Improvement of Biomedical Structural Polymers by Synthetic Biology Methods

Materials that have a biological origin find many applications in both Biomedicine and other Sciences. However, the properties of these materials are difficult to change, since natural biosynthetic mechanisms are difficult to explain, simulate, or adjust. Thus, many materials of biological origin are isolated from natural tissues or their substitutes are produced recombinantly, and then modified in the process of experimental application. A major shift in this paradigm is caused by the emerging field of synthetic biology, which introduces innovations in the "tool kit" of methods for tuning biomolecules and biosynthetic mechanisms. Relative to materials, this led to higher product titers due to reprogrammed natural biosynthesis and allowed the development of new materials by combining the desired domains. Here we can focus on recent applications of synthetic biology to bio-derived ribosomal and non-ribosomal polymer materials for biomedical applications. It is also interesting to describe modern methods that will affect the production and design of biomaterials in the near future. Continuous innovation at the intersection of synthetic biology and materials science promises to usher in a new era of biomaterial design and synthesis.

Crack Tip Radius Effect on Fatigue Crack Growth and Near Tip Fields in Plastically Compressible Materials

Motivated by the prospective uses of plastically compressible materials such as, metallic and polymeric foams, transformation toughened ceramics, toughened structural polymers etc., the present authors investigate the crack-tip radius effect on fatigue crack growth (FCG) of a mode I crack and near-tip stress-strain fields in such plastically compressible solids. These plastically compressible materials have been characterised by elastic-viscoplastic constitutive equations. Simulations are conducted for plane strain geometry with two different hardness functions: one is bilinear hardening and the other one is hardening-softening-hardening. It has been observed that plastic compressibility as well as strain softening lead to significant deviation in the amount of crack growth. It has further been revealed that the nature of FCG is appreciably affected by initial crack-tip radius. Even though it may look from outside that the increase in tip radius will lead to decrease in FCG, but the nature of FCG variation with respect to tip radius is found to be a combined effect of tip radius, plastic compressibility and work or strain softening etc.

Trees as bioindicators of environmental pollution and its impact on wood chemical composition

Trees provide one of the most versatile biomass resources for many applications, namely wood. The chemical composition of wood determines its properties, being of real significance for its further capitalization, and depending on many factors. In nature, trees’ biomass is subjected to considerable pollution stress with further alteration of their normal growth conditions. Some correlations have been established between wood’s chemical composition and its further exploitation accordingly to particular circumstances of climate changes and pollution. The content of the main structural polymers from wood, cellulose and lignin, as well other components undergoes notable changes under the influence of pollution phenomena.

Origin, Impact and Control of Lignocellulosic Inhibitors in Bioethanol Production—A Review

Bioethanol production from lignocellulosic biomass is still struggling with many obstacles. One of them is lignocellulosic inhibitors. The aim of this review is to discuss the most known inhibitors. Additionally, the review addresses different detoxification methods to degrade or to remove inhibitors from lignocellulosic hydrolysates. Inhibitors are formed during the pretreatment of biomass. They derive from the structural polymers-cellulose, hemicellulose and lignin. The formation of inhibitors depends on the pretreatment conditions. Inhibitors can have a negative influence on both the enzymatic hydrolysis and fermentation of lignocellulosic hydrolysates. The inhibition mechanisms can be, for example, deactivation of enzymes or impairment of vital cell structures. The toxicity of each inhibitor depends on its chemical and physical properties. To decrease the negative effects of inhibitors, different detoxification methods have been researched. Those methods focus on the chemical modification of inhibitors into less toxic forms or on the separation of inhibitors from lignocellulosic hydrolysates. Each detoxification method has its limitations on the removal of certain inhibitors. To choose a suitable detoxification method, a deep molecular understanding of the inhibition mechanism and the inhibitor formation is necessary.

Roles of cytochromes P450 in plant reproductive development

The cytochrome P450 superfamily is a large enzymatic protein family that is widely distributed along diverse kingdoms. In plants, CYPs participate in a vast array of pathways leading to the synthesis and modification of multiple metabolites with variable and important functions during different stages of plant development. This includes the biosynthesis and degradation of a great assortment of compounds implicated in a variety of physiological responses such as signaling and defense, organ patterning and the biosynthesis of structural polymers among others. In this review we summarize the characteristics of the different families of plant CYPs, focusing on the most recent advances in elucidating the roles of CYPs in plant growth and development and more specifically, during plant gametogenesis, fertilization and embryogenesis.