Amarjeet S. Bassi
University of Western Ontario
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Critical Reviews in Biotechnology | 2005
Ying Zheng; Ernest K. Yanful; Amarjeet S. Bassi
ABSTRACT With more and more plastics being employed in human lives and increasing pressure being placed on capacities available for plastic waste disposal, the need for biodegradable plastics and biodegradation of plastic wastes has assumed increasing importance in the last few years. This review looks at the technological advancement made in the development of more easily biodegradable plastics and the biodegradation of conventional plastics by microorganisms. Additives, such as pro-oxidants and starch, are applied in synthetic materials to modify and make plastics biodegradable. Recent research has shown that thermoplastics derived from polyolefins, traditionally considered resistant to biodegradation in ambient environment, are biodegraded following photo-degradation and chemical degradation. Thermoset plastics, such as aliphatic polyester and polyester polyurethane, are easily attacked by microorganisms directly because of the potential hydrolytic cleavage of ester or urethane bonds in their structures. Some microorganisms have been isolated to utilize polyurethane as a sole source of carbon and nitrogen source. Aliphatic-aromatic copolyesters have active commercial applications because of their good mechanical properties and biodegradability. Reviewing published and ongoing studies on plastic biodegradation, this paper attempts to make conclusions on potentially viable methods to reduce impacts of plastic waste on the environment.
Chemical Engineering Journal | 2001
Qingdao Lan; Amarjeet S. Bassi; Jesse Zhu; Argyrios Margaritis
Abstract An empirical model modified from the Langmuir isotherm model to account for the effects of ionic strength on the equilibrium characteristics of protein adsorption onto ion exchange/affinity adsorbents has been proposed and tested against experimental and literature data. The equilibrium isotherms for BSA adsorption onto a polystyrenic anion exchanger, Diaion HPA25, were established for five different NaCl concentrations at 25°C, pH 7.0. The apparent Langmuir parameters in the new model (qm′ and Kd′), which replace the Langmuir parameters (qm and Kd) in the original Langmuir model, were determined by non-linear curve fitting. The proposed model has been shown to be applicable to various protein/adsorbent systems.
Journal of Chemical Technology & Biotechnology | 1999
Colin Flock; Amarjeet S. Bassi; Mark Gijzen
In this study, the removal of phenol and 2-chlorophenol using soybean seed-hulls in the presence of hydrogen peroxide is demonstrated. The performance of a stirred membrane reactor containing soluble purified SBP was compared with a batch stirred reactor containing raw soybean seed-hulls. The purified enzyme reactor proved to be ineffective while excellent results were obtained with the crude seed-hulls for the removal of phenol and 2-chlorophenol. Four sequential batch reactors containing raw seed-hulls achieved greater than 96% removal of phenol with a retention time of 20min in each reactor. A single batch reactor containing raw seed-hulls was effective in removing greater than 98.5% of 2-chlorophenol (initially at 1000 ppm) in less than 15 min. The performance of these reactors is comparable to existing HRP-based technology. The stability of the soybean peroxidase (SBP) enzyme was also examined in the presence of detergents (SDS, Tween 20 and Triton X-100). Low concentrations of the detergents significantly increased the enzyme activity and higher concentrations of detergents (up to 20% w/v) did not inactivate the SBP enzyme. These results demonstrate that SBP has good potential for the treatment of phenol contaminated solutions.
Critical Reviews in Biotechnology | 1995
Ashok Mulchandani; Amarjeet S. Bassi
Biosensors are useful analytical devices that can be integrated with on-line process monitoring schemes. In this article, the principles and applications of these devices for bioprocess monitoring are considered. Several different types of biosensors are described, and the applications and limitations of flow injection analysis (FIA) for these applications are discussed. It is hoped that the background provided here can be useful to researchers in this area.
Biotechnology Advances | 2016
Mengyue Gong; Amarjeet S. Bassi
Carotenoids have been receiving increasing attention due to their potential health benefits. Microalgae are recognized as a natural source of carotenoids and other beneficial byproducts. However, the production of micro-algal carotenoids is not yet sufficiently cost-effective to compete with traditional chemical synthetic methods and other technologies such as extraction from plant based sources. This review presents the recent biotechnological developments in microalgal carotenoid production. The current technologies involved in their bioprocessing including cultivation, harvesting, extraction, and purification are discussed with a specific focus on downstream processing. The recent advances in chemical and biochemical synthesis of carotenoids are also reviewed for a better understanding of suitable and economically feasible biotechnological strategies. Some possible future directions are also proposed.
