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Dhillon G.S.,University of Québec | Brar S.K.,University of Québec | Verma M.,Institute de Recherche et de Developpement en Agroenvironnement Inc. IRDA | Tyagi R.D.,University of Québec
Food and Bioprocess Technology | Year: 2011

Citric acid consumption is escalating gradually, witnessing high annual growth rate due to more and more advanced applications coming to light. The present review discusses different aspects of fermentation and effects of various environmental parameters and deals with the potential ways to increase the yield of citric acid to meet the ever-increasing demands of this commercially important organic acid. Different techniques for the hyperproduction of citric acid are continuously being studied from the past few decades and still there is a gap, and hence, there is an obvious need to consider new pragmatic ways to achieve industrially feasible and environmentally sustainable bio-production of citric acid. The utilization of inexpensive agro-industrial wastes and their by-products through solid-state fermentation by existing and genetically engineered strains is a potential route. This review also deals with downstream processing considering the classical and advanced approaches, which also need significant improvement. In situ product recovery method which leads to improved yields and productivity can be further optimized for large-scale production and recovery of citric acid. © 2010 Springer Science + Business Media, LLC.


Dhillon G.S.,University of Québec | Brar S.K.,University of Québec | Kaur S.,University of Québec | Kaur S.,Banaras Hindu University | Verma M.,Institute de recherche et de developpement en agroenvironnement Inc. IRDA
Industrial Crops and Products | Year: 2013

Solid-state citric acid fermentation was conducted in a 12-L rotating drum type bioreactor. The effect of inducers, ethanol and methanol were studied on citric acid bioproduction by Aspergillus niger NRRL 567 cultivated on apple pomace as a solid-substrate. Optimum conditions achieved for higher citric acid bioproduction (220.6 ± 13.9. g/kg dry solids, DS) were 3% (v/v) methanol, intermittent agitation of 1. h after every 12. h at 2. rpm and 1. vvm of aeration rate and 120. h incubation time. The response surface optimization proved effective for higher citric acid extraction from fermented solid-substrate. Higher citric acid extraction of 294.19. g/kg DS was achieved at optimum conditions: extraction time of 20. min, agitation rate of 200. rpm and extractant volume of 15. ml by response surface methodology. © 2012 Elsevier B.V.


Dhillon G.S.,University of Québec | Brar S.K.,University of Québec | Verma M.,Institute de Recherche et de Developpement en Agroenvironnement Inc. IRDA | Tyagi R.D.,University of Québec
Food Chemistry | Year: 2011

Ever-growing demand for citric acid (CA) and urgent need for alternative sources has served as a driving force for workers to search for novel and economical substrates. Submerged fermentation was conducted using apple (Malus domestica) pomace ultrafiltration sludge as an inexpensive substrate for CA bioproduction, using Aspergillus niger NRRL567. The crucial parameters, such as total suspended solids and inducer concentration, were optimised by response surface methodology for higher CA production. The optimal CA concentrations of 44.9 g/100 g and 37.9 g/100 g dry substrate were obtained with 25 g/l of initial total solids and 3% (v/v) methanol and 25 g/l of total solids and 3% (v/v) ethanol concentration, respectively, after the 144 h of fermentation. Results indicated that total solids concentration, and methanol as an inducer, were effective with respect to higher CA yield and also indicated the possibility of using apple pomace sludge as a potential substrate for economical production of CA. © 2011 Elsevier Ltd. All rights reserved.


Gassara F.,University of Québec | Brar S.K.,University of Québec | Verma M.,Institute de recherche et de developpement en agroenvironnement inc. IRDA | Tyagi R.D.,University of Québec
Chemosphere | Year: 2013

Many endocrine disruptor compounds, such as bisphenol A (BPA) are used today and released into the environment at low doses but they are barely degraded in wastewater treatment plants. One of the potential alternatives to effectively degrade endocrine disruptor compounds is based on the use of the oxidative action of extracellular fungal enzymes. The aim of this work is to study the ability of free and encapsulated enzymes (manganese peroxidase, lignin peroxidase and laccase) to degrade BPA. Higher degradation of BPA (90%) by ligninolytic enzymes encapsulated on polyacrylamide hydrogel and pectin after 8. h was obtained. The degradation of BPA while using the free enzyme (26%) was lower than the value obtained with encapsulated enzymes. The presence of pectin in the formulation significantly (p>. 0.05) enhanced the activity of enzymes. Kinetics of BPA degradation showed an increase in Vm, while Km remained constant when enzymes were encapsulated. Hence, encapsulation protected the enzymes from non-competitive inhibition. © 2013 Elsevier Ltd.


