Bioelectrochemical Detoxification of Phenolic Compounds during Enzymatic Pre-Treatment of Rice Straw

( Sanath Kondaveeti ),( Raviteja Pagolu ),( Sanjay K. S. Patel ),( Ashok Kumar ),( Aarti Bisht ),( Devashish Das ),( Vipin Chandra Kalia ),( In-won Kim ),( Jung-kul Lee ) 한국미생물 · 생명공학회 2019 Journal of microbiology and biotechnology Vol.29 No.11

The use of lignocellulosic biomass such as rice straw can help subsidize the cost of producing value-added chemicals. However, inhibitory compounds, such as phenolics, produced during the pre-treatment of biomass, hamper the saccharification process. Laccase and electrochemical stimuli are both well known to reduce phenolic compounds. Therefore, in this study, we implemented a bioelectrochemical detoxification system (BEDS), a consolidated electrochemical and enzymatic process involving laccase, to enhance the detoxification of phenolics, and thus achieve a higher saccharification efficiency. Saccharification of pretreated rice straw using BEDS at 1.5 V showed 90% phenolic reduction (Ph_r), thereby resulting in a maximum saccharification yield of 85%. In addition, the specific power consumption when using BEDS (2.2 W/Kg Ph_r) was noted to be 24% lower than by the electrochemical process alone (2.89 W/kg Ph_r). To the best of our knowledge, this is the first study to implement BEDS for reduction of phenolic compounds in pretreated biomass.

Conversion of simulated biogas to electricity: Sequential operation of methanotrophic reactor effluents in microbial fuel cell

Kondaveeti, Sanath,Patel, Sanjay K.S.,Pagolu, Raviteja,Li, Jinglin,Kalia, Vipin C.,Choi, Myung-Seok,Lee, Jung-Kul Elsevier 2019 ENERGY Vol.189 No.-

<P><B>Abstract</B></P> <P>The utilization of the greenhouse gases (methane (CH<SUB>4</SUB>) and carbon dioxide (CO<SUB>2</SUB>)) seems a suitable alternative feed to produce biofuels and value-added products to reduce their emissions. In addition, the conversion of methanol containing methanotrophic effluents to electricity using microbial fuel cells (MFCs) is limited. The sequential operation of MFC to generate electricity has proven to be beneficial because of the increase in operational performance in comparison with single stage systems. Therefore, in the present study, the methanotrophic reactor effluents were operated in air cathode MFC for electricity generation for the first time. The methanotrophic reactor with <I>Methylosinus sporium</I> produced a maximum methanol concentration of 6.45 mM using simulated biogas (4:1 (v/v) CH<SUB>4</SUB>:CO<SUB>2</SUB>) with a 50% CH<SUB>4</SUB> content. Maximum power densities of 235 and 270 mW/m<SUP>2</SUP> were noted with methanotrophic reactor effluents from pure CH<SUB>4</SUB> (MFC-1) and simulated biogas (4:1 (v/v) CH<SUB>4</SUB>:CO<SUB>2</SUB>) (MFC-2), respectively. Electrochemical impedance spectroscopy analysis revealed the presence of high charge transfer resistance as a major limitation for electricity generation. This is the first report on the sequential operation to produce methanol and electricity using simulated biogas. The system might have potential for field applications using real biogas generated through the anaerobic digestion of biowaste materials.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Methanotrophic reactor effluents were used to generate electricity using microbial fuel cells. </LI> <LI> Simulated biogas (4:1 (v/v) CH4:CO2) as feed showed higher methanol/electricity production than pure CH<SUB>4</SUB>. </LI> <LI> Maximum power density of 270 mW/m<SUP>2</SUP> was noted with the effluents from simulated biogas. </LI> <LI> This is the first report on the sequential operation to produce electricity from simulated biogas. </LI> </UL> </P>

Eco-Friendly Composite of Fe₃O₄-Reduced Graphene Oxide Particles for Efficient Enzyme Immobilization

Sanjay K. S PATEL,Raviteja PAGOLU,DIBYA BHOL,Jung-Kul LEE 한국생물공학회 2017 한국생물공학회 학술대회 Vol.2017 No.10

