Chemoenzymatic Fractionation and Characterization of Pretreated Birch Outer Bark

In this study, the application of different chemical and enzymatic treatment methods for the fractionation of the birch outer bark components was evaluated. More specifically, untreated and steam exploded, hydrothermally and organosolv treated bark samples were incubated with enzyme mixtures that consisted of cellulases, hemi-cellulases and esterases, and the effect of enzymes was analyzed with P-31 NMR and {C-13-H-1} HSQC. The biocatalysts performed the cleavage of ester bonds resulting in reduction of methoxy and aliphatic groups in the remaining solid fraction, whereas the aromatic fraction remained intact. Moreover, the suberin and lignin fraction were isolated chemically and their properties were characterized by gas chromatography (GC MS), P-31 NMR, {C-13-H-1} HSQC and gel permeation chromatography (GPC). It was demonstrated that the lignin fraction was enriched in guaiacyl phenolics but still contained some associated aliphatic acids and carbohydrates, whereas the suberin fraction presented a polymodal pattern of structures with different molecular weight distributions. This work will help in getting a deeper fundamental knowledge of the bark structure, the intermolecular connection between lignin and suberin fractions, as well as the potential use of enzymes in order to degrade the recalcitrant bark structure toward its valorization

Production of Omega-3 Fatty Acids from the Microalga Crypthecodinium cohnii by Utilizing Both Pentose and Hexose Sugars from Agricultural Residues

The core objective of this work was to take advantage of the unexploited wheat straw biomass, currently considered as a broadly available waste stream from the Greek agricultural sector, towards the integrated valorization of sugar streams for the microbial production of polyunsaturated omega-3 fatty acids (PUFAs). The OxiOrganosolv pretreatment process was applied using acetone and ethanol as organic solvents without any additional catalyst. The results proved that both cellulose-rich solid pulp and hemicellulosic oligosaccharides-rich aqueous liquid fraction after pretreatment can be efficiently hydrolyzed enzymatically, thus resulting in high yields of fermentable monosaccharides. The latter were supplied as carbon sources to the heterotrophic microalga Crypthecodinium cohnii for the production of PUFAs, more specifically docosahexaenoic acid (DHA). The solid fractions consisted mainly of hexose sugars and led to higher DHA productivity than their pentose-rich liquid counterparts, which can be attributed to the different carbon source and C/N ratio in the two streams. The best performance was obtained with the solid pulp pretreated with ethanol at 160 °C for 120 min and an O2 pressure of 16 bar. The total fatty acids content reached 70.3 wt% of dried cell biomass, of which 32.2% was DHA. The total DHA produced was 7.1 mg per g of untreated wheat straw biomass

Isolation and Characterization of Organosolv and Alkaline Lignins from Hardwood and Softwood Biomass

Isolation of lignins from hardwood and softwood biomass samples, containing 26.1\% and 28.1\% lignin, respectively, has been performed with the use of alkaline and organosolv pretreatment methods. The effect of catalyst loading, ethanol content, particle size, and pretreatment time on the yields and properties of the isolated lignins were investigated. Alkaline lignins had higher carbohydrate content-up to 30\%- and exhibited higher molecular weights in the range of 3000 Da, with a maximum phenolic hydroxyl content of 1 mmol g(-1) for birch and 2 mmol g(-1) for spruce. Organosolv lignins, on the other hand, showed high purity-93\% or higher-despite the more extensive biomass dissolution into the pretreatment medium; they also exhibited a lower range of molecular weights between 600 and 1600 Da depending on the source and pretreatment conditions. Due to the lower molecular weight, phenolic hydroxyl content was also increased, reaching as high as 4 mmol g(-1) with a simultaneous decrease in aliphatic hydroxyl content as low as 0.6 mmol g(-1). Efficient lignin dissolution of 62\% for spruce and 69\% for birch, achieved at optimal pretreatment conditions, was combined with extensive hemicellulose removal

Fungal Biotechnology in Space: Why and How?

Fungi have been companions of mankind for millennia. Mushrooms inspired our eating culture, and yeasts and filamentous fungi were developed into highly efficient cell factories during the last 100 years to produce many products utilized in different industries worldwide. What more is to come in the next 100 years? We propose here that fungi can become important cell factories for life in space, especially regarding the filamentous fungus Aspergillus niger as the cutting-edge must-have for space travel in the twenty-first century and beyond. First, it is one of the most robust and efficient production systems used nowadays in industrial biotechnology. Second, it is a multipurpose cell factory that produces a diverse range of organic acids, proteins, enzymes and natural products. And third, it is a common fungal isolate of the International Space Station. A. niger could thus become an essential companion of astronauts for the autonomous production of food, enzymes and antibiotics during space travel. What needs to be done to achieve these visionary goals? In this chapter, we will discuss the opportunities of A. niger as a cell factory spanning from Earth to space. We summarize the current state of the art of A. niger biotechnology on Earth and discuss the general tools and technologies still in need of development to take a new step for mankind: space biotechnology