Characterization of lignin-degrading enzymes (LDEs) from a dimorphic novel fungus and identification of products of enzymatic breakdown of lignin

Abstract

Lignin is a major component of all plants, the degradation of which remains a major challenge to date owing to its recalcitrant nature. Several classes of fungi have been studied to carry out this process to some extent, but overall the process remains inefficient. We have isolated a novel alkalophilic dimorphic lignin-degrading Deuteromycete from soil, identified as “uncultured” and coded as MVI.2011. Supernatant from 12-h culture of MVI.2011 in optimized mineral medium containing lignin pH 9.0 was analysed for Lignin Peroxidase, Manganese Peroxidase and Laccase. Enzyme purification was carried out by standard protocols using ammonium sulphate precipitation followed by further purification by Gel Permeation Chromatography. Analysis of total protein, specific enzyme activity and molecular weight of the GPC-purified LiP, MnP and Laccase showed 93.83 μg/ml, 5.27 U/mg, 42 kDa; 78.13 μg/ml, 13.18 U/mg, 45 kDa and 85.81 μg/ml, 4.77 U/mg, 62 kDa, respectively. The purified enzymes possessed high activity over a wide range of pH (4–11), and temperature (30–55 °C). The optimum substrate concentration was 20 μg/ml of lignin for all the three enzymes. CD spectra suggested that the predominant secondary structure was helix in LiP, and, turns in MnP and Laccase. The breakdown products of lignin degradation by MVI.2011 and the three purified enzymes were detected and identified by FTIR and GC–MS. They were oxalic acid, hentriacontane, derivatives of octadecane, nonane, etc. These vital compounds are certain to find application as biofuels, an alternate energy source in various industries.Electronic supplementary materialThe online version of this article (doi:10.1007/s13205-016-0384-z) contains supplementary material, which is available to authorized users.

Symbiotic Plant Biomass Decomposition in Fungus-Growing Termites

“…Alternatively, enzyme production could be plastic depending on plant species availability and seasonality. These alternative hypotheses could be explored by coupling substrate preference determination with enzyme assays (e.g., chromogenic substrates, AZCL, lignin-degrading enzyme assays [5,134,135,136]) and symbiont CAZyme gene expression in fungus combs and termite guts after termite foraging on different substrates, either in natural environments over geographical locations with different plant communities or through laboratory experimentation.…”

Optimization of submerged cultivation parameters for a novel biological pretreatment of rice straw to enhance enzymatic hydrolysis

“…JN606084.1) was reportedly isolated from soil samples . The characterization of the fungus and its enzymes were already done and reported . Pure isolate of this fungus was obtained and preserved on SDA slants and stored in 4°C.…”

“…JN606084.1) has been known to be releasing ligninases, the key enzymes responsible for biological delignification of lignocelluloses. Growth of the fungus in basal mineral medium containing 0.1% of commercial lignin led to the release of lignin peroxidase, manganese peroxidase and laccase within 12 h of incubation, their activities 9.39 units mL −1 , 2.093 units mL −1 and 3.5 units mL −1 , respectively . Previously, studies were conducted by Sreemahadevan et al .…”

“…Therefore, to address and to minimize the issue of MVI.2011’s cellulolytic and hemicellulolytic activities, submerged cultivation conditions can be optimized. This in turn will improve the saccharification efficiency of pretreated rice straw and can make MVI.2011 as a better alternative to other lignin degrading fungi because, MVI.2011 can grow rapidly and release ligninases within a few days .…”

"Lignocellulose Degrading Enzymes from Fungi and Their Industrial Applications"

“…Sahadevan 128 reported lignin-degrading enzymes, LiP, MnP and Laccase from MVI.2011 an alkalophilic fungus to afford an appropriate biological substitute to treat highly alkaline effluents like pulp, paper industry and waste water. Indira Priyadarsini 129 described that the ability of fungi to produce laccase was linked with the effective decolorization of azo dyes which can be exploited for the screening of laccase producers.…”