Browsing by Author "Rajeswari, Gunasekaran"

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    Bioprocessing of fermentable sugars derived from water hyacinth into microbial lipids and single cell proteins by oleaginous yeast Rhodosporidium toruloides NCIM 3547
    (Springer, 2021-10-09) Alankar, Senthilnathan Sri Laxma; Sajesh, Nithianandam; Rastogi, Shrestha; Sakhuja, Simar; Rajeswari, Gunasekaran; Kumar, Vinod; Chandel, Anuj Kumar; Jacob, Samuel
    In this study, we employed microwave-acid pretreatment for water hyacinth (WH) to obtain liquid hydrolysate that contains sugars derived from holocellulosic components of biomass for further oleaginous yeast fermentation. In order to remove the inhibitors such as furans after acid treatment, detoxification of hydrolysate was done and we compared the efficiency of this step with non-detoxified hydrolysate towards capability of the Rhodosporidium toruloides NCIM 3547 (an oleaginous yeast) to produce microbial lipid and single cell protein. The results indicated that the reducing sugar concentration was found to be higher in non-detoxified hydrolysate (65.41 g/L) than detoxified one (59.18 g/L). When the non-detoxified liquid hydrolysate was supplemented with yeast extract as a complex organic source for R. toruloides, resulted in a maximum lipid yield of about 0.813 ± 0.041 (g/g) and 53.60 ± 2.68 (g/g) of single cell protein content with 0.038 g/L/d of protein productivity. Two kinetic models, hybrid Logistic-Monod and Luedeking-Piret, were employed to assess the microbial growth and the substrate utilization that were found to be in well agreement with the experimental data with a coefficient of determination (R2) value ranging from 0.95 to 0.99 thereby demonstrating the efficiency of the hydrolysate supplemented media. Furthermore, GC-MS analysis of transesterified lipids revealed the presence of various FAME (fatty acid methyl esters) and also the presence of increased levels of total saturated fatty acids (35.03%) advocates its high potential in biodiesel production. This study demonstrates the feasibility of sustainable valorization of WH-derived liquid hydrolysate towards a greener biorefinery framework.
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    A concerted enzymatic de-structuring of lignocellulosic materials using a compost-derived microbial consortia favoring the consolidated pretreatment and bio-saccharification
    (Elsevier, 2024-01-13) Rajeswari, Gunasekaran; Kumar, Vinod; Jacob, Samuel
    The robustness of microbial consortia isolated from compost habitat encompasses the complementary metabolism that aids in consolidated bioprocessing (CBP) of lignocellulosic biomass (LCB) by division of labor across the symbionts. Composting of organic waste is deemed to be an efficient way of carbon recycling, where the syntrophic microbial population exerts a concerted action of lignin and polysaccharide (hemicellulose and cellulose) component of plant biomass. The potential of this interrelated microorganism could be enhanced through adaptive laboratory evolution (ALE) with LCB for its desired functional capabilities. Therefore, in this study, microbial symbionts derived from organic compost was enriched on saw dust (SD) (woody biomass), aloe vera leaf rind (AVLR) (agro-industrial waste) and commercial filter paper (FP) (pure cellulose) through ALE under different conditions. Later, the efficacy of enriched consortium (EC) on consolidated pretreatment and bio-saccharification was determined based on substrate degradation, endo-enzymes profiling and fermentable sugar yield. Among the treatment sets, AVLR biomass treated with EC-5 has resulted in the higher degradation rate of lignin (47.01 ± 0.66%, w/w) and polysaccharides (45.87 ± 1.82%, w/w) with a total sugar yield of about 60.01 ± 4.24 mg/g. In addition, the extent of structural disintegration of substrate after EC-treatment was clearly deciphered by FTIR and XRD analysis. And the factors of Pearson correlation matrix reinforces the potency of EC-5 by exhibiting a strong positive correlation between AVLR degradation and the sugar release. Thus, a consortium based CBP could promote the feasibility of establishing a sustainable second generation biorefinery framework.
