A solid state fungal fermentation-based strategy for the hydrolysis of wheat straw

This paper reports a solid-state fungal fermentation-based pre-treatment strategy to convert wheat straw into a fermentable hydrolysate. Aspergillus niger was firstly cultured on wheat straw for production of cellulolytic enzymes and then the wheat straw was hydrolyzed by the enzyme solution into a fermentable hydrolysate. The optimum moisture content and three wheat straw modification methods were explored to improve cellulase production. At a moisture content of 89.5%, 10.2 ± 0.13 U/g cellulase activity was obtained using dilute acid modified wheat straw. The addition of yeast extract (0.5% w/v) and minerals significantly improved the cellulase production, to 24.0 ± 1.76 U/g. The hydrolysis of the fermented wheat straw using the fungal culture filtrate or commercial cellulase Ctec2 was performed, resulting in 4.34 and 3.13 g/L glucose respectively. It indicated that the fungal filtrate harvested from the fungal fermentation of wheat straw contained a more suitable enzyme mixture than the commercial cellulase

Real Exchange Rate, Foreign Trade and Employment: Evidence from China

Coordination of macro-economic development and employment is an essential issue for China's social development, which largely depends on economic expansion, as well as integration into the global market to create jobs. Through the literature review and empirical test, this paper analyses the relationship between macro-economic policy and employment, and discusses the impact of real exchange rate and foreign trade on employment. The research indicates that a stable and competitive exchange rate policy plays an indispensable role in employment promotion, more effective than monetary and fiscal policies, while the export growth also plays a positive role in employment promotion.China, employment, foreign trade, real exchange rate

Assessing Quality of Consumer Reviews in Mobile Application Markets: A Principal Component Analysis Approach

This study presents a simple, theory-based method for calculating a metric which reflects the quality of online consumer reviews in mobile application markets. Derived from prior online consumer review studies based on psychology, information quality, and economics literature, a metric for measuring online consumer review quality is developed. The metric is a weighted sum of three variables (Squared Star Rating, Log-transformed Word Count, and Sum of Squared Negative and Positive Sentiment), and weights for calculating the metric are estimated by using Principal Component Analysis (PCA) technique. Preliminary assessment of the proposed method shows that metrics computed by using the proposed method are positively correlated with helpfulness ranks of mobile application reviews in Google Play. However, PCA results show that one of the variables (i.e., sentiment) used for developing the metric did not load consistently on the first factor component. From the findings of the preliminary evaluation on the metric, limitations and future research directions of the proposed method are discussed

Mycelial growth interactions and mannan-degrading enzyme activities from fungal mixed cultures grown on palm kernel cake

Palm kernel cake (PKC), a by-product of the palm kernel oil extraction process contains mannan as its main polysaccharide. Mixed culture microbial degradation may enhance mannan-degrading enzymes production. Therefore, the objective of the study was to examine the nature of mycelial interactions and corresponding production of mannan-degrading enzymes of PKC. Fungal interactions was carried out using Sclerotium rolfsii and Aspergillus niger co-cultured with three Trichoderma strains (Trichoderma harzianum, Trichoderma longiobrachiatum and Trichoderma koningii) on potato dextrose agar (PDA) in disposable petri-dishes. Measurements of growth diameters were taken on days 2 and 13. For mannan-degrading enzyme production, single and co-cultures of these fungi were carried out under submerged cultivation for 13 days with PKC as the carbon source. About 57% of observed interactions on PDA were deadlock, 29% replacement and 14% intermingling. In Trichoderma sp./A. niger mixed cultures, there was an overall significant enhancement of enzyme: 2 to 200 fold (β-D-mannanase), 8 to 25 fold (β-mannosidase) and from no change to 15 fold increase (α-galactosidase). There was no obvious relationship between enzyme production and protein yield. However, co-culturing of A. niger with the Trichoderma strains showed an enhancement of mannan-degrading enzyme activities without reducing biomass yield