Hydrogels have become one of the potential polymers used with great performance for many issues and can be promoted as biomaterials with highly innovative characteristics and different uses. Gelatin is obtained from collagen, a co-product of the meat industry. Thus, converting wastes such as cartilage, bones, and skins into gelatin would give them added value. Furthermore, biodegradability, non-toxicity, and easy cross-linking with other substances can promote polymers with high performance and low cost for many applications, turning them into sustainable products with high acceptance in society. Gelatin-based hydrogels have been shown to be useful for different applications with important and innovative characteristics. For instance, these hydrogels have been used for biomedical applications such as bone reconstruction or drug delivery. Furthermore, they have also shown substantial performance and important characteristics for remediation for removing pollutants from water, watercourse, and effluents. After its uses, gelatin-based hydrogels can easily biodegrade and, thus, can be sustainably used in the environment. In this study, gelatin was shown to be a potential polymer for hydrogel synthesis with highly renewable and sustainable characteristics and multiple uses.

The degradation of water resources is related to anthropic actions such as rapid urbanization and industrial and agricultural activities with inefficient land use and occupation management. Water pollution caused by organic and inorganic contaminants represents a current challenge for researchers and humanity. One of the techniques used to remove pollutants from aquatic environments is bioremediation, through the metabolism of living organisms, and especially phytoremediation, with plants as a decontamination agent. Aiming to demonstrate the current mechanisms, solutions, and perspectives regarding bioremediation, and especially phytoremediation in aquatic environments, a literature review was conducted, highlighting the following subjects: heavy metals as contaminants, phytoremediation, evaluation of resistance mechanisms, removal of heavy metals by microorganisms and biofilters of the artificial floating islands type. From the literature research carried out, it can be concluded that alternatives such as macrophyte plants have proved to be an effective and efficient alternative with a high potential for removal of contaminants in aquatic environments, including concomitantly with microorganisms. There was no mechanism well-defined for specific absorption of heavy metals by plants; however, some results can indicate that if there was sporadic contamination with some contaminants, the plants can be indicators with some adsorption and absorption, even with low concentration in the watercourse by the moment of the evaluation. It is necessary to study bioremediation methods, resistance mechanisms, tolerance, and removal efficiencies for each biological agent chosen. Within the bioremediation processes of aquatic environments, the use of macrophyte plants with a high capacity for phytoremediation of metals, used combined with bioremediating microorganisms, such as biofilters, is an interesting perspective to remove contaminants.

This study aimed to evaluate the environmental conditions for enzyme activity of catechol 1,2-dioxygenase (C1,2O) and catechol 2,3-dioxygenase (C2,3O) produced by Gordonia polyisoprenivorans in cell-free and immobilized extracts. The optimum conditions of pH, temperature, time course and effect of ions for enzyme activity were determined. Peak activity of C1,2O occurred at pH 8.0. The isolate exhibited the highest activity of C2,3O at pH 7.0 and 8.0 for the cell-free extract and immobilized extract, respectively. This isolate exhibited important characteristics such as broad range of pH, temperature and time course for enzyme activity.