Canna edulis Leaf Extract-Mediated Preparation of Stabilized Silver Nanoparticles

Sachin V. OTARI,Muhammad Zahid ANWAR,Raviteja PAGOLU,DIBYA BHOL,Jung-Kul LEE 한국생물공학회 2017 한국생물공학회 학술대회 Vol.2017 No.10

Immobilization of Xylanase Using a Protein-Inorganic Hybrid System

( Ashok Kumar ),( Sanjay K. S. Patel ),( Bharat Mardan ),( Raviteja Pagolu ),( Rowina Lestari ),( Seong-hoon Jeong ),( Taedoo Kim ),( Jung Rim Haw ),( Sang-yong Kim ),( In-won Kim ),( Jung-kul Lee ) 한국미생물생명공학회(구 한국산업미생물학회) 2018 Journal of microbiology and biotechnology Vol.28 No.4

In this study, the immobilization of xylanase using a protein-inorganic hybrid nanoflower system was assessed to improve the enzyme properties. The synthesis of hybrid xylanase nanoflowers was very effective at 4°C for 72 h, using 0.25 mg/ml protein, and efficient immobilization of xylanase was observed, with a maximum encapsulation yield and relative activity of 78.5% and 148%, respectively. Immobilized xylanase showed high residual activity at broad pH and temperature ranges. Using birchwood xylan as a substrate, the V_max and K_m values of xylanase nanoflowers were 1.60 mg/ml and 455 μmol/min/mg protein, compared with 1.42 mg/ml and 300 μmol/min/mg protein, respectively, for the free enzyme. After 5 and 10 cycles of reuse, the xylanase nanoflowers retained 87.5% and 75.8% residual activity, respectively. These results demonstrate that xylanase immobilization using a proteininorganic hybrid nanoflower system is an effective approach for its potential biotechnological applications.

Fe₂O₃ yolk-shell particle-based laccase biosensor for efficient detection of 2,6-dimethoxyphenol

Patel, Sanjay K.S.,Anwar, Muhammad Z.,Kumar, Ashok,Otari, Sachin V.,Pagolu, Ravi T.,Kim, Sang-Yong,Kim, In-Won,Lee, Jung-Kul Elsevier 2018 Biochemical engineering journal Vol.132 No.-

<P><B>Abstract</B></P> <P>The structural morphology and composition of a support play a key role in the performance of nanoparticle-based enzymatic biosensors. In the present study, the influence of different functional groups, including glutaraldehyde, 3-aminopropyltriethoxysilane, carbodiimide, cyano, and polyethyleneimine for the immobilization of laccase on synthesized Fe<SUB>2</SUB>O<SUB>3</SUB> yolk-shell and commercially available Fe<SUB>2</SUB>O<SUB>3</SUB>, SrFe<SUB>12</SUB>O<SUB>19</SUB>, and Y<SUB>3</SUB>Fe<SUB>5</SUB>O<SUB>12</SUB> particles was analyzed. Glutaraldehyde-activated particles showed higher laccase activity after immobilization and higher relative detection currents for 2,6-dimethoxyphenol (2,6-DMP). The multi-shelled structural morphology of Fe<SUB>2</SUB>O<SUB>3</SUB> yolk-shell particles significantly improved the biosensing properties of immobilized laccase compared to that of spherical pure Fe<SUB>2</SUB>O<SUB>3</SUB> and composite SrFe<SUB>12</SUB>O<SUB>19</SUB> and Y<SUB>3</SUB>Fe<SUB>5</SUB>O<SUB>12</SUB> particles. The prepared biosensors showed high selectivity towards 2,6-DMP, with a sensitivity of 452 μA/mM/cm<SUP>2</SUP>. Under optimum conditions, the linear ranges of detection were as follows: 2,6-DMP (0.025–750 μM), guaiacol (0.10–250 μM), pyrogallol (0.25–250 μM), and 3,4-dihydroxy-<SMALL>L</SMALL>-phenylalanine (1.0–125 μM), with limit of detection values of 0.010, 0.052, 0.093, and 0.273 μM, respectively. Laccase immobilized on bio-friendly multi-shelled Fe<SUB>2</SUB>O<SUB>3</SUB> yolk-shell particles showed a broad linear range of detection, the lowest limit of detection, high sensitivity and stability, good reproducibility, anti-interference and recovery, and insignificant inhibition by laccase inhibitors.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Fe<SUB>2</SUB>O<SUB>3</SUB> yolk-shell particles were used to prepare laccase biosensors. </LI> <LI> Particle composition and morphology exhibited significant variation in biosensing. </LI> <LI> Fe<SUB>2</SUB>O<SUB>3</SUB> yolk-shell biosensor showed a high selectivity towards 2,6-dimethoxyphenol. </LI> <LI> A broad linear range of detection with the lowest limit of detection (0.01 μM) was observed. </LI> </UL> </P>

