Influence of galactosidases on glycosaminoglycan removal Vis-à-Vis opening up of skin matrix to enable complete rehydration.

Enzymatic interventions in animal skin processing are increasingly being considered as safe and benign technology options due to the reduction and replacement of potential harmful chemicals. In this study, galactosidases have been employed for rehydration of preserved skins and hides to improve the process efficiency and minimize hazardous sodium sulfide. The purpose of rehydration is to ensure the skin is hydrated uniformly to facilitate subsequent physico-chemical processes of leather making. Improper rehydration leads to reduction in the quality and value of the leather. The efficacy of the enzymatic process was studied using histological images and scanning electron microscopic analysis. Pollution load changes and the extent of carbohydrate removal were also quantified. The study indicates possibility for substantial reduction in process duration and water input (up to 30%) during rehydration of preserved animal skins when galactosidases are used as rehydration aid without affecting the quality of the leather. Thus use of galactosidases in rehydration ensures uniform accelerated rehydration and provides significant environmental benefits to tanning industry, by reducing harmful substances in subsequent operations.

Alkaline protease for an efficacious rehydration of skin matrix by a novel Bacillus crolab MTCC 5468 in sustainable leather production: a green approach.

OBJECTIVES: The utilization of biotechnology in leather sector has more extensive in modern years; more particular to proteolytic enzymes and employed in several steps of the leather making such as soaking, dehairing, bating, solid waste management etc. The current study evaluates the performance of alkaline protease from Bacillus crolab MTCC 5468 in single soaking of goat skins matrix by comparing with the conventional multiple soaking processes. RESULTS: According to the obtained results, the optimum concentration for maximum rehydration of goat skins was accomplished at 1.0% (v/w) of alkaline protease at duration of 3 h over traditional rehydration method (4-6 h). The moisture level, total protein, chloride content and total organic carbon of enzymatic rehydration was superior to that of conventional rehydration and it was also used to measure the effectiveness of rehydration process. Scanning electron microscopic images of enzymatically processed leather exhibits enhanced opening of fiber bundles and smooth grain surface than conventional method. Furthermore, the alkaline protease treated leather exhibited improved moisture uptake, removal of chlorides and suppleness because of hydrolysis of non-collagenous proteins as indicated by well opened up fiber bundles in histological analysis. CONCLUSIONS: The application of alkaline protease in rehydration operation of leather production confirmed scope for diminishing water quantity around 66.6%, soaking duration at 50%, minimizing use of harmful dehairing chemicals at 50-60%, thereby, eliminating the bating operation during pre-tanning. These outcomes suggest that alkaline protease have potential application in rehydration of skins for immense environmental concerns of leather tanning sectors.

Studies on the use of sodium polyacrylate (SPA) for low-salt animal skin preservation.

Salt-based preservation is practiced for decades in the leather industry because of its versatility, cost-effectiveness, and availability. The salt removed from the soaking process causes significant pollution including organic and elevated total dissolved solids (TDS). Hence, a low-salt skin preservation method using commercial sodium polyacrylate with a reduced quantity of sodium chloride aiming to retain leather properties and pollution reduction was the principal focus of the study. Commercial sodium polyacrylate initially characterized for water absorption capacity along with structural and functional properties is confirmed by NMR and IR spectroscopic techniques. In preliminary experiments, the process parameters attained optimized conditions of sodium polyacrylate (SPA) quantity (5%), a minimal amount of salt (15%), and contact time (4 h) required for skin preservation. Besides, reusability studies after SPA recovery (95%) were applied to skins with an optimized quantity of SPA and salt subsequently stored for 15 days along with control (40% salt). The results revealed that SPA with low salt aided an adequate curing efficiency with a substantial reduction (> 65%) of TDS and comparable physical and organoleptic properties on par with the conventional method. Overall, SPA supported low-salt skin preservation reduces pollutant load (TDS) caused due to using of 40% sodium chloride in the conventional curing process.

Bio-engineering and cellular imaging of silver nanoparticles as weaponry against multidrug resistant human pathogens.

