are important for productivity level performance. After controlling for other factors, we find that product market competition has a positive impact on the performance of mediumsized and large-sized firms, and that skill shortages have a negative impact on the performance of small-sized and medium-sized firms.JEL Classification: L0, O0
Caenorhabditis elegans is an important model organism for studying stress response mechanisms. In this paper, C. elegans was used to evaluate the antioxidant effects of acid hydrolysates from Auricularia auricular polysaccharides.
Background
As one of the major components of lignocellulosic biomass, lignin has been considered as the most abundant renewable aromatic feedstock in the world. Comparing with thermal or catalytic strategies for lignin degradation, biological conversion is a promising approach featuring with mild conditions and diversity, and has received great attention nowadays.
Results
In this study, a consortium of white rot fungi composed of Lenzites betulina and Trametes versicolor was employed to enhance the ligninolytic enzyme activity of laccase (Lac) and manganese peroxidase (MnP) under microbial synergism. The maximum enzymatic activity of Lac and MnP was individually 18.06 U mL−1 and 13.58 U mL−1 along with a lignin degradation rate of 50% (wt/wt), which were achieved from batch cultivation of the consortium. The activities of Lac and MnP obtained from the consortium were both improved more than 40%, as compared with monocultures of L. betulina or T. versicolor under the same culture condition. The enhanced biodegradation performance was in accordance with the results observed from scanning electron microscope (SEM) of lignin samples before and after biodegradation, and secondary-ion mass spectrometry (SIMS). Finally, the analysis of heteronuclear single quantum coherence (HSQC) NMR and gas chromatography–mass spectrometry (GC–MS) provided a comprehensive product mapping of the lignin biodegradation, suggesting that the lignin has undergone depolymerization of the macromolecules, side-chain cleavage, and aromatic ring-opening reactions.
Conclusions
Our results revealed a considerable escalation on the enzymatic activity obtained in a short period from the cultivation of the L. betulina or T. versicolor due to the enhanced microbial synergistic effects, providing a potential bioconversion route for lignin utilization.
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