Providing Stability to High Internal Phase Emulsion Gels Using Brewery Industry By-Products as Stabilizers

The modern brewing industry generates high amounts of solid wastes containing biopolymers—proteins and polysaccharides—with interesting technological and functional properties. The novelty of this study was to use raw by-product from the brewing industry in the development of high internal phase emulsion (HIPE) gels. Thus, the influence of the emulsion’s aqueous phase pH and the by-product’s concentration on structural and physical stability of the emulsions was studied. The microstructure was analyzed using cryo-field emission scanning electron microscopy. To evaluate the rheological behavior, oscillatory tests (amplitude and frequency) and flow curves were conducted. Moreover, the physical stability of the emulsions and the color were also studied. The increase in by-product concentration and the pH of the aqueous phase allowed development of HIPE gels with homogeneously distributed oil droplets of regular size and polyhedral structure. The data from the rheology tests showed a more stable structure at higher pH and higher by-product concentration. This study widens the possibilities of valorizing the brewing industry’s by-products as stabilizers when designing emulsions.

Mutagenesis of the l-Amino Acid Ligase RizA Increased the Production of Bioactive Dipeptides

The l-amino acid ligase RizA from B. subtilis selectively synthesizes dipeptides containing an N-terminal arginine. Many arginyl dipeptides have salt-taste enhancing properties while Arg-Phe has been found to have an antihypertensive effect. A total of 21 RizA variants were created by site-directed mutagenesis of eight amino acids in the substrate binding pocket. The variants were recombinantly produced in E. coli and purified by affinity chromatography. Biocatalytic reactions were set up with arginine and four amino acids differing in size and polarity (aspartic acid, serine, alanine, and phenylalanine) and were analyzed by RP-HPLC with fluorescence detection. Variant T81F significantly improved the yield in comparison to wild type RizA for aspartic acid (7 to 17%), serine (33 to 47%) and alanine (12 to 17%). S84F increased product yield similarly for aspartic acid (7 to 17%) and serine (33 to 42%). D376E increased the yield with alanine (12 to 19%) and phenylalanine (11 to 26%). The largest change was observed for S156A, which showed a yield for Arg-Phe of 40% corresponding to a 270% increase in product concentration. This study expands the knowledge about positions governing the substrate specificity of RizA and may help to inform future protein engineering endeavors.

AID FOR TRADE FLOWS AND POVERTY REDUCTION

The effectiveness of Aid for Trade (AfT) interventions, including with respect to recipient countries’ trade performance, has now been well explored in the literature. However, in spite of the voluminous literature on the poverty effect of the total official development aid, the effect of AfT flows on poverty has received little attention on the empirical front. This paper aims to contribute to the policy debate on this matter by investigating the effect of AfT flows on poverty in recipient countries. In particular, the analysis explores whether this effect translates through countries’ level of export product concentration, as the latter can influence income inequality, and hence the transformation of economic growth into poverty reduction in recipient countries. The empirical analysis, based on 100[Formula: see text]AfT recipient countries, has shown that AfT interventions are associated with poverty reduction in countries that diversify their export products, including toward manufacturing products. Additionally, AfT flows dampen the positive poverty effect of income inequality, and lead to greater poverty reduction in countries with a great extent of fiscal redistribution. Finally, the analysis has shown that AfT interventions mitigate the positive poverty effect of import product concentration. These results have important policy implications.

Development of thermostable sucrose phosphorylase by semi-rational design for efficient biosynthesis of alpha-D-glucosylglycerol

