Approaches in biotechnological applications of natural polymers

Natural polymers, such as gums and mucilage, are biocompatible, cheap, easily available and non-toxic materials of native origin. These polymers are increasingly preferred over synthetic materials for industrial applications due to their intrinsic properties, as well as they are considered alternative sources of raw materials since they present characteristics of sustainability, biodegradability and biosafety. As definition, gums and mucilages are polysaccharides or complex carbohydrates consisting of one or more monosaccharides or their derivatives linked in bewildering variety of linkages and structures. Natural gums are considered polysaccharides naturally occurring in varieties of plant seeds and exudates, tree or shrub exudates, seaweed extracts, fungi, bacteria, and animal sources. Water-soluble gums, also known as hydrocolloids, are considered exudates and are pathological products; therefore, they do not form a part of cell wall. On the other hand, mucilages are part of cell and physiological products. It is important to highlight that gums represent the largest amounts of polymer materials derived from plants. Gums have enormously large and broad applications in both food and non-food industries, being commonly used as thickening, binding, emulsifying, suspending, stabilizing agents and matrices for drug release in pharmaceutical and cosmetic industries. In the food industry, their gelling properties and the ability to mold edible films and coatings are extensively studied. The use of gums depends on the intrinsic properties that they provide, often at costs below those of synthetic polymers. For upgrading the value of gums, they are being processed into various forms, including the most recent nanomaterials, for various biotechnological applications. Thus, the main natural polymers including galactomannans, cellulose, chitin, agar, carrageenan, alginate, cashew gum, pectin and starch, in addition to the current researches about them are reviewed in this article.. }To the Conselho Nacional de Desenvolvimento Cientfíico e Tecnológico (CNPq) for fellowships (LCBBC and MGCC) and the Coordenação de Aperfeiçoamento de Pessoal de Nvíel Superior (CAPES) (PBSA). This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit, the Project RECI/BBB-EBI/0179/2012 (FCOMP-01-0124-FEDER-027462) and COMPETE 2020 (POCI-01-0145-FEDER-006684) (JAT)

Biocomposites from polyhydroxybutyrate and bio-fillers by solvent casting method

Biocomposites from polyhydroxybutyrate (PHB) and some bio-fillers such as lignin (L), alpha cellulose (AC) and cellulose nanofibrils (CNFs) were prepared to investigate the effect of the bio-fillers on the properties of PHB by a solvent casting method. The thermal properties by thermogravimetry analysis (TGA-DTG and DTA) and differential scanning calorimetry (DSC) were determined; morphological characterization by scanning electron microscopy (SEM) and structural analysis by X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) of the biocomposites were performed. TGA curves showed that the highest values for T-10\%, T-50\% of the biocomposites were 278.2(degrees)C for PHB+2\%AC and 291.7(degrees)C for PHB+2\%CNFs; however, the best value for T-75\% was obtained as 381.5(degrees)C for PHB+2\%L. According to DTG curves, the best results were found for PHB+0.5\%L and PHB+0.5\%CNFs. DTA showed an increase in temperature of maximum degradation with loading of lignin and CNFs. The addition of bio-fillers increases T-c and T-m for both first cooling/heating and second cooling/heating. T-c and T-m values for first cooling/healing were found to be lower as compared with second cooling/healing. Furthermore, the addition of bio-fillers acts as a nucleating agent in PHB and SEM pictures showed the porous structure in all biocomposites. SEM images revealed uniform distribution of the reinforcing particles in the polymer at low loadings (0.5 wt\%), while higher loadings (2 wt\%) of L and CNFs contributed to easy aggregation within the PHB matrix. In XRD studies, PHB in the range 5-55 degrees shows 6 main peaks. XRD patterns of the PHB biocomposites revealed 3 main peaks at 13.57(degrees), 16.87(degrees) and 22.1 degrees, and the other peaks disappeared in the patterns. The largest and lowest values of X-c were found for PHB+2\%AC and PHB+2\%CNFs, respectively

Production of bacterial cellulose from alternative low-cost substrates

Cellulose is the most widely used biopolymer on Earth. Its large-scale production is mainly from lignocellulosic material (plant origin), however, this plant material is not the only source of this valuable polymer, since microorganisms, like bacteria, naturally produce cellulose, especially those of the genus Komagateibacter (formerly Gluconacetobacter). This type of cellulose is of great interest because of its unique properties such as high purity and resistance, nevertheless, it has not been produced in a large-scale industrial process to date using low-cost substrates, one of the key aspects that should be considered for the industrial obtaining of any biotechnological product. As a main finding we found that the majority of low-cost culture media discussed could have the potential to produce bacterial cellulose on an industrial scale, since in most cases they yield more cellulose (with similar physical chemical characteristics) to those obtained in standard media. However, for an appropriate large-scale production, a specific knowledge about these by-products (since their composition and characteristics, which have a direct impact on the productivity of this biopolymer, are quite heterogeneous) and a proper standardization of them would also be required. Research staff of many industries could use the information presented here to help design a process to use their respective byproducts as substrate to obtain a product with a high added value as bacterial cellulose