Sujata Sinha

A New Bifunctional Chitosanase Enzyme from Streptomyces sp. and Its Application in Production of Antioxidant Chitooligosaccharides

Chitosanases produced by microbes and plants are getting attention to explore vastly available marine waste. Chitooligosaccharides and glucosamine can be produced using chitosanase enzyme and have applications in food, pharma and other industries. A potential microbial chitosanase source was found after isolation and screening of chitosan degrading microbes from garden soil. An isolate, designated as C6 produced chitosanase enzyme upon induction by chitosan substrates. Production of 6 U/ml of chitosanase enzyme was achieved from this isolate on chitosan minimal salt broth medium at 32xa0°C after 3xa0days of growth. The enzyme was able to hydrolyse both chitosan and cellulosic substrates. Enzymatic production of d-glucosamine and chitooligosaccharides were studied with various chitosan substrates using crude enzyme. The yield of glucosamine was found to be 40% after 2xa0h of reaction at 40xa0°C, and chitosan oligomers were produced having two to six polymerizations at 60xa0°C reaction temperature. The hydrolysates showed 50% antioxidant activity as compared to ascorbic acid.

Electrospun polyacrylonitrile nanofibrous membranes for chitosanase immobilization and its application in selective production of chitooligosaccharides.

Polyacrylonitrile nanofibrous membranes (PANNFM) were prepared by electrospinning from 10 wt.% of PAN solution and its surface was modified by amidination reaction. A new chitosan degrading enzyme from Aspergillus sp. was covalently immobilized on PANNFM. Immobilization efficiency of 80% was achieved by activating PANNFM surface for 30 min followed by 2 h treatment with enzyme solution. The optimum temperature and pH for immobilized enzyme were 50°C and 5.8, respectively. The immobilized chitosanase retained >70% activity after ten repeated batch reaction and could be stored up to 60 days at 4°C with minor loss in activity. Chitosan hydrolysis using different substrates were studied using immobilized chitosanase in batch conditions. Continuous selective production of chitooligosaccharides (dimer to hexamer) by changing the temperature was achieved by PANNFM-chitosanase.

Modelling of the cooling process on the runout table of a hot strip mill-a parallel approach

This paper deals with the development of a new model for the cooling process on the runout table of hot strip mills. The suitability of different numerical methods for the solution of the proposed model equation from the point of view of accuracy and computation time are studied. Parallel solutions for the model equation are proposed. The numerical methods discussed are the finite difference method, the orthogonal method, and the integral profile method.

Recent Progress in Chitosanase Production of Monomer-Free Chitooligosaccharides: Bioprocess Strategies and Future Applications

Biological activities of chitosan oligosaccharides (COS) are well documented, and numerous reports of COS production using specific and non-specific enzymes are available. However, strategies for improving the overall yield by making it monomer free need to be developed. Continuous enzymatic production from chitosan derived from marine wastes is desirable and is cost-effective. Isolation of potential microbes showing chitosanase activity from various ecological niches, gene cloning, enzyme immobilization, and fractionation/purification of COS are some areas, where lot of work is in progress. This review covers recent measures to improve monomer-free COS production using chitosanase/non-specific enzymes and purification/fractionation of these molecules using ultrafiltration and column chromatographic techniques. Various bioprocess strategies, gene cloning for enhanced chitosanase enzyme production, and other measures for COS yield improvements have also been covered in this review. COS derivative preparation as well as COS-coated nanoparticles for efficient drug delivery are being focused in recent studies.

Microbial degradation of chitin waste for production of chitosanase and food related bioactive compounds.

Ecological samples rich in microbial diversity like cow dung, legume rhizosphere, fish waste and garden soil were used for isolation of chitosan-degrading microorganisms. Selected isolates were used for production of chitosanaseand food related bioactive compounds by conversion of biowaste. Production of glucosamine (Gln), N-acetylglucosamine (NAG), chitooligosaccharides (COS), antioxidants, antibacterial compounds and prebiotics was carried out by microbial fermentation of biowaste. The highest chitosanase activity (8 U/mL) was observed in Aspergillus sp. isolated from fish market waste and it could produce Gln and NAG while Streptomyces sp. isolated from garden soil was able to produce COS along with Gln and NAG. Radical scavenging activity was observed in culture supernatants of 35% of studied isolates, and 20% isolates secreted compounds which showed positive effect on growth of Bifidobacterium. Antibacterial compounds were produced by 40% of selected isolates and culture supernatants of two microbial isolates, Streptomyces zaomyceticus C6 and one of garden soil isolates, were effective against both gram positive and negative bacteria.

