Ligninolytic enzymes and its mechanisms for degradation of lignocellulosic waste in environment

Abstract

Ligninolytic enzymes play a key role in degradation and detoxification of lignocellulosic waste in environment. The major ligninolytic enzymes are laccase, lignin peroxidase, manganese peroxidase, and versatile peroxidase. The activities of these enzymes are enhanced by various mediators as well as some other enzymes (feruloyl esterase, aryl-alcohol oxidase, quinone reductases, lipases, catechol 2, 3-dioxygenase) to facilitate the process for degradation and detoxification of lignocellulosic waste in environment. The structurally laccase is isoenzymes with monomeric or dimeric and glycosylation levels (10-45%). This contains four copper ions of three different types. The enzyme catalyzes the overall reaction:While, lignin peroxidase is a glycoprotein molecular mass of 38-46 kDa containing one mole of iron protoporphyrin IX per one mol of protein, catalyzes the H 2 O 2 dependent oxidative depolymerization of lignin. The manganese peroxidase is a glycosylated heme protein with molecular mass of 40-50kDa. It depolymerizes the lignin molecule in the presence of manganese ion. The versatile peroxidase has broad range substrate sharing typical features of the manganese and lignin peroxidase families. Although ligninolytic enzymes have broad range of industrial application specially the degradation and detoxification of lignocellulosic waste discharged from various industrial activities, its large scale application is still limited due to lack of limited production. Further, the extremophilic properties of ligninolytic enzymes indicated their broad prospects in varied environmental conditions. Therefore it needs more extensive research for understanding its structure and mechanisms for broad range commercial applications.

Shewanella baltica strain JD0705 isolated from the mangrove wetland soils in Thailand and characterization of its ligninolytic performance

“…Laccases play a vital role in the depolymerization of lignin and its derivatives for delignification (Kumar and Chandra 2020). In this study, the laccase-producing S. baltica strain JD0705 was used to biologically delignify the rice husk powder.…”

“…The hydrolysis result showed that the delignified rice husk powder yielded more fermented sugar than the undelignified biomass. Laccases depolymerize and degrade the lignin molecules by several subsequent mechanisms including the generation of phenoxy radicals, aromatic ring cleavage, alkyl-aryl cleavage, c-oxidation and c-c cleavage (Kumar and Chandra 2020). Laccases are considered as a green tool in various biotechnological processes in the near future (Giardina et al 2010) because of their unique oxidizing mechanism and liberating only water molecules as the by-product (Kumar and Chandra 2020).…”

“…Laccases depolymerize and degrade the lignin molecules by several subsequent mechanisms including the generation of phenoxy radicals, aromatic ring cleavage, alkyl-aryl cleavage, c-oxidation and c-c cleavage (Kumar and Chandra 2020). Laccases are considered as a green tool in various biotechnological processes in the near future (Giardina et al 2010) because of their unique oxidizing mechanism and liberating only water molecules as the by-product (Kumar and Chandra 2020). Therefore, S. baltica strain JD0705 was preferred for the delignification activities of lignocellulosic biomass and related materials under mild conditions, without any additives or acid-base solutions.…”

The Potential of Peroxidases Extracted from the Spent Mushroom (Flammulina velutipes) Substrate Significantly Degrade Mycotoxin Deoxynivalenol

“…These ligninolytic peroxidases have extremely low specificity for substrates. While MnP degrades lignin and phenolic compounds by oxidizing the substrate in the presence of H 2 O 2 and Mn 2+ [ 27 ], LiP degrades various xenobiotic compounds by oxidizing substrates that contain H 2 O 2 and veratryl alcohol [ 27 ]. Moreover, these peroxidases are widely applied in the paper industry and environment protection [ 40 ], because they not only degrade lignin but also a wide range of environmental contaminants, such as phenols, polycyclic aromatic hydrocarbons, and aromatic water-pollutants [ 41 ].…”

“…It is known that the main extracellular ligninolytic enzymes consist of lignin peroxidase (LiP), manganese peroxidase (MnP), and laccase. All these ligninolytic peroxidases are involved in lignin biodegradation [ 27 ]. Studies showed that the peroxidases of white-rot fungi can oxidize the benzene rings of phenols, non-phenolic aromatics, and amino-aromatic compounds into phenol oxides and hydroxyl free radicals via the epoxide ring-opening reactions [ 28 ].…”