Purification, Biochemical Characterization of a Macrotermes gilvus Cellulase and Zymogram Analysis

Recycling of printed Xerographic paper using Aspergillus assiutensis enzyme cocktail: an integrated approach to sustainable development

To overcome the human and animal survivability risk, sustainable development is the only option on earth that can be achieved through the maximum use of renewable environmental resources. Recycling of waste paper is an emerging waste management approach to conserve natural resources. Herein, we studied enzyme-mediated process to recycle the xerographic paper by using the crude fungal extract from indigenously isolated fungi identified as Aspergillus assiutensis. The fungal enzyme cocktail has been characterized for the production of multiple enzymes namely cellulase, amylase, xylanase, pectinase, and protease. All these enzymes have pH optima in the acidic range and except cellulase and all the enzymes are stable from 10 to 80 C. In the zymogram analysis, pectinase, xylanase, amylase, and cellulase were detected at 68 kDa, ~ 54 kDa, 38 kDa, and 30 kDa, respectively. Also, the presence of protease was confirmed by the clear zone at 68, 31, and 16 kDa. A 26% decrease in the kappa number and reduction in Hex A of the pulp was observed on the treatment of the pulp with enzyme as compared to the control pulp without any treatment. The physical and chemical properties of the pulp were also improved by enzyme-mediated pulping as compared to the control The physiochemical parameter of the effluent like TDS was reduced (397 ppm) significantly in comparison to chemical deinking process and it was within the permissible limit. BOD and alkalinity were reduced when the enzymes and chemical dosage were used in combination. These results indicate that chemi-enzymatic deinking is most promising to reduce or remove the pollution parameters including ink and this approach can be used in the paper and pulp industry for sustainable development.

A trimeric glycosylated GH45 cellulase from the red abalone (Haliotis rufescens) exhibits endo and exoactivity

The red abalone (Haliotis rufescens) represents North America's most important aquaculture species. Its hepatopancreas is rich in cellulases and other polysaccharide-degrading enzymes, which provide it the remarkable ability to digest cellulose-rich macroalgae; nevertheless, its cellulolytic systems are poorly explored. This manuscript describes some functional and structural properties of an endogenous trimeric glycosylated endoglucanase from H. rufescens. The purified enzyme showed a molecular mass of 23.4 kDa determined by MALDI-TOF mass spectrometry, which behaved as a homotrimer in gel filtration chromatography and zymograms. According to the periodic acid-Schiff reagent staining, detecting sugar moieties in SDS-PAGE gel confirmed that abalone cellulase is a glycoprotein. Hydrolysis of cello-oligosaccharides and p-nitrophenyl-β-D-glucopyranosides confirmed its endo/exoactivity. A maximum enzyme activity toward 0.5% (w/v) carboxymethylcellulose of 53.9 ± 1.0 U/mg was achieved at 45°C and pH 6.0. We elucidated the abalone cellulase primary structure using proteases and mass spectrometry methods. Based on these results and using a bioinformatic approach, we identified the gene encoding this enzyme and deduced its full-length amino acid sequence; the mature protein comprised 177 residues with a calculated molecular mass of 19.1 kDa and, according to sequence similarity, it was classified into the glycosyl-hydrolase family 45 subfamily B. An AlphaFold theoretical model and docking simulations with cellopentaose confirmed that abalone cellulase is a β-sheet rich protein, as also observed by circular dichroism experiments, with conserved catalytic residues: Asp26, Asn109, and Asp134. Interestingly, the AlphaFold-Multimer analysis indicated a trimeric assembly for abalone cellulase, which supported our experimental findings. The discovery and characterization of these enzymes may contribute to developing efficient cellulose bioconversion processes for biofuels and sustainable bioproducts.