Dhillon G.S.,University of Québec | Brar S.K.,University of Québec | Verma M.,Institute de recherche et de developpement en agroenvironnement Inc. IRDA | Tyagi R.D.,University of Québec
Biochemical Engineering Journal | Year: 2011

In view of ever growing demand of citric acid, there is an urgent need to look for inexpensive and novel substrates for feasible production of citric acid. In this context, the present study was carried out to evaluate the potential of different agro-industrial wastes for hyper production of citric acid through solid-state and submerged fermentation by Aspergillus niger NRRL 567 and NRRL 2001. It was found that among all the solid substrates utilized, apple pomace with 66.0 ± 1.9. g/kg of dry substrate proved to be an excellent substrate for citric acid production by A. niger NRRL 567 at 72. h of incubation. A. niger NRRL 2001 resulted in slightly lower citric acid concentration of 61.0 ± 1.9. g/kg of dry substrate at the same incubation time. APS-1 (apple pomace ultrafiltration sludge-1) gave highest citric acid production rate of 9.0 ± 0.3. g/l and 8.9 ± 0.3. g/l of substrate by A. niger NRRL 567 and NRRL 2001 by submerged fermentation, respectively. Further study with apple pomace and apple pomace ultrafiltration sludge-1 by A. niger NRRL 567 was carried out. Addition of 3% (v/w) ethanol and 4% (v/w) methanol to apple pomace gave significantly higher citric acid values of 127.9 ± 4.3. g/kg and 115.8 ± 3.8. g/kg of dry substrate by A. niger NRRL 567 by solid-state fermentation. Higher citric acid values of 18.2 ± 0.4. g/l and 13.9 ± 0.4. g/l of apple pomace ultrafiltration sludge-1 were attained after addition of 3% (v/v) ethanol and 4% (v/v) methanol, respectively by A. niger NRRL 567. Apple pomace solid waste and apple pomace ultrafiltration sludge-1 thus proved to be an excellent source for citric acid production, of the different substrates chosen. © 2011 Elsevier B.V.


Dhillon G.S.,University of Québec | Brar S.K.,University of Québec | Kaur S.,Banaras Hindu University | Verma M.,Institute de Recherche et de Developpement en Agroenvironnement Inc. IRDA
Critical Reviews in Biotechnology | Year: 2012

In recent years, the green approach of nanoparticle synthesis by biological entities has been gaining great interest over various other physico-chemical methods, which are laden with many disadvantages. The important challenging issues in current nanotechnology include the development of reliable experimental techniques for the synthesis of nanoparticles of different compositions and sizes along with high monodispersity. Biological systems offer unique promising features to tailor nanomaterials with predefined properties. Fungi are the favorite choice of microorganisms due to the wide variety of advantages they offer over bacteria, yeast, actinomycetes, plants, and other physico-chemical techniques. The use of microorganisms for the deliberate synthesis of nanoparticles is a fairly new and exciting area of research with considerable potential for further development. This review describes an overview of the current green approaches for the synthesis of nanoparticles with particular emphasis on fungi, which are gaining worldwide popularity as nano-factories for the green synthesis of nanoparticles. © 2012 Informa Healthcare USA, Inc.


Dhillon G.S.,University of Québec | Kaur S.,Banaras Hindu University | Brar S.K.,University of Québec | Verma M.,Institute de Recherche et de Developpement en Agroenvironnement Inc. IRDA
Critical Reviews in Biotechnology | Year: 2013

Chitosan, copolymer of glucosamine and N-acetyl glucosamine is mainly derived from chitin, which is present in cell walls of crustaceans and some other microorganisms, such as fungi. Chitosan is emerging as an important biopolymer having a broad range of applications in different fields. On a commercial scale, chitosan is mainly obtained from crustacean shells rather than from the fungal sources. The methods used for extraction of chitosan are laden with many disadvantages. Alternative options of producing chitosan from fungal biomass exist, in fact with superior physico-chemical properties. Researchers around the globe are attempting to commercialize chitosan production and extraction from fungal sources. Chitosan extracted from fungal sources has the potential to completely replace crustacean-derived chitosan. In this context, the present review discusses the potential of fungal biomass resulting from various biotechnological industries or grown on negative/low cost agricultural and industrial wastes and their by-products as an inexpensive source of chitosan. Biologically derived fungal chitosan offers promising advantages over the chitosan obtained from crustacean shells with respect to different physico-chemical attributes. The different aspects of fungal chitosan extraction methods and various parameters having an effect on the yield of chitosan are discussed in detail. This review also deals with essential attributes of chitosan for high value-added applications in different fields. © 2013 Informa Healthcare USA, Inc.


