Biochar is a carbon rich product from the incomplete combustion of biomass and it has been shown to reduce bioavailability of organic contaminants through adsorption. This study investigated the influence of 0%, 1%, 5% and 10% of two different particle sized wood biochars (≤2 mm and 3-7 mm) on the bioaccessibility of (14)C-phenanthrene (10 mg kg(-1)) in aged soil. The extent of (14)C-phenanthrene mineralisation by phenanthrene-degrading Pseudomonas sp. inoculum was monitored over a 14 day period in respirometric assays and compared to hydroxypropyl-β-cyclodextrin (HPCD) aqueous extraction. Notably, biochar amendments showed significant reduction in extents of mineralisation and HPCD extraction. Linear correlations between HPCD extractability and the total amount mineralised revealed good correlations, with 2 mm biochar showing a best fit (r(2) = 0.97, slope = 1.11, intercept = 1.72). Biochar reduced HPCD extractability and bioaccessibility of (14)C-phenanthrene to microorganisms in a similar manner. Biochar can aid risk reduction to phenanthrene exposure to biota in soil and HPCD can serve as a useful tool to assess the extent of exposure in biochar-amended soils.

ABSTRACT:In this study, the relevance of the presence of Escherichia coli in drinking water as an indicator of point-of-use chlorination efficiency is examined. The survival of clinical isolates of human enteric pathogenic bacteria (Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella typhi, Shigella dysenteriae, Staphylococcus aureus, Streptococcus faecalis and Vibrio cholerae) as well as E. coli was monitored as a function of effective germicidal concentration and contact time. The inactivation kinetics indicated that the minimum effective dose for three-log units (99.9%) inactivation of E. coli (C·T99.9% = 10 mgl -1 -min) can sufficiently eliminate the other pathogens (C·T99.9% ranged from 5.6-10.5 mgl -1 -min); the exception being K. pneumoniae, which required more than 1.4-times higher dose. In general, the results implied that the branded hypochlorite solution should effectively inactivate almost all vegetative bacteria in household drinking water at the manufacturer's recommended dosage of 0.5 mgl -1 after at least 30 minutes contact time. The application of point-of-use chemical disinfectants to drinking water in households will significantly reduce the incidence of water-borne infections particularly in rural communities where central treatment of water is mostly unavailable. © JASEM http://dx.doi.org/10.4314/jasem.v20i4.7

Five new phenolic siderophores 1–5 were isolated from the organic extract of a culture broth in a modified SGG medium of Pseudomonas sp. UIAU-6B, obtained from sediments collected from the Oyun river in North Central Nigeria. The structure of the new compounds, pseudomonin A–C (1–3) and pseudomobactin A and B (4 and 5) isolated alongside two known compounds, pseudomonine (6) and salicylic acid (7), were elucidated based on high-resolution mass spectrometry, 1D and 2D NMR analyses. The absolute configuration of the threonine residue in compounds 1–5 was determined by Marfey analysis. The antimicrobial evaluation of compound 4 exhibited the most potent activity against vancomycin-sensitive Enterococcus faecium VS144754, followed by 3 and 5, with MIC values ranging from 8 to 32 µg/mL. Compounds 2 and 3 exhibited moderate activity against Mycobacterium tuberculosis H37Rv, with MIC values of 7.8 and 15.6 µg/mL, respectively. Plausible biosynthetic hypotheses toward the new compounds 1–5 were proposed.

Abstract:The impact of increasing amendments of two particle sizes of biochar (≤2 mm and 3-7 mm), applied at 0%, 0.01%, 0.1% and 1% concentrations, on the development of indigenous phenanthrene catabolism was investigated in two soils with different soil organic matter contents. Mineralisation of 14 C-phenanthrene was measured after 1, 20, 60 and 100 d soil-phenanthrene-biochar aging period. The presence of biochar in the pasture soil (low OM) resulted in a decrease in the lag phase of 14 C-phenanthrene mineralisation, with higher maximum rates of mineralisation following 20 d aging. Higher extents of 14 C-phenanthrene mineralisation were observed in the Kettering loam soil (high OM), which was more prominent with 0.01% biochar amendments (p < 0.05) at 61.2% and 64.9% in ≤2 mm and 3-7 mm biochar amended soils, respectively. This study illustrates the potential role for biochar to enhance microbial catabolic activity to degrade common petroleum contaminants. It however depends on contaminant concentration, aging period, and soil properties. OPEN ACCESSEnvironments 2014, 1 61