Engineering hydroxyproline-O-glycosylated biopolymers to reconstruct the plant cell wall for improved biomass processability.

Reconstructing the chemical and structural characteristics of the plant cell wall represents a promising solution to overcoming lignocellulosic biomass recalcitrance to biochemical deconstruction. This study aims to leverage hydroxyproline (Hyp)-O-glycosylation, a process unique to plant cell wall glycoproteins, as an innovative technology for de novo design and engineering in planta of Hyp-O-glycosylated biopolymers (HypGP) that facilitate plant cell wall reconstruction. HypGP consisting of 18 tandem repeats of "Ser-Hyp-Hyp-Hyp-Hyp" motif or (SP4)18 was designed and engineered into tobacco plants as a fusion peptide with either a reporter protein enhanced green fluorescence protein or the catalytic domain of a thermophilic E1 endoglucanase (E1cd) from Acidothermus cellulolyticus. The engineered (SP4)18 module was extensively Hyp-O-glycosylated with arabino-oligosaccharides, which facilitated the deposition of the fused protein/enzyme in the cell wall matrix and improved the accumulation of the protein/enzyme in planta by 1.5-11-fold. The enzyme activity of the recombinant E1cd was not affected by the fused (SP4)18 module, showing an optimal temperature of 80°C and optimal pH between 5 and 8. The plant biomass engineered with the (SP4)18 -tagged protein/enzyme increased the biomass saccharification efficiency by up to 3.5-fold without having adverse impact on the plant growth.

Obtaining and Characterization of the PLA/Chitosan Foams with Antimicrobial Properties Achieved by the Emulsification Combined with the Dissolution of Chitosan by CO2 Saturation.

A new method of obtaining functional foam material has been proposed. The materials were created by mixing the poly lactic acid (PLA) solution in chloroform, chitosan (CS) dissolved in water saturated with CO2 and polyethylene glycol (PEG), and freeze-dried for removal of the solvents. The composite foams were characterized for their structural (SEM, FT-IR, density, porosity), thermal (DSC), functional (hardness, elasticity, swelling capacity, solubility), and biological (antimicrobial and cytotoxic) properties. Chitosan in the composites was a component for obtaining their foamed form with 7.4 to 22.7 times lower density compared to the neat PLA and high porosity also confirmed by the SEM. The foams had a hardness in the range of 70-440 kPa. The FT-IR analysis confirmed no new chemical bonds between the sponge ingredients. Other results showed low sorption capacity (2.5-7.2 g/g) and solubility of materials (less than 0.2%). The obtained foams had the lower Tg value and improved ability of crystallization compared to neat PLA. The addition of chitosan provides the bacteriostatic and bactericidal properties against Escherichia coli and Staphylococcus aureus. Biocompatibility studies have shown that the materials obtained are not cytotoxic to the L929 cell line.

The Production Possibility of the Antimicrobial Filaments by Co-Extrusion of the PLA Pellet with Chitosan Powder for FDM 3D Printing Technology.

The last decades have witnessed a major advancement and development in three-dimensional (3D) printing technology. In the future, the trend's utilization of 3D printing is expected to play an important role in the biomedical field. This work presents co-extrusion of the polylactic acid (PLA), its derivatives (sPLA), and chitosan with the aim of achieving filaments for printing 3D objects, such as biomedical tools or implants. The physicochemical and antimicrobial properties were evaluated using SEM, FT-IR, DSC, instrumental mechanical test, and based on the ASTM E2149 standard, respectively. The addition of chitosan in the PLA and sPLA filaments increased their porosity and decreased density. The FT-IR analysis showed that PLA and chitosan only formed a physical mixture after extrusion. The addition of chitosan caused deterioration of the mechanical properties of filaments, especially elongation at break and Young's modulus. The addition of chitosan to the filaments improved their ability to crystallize and provide their antimicrobial properties against Escherichia coli and Staphylococcus aureus.

Effect of Germination Conditions and Mashing Temperature on the Amylolytic Enzyme Activity and Degree of Starch Saccharification of Brown Rice Cultivars During Syrup Production.

The germination process activates amylolytic enzymes that can produce rice syrup through mashing, however the factors affecting enzyme activities and soluble saccharides have not been investigated. This study characterized amylolytic enzymes activities, including α-amylase, ß-amylase, and α-glucosidase, and soluble saccharides from germinated rice cultivars of four rice cultivars, including waxy, short grain, medium grain, and long grain, under aerobic and anaerobic germination conditions over 4 days and then mashed at 55, 65, 75, and 85 °C. The results showed that the long-grain rice had higher activities of all three enzymes, whereas the waxy rice exhibited lower activities. Glucose and maltose were the predominant saccharides at low mashing temperatures of 55 °C and 65 °C; saccharides of degree of polymerization 3 to 7 became significant at mashing temperatures of 75 °C and 85 °C. The amount and composition of saccharides were strongly influenced by rice cultivar, and germination and mashing conditions. The findings highlight the importance of rice components and starch structure on the amount and composition of soluble saccharides from germinated brown rice. PRACTICAL APPLICATION: Rice syrup is commercially produced by the addition of external bacterial enzymes to brown or milled rice. Germinated brown rice is naturally rich in nutrients and amylases, both are produced during the germination process. Because of the presence of naturally activated amylases, germinated brown rice could be used to produce rice syrup without the addition of external enzymes while preserving the nutrients from germination of brown rice.