Chitosanase Linked PAN Nanofibres for Enzymatic Production of Glucosamine

Electrospun PAN nanofibres (7.5 wt %) was used for immobilization of chitosan degrading enzyme from Aspergillus sp. Glutaraldehyde (10%) was used as cross linking agent for enzyme immobilization. Protein loading was quantitative after treatment (30 minutes) with glutaraldehyde and activity retention of the immobilized enzyme was 70%. Immobilization conditions and characterization of the immobilized enzymes were carried out. Glucosamine from different chitosan substrates using immobilized enzyme was produced. Yield of glucosamine from crab shell and shrimp shell chitosan was as high as 70% and 40% respectively by immobilized enzyme as compared to free enzyme. Immobilization of chitosanase improved its thermal stability, storage stability and could be used multiple times with minor loss in activity.

Enzymatic production of glucosamine and chitooligosaccharides using newly isolated exo-β-d-glucosaminidase having transglycosylation activity

Exochitosanase secreting fungus (A. fumigatus IIT-004) was isolated from fish waste using 1xa0% (w/v) chitosan as sole carbon source after multistage screening. Chitosan-dependent exochitosanase enzyme production (6xa0IUxa0ml−1) in log phase of growth (chitosan utilization rate 0.11xa0gxa0g−1 cell h−1) was observed for Aspergillus fumigatus in chitosan minimal salt medium and there was no enzyme production in glucose medium. Enzyme production was found to be extracellular and subjected to purification by a number of steps like acetone fractionation as well as column chromatography. 40xa0% yield and 26-fold of enzyme purification was achieved after all the steps. Purified enzyme was characterized for optimum temperature, pH, ionic strength and substrate specificity. The Km and Vmax for purified exochitosanase enzyme was calculated to be 8xa0mgxa0ml−1 and 5.2xa0×xa010−6 molxa0mg−1 min−1. Enzyme was immobilized on polyacrylonitrile nanofibres membrane matrix by adsorption as well as amidination. Enzymatic production of glucosamine was achieved using various chitosan substrates by free/immobilized exochitosanase and compared. Isolated and purified exochitosanase also showed transglycosylation activity.

Real time simulator for the runout table of hot strip mills

In a hot strip mill, the strip is cooled by spraying water from top and bottom on the runout table (ROT), before the strip is coiled. The desired mechanical properties and metallurgical structure of the strip is achieved by controlling the cooling rate and temperature of the strip on the ROT. This paper describes a novel real time simulator for ROTs. The simulator has been implemented in parallel on a multi-transputer system. The proposed simulator can interact with a controller in real time and can serve as a valuable design tool for evaluating the performance of controllers for ROTS. In addition, the simulator can be used as a tool for the design of new ROT layouts as well.

NAD (H) Linked Enzyme Catalyzed Reactions using Coupled Enzymes in a Composite Nanoparticle System

Different approaches for cofactor recycling/regeneration have been studied and one of them is havingxa0regenerating enzyme immobilized on some suitable support. Here, we are reporting the cofactor NAD (H) recyclingxa0with the help of free enzymes and enzymes loaded on nanoparticles. Baker’s yeast alcohol dehydrogenase (ADH)xa0and formate dehydrogenase (FDH) from Candida boidinii were immobilized on alumina nanoparticles and appliedxa0to catalyze the coupled reactions for production of n-propanol. Cofactor regeneration within the reaction cycle wasxa0achieved as a result of collision between enzyme loaded particles and free cofactor. Brownian motion providedxa0effective interactions among the catalytic components, and thus realized a dynamic shuttling of the cofactor betweenxa0the two enzymes to keep the reaction cycles continuing. Maximum recycle rate of 6650 cycles/hr was obtained and itxa0decreased with increasing cofactor concentration within the reaction system, for free as well as immobilized system.It was concluded that particles attached enzymes could be one of the new biochemical strategy used for cofactorxa0dependent biotransformation.