Sucrose phosphorylase (SPase) can specifically catalyze transglycosylation reactions and can be used to enzymatically synthesize α-D-glycosides. However, the low thermostability of SPase has been a bottleneck for its industrial application. In this study, a SPase gene from Leuconostoc mesenteroides ATCC 12,291 (LmSPase) was synthesized with optimized codons and overexpressed successfully in Escherichia coli. A semi-rational design strategy that combined the FireProt (a web server designing thermostable proteins), structure–function analysis, and molecular dynamic simulations was used to improve the thermostability of LmSPase. Finally, one single-point mutation T219L and a combination mutation I31F/T219L/T263L/S360A (Mut4) with improved thermostability were obtained. The half-lives at 50 °C of T219L and Mut4 both increased approximately two-fold compared to that of wild-type LmSPase (WT). Furthermore, the two variants T219L and Mut4 were used to produce α-D-glucosylglycerol (αGG) from sucrose and glycerol by incubating with 40 U/mL crude extracts at 37 °C for 60 h and achieved the product concentration of 193.2 ± 12.9 g/L and 195.8 ± 13.1 g/L, respectively, which were approximately 1.3-fold higher than that of WT (150.4 ± 10.0 g/L). This study provides an effective strategy for improving the thermostability of an industrial enzyme. Key points • Predicted potential hotspot residues directing the thermostability of LmSPase by semi-rational design • Screened two positive variants with higher thermostability and higher activity • Synthesized α-D-glucosylglycerol to a high level by two screened positive variants

Do Donors provide higher Aid for Trade flows to Recipient-Countries that Diversify Export Products or Is It the Other Way Around?

This article has explored whether Aid for Trade (AfT) flows that accrue to recipient-countries depend on the latter’s level of export product concentration. The analysis covers a sample of 132 countries over the period 2002–2017. The findings indicate that least developed countries (LDCs) receive higher AfT flows when they experience a rise in the level of export product concentration, while NonLDCs enjoy higher AfT flows when they diversify export products. Interestingly, higher amounts of AfT accrue to countries that diversify their export product basket towards manufacturing products, although different result patterns appear for the components of manufactured exports. JEL: F35; F14; O14

Quarter of a century of forest fertilization and liming research at the Department of Silviculture in Prague, Czech Republic

Fertilization and liming began to be used in forestry at the beginning of the 20th century in order to increase growth, for improvement of health status or higher resistance to biotic and abiotic factors. The review summarizes results of 48 studies of forest fertilization, nutrition and liming published in scientific journals by authors of Department of Silviculture in Prague over the past more than 20 years. They deal mainly with monitoring of the effect of fertilization and liming applied during planting or shortly after planting of 18 tree species. Moreover, the results of fertilization in older stands are presented. Separate chapters deal with enhancing substrates (soil conditioners and phytohormones). All forest vegetation ranges are covered, from lowland forests to the subalpine belt of grass vegetation in 11 Natural Forest Areas. Forest fertilizing and liming proved beneficial according to most of the studies. The use of fertilizers can be detected in soils after decades. On the other hand, only in a minority of cases was fertilization reflected in the chemistry of the assimilation apparatus and other parts of the trees for a longer period. The main positive effect of fertilization and liming was increase of tree growth and foliation and decrease of mortality and yellowing symptoms. Inconsistent results were documented in some cases, especially for brassinosteroids and alginite compared to good results in slow release fertilizer done by spot-application. The type of product, concentration, time and method of application play an important role in the appropriate use of fertilization and liming.

Moonlighting Proteins: The Case of the Hexokinases

Moonlighting proteins are defined as proteins with two or more functions that are unrelated and independent to each other, so that inactivation of one of them should not affect the second one and vice versa. Intriguingly, all the glycolytic enzymes are described as moonlighting proteins in some organisms. Hexokinase (HXK) is a critical enzyme in the glycolytic pathway and displays a wide range of functions in different organisms such as fungi, parasites, mammals, and plants. This review discusses HXKs moonlighting functions in depth since they have a profound impact on the responses to nutritional, environmental, and disease challenges. HXKs’ activities can be as diverse as performing metabolic activities, as a gene repressor complexing with other proteins, as protein kinase, as immune receptor and regulating processes like autophagy, programmed cell death or immune system responses. However, most of those functions are particular for some organisms while the most common moonlighting HXK function in several kingdoms is being a glucose sensor. In this review, we also analyze how different regulation mechanisms cause HXK to change its subcellular localization, oligomeric or conformational state, the response to substrate and product concentration, and its interactions with membrane, proteins, or RNA, all of which might impact the HXK moonlighting functions.