Critical Reviews in Biotechnology | 2013
Ana-Maria Aguirre; Amarjeet S. Bassi; Priyanka Saxena
In recent years, the not too distant exhaustion of fossil fuels is becoming apparent. Apart from this, the combustion of fossil fuels leads to environmental concerns, the emission of greenhouse gases and issues with global warming and health problems. Production of biodiesel from microalgae may represent an attractive solution to the above mentioned problems, and can offer a renewable source of fuel with fewer pollutants. This review presents a compilation of engineering challenges related to microalgae as a source of biodiesel. Advantages and current limitations for biodiesel production are discussed; some aspects of algae cells biology, with emphasis on cell wall composition, as it represents a barrier for fatty acid extraction and lipid droplets are also presented. In addition, recent advances in the different stages of the manufacturing process are included, starting from the strain selection and finishing in the processing of fatty acids into biodiesel.
Food Research International | 1998
Amarjeet S. Bassi; E. Lee; Jesse Zhu
A biosensor for the determination of fructose was constructed by the immobilization of the enzyme fructose dehydrogenase (FDH) behind a thin non-conducting electropolymer film of 1,3 phenylene diamine-resorcinol. Two different types of electrochemical mediators, soluble hexacyanoferrate (III) (FeCN) and the water insoluble tetracyanoquinodimethane (TCNQ) were applied as redox mediators for the amperometric measurement of fructose. Optimization of the biosensor was done with respect to operating conditions by varying the operating parameters such as pH, temperature, mediator concentration, and enzyme loading. The optimized biosensor was found to have a minimum detection limit of 10 μM with a linear range upto 1.0 mM. The performance of the two mediators was also compared with respect to stability. A simple, lumped parameter mathematical model was proposed to describe the steady state response of the biosensor and experimentally verified with the constructed biosensors.
Critical Reviews in Biotechnology | 1991
Argyrios Margaritis; Amarjeet S. Bassi
Certain aerobic, Gram-negative bacteria, including the epiphytic plant pathogen, Pseudomonas syringae, possess a membrane protein that enables them to nucleate crystallization in supercooled water. Currently, these ice-nucleating (IN) bacteria are being used in snow making and have potential applications in the production and texturing of frozen foods, and as a replacement of silver iodide in cloud seeding. A negative aspect of these IN bacteria is frost damage to plant surfaces. Thus, of the various types of biological ice nucleators, bacteria have been the subject of most research and also appear relevant to the anticipated practical uses. The intent of this review is to explain the identification and ecology of the ice-nucleating bacteria, as well as to discuss aspects of molecular biology related to ice nucleation and consider existing and potential applications of this unique phenomenon.
IEEE Transactions on Nanobioscience | 2008
Wei Wei Wang; George K. Knopf; Amarjeet S. Bassi
A photoreceptor array that exploits the light sensitive bacteriorhodopsin (bR) films has been manufactured on a flexible indium-tin-oxide (ITO) coated plastic film using electrophoretic sedimentation technique (EPS). The effective sensing area of each photoreceptor is 2 × 2 mm2, separated by 1 mm and arranged in a 4 × 4 array. A switched integrator with gain on the order of 1010 is used to amplify the signal to a suitable level. When exposed to light, the differential response characteristic is attributed to charge displacement and recombination within bR molecules, as well as loading effects of the attached amplifier. The peak spectral response occurs at 568 nm and is linear over the tested light power range of 200 ¿ W to 12 mW. The response remains linear at other tested wavelengths, but with reduced amplitude. Initial tests have indicated that responsivity among all photoreceptors is greater than 71% of the average value, 465.25 mV/mW. The differential nature of the signal generated by bR makes it a suitable sensing material for vision applications such as motion detection. The prototype array demonstrates this property by employing Reichardts delay-and-correlate algorithm. Furthermore, fabricating sensor arrays on flexible substrates introduces a new design approach that enables non-planar imaging surfaces.
Catalysis Today | 2001
Zuohong Geng; K. Jagannadha Rao; Amarjeet S. Bassi; Mark Gijzen; Nupura Krishnamoorthy
Soybean seed hull peroxidase (SBP) is an inexpensive oxidoreductive enzyme and could potentially be used to oxidise/polymerise various organic pollutants present in the industrial and petrochemical wastes. SBP is able to retain its catalytic properties under wide ranges of pH and at elevated temperatures. In this study, a systematic evaluation of the biocatalytic properties of SBP was carried out. The optimal pH for SBP activity is pH 6.0 and significant activity was observed between 2.2 and 8.0. SBP also showed three times higher activity at an elevated temperature of 80°C and at pH 6.0 when compared to the activity at room temperature. The pH and temperature of the reaction mixture were found to significantly influence the SBP activity. SBP is fairly active in organic solvents. The enzyme exhibited highest activity in the presence of 16.67% (w/v) ethanol followed by acetone, methanol and acetonitrile. The enzyme activity was reduced with an increase in concentration of the organic solvent. SBP also showed maximum activity at different concentrations of acetone using a phosphate buffer, pH 6.0 than with the other pH buffers. Benzene/acetone mixture seems to be another better solvent system for SBP where it showed about 65% of its activity at 16.67% (w/v) concentration.