Application of enzymatic and bacterial biodelignification systems for enhanced breakdown of model lignocellulosic wastes.

This paper explores the extent to which enzymatic and bacterial biodelignification systems can breakdown lignocellulose in model wastes to potentially enhance biogas generation. Two representative lignocellulosic wastes (newspaper and softwood) commonly found largely undegraded in old landfills were used. A fungal peroxidase (lignin peroxidase) enzyme and a recently isolated lignin-degrading bacterial strain (Agrobacterium sp.) were used. Tests were conducted in stirred bioreactors with methanogens from sewage sludge added to produce biogas from breakdown products. Addition of lignin peroxidase resulted in ~20% enhancement in cumulative methane produced in newspaper reactors. It had a negative effect on wood. Agrobacterium sp. strain enhanced biodegradation of both wood (~20% higher release of soluble organic carbon and enhanced breakdown) and newspaper (~2-fold biogas yield). The findings of this paper have important implications for enhanced breakdown in old landfills that are rich in these wastes, and anaerobic operations utilising lignocellulosic wastes for higher degradation efficiencies and biogas production.

The case for examining fluid flow in municipal solid waste at the pore-scale - A review.

In this paper, we discuss recent efforts from the last 20 years to describe transport in municipal solid waste (MSW). We first discuss emerging themes in the field to draw the reader's attention to a series of significant challenges. We then examine contributions regarding the modelling of leachate flow to study transport via mechanistic and stochastic approaches, at a variety of scales. Since MSW is a multiphase, biogeochemically active porous medium, and with the aim of providing a picture of transport phenomena in a wider context, we then discuss a selection of studies on leachate flow incorporating some of the complex landfill processes (e.g. biodegradation and settlement). It is clear from the literature survey that our understanding of transport phenomena exhibited by landfilled waste is far from complete. Attempts to model transport have largely consisted of applying representative elementary-scale models (the smallest volume which can be considered representative of the entire waste mass). Due to our limited understanding of fluid flow through landfilled waste, and the influence of simultaneously occurring biogeomechanical processes within the waste mass, elementary-scale models have been unable to fully describe the flow behaviour of MSW. Pore-scale modelling and experimental studies have proven to be a promising approach to study fluid flow through complex porous media. Here, we suggest that pore-scale modelling and experimental work may provide valuable insights into transport phenomena exhibited by MSW, which could then be used to revise elementary-scale models for improved representation of field-scale problems.

Vanillin analog--vanillyl mandelic acid, a novel specific inhibitor of snake venom 5'-nucleotidase.

Snake venom 5'-nucleotidase (5'NUC) plays a very important role in envenomation strategies; however, apart from its modulation of hemostatic functions, its other pharmacological effects are not yet well characterized. Several studies have used specific inhibitors of enzyme toxins as a biochemical or pharmacological tool to characterize or establish its mechanism of action. We report here for the first time vanillin mandelic acid (VMA), an analog of vanillin, to potentially, selectively, and specifically inhibit venom 5'NUC activity among other enzymes present in venoms. VMA is much more potent in inhibiting 5'NUC activity than vanillyl acid (VA). The experimental results obtained are in good agreement with the in silico molecular docking interaction data. Both VA and VMA are competitive inhibitors as evident by the inhibition-relieving effect upon increasing the substrate concentration. VMA also dose-dependently inhibited the anticoagulant effect in Naja naja venom. In this study, we report novel non-nucleoside specific inhibitors of snake venom 5'NUC and experimentally demonstrate their involvement in the anticoagulant activity of N. naja venom. Hence, we hypothesize that VMA can be used as a molecular tool to evaluate the role of 5'NUC in snake envenomation and to develop prototypes and lead compounds with potential therapeutic applications against snake bites.