Showing papers by "Sathyanarayana N. Gummadi published in 2023"

Investigation of a robust pretreatment technique based on ultrasound-assisted, cost-effective ionic liquid for enhancing saccharification and bioethanol production from wheat straw

Abstract: Abstract Application of cost-effective pretreatment of wheat straw is an important stage for massive bioethanol production. A new approach is aimed to enhance the pretreatment of wheat straw by using low-cost ionic liquid [TEA][HSO 4 ] coupled with ultrasound irradiation. The pretreatment was conducted both at room temperature and at 130 °C with a high biomass loading rate of 20% and 20% wt water assisted by ultrasound at 100 W-24 kHz for 15 and 30 min. Wheat straw pretreated at 130 °C for 15 and 30 min had high delignification rates of 67.8% and 74.9%, respectively, and hemicellulose removal rates of 47.0% and 52.2%. Moreover, this pretreatment resulted in producing total reducing sugars of 24.5 and 32.1 mg/mL in enzymatic saccharification, respectively, which corresponds to saccharification yields of 67.7% and 79.8% with commercial cellulase enzyme CelluMax for 72 h. The ethanol generation rates of 38.9 and 42.0 g/L were attained for pretreated samples for 15 and 30 min, equivalent to the yields of 76.1% and 82.2% of the maximum theoretical yield following 48 h of fermentation. This demonstration provided a cheap and promising pretreatment technology in terms of efficiency and shortening the pretreatment time based on applying low-cost ionic liquid and efficient ultrasound pretreatment techniques, which facilitated the feasibility of this approach and could further develop the future of biorefinery.

Candida parapsilosis carbonyl reductase as a tool for preliminary screening of inhibitors for alcohol dehydrogenase induced skin sensitization

Abstract: Human alcohol dehydrogenases, specifically ADH1 oxidize primary alcohols to aldehydes in the skin. These aldehydes act as haptens, leading to sensitization. Inhibition of these ADH enzymes may help in combating skin allergies. In the present study, the recombinantly purified stereospecific enzyme from Candida parapsilosis ATCC 7330, Candida parapsilosis Carbonyl Reductase (CpCR) has 23.31 % sequence similarity with human alcohol dehydrogenase ADH1B1. These two enzymes have perfectly overlapping cofactor and zinc binding domains. CpCR was found to oxidize primary alcohols to their corresponding aldehydes. Oxidation of primary alcohols by CpCR was further optimized with cinnamyl alcohol as the model substrate that initially showed a conversion of 56 % ± 0.25, and upon optimization increased to 98.2 % ± 0.23. An increase of 20–50 % in the conversion rate has been observed for various primary alcohols under the optimized reaction conditions. A simple and efficient model was designed for the screening of compounds that inhibit CpCR with the possibility of mitigating the action of skin allergens by inhibiting ADH1. p-Nitrophenylglyoxal (PNG) was found to be a good inhibitor for CpCR which showed inhibitory activity at very low concentration (IC50,100 mM ± 1.27) as compared to the standard inhibitor 4-methyl pyrazole (4MP) (IC50, 400 mM ± 2.05).

Assessment of process integration approach for coir biosoftening and lignin‐modifying enzyme production from agro residues

Abstract: Lignin present in the inner core of natural lignocellulosic fibers is preferably removed for use in the textile industry as it hinders fiber spinnability. This study focuses on integrating the bioprocessing of agro residues and a natural fiber source (coir) for the effective production of lignin‐modifying enzymes while simultaneously softening the natural fibers. The lignin content in the raw fibers (42.17%) could be reduced by 14–31% by treating them with Phanerochaete chrysosporium for 30 days in the presence of agro waste, such as paddy straw, groundnut husk, corn husk, coir pith, sugarcane bagasse, saw dust and coconut leaf. Among the lignocellulosic wastes tested, P. chrysporium‐fermented groundnut husk with coir produced the maximum yield of lignin‐modifying enzymes (lignin peroxidase, 2.05 U mg−1; manganese peroxidase, 7.50 U mg−1; laccase, 0.43 U mL−1), while the tensile strength of the fiber was decreased by 9.9% compared with the raw fiber (110.14 MPa) on 30 days of incubation. Similarly, SB dust demonstrated good lignin‐modifying enzyme activity (lignin peroxidase, −1.57 U mg−1; manganese peroxidase, 8.14 U mg−1; and laccase, 0.35 U mg−1) as well as the tensile strength of the coir also being increased. A reduction in flexural rigidity owing to delignification was observed and hence a minimum 16% increase in softness was achieved in the integrated process. Our study presents an efficient strategy that exploits low‐cost agro residues for enzyme production and generates bio‐softened coir of acceptable quality in the export and domestic markets. © 2023 Society of Industrial Chemistry and John Wiley & Sons Ltd.