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)

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Not AvailableCage culture of Etroplus suratensis (Pearlspot) was carried out in Krishnagiri reservoir, India, a highly productive reservoir to analyze the feasibility of growing this species in freshwater cages and to investigate the effect on selected environmental parameters. Fish of average weight 5.98 ± 0.52 g were stocked at 10 ind. m3 in High-Density Poly-Ethylene floating cages (3 × 3 × 2 m) made of nylon knotless net with 12 mm mesh size. Fish were fed commercial pellet feed containing 32% protein at 5–3% of body weight a day. A reference point was fixed 100 m away from the cage site to compare the water quality as well as plankton abundance with the cage site. After 7 months, the fish grew to 90.31 ± 2.48 g, with low mean weight gain during the first 2 months, and a steady increase thereafter. Overall, the growth of Etroplus in terms of the analyzed parameters viz. specific growth rate, food conversion ratio, feed efficiency ratio, and protein efficiency ratio viz. 1.3 ± 0.013, 2.87 ± 0.08, 0.35 ± 0.01 and 1.01 ± 0.03, respectively, was found to be satisfactory in freshwater cages irrespective of low survival (52%). Zooplankton and phytoplankton density at the cage was significantly higher throughout the study, maybe due to the abundance of primary nutrients from the decomposition of leftover feed.Not Availabl

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Not AvailableFor natural ecosystems as well as human development, freshwater bodies like reservoirs are critically important. Krishnagiri reservoir, a moderately impacted tropical reservoir of India, is an important source of freshwater. However, eutrophication status due to anthropogenic activities is a major threat to this reservoir. This endeavour aimed to determine the spatio-temporal differences for selected (21) limnological parameters along with trophic status of Krishnagiri reservoir for its sustainable management. Samples (water and plankton) were collected from 11 sites covering entire reservoir during pre-monsoon, monsoon and post-monsoon season. Limnological parameters showed some spatio-temporal variations, the season has more impacts on water quality than sites as evidenced by cluster analysis. Principal component analysis distinguished the seasons based on major influencing water quality parameters. The reservoir trophic status fluctuated from eutrophic to hyper-eutrophic. Water quality index showed that the reservoir falls under unsuitable category. Additionally, cyanobacterial bloom formation was observed in all the seasons, with dominance of Microcystis sp. This investigation can be used as a baseline for studies pertaining to nutrient and sediment loading, and immediate action is required for employment of integrated management plan to restore this aquatic ecosystem. The study also recommends strategies for sustainable management of the aquatic bioresources.Not Availabl

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Not AvailableThe pattern of a fish assemblage of a large reservoir, Stanley (also called as Mettur) in Peninsular India was studied to derive various management protocols, specifically fish enhancement. The investigation was carried out in the spatial and temporal scale of the reservoir during 2017–2019. A total of 52 species belonging to 35 genera were recorded indicating high species richness. Simpson (0.17), Shannon (0.17), dominance (0.104), and evenness (0.52) indices did not show significant differences among zones whereas there was a significant difference during different seasons. On a temporal scale, maximum species were recorded in monsoon (47) followed by post-monsoon (43) and pre-monsoon season (33). On a spatial scale, it represented that riverine (47) and transitional zone (37) showed more species richness compared to lacustrine zone (30). Based on the catch structure of this reservoir, it is evident that exotic fishes play a major role in the recent past. One species under critically endangered and endangered, three species under near threatened, and two under vulnerable species were observed in the catch during this study period. The trophic guild of fishes showed the dominancy of planktivores. Abiotic factors such as temperature, pH, and chlorophyll were found directly influencing the species abundance. The study suggested management measures, including observation of closed fishing season, protection of breeding grounds, use of fish aggregating devices, mesh size regulation, and fish seed stocking in the reservoir.Not Availabl