Alkaliphilic Enzymes and Their Application in Novel Leather Processing Technology for Next-Generation Tanneries

Bioremediation efficiency of free and immobilized form of Aspergillus niger and Aspergillus tubigenesis biomass on tannery effluent

Untreated tannery effluent discharge, which causes severe environmental pollution. This research was performed to assess the bioremediation (multi-pollutant adsorption) potential of pre-identified and multi metal tolerant Aspergillus niger and Aspergillus tubigenesis through a stirred tank bioreactor in free and immobilized form. Physicochemical property analysis results showed that most of the tannery effluent properties were beyond the permissible limits. These A. niger and A. tubigenesis effectively immobilized on corncob and coir solid support material. The stirred tank bioreactor based bioremediation study revealed that the fungal biomass (Aspergillus niger and Aspergillus tubigenesis) immobilized coir and corncob material demonstrated remarkable multi-pollutant (TSS: 22.5% & 13.5%, TS: 29% & 22%, BOD: 21% & 10%, TDS: 28% & 19%, COD: 30% & 22%, Cr: 27% & 19%, Cu: 28% & 12%, and Pb: 48% & 29% respectively) adsorption potential in a week of treatment. Moreover, it reduced the toxicity of tannery effluent and promotes the sprouting of Oriza sativa seeds, as demonstrated by petri plate bioassay. These finding suggest that the metal-tolerant fungal isolates A. niger and A. tubigenesis demonstrated impressive bioremediation proficiencies in an immobilized state. A field investigation is required to assess the feasibility of this strategy on tannery effluent.

Biochemical characterization of a partially purified protease from Aspergillus terreus 7461 and its application as an environmentally friendly dehairing agent for leather industry

Proteases can be used in several biotechnological processes including detergent, food and leather industries. In the leather industry, dehairing is carried out by chemicals, which pollute the environment. Therefore, to make the hair removal process environmentally friendly, a protease produced by Aspergillus terreus has been purified, biochemically characterized and had an efficient ability to remove hair from bovine leather. The protease was produced using 1% wheat bran and was purified 2.3-fold using two chromatographic steps showing a molecular weight of 90 kDa. Optimal temperature and pH were 50 °C and 6.5, respectively. Thermal stability was up to 1 h at 50 °C. Protease was stable to detergents like Tween 80 and to organic solvents. The activity was activated by Ca²⁺ and inhibited by Hg²⁺ and Cu²⁺. The enzyme was classified as serine protease, by the inhibition by PMSF and was stable to reducing agents. It hydrolyzed casein, azocasein, BSA, egg albumin and BTpNA. The Km and Vmax values were 0.65 ± 0.03 mg/mL and 3.66 ± 0.18 μmol/min, respectively. Remarkable properties about temperature, pH, stability to detergents and reducing agents ensure that the protease from A. terreus can be an excellent candidate for industrial applications, particularly in the leather industry.

Alkaliphiles: The Versatile Tools in Biotechnology

The extreme environments within the biosphere are inhabited by organisms known as extremophiles. Lately, these organisms are attracting a great deal of interest from researchers and industrialists. The motive behind this attraction is mainly related to the desire for new and efficient products of biotechnological importance and human curiosity of understanding nature. Organisms living in common "human-friendly" environments have served humanity for a very long time, and this has led to exhaustion of the low-hanging "fruits," a phenomenon witnessed by the diminishing rate of new discoveries. For example, acquiring novel products such as drugs from the traditional sources has become difficult and expensive. Such challenges together with the basic research interest have brought the exploration of previously neglected or unknown groups of organisms. Extremophiles are among these groups which have been brought to focus and garnering a growing importance in biotechnology. In the last few decades, numerous extremophiles and their products have got their ways into industrial, agricultural, environmental, pharmaceutical, and other biotechnological applications.Alkaliphiles, organisms which thrive optimally at or above pH 9, are one of the most important classes of extremophiles. To flourish in their extreme habitats, alkaliphiles evolved impressive structural and functional adaptations. The high pH adaptation gave unique biocatalysts that are operationally stable at elevated pH and several other novel products with immense biotechnological application potential. Advances in the cultivation techniques, success in gene cloning and expression, metabolic engineering, metagenomics, and other related techniques are significantly contributing to expand the application horizon of these remarkable organisms of the 'bizarre' world. Studies have shown the enormous potential of alkaliphiles in numerous biotechnological applications. Although it seems just the beginning, some fantastic strides are already made in tapping this potential. This work tries to review some of the prominent applications of alkaliphiles by focusing such as on their enzymes, metabolites, exopolysaccharides, and biosurfactants. Moreover, the chapter strives to assesses the whole-cell applications of alkaliphiles including in biomining, food and feed supplementation, bioconstruction, microbial fuel cell, biofuel production, and bioremediation.