Improved catalytic functionalities of purified pristine and chitosan-immobilized polygalacturonase, and pectin lyase

Crude Enzyme Concentrate of Filamentous Fungus Hydrolyzed Chitosan to Obtain Oligomers of Different Sizes

Chitosan is a non-cytotoxic polysaccharide that, upon hydrolysis, releases oligomers of different sizes that may have antioxidant, antimicrobial activity and the inhibition of cancer cell growth, among other applications. It is, therefore, a hydrolysis process with great biotechnological relevance. Thus, this study aims to use a crude enzyme concentrate (C_EC) produced by a filamentous fungus to obtain oligomers with different molecular weights. The microorganism was cultivated in a liquid medium (modified Czapeck-with carboxymethylcellulose as enzyme inducer). The enzymes present in the C_EC were identified by LC-MS/MS, with an emphasis on cellobiohydrolase (E.C 3.2.1.91). The fungus of the Aspergillus genus was identified by amplifying the ITS1-5.8S-ITS2 rDNA region and metaproteomic analysis, where the excreted enzymes were identified with sequence coverage greater than 84% to A. nidulans. Chitosan hydrolysis assays compared the C_EC with the commercial enzyme (Celluclast 1.5 L^®). The ability to reduce the initial molecular mass of chitosan by 47.80, 75.24, and 93.26% after 2.0, 5.0, and 24 h of reaction, respectively, was observed. FTIR analyses revealed lower absorbance of chitosan oligomers' spectral signals, and their crystallinity was reduced after 3 h of hydrolysis. Based on these results, we can conclude that the crude enzyme concentrate showed a significant technological potential for obtaining chitosan oligomers of different sizes.

Mechano-chemical and biological energetics of immobilized enzymes onto functionalized polymers and their applications

Enzymes of commercial importance, such as lipase, amylase, laccase, phytase, carbonic anhydrase, pectinase, maltase, glucose oxidase etc., show multifunctional features and have been extensively used in several fields including fine chemicals, environmental, pharmaceutical, cosmetics, energy, food industry, agriculture and nutraceutical etc. The deployment of biocatalyst in harsh industrial conditions has some limitations, such as poor stability. These drawbacks can be overcome by immobilizing the enzyme in order to boost the operational stability, catalytic activity along with facilitating the reuse of biocatalyst. Nowadays, functionalized polymers and composites have gained increasing attention as an innovative material for immobilizing the industrially important enzyme. The different types of polymeric materials and composites are pectin, agarose, cellulose, nanofibers, gelatin, and chitosan. The functionalization of these materials enhances the loading capacity of the enzyme by providing more functional groups to the polymeric material and hence enhancing the enzyme immobilization efficiency. However, appropriate coordination among the functionalized polymeric materials and enzymes of interest plays an important role in producing emerging biocatalysts with improved properties. The optimal coordination at a biological, physical, and chemical level is requisite to develop an industrial biocatalyst. Bio-catalysis has become vital aspect in pharmaceutical and chemical industries for synthesis of value-added chemicals. The present review describes the current advances in enzyme immobilization on functionalized polymers and composites. Furthermore, the applications of immobilized enzymes in various sectors including bioremediation, biosensor and biodiesel are also discussed.

Chemical and physical Chitosan modification for designing enzymatic industrial biocatalysts: How to choose the best strategy?

Chitosan is one of the most abundant natural polymer worldwide, and due to its inherent characteristics, its use in industrial processes has been extensively explored. Because it is biodegradable, biocompatible, non-toxic, hydrophilic, cheap, and has good physical-chemical stability, it is seen as an excellent alternative for the replacement of synthetic materials in the search for more sustainable production methodologies. Thus being, a possible biotechnological application of Chitosan is as a direct support for enzyme immobilization. However, its applicability is quite specific, and to overcome this issue, alternative pretreatments are required, such as chemical and physical modifications to its structure, enabling its use in a wider array of applications. This review aims to present the topic in detail, by exploring and discussing methods of employment of Chitosan in enzymatic immobilization processes with various enzymes, presenting its advantages and disadvantages, as well as listing possible chemical modifications and combinations with other compounds for formulating an ideal support for this purpose. First, we will present Chitosan emphasizing its characteristics that allow its use as enzyme support. Furthermore, we will discuss possible physicochemical modifications that can be made to Chitosan, mentioning the improvements obtained in each process. These discussions will enable a comprehensive comparison between, and an informed choice of, the best technologies concerning enzyme immobilization and the application conditions of the biocatalyst.

Biopolymers and nanostructured materials to develop pectinases-based immobilized nano-biocatalytic systems for biotechnological applications

Pectinases are the emerging enzymes of the biotechnology industry with a 25% share in the worldwide food and beverage enzyme market. These are green and eco-friendly tools of nature and hold a prominent place among the commercially produced enzymes. Pectinases exhibit applications in various industrial bioprocesses, such as clarification of fruit juices and wine, degumming, and retting of plant fibers, extraction of antioxidants and oil, fermentation of tea/coffee, wastewater remediation, modification of pectin-laden agro-industrial waste materials for high-value products biosynthesis, manufacture of cellulose fibres, scouring, bleaching, and size reduction of fabric, cellulosic biomass pretreatment for bioethanol production, etc. Nevertheless, like other enzymes, pectinases also face the challenges of low operational stability, recoverability, and recyclability. To address the above-mentioned problems, enzyme immobilization has become an eminently promising approach to improve their thermal stability and catalytic characteristics. Immobilization facilitates easy recovery and recycling of the biocatalysts multiple times, leading to enhanced performance and commercial feasibility.In this review, we illustrate recent developments on the immobilization of pectinolytic enzymes using polymers and nanostructured materials-based carrier supports to constitute novel biocatalytic systems for industrial exploitability. The first section reviewed the immobilization of pectinases on polymers-based supports (ca-alginate, chitosan, agar-agar, hybrid polymers) as a host matrix to construct robust pectinases-based biocatalytic systems. The second half covers nanostructured supports (nano-silica, magnetic nanostructures, hybrid nanoflowers, dual-responsive polymeric nanocarriers, montmorillonite clay), and cross-linked enzyme aggregates for enzyme immobilization. The biotechnological applications of the resulted immobilized robust pectinases-based biocatalytic systems are also meticulously vetted. Finally, the concluding remarks and future recommendations are also given.