Delignification and enhanced gas release from soil containing lignocellulose by treatment with bacterial lignin degraders.

AIMS: The aim of the study was to isolate bacterial lignin-degrading bacteria from municipal solid waste (MSW) soil, and to investigate whether they could be used to delignify lignocellulose-containing soil, and enhance methane release. METHODS AND RESULTS: A set of 20 bacterial lignin degraders, including 11 new isolates from MSW soil, were tested for delignification and phenol release in soil containing 1% pine lignocellulose. A group of seven strains were then tested for enhancement of gas release from soil containing 1% lignocellulose in small-scale column tests. Using an aerobic pretreatment, aerobic strains such as Pseudomonas putida showed enhanced gas release from the treated sample, but four bacterial isolates showed 5-10-fold enhancement in gas release in an in situ experiment under microanaerobic conditions: Agrobacterium sp., Lysinibacillus sphaericus, Comamonas testosteroni and Enterobacter sp. CONCLUSIONS: The results show that facultative anaerobic bacterial lignin degraders found in landfill soil can be used for in situ delignification and enhanced gas release in soil containing lignocellulose. SIGNIFICANCE AND IMPACT OF THE STUDY: The study demonstrates the feasibility of using an in situ bacterial treatment to enhance gas release and resource recovery from landfill soil containing lignocellulosic waste.

Spectroscopic studies of the interaction of aspirin and its important metabolite, salicylate ion, with DNA, A·T and G·C rich sequences.

Among different biological effects of acetylsalicylic acid (ASA), its anticancer property is controversial. Since ASA hydrolyzes rapidly to salicylic acid (SA), especially in the blood, interaction of both ASA and SA (as the small molecules) with ctDNA, oligo(dA·dT)15 and oligo(dG·dC)15, as a possible mechanism of their action, is investigated here. The results show that the rate of ASA hydrolysis in the absence and presence of ctDNA is similar. The spectrophotometric results indicate that both ASA and SA cooperatively bind to ctDNA. The binding constants (K) are (1.7±0.7)×10(3) M(-1) and (6.7±0.2)×10(3) M(-1) for ASA and SA, respectively. Both ligands quench the fluorescence emission of ethidium bromide (Et)-ctDNA complex. The Scatchard plots indicate the non-displacement based quenching (non-intercalative binding). The circular dichroism (CD) spectra of ASA- or SA-ctDsNA complexes show the minor distortion of ctDNA structure, with no characteristic peaks for intercalation of ligands. Tm of ctDNA is decreased up to 3°C upon ASA binding. The CD results also indicate more distortions on oligo(dG·dC)15 structure due to the binding of both ASA and SA in comparison with oligo(dA·dT)15. All data indicate the more affinity for SA binding with DNA minor groove in comparison with ASA which has more hydrophobic character.