'Go green' has also been implied to nanotechnology by harbouring eco-benign principle for a cleaner production of silver nanoparticles (AgNPs). This was achieved using a nitrate reducing Bacillus subtilis L1 (KT266579.1) inhabiting rhizosphere soil under optimized laboratory conditions, highlighting on its antibacterial modus operandi. Nano-characteristics and antimicrobial mechanism were investigated using spectroscopic and electron microscopic studies. Spectroscopic and microscopic characterization revealed typical surface plasmon resonance (SPR) with λmax 420 nm showing mean particle size of ~28.30 nm and spherical shaped nanoparticles. Antimicrobial susceptibility pattern of clinically important pathogens (n = 15) exposed to AgNPs at 10 µg, 15 µg and 20 µg/mL for 18 h was found significant in a dose dependent fashion. Electron and atomic force microscopic (AFM) studies have demonstrated the typical bactericidal effect of AgNPs (<25 µg/mL) associated with 'pitting effect', cell shrinkage and increase in surface roughness. The EDX spectrum of the control and treated bacteria showed the intrusion of AgNPs inside the bacterial cells endorsing the event of bacterial paralysis. DNA fragmentation assay demonstrated significant DNA damage in the form of smear, indicative of genotoxicity at ≤32 µg and ≤16 µg/mL of AgNPs respectively for Gram positive and negative strains in <12 h. These results suggest that AgNPs possess excellent antimicrobial activity, providing a potential lead for developing a broad spectrum antibacterial agent and extending its therapeutic modalities targeting antibiotic resistant strains at gene level.

Green processing: minimising harmful substances in leather making.

Conventional leather processing poses serious threat to the environment due to its numerous chemical treatments which include hazardous chemicals such as sodium sulphide and lime. To minimise the pollutants and harmful substances during leather processing, an enzymatic rehydration-dehairing-fibre-opening process has been achieved in shortest possible time compared to conventional process. The physicochemical characteristics of experimental leathers were found to be comparable with those of conventionally processed leathers. The releases of sugar and proteoglycans were found to be in congruence with the scanning electron micrographs and histology. TGA and DSC results ascertained the stability of enzymatically processed leathers. Pollution load in terms of TOC, BOD, COD, and TDS was reduced up to 80% compared to that of the conventional process. The present work provides immense potential for a new approach in leather making with environmental safeguards. Graphical abstract.

Bio-fabrication of pigment-capped silver nanoparticles encountering antibiotic-resistant strains and their cytotoxic effect towards human epidermoid larynx carcinoma (HEp-2) cells.

Bacterial biomolecule-mediated nanoparticle (NP) synthesis constitutes a reliable, eco-friendly approach that ameliorates green-chemistry principles. In this study, stable silver nanoparticles were synthesized by exposing aqueous silver ions to an extracellular diffusible pigment produced by Pseudomonas aeruginosa (PA6) under optimized laboratory conditions. Spectroscopic and microscopic analyses showed the typical characteristics of silver with an average size of ∼28.30 nm and spherical shape. The particles were polydispersed and showed no definite agglomeration with a zeta potential of -32.3 mV, conferring stability. Antimicrobial studies were carried out using 5, 15, 25 and 50 µg mL-1 concentrations of pcAgNPs, which showed significant antibacterial activity toward clinically important pathogens at all concentrations compared to with the control sample. The bactericidal effect induced by pcAgNPs associated with cell damage was well demonstrated using electron microscopic studies. ROS production was measured using the DCFH-DA method and the oxidative stress was assessed by measuring the reduced glutathione (GSH) levels. Cytotoxicity studies on HEp-2 (Human Epidermoid Larynx Carcinoma) cells exposed to pcAgNPs showed dose-dependent cytotoxic effect with IC50 of 14.8 µg mL-1 compared to with IC50 of 7.38 µg mL-1 for the Vero cell control. Mechanistically, the pcAgNPs activated p53 that induced catalase, leading to apoptosis and DNA fragmentation via a p53 transcriptional pathway and electron transport arrest, which resulted in cell death. This synergistic efficacy of pigment-AgNPs demonstrated excellent antimicrobial and anti-proliferative activities, providing a potential lead for developing a broad-spectrum antibacterial agent and improving the therapeutic modalities targeting carcinoma cells at the gene level.