Thomas Geissmann

Characterization of the d-Xylulose 5-Phosphate/d-Fructose 6-Phosphate Phosphoketolase Gene (xfp) from Bifidobacterium lactis

A D-xylulose 5-phosphate/D-fructose 6-phosphate phosphoketolase (Xfp) from the probiotic Bifidobacterium lactis was purified to homogeneity. The specific activity of the purified enzyme with D-fructose 6-phosphate as a substrate is 4.28 Units per mg of enzyme. K(m) values for D-xylulose 5-phosphate and D-fructose 6-phosphate are 45 and 10 mM, respectively. The native enzyme has a molecular mass of 550,000 Da. The subunit size upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis (90,000 Da) corresponds with the size (92,529 Da) calculated from the amino acid sequence of the isolated gene (named xfp) encoding 825 amino acids. The xfp gene was identified on the chromosome of B. lactis with the help of degenerated nucleotide probes deduced from the common N-terminal amino acid sequence of both the native and denatured enzyme. Comparison of the deduced amino acid sequence of the cloned gene with sequences in public databases revealed high homologies with hypothetical proteins (26 to 55% identity) in 20 microbial genomes. The amino acid sequence derived from the xfp gene contains typical thiamine diphosphate (ThDP) binding sites reported for other ThDP-dependent enzymes. Two truncated putative genes, pta and guaA, were localized adjacent to xfp on the B. lactis chromosome coding for a phosphotransacetylase and a guanosine monophosphate synthetase homologous to products of genes in Mycobacterium tuberculosis. However, xfp is transcribed in B. lactis as a monocistronic operon. It is the first reported and sequenced gene of a phosphoketolase.

Persistent and transient cost efficiency—an application to the Swiss hydropower sector

Electricity prices on the European market have decreased significantly over the past few years, resulting in a deterioration of Swiss hydropower firms’ competitiveness and profitability. One option to improve the sector’s competitiveness is to increase cost efficiency. The goal of this study is to quantify the level of persistent and transient cost efficiency of individual firms by applying the generalized true random effects (GTRE) model introduced by Colombi et al. (Journal of Productivity Analysis 42(2): 123–136, 2014) and Filippini and Greene (Journal of Productivity Analysis 45(2): 187–196, 2016). Applying this newly developed GTRE model to a total cost function, the level of cost efficiency of 65 Swiss hydropower firms is analyzed for the period between 2000 and 2013. A true random effects specification is estimated as a benchmark for the transient level of cost efficiency. The results show the presence of both transient as well as persistent cost inefficiencies. The GTREM predicts the aggregate level of cost inefficiency to amount to 21.8% (8.0% transient, 13.8% persistent) on average between 2000 and 2013. These two components differ in interpretation and implication. From an individual firm’s perspective, the two types of cost inefficiencies might require a firm’s management to respond with different improvement strategies. The existing level of persistent inefficiency could prevent the hydropower firms from adjusting their production processes to new market environments. From a regulatory point of view, the results of this study could be used in the scope and determination of the amount of financial support given to struggling firms.

Knowledge Economy and Industry Performance in China: A Provincial Level Analysis

We construct a framework for investigating the effects of knowledge on industry performance. Using Chinese provincial industry data from 2000 to 2012, we decompose total factor productivity (TFP) change into the four components of embodied technical change, disembodied technical change, scale efficiency change, and technical efficiency change. Our results show a considerably stronger positive effect of advanced knowledge on production technology than of basic knowledge. International knowledge spillovers, particularly trade-induced spillovers, are more effective in inducing TFP growth than domestic spillovers. Our analysis further illustrates a discrepancy in TFP growth rates between regions. We also find TFP of the Central and West Region to be catching-up with the East Region. On average, scale efficiency change is the major contributing factor to regional disparities in terms of TFP change. From a policy point of view, the government should improve, for example, the level of knowledge through educational programs, and further focus on policies on urbanization or the development of regional centers to develop a competitive labor market, as well as on policies encouraging international trade.

A Green Bargain? The Impact of an Energy Saving Program on Productivity Growth in China's Iron and Steel Industry

The impact of environmental regulation on firm productivity has been long been debated, however, mainly for western economies and with limited firm-level evidence. We study the impact of a large-scale national energy saving program (the Top 1000 Energy-Consuming Enterprises Program, or T1000P, 2006-2010) in China on firm productivity in the iron and steel industry. The T1000P assigned targets for reducing the energy consumption of approximately 1000 most energy-consuming industrial firms. Using detailed data from the China Industrial Census on 5,340 firms for the period of 2003 to 2008, we estimate a positive effect of the T1000P on firms in the iron and steel industry. Specifically, we find T1000P firms are associated with significantly greater annualized TFP change (an increase of 3.1 percent on average), suggesting the competitiveness of treated firms increased. Effects on technical change and scale efficiency change are positive and statistically significant, and contribute about equally to the overall treatment effect. Results are robust to instrumenting for policy exposure and other alternative specifications. Private benefits to firms from the policy likely reflect the combination of incentives and targets applied under the program.

Mail Composition and Recipients’ Reaction to Direct Mail

Letter mail services have come under pressure from the emergence of electronic communication channels.