Repeated batch methanol production from a simulated biogas mixture using immobilized <i>Methylocystis bryophila</i>

Patel, Sanjay K.S.,Kondaveeti, Sanath,Otari, Sachin V.,Pagolu, Ravi T.,Jeong, Seong Hun,Kim, Sun Chang,Cho, Byung-Kwan,Kang, Yun Chan,Lee, Jung-Kul Pergamon Press 2018 Energy Vol.145 No.-

<P><B>Abstract</B></P> <P>In this study, biological methanol production under repeated batch conditions by immobilized <I>Methylocystis bryophila</I>, using simulated biogas of methane (CH<SUB>4</SUB>) and carbon dioxide (CO<SUB>2</SUB>) as a feed is demonstrated for the first time. The composition of the simulated gas mixtures significantly influenced methanol production by <I>M. bryophila,</I> and in all cases, higher concentrations were achieved than with pure CH<SUB>4</SUB> alone. Under optimum conditions, maximum methanol concentrations of 4.88 mmol L<SUP>−1</SUP>, 7.47 mmol L<SUP>−1</SUP>, and 7.02 mmol L<SUP>−1</SUP> were achieved using the gas mixtures CH<SUB>4</SUB>:CO<SUB>2</SUB> (2:1 ratio), CH<SUB>4</SUB>:hydrogen [H<SUB>2</SUB>, (4:1 ratio)], and CH<SUB>4</SUB>:CO<SUB>2</SUB>:H<SUB>2</SUB> (6:3:2 ratio), respectively, as feed, with a fixed CH<SUB>4</SUB> concentration of 30%. Methanol yield was increased to 7.85 mmol L<SUP>−1</SUP> using covalently immobilized cells and the simulated gas mixture CH<SUB>4</SUB>:CO<SUB>2</SUB>:H<SUB>2</SUB> (6:3:2 ratio). Under repeated batch conditions, immobilized cells produced a significantly higher cumulative methanol concentration (25.75 mmol L<SUP>−1</SUP>) than free cells (15.50 mmol L<SUP>−1</SUP>), using a simulated biogas mixture of CH<SUB>4</SUB>:CO<SUB>2</SUB> (2:1) and eight reuse cycles, suggesting that this mixture can potentially be utilized as a feed for the production of methanol. Furthermore, the effective utilization of low-cost feedstock, derived from natural sources, containing gas mixtures of CH<SUB>4</SUB>:CO<SUB>2</SUB>, CH<SUB>4</SUB>:H<SUB>2</SUB>, or CH<SUB>4</SUB>:CO<SUB>2</SUB>:H<SUB>2</SUB>, constitute an economical and environmentally friendly approach to the reduction of greenhouse gases.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Methanol production was demonstrated by immobilized <I>Methylocystis bryophilla.</I> </LI> <LI> Simulated biogas as feed showed higher methanol production than pure CH<SUB>4</SUB>. </LI> <LI> A maximum methanol production of 7.85 mM was obtained from CH<SUB>4</SUB>:CO<SUB>2</SUB>:H<SUB>2</SUB>. </LI> <LI> Immobilized cells produced a higher cumulative methanol (25.75 mM) than free cells. </LI> </UL> </P>