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BACKGROUND: Appropriate pretreatment strategies that fractionate sugarcane bagasse (SB) are essential for the successful use of this feedstock in ethanol production. In this paper, we investigate a purely enzymatic process to achieve increased production of reducing sugars (RS) from SB in the presence of MgO nanoparticles (MgN) subjected to a three‐step sequential enzyme treatment. RESULT: Pretreatment of SB with protease activated by magnesium oxide nanoparticles (MgN‐pro) at 95 °C showed an increase in amino acid production by 6.18‐fold compared to the untreated enzyme set at the same temperature. High‐performance liquid chromatography (HPLC) studies showed an 18‐fold removal of lignin from the samples subjected to protease (+ MgN) treatment compared to untreated samples. When the MgN‐pro pretreated samples were subjected to pretreatment with xylanase activated by magnesium oxide nanoparticles (MgN‐xyl), more than 30‐fold increased RS was produced at 8 °C compared to cellulase (cel) pretreated samples. Xylanase pretreated SB samples produced 1.82‐ and 1.91‐fold increased reducing sugar and glucose respectively at 8 °C in the presence of MgN compared to untreated samples at the same temperature. CONCLUSION: The results presented here show the efficiency of the proposed method for improving the enzymatic digestibility of SB and explain the pretreatment action mechanism. These findings have potential implications in bio‐ethanol, bio‐fuel, and agro industries. © 2018 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

In this paper we show that hydroxyapatite nanoparticles (NP) can not only act as a chaperon (by imparting thermostability) but can serve as a synthetic enhancer of activity of an isolated extracellular pectate lyase (APL) with low native state activity. The purified enzyme (an attenuated strain of Macrophomina phaseolina) showed feeble activity at 50°C and pH 5.6. However, on addition of 10.5 µg/ml of hydroxyapatite nanoparticles (NP), APL activity increased 27.7 fold with a 51 fold increase in half-life at a temperature of 90°C as compared to untreated APL. The chaperon like activity of NP was evident from entropy–enthalpy compensation profile of APL. The upper critical temperature for such compensation was elevated from 50°C to 90°C in presence of NP. This dual role of NP in enhancing activity and conferring thermostability to a functionally impaired enzyme is reported for the first time. [ABSTRACT FROM AUTHOR]

Catalyst-mediated bioprocessing at an industrial scale is dependent on the sustained stability and activity of the biocatalyst. Here, we demonstrate that strategy employed to increase the stability and activity of a mesophilic lipase immobilized on graphene oxide (GO). The protein adsorption capacity of GO is much higher than of other large surface area carbonaceous materials. Its structure and physicochemical properties are reported beneficial for enzymatic activity modifications. A purified lipase from Brevibacillus borstelensis NLIP05 immobilized on GO showed remarkable increase in thermostability (at 95°C) over a broad alkaline pH range (pH 7-12) compared to the free enzyme. Thermodynamic analysis of the GO-lip showed decreases in K m and activation energy (E a ) with increased V max and deactivation energy (E d ) at both 45 and 95°C. The decrease in decay constant (k) coupled with the increase in t 1/2 value with temperature increase were salient features of the GO-lip system. This implies that GO-based immobilization conferred structural stability to the enzyme at higher temperature indicating chaperone like activity. Our findings support suitability of immobilized lipase on GO nanosupport for possible production of value-added materials with varied biological applications in the form of active pharmaceutical substances, synthetic building blocks, and effective synthesis of surfactants. The enhanced stability and activity of lipase indicate major application of GO on an industrial scale., (© 2018 Elsevier Inc. All rights reserved.)