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Dhillon G.S.,University of Quebec | Brar S.K.,University of Quebec | Kaur S.,University of Quebec | 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. Source


Dhillon G.S.,University of Quebec | Brar S.K.,University of Quebec | Verma M.,Institute de Recherche et de Developpement en Agroenvironnement Inc. IRDA | Tyagi R.D.,University of Quebec
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. Source


Dhillon G.S.,University of Quebec | Brar S.K.,University of Quebec | Verma M.,Institute de Recherche et de Developpement en Agroenvironnement Inc. IRDA | Tyagi R.D.,University of Quebec
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. Source


Dhillon G.S.,University of Quebec | Brar S.K.,University of Quebec | 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. Source


Dhillon G.S.,University of Quebec | Kaur S.,Banaras Hindu University | Brar S.K.,University of Quebec | 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. Source

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