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    Lignocellulose-derived arabinose for energy and chemicals synthesis through microbial cell factories: a review
    (MDPI, 2023-05-16) Jacob, Samuel; Dilshani, Aswin; Rishivanthi, Srinivasan; Khaitan, Pratham; Vamsidhar, Adhinarayan; Rajeswari, Gunasekaran; Kumar, Vinod; Rajak, Rajiv Chandra; Din, Mohd Fadhil Md.; Zambare, Vasudeo
    The exploration of natural substrates for microbial conversion to synthesize industrial platform and fuel chemicals seems to be inevitable within a circular bioeconomy context. Hemicellulose is a natural carbohydrate polymer consisting of a variety of pentose (C5) sugar monomers such as arabinose, mannose, erythrose, and xylose. Among the C5 sugars, L-arabinose (L-Ara) is the second-most-abundant pentose sugar in the lignocellulosic biomass after xylose. L-Ara has been used as an industrial carbon source to produce several value-added chemicals such as putrescine, which is used to synthesize polymers in the textile industry; sugar alcohols that are used as sweeteners in diet foods; and amino acids such as L-lysine, L-glutamate, L-arginine, and L-ornithine, which are used in nutritional supplements, fertilizers, and other products in the food and beverage industries. L-Ara, a natural non-caloric sweetener, is used as a substitute in the food and beverage industry, when the risk of blood sugar and lipid levels could be reduced. Major use of L-Ara is also found in the medical and pharmaceutical sectors to treat several conditions, including mineral absorption disorder, constipation, and diabetes, among others. In recent years, there has been a rising interest in synthesizing various sugar alcohols and derivatives, including arabitol, xylitol, and 2,3-butanediol, through the modification of producer organisms either genetically or metabolically to produce value-added products. Understanding the current demand and the need to increase the diversified production of industrial green chemicals with the reduced waste of useful lignocellulosic resources, this review focuses on the background of L-Ara and its various sources, microbes that utilize L-Ara to produce high-value-added products, and the future prospects for strain improvements to increase the yield of high-value-added products.
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    Paradigm of integrative OMICS of microbial technology towards biorefinery prospects
    (Elsevier, 2024-05-11) Jacob, Samuel; Rajeswari, Gunasekaran; Rai, Awantika; Tripathy, Sushree Shweta; Gopal, Swathy; Das, Eeshita; Kumar, Vinod; Jeevan Kumar, S. P.; Aminabhavi, Tejraj M.; Garlapati, Vijay Kumar
    Climate change, finite natural resources, and increasing population necessitate producing sustainable energy with positive economic growth. Recent advances in OMICS coupled with genome editing and synthetic biology have paved the way for the development of sustainable technologies. These techniques help identify critical genes/pathways and re-construct and redesign biological pathways to develop eco-friendly and economically viable industrial metabolites. With the help of microbial technology, biorefinery-related research is actively pursued in many countries to develop microbial strains, producing varied value-added biochemicals and biofuels. The application of multi-omics data in deciphering key genes, their manipulation, and outcomes implies the domain's potential to find new horizons in biorefineries using microbial factories to produce various biofuels and biorefinery products. This review illustrates OMICS role in developing industrial chemicals and microbial biorefineries. Besides, prospects for genome editing and synthetic biology have been elucidated.
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    Unlocking the potential of insect and ruminant host symbionts for recycling of lignocellulosic carbon with a biorefinery approach: a review
    (BMC (part of Springer Nature), 2021-05-27) Rajeswari, Gunasekaran; Jacob, Samuel; Chandel, Anuj Kumar; Kumar, Vinod
    Uprising fossil fuel depletion and deterioration of ecological reserves supply have led to the search for alternative renewable and sustainable energy sources and chemicals. Although first generation biorefinery is quite successful commercially in generating bulk of biofuels globally, the food versus fuel debate has necessitated the use of non-edible feedstocks, majorly waste biomass, for second generation production of biofuels and chemicals. A diverse class of microbes and enzymes are being exploited for biofuels production for a series of treatment process, however, the conversion efficiency of wide range of lignocellulosic biomass (LCB) and consolidated way of processing remains challenging. There were lot of research efforts in the past decade to scour for potential microbial candidate. In this context, evolution has developed the gut microbiota of several insects and ruminants that are potential LCB degraders host eco-system to overcome its host nutritional constraints, where LCB processed by microbiomes pretends to be a promising candidate. Synergistic microbial symbionts could make a significant contribution towards recycling the renewable carbon from distinctly abundant recalcitrant LCB. Several studies have assessed the bioprospection of innumerable gut symbionts and their lignocellulolytic enzymes for LCB degradation. Though, some reviews exist on molecular characterization of gut microbes, but none of them has enlightened the microbial community design coupled with various LCB valorization which intensifies the microbial diversity in biofuels application. This review provides a deep insight into the significant breakthroughs attained in enrichment strategy of gut microbial community and its molecular characterization techniques which aids in understanding the holistic microbial community dynamics. Special emphasis is placed on gut microbial role in LCB depolymerization strategies to lignocellulolytic enzymes production and its functional metagenomic data mining eventually generating the sugar platform for biofuels and renewable chemicals production.