Purification and characterization of amylases from three freshwater fish species providing new insight application as enzyme molecular markers for zymography

Purification of amylases from digestive tracts of three freshwater fish species with Q-Sepharose Fast Flow and Sephacryl S-200 columns displayed two isoforms of amylases from Osteochilus hasselti (O1, O2) and three isoforms of those from both Hampala dispar (UB, H1, H2) and Puntioplites proctozystron (P1, P2, P3). The optimum pH values displayed at 7.0 and 8.0, while the optimum temperatures revealed at 40 and 50 °C. Almost isoenzyme activities were activated by NaCl and CaCl2, whereas EDTA and SDS strongly inhibited all enzymatic activities. Verification with an atomic absorption spectrophotometry exhibited the presence of Ca2+ ions in the range of 0.02-13.53 ppm per mg protein indicating that amylases are Ca2+ dependent. Molecular weight analysis revealed 12 to 147 kDa. The UB, O1, and H2 amylases with appropriate molecular masses of 64, 49, and 25 kDa validated with LC-MS/MS were selected. Three certain enzymes revealed high stability in a sample buffer after five cycles of freeze-thawing process upon storage at - 20 °C for 12 weeks. No protein degradation was observed on polyacrylamide gel, and the enzymes still displayed sharp and clear bands on zymograms. The result suggested that the purified fish amylases, which expressed high activities and stabilities, were potentially used as enzyme molecular weight markers for zymography.

Bacterial cellulase from the intestinal tract of the sugarcane borer

Cellulolytic enzymes have wide use in several industrial segments (e.g. biofuels, pulp and paper, food, and cosmetics). However, one of the challenges is their large-scale production with high specific activity to eliminate the dependence of the purchase of enzymatic cocktails produced by commercial parties. The aims of this study were (1) isolation, selection, and partial characterization of bacterial cellulases present in the intestinal tract of the sugarcane borer and (2) to identify cellulase-producing bacteria by analyzing the 16S rDNA gene. Cellulase production and purification assays resulted in similar electrophoretic profiles between four bacterial strains. These strains were identified as Klebsiella pneumoniae, Klebsiella sp., and Bacillus sp. K. pneumoniae was the main cellulase-producing microorganism. Our results show the possibility of finding cellulolytic microorganisms that inhabit the gut of herbivorous animals, especially those that are predators of important crops of economic value. Furthermore, K. pneumoniae cellulase is of medical importance. In hospitals, health professionals, hospital technicians, patients and visitors wear clothes containing cellulose. Thus, K. pneumoniae within hospitals can contaminate these clothes and be spread to the environment. In that case, it would be important for the hospital's chemical sterilization products to have at least one cellulase inhibitor.

A novel beta-1,4 glucanase produced by symbiotic Bacillus sp. CF96 isolated from termite (Anacanthotermes)

A novel beta-1,4-glucanase was purified and characterized from symbiotic Bacillus sp. CF96 of termite. The SDS-PAGE and zymogram analyses revealed a molecular mass of 35.6 kDa. Optimal activity was at 50 °C and pH 5.5, while the enzyme was active over a wide range of temperature 20-80 °C and pH 4-10 and interestingly more than 60% of the maximum activity remained up to pH 9. The enzyme activity increased in the presence of hexane, chloroform and methanol (20% v/v). while, the enzyme activity was inhibited by metal ions such as Mn²⁺, Hg²⁺, Cu²⁺, Zn²⁺, Mg²⁺, Fe²⁺. The isolated enzyme was able to degrade carboxymethyl cellulose (CMC), avicel and cellulose. Cellobiose was the hydrolytic product of enzymatic reaction based on thin layer chromatography (TLC) analysis. Regarding beta-1,4 endo/exoglucanase activity and high temperature, pH and solvent stability, the enzyme has potential for various industrial applications especially in designing pesticide for termite.

Purification and Characterization of the Total Cellulase Activities (TCA) of Cellulolytic Microorganisms

Cellulose is the earth's most abundant plant polysaccharide containing a large array of glucose units linked through β (1 → 4) linkages by existing in both crystalline and amorphous forms. Cellulose is widely distributed in plants, constituting up to 40-50% overall dry weight of the plant biomass. Majorly, microorganisms secrete three types of enzymes such as endoglucanases, exoglucanases, and beta-glucosidase for the hydrolysis of cellulose, contributing to the total cellulase activity. Industrially, the cellulolytic microorganisms are assessed based on their total cellulolytic activities. Similarly, total cellulase activity can also be used for the isolation and characterization of the cellulolytic microorganisms. In this chapter, we have specifically discussed about the methods used for the purification and characterization of the total cellulase activities of the microorganisms such as filter paper assay and cellulase zymogram assay. Our present chapter can be used as primer for characterizing cellulolytic abilities of cellulose-degrading microorganisms.