Dhillon G.S.,University of Québec | Kaur S.,University of Québec | Kaur S.,Banaras Hindu University | Brar S.K.,University of Québec | Verma M.,Institute de recherche et de developpement en agroenvironnement inc. IRDA
Industrial Crops and Products | Year: 2012

The effect of different inducers on the cellulase and hemicellulase bioproduction by Aspergillus niger NRRL-567 using apple pomace as a substrate was investigated. Rapid production of different cellulase enzymes namely, FPase (filter paper cellulase), CMCase (carboxymethyl cellulase), BGL (β-glucosidase), and xylanase were observed with peak activity reaching between 48 and 72h of fermentation period. The higher FPase and BGL activities of 133.68±5.44IU/gram dry substrate (gds) and 60.09±3.43IU/gds, respectively were observed while using CuSO 4 and veratryl alcohol after 48h of incubation time. The higher CMCase activity of 172.31±14.21IU/gds was obtained with lactose after 48h of incubation period. Similarly, higher xylanase activity of 1412.58±27.9IU/gds was observed with veratryl alcohol after 72h of fermentation time. This study sheds light on the rapid bioproduction of fungal cellulase and hemicellulase using low cost waste, apple pomace as substrate when supplemented with different inducers. © 2012 Elsevier B.V.


Dhillon G.S.,University of Québec | Brar S.K.,University of Québec | Verma M.,Institute de recherche et de developpement en agroenvironnement Inc. IRDA
International Journal of Food Science and Technology | Year: 2012

Submerged citric acid (CA) bioproduction was carried out by Aspergillus niger NRRL-567 using various industrial wastes, such as brewery spent liquid (BSL), lactoserum and starch industry water sludge. CA bioproduction was carried out by varying the temperature (25-35°C), pH (3-5), addition of inducers, incubation time and supplementation with different proportions of apple pomace ultrafiltration sludge (APS). The results indicated that under the best conditions with 3% (v/v) methanol, the optimal concentration of 11.34gL -1 CA was recorded using BSL at pH 3.5 and temperature 30°C after 120-h incubation period. Supplementation of methanol resulted in an increase of 56% CA production. Meanwhile, under similar conditions, higher concentration of 18.34gL -1 CA was reported with the supplementation of BSL with 40% (v/v) APS having suspended solids concentration of 30gL -1. The present study demonstrated the potential of BSL supplemented with APS as an alternative cheap substrate for CA fermentation. © 2011 The Authors. International Journal of Food Science and Technology © 2011 Institute of Food Science and Technology.


Ajila C.M.,University of Québec | Brar S.K.,University of Québec | Verma M.,Institute de Recherche et de Developpement en Agroenvironnement Inc. IRDA | Tyagi R.D.,University of Québec | Valero J.R.,University of Québec
Food Chemistry | Year: 2011

Apple pomace is a by-product from the apple processing industry and can be used for the production of value-added phenolic compounds. A study was carried out to understand the changes and liberation of phenolic compounds and improvement in antioxidant activity during solid-state fermentation of apple pomace using Phanerocheate chrysosporium. The solid-state fermentation of apple pomace using P. chrysosporium mobilised the polyphenolic compounds and improved the nutraceutical properties. The polyphenol content in acetone extract increased and the results were statistically significant (P < 0.05) from 4.6 to 16.12 mg GAE/g dry weight during solid-state fermentation. The effect of various solvents, temperature, time and detergents were also investigated for the extraction of polyphenolics by ultrasonication and microwave-assisted extraction methods. The polyphenol content of the extracts was found to be in the range of 5.78-16.12 mg GAE/g DW of samples, depending on the solvent, extraction time and temperature. Antioxidant activities of polyphenol extracts were tested using the 2,2-diphenyl-1-picryhydrazyl (DPPH) radical methods, where the IC 50 ranged from 12.24 to 23.42 μg DW sample, depending on the extraction conditions and the antioxidant activities correlated well with the polyphenol concentrations. © 2010 Elsevier Ltd. All rights reserved.

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