Effect of enzyme additions on methane production and lignin degradation of landfilled sample of municipal solid waste

Making lignin accessible for anaerobic digestion by wet-explosion pretreatment

“…Although lignin is known to be highly recalcitrant to microbes such as bacterial and fungi, several degradation pathways have been explored after lignin modification (Abdel-Hamid et al, 2013;Bugg et al, 2011). Jayasinghe et al observed higher methane production rates in enzyme amended samples of lignin rich substrate due to the lignin depolymerization by lignin peroxidase (LiP), manganese peroxidase (MnP) enzymes (Jayasinghe et al, 2011). Strong oxidants such as LiP with high redox potential are able to oxidize non-phenolic structures of lignin while oxidation of phenolic structures of lignin is catalyzed by MnP (Mn-dependent enzyme) (Bugg et al, 2011).…”

“…Strong oxidants such as LiP with high redox potential are able to oxidize non-phenolic structures of lignin while oxidation of phenolic structures of lignin is catalyzed by MnP (Mn-dependent enzyme) (Bugg et al, 2011). A study showed microbes in anaerobic digester are able to utilize lignin oxidative products as a carbon source (Jayasinghe et al, 2011); however, higher resistance was found to high molecular or polymeric lignin. Our study showed significant improved depolymerization of lignin as a result of pretreatment.…”

Enhanced performance of the aerobic landfill reactor by augmentation of manganese peroxidase

“…Higher enzyme doses (0.12 mg/g of DS and 0.16 mg/g of DS) showed lower CO 2 production rates than the treatment with enzyme dose of 0.08 mg/g of DS. Several factors could contribute to this behaviour, including the toxicity and inhibitory effects of excess enzyme, which would in turn shift the enzyme-catalytic reaction pathways in a different direction, and decrease the available amount of electron mediators, such as cation radicals (Jayasinghe et al, 2011). The toxic effect can be caused by the excess production of lignin monomers, which are toxic to microbes.…”

“…Examples of commercially available lignin degraders are LiP, MnP, soybean peroxidase (SbP), horseradish peroxidase (HRP), and laccases. Of these peroxidases, LiP and MnP are described as true lignin degraders due to the high potential redox value (Jayasinghe et al, 2011). Also, Hettiaratchi et al (2014) demonstrated that MnP is a better enhancement agent than LiP.…”

“…This enhancement could be achieved through leachate augmentation including addition of sludge, addition of supplemental nutrients, and augmentation of leachate with potential enzymes. Among these techniques, the addition of sludge is the most common and oldest practice (Jayasinghe et al, 2011).…”