Browsing by Author "Ahmad, Ejaz"
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Item Open Access High yield recovery of 2,3-butanediol from fermented broth accumulated on xylose rich sugarcane bagasse hydrolysate using aqueous two-phase extraction system(Elsevier, 2021-06-26) Narisetty, Vivek; Amraoui, Yassin; Abdullah, Alamri; Ahmad, Ejaz; Agrawal, Deepti; Parameswaran, Binod; Pandey, Ashok; Goel, Saurav; Kumar, VinodDownstream processing of chemicals obtained from fermentative route is challenging and cost-determining factor of any bioprocess. 2,3-Butanediol (BDO) is a promising chemical building block with myriad applications in the polymer, food, pharmaceuticals, and fuel sector. The current study focuses on the recovery and purification of BDO produced (68.2 g/L) from detoxified xylose-rich sugarcane bagasse hydrolysate by a mutant strain of Enterobacter ludwigii. Studies involving screening and optimization of aqueous-two phase system (ATPS) revealed that 30% w/v (NH4)2SO4 addition to clarified fermentation broth facilitated BDO extraction in isopropanol (0.5 v/v), with maximum recovery and partition coefficient being 97.9 ± 4.6% and 45.5 ± 3.5, respectively. The optimized protocol was repeated with unfiltered broth containing 68.2 g/L BDO, cell biomass, and unspent protein, which led to the partitioning of 66.7 g/l BDO, 2.0 g/L xylose and 9.0 g/L acetic acid into organic phase with similar BDO recovery (97%) and partition coefficient (45).Item Open Access Recent advances in the production of 2,5-furandicarboxylic acid from biorenewable resources(Elsevier, 2023-05-22) Prasad, Shivshankar; Khalid, Al Jaradah; Narishetty, Vivek; Kumar, Vinod; Dutta, Suman; Ahmad, EjazBio-based renewable resources have emerged as strong contenders to produce fuels and chemicals via carbon–neutral and eco-friendly methods. In particular, 2,5 furandicarboxylic acid (FDCA) which is listed among the top 12 platform molecules, can be used to produce bio-based polymer as an alternative to polyethylene terephthalate (PET). Notably, FDCA can be produced from an array of biorenewable resources using catalytic materials. However, biomass-derived 5-hydroxymethylfurfural (HMF) remains the primary feedstock to produce FDCA. Thus, the current review focuses on the recent advances in FDCA application and production via catalytic routes, particularly from HMF and other biorenewable feedstocks. Accordingly, the effect of different noble metal and noble metal-free catalytic materials on feedstock conversion and FDCA yield has been discussed. Moreover, the effect of operating conditions such as solvent, bases, oxygen sources, temperature and pressure has been discussed.Item Open Access Valorisation of xylose to renewable fuels and chemicals, an essential step in augmenting the commercial viability of lignocellulosic biorefineries(Royal Society of Chemistry, 2021-10-26) Narisetty, Vivek; Cox, Rylan; Bommareddy, Rajesh; Agrawal, Deepti; Ahmad, Ejaz; Pant, Kamal Kumar; Chandel, Anuj Kumar; Bhatia, Shashi Kant; Kumar, Dinesh; Binod, Parmeswaran; Gupta, Vijai Kumar; Kumar, VinodBiologists and engineers are making tremendous efforts in contributing to a sustainable and green society. To that end, there is growing interest in waste management and valorisation. Lignocellulosic biomass (LCB) is the most abundant material on the earth and an inevitable waste predominantly originating from agricultural residues, forest biomass and municipal solid waste streams. LCB serves as the renewable feedstock for clean and sustainable processes and products with low carbon emission. Cellulose and hemicellulose constitute the polymeric structure of LCB, which on depolymerisation liberates oligomeric or monomeric glucose and xylose, respectively. The preferential utilization of glucose and/or absence of the xylose metabolic pathway in microbial systems cause xylose valorization to be alienated and abandoned, a major bottleneck in the commercial viability of LCB-based biorefineries. Xylose is the second most abundant sugar in LCB, but a non-conventional industrial substrate unlike glucose. The current review seeks to summarize the recent developments in the biological conversion of xylose into a myriad of sustainable products and associated challenges. The review discusses the microbiology, genetics, and biochemistry of xylose metabolism with hurdles requiring debottlenecking for efficient xylose assimilation. It further describes the product formation by microbial cell factories which can assimilate xylose naturally and rewiring of metabolic networks to ameliorate xylose-based bioproduction in native as well as non-native strains. The review also includes a case study that provides an argument on a suitable pathway for optimal cell growth and succinic acid (SA) production from xylose through elementary flux mode analysis. Finally, a product portfolio from xylose bioconversion has been evaluated along with significant developments made through enzyme, metabolic and process engineering approaches, to maximize the product titers and yield, eventually empowering LCB-based biorefineries. Towards the end, the review is wrapped up with current challenges, concluding remarks, and prospects with an argument for intense future research into xylose-based biorefineries.