Dazomet was fungicidal to sclerotia of Sclerotinia sclerotiorum (Lib.) de Bary, from pure culture or collected from different agricultural crops, in soil over a range of temperatures from 5 to 20°C and its effect became operative within 2 days at 20°C ; after 8 days no viable sclerotia were recorded at any of the temperatures. It was more effective in action on sclerotia than either nitrolim or dicyanidiamide which inhibit the formation of stipes and apothecia but do not kill all the sclerotia under the experimental conditions used.
Summary The weathering of primary rock-forming minerals beneath crustose lichens is due principally to the activity of the fungal component in excreting extracellular organic acids, particularly oxalic acid. This results in extensive surface etching of the minerals, the conversion of some minerals to siliceous relics, the formation of poorly ordered weathering products and the crystallization of oxalates at the rock/lichen interface and within the lichen thallus. Interpretation of these features is facilitated by the fact that they can be simulated experimentally. The relevance of lichen weathering to the pedogenic weathering predominant in soils under a cool temperature climate is discussed.
Protoplast preparations made from Saccharomyces cerevisiae by prolonged treatment with snail digestive juice contained fibrils and chitinous bud-scar residues from the original cell wall.
No abstract is provided for this article.
<p>Viruses play a crucial and underexplored role in soil microbial ecosystems, but soil viral ecology has focused exclusively on DNA viruses. The role of RNA viruses in soil ecosystems has therefore been largely overlooked, despite their significant impact on public health and food security. Here, we report the first ever study to apply viromics to survey soil RNA viral communities from five sites along an altitudinal primary productivity gradient in the UK. We identified over 3,000 viral sequences, of which over half were unclassified, and newly identified viruses were placed in a global context by the phylogenetic comparison of their RNA-dependent RNA polymerase genes. Unlike DNA viral communities, the RNA viromes were heavily dominated by viruses of eukaryotes, including pathogens of plants, fungi, vertebrates and invertebrates. Sampling sites showed minimal similarity in viral community composition, suggesting that we have just scratched the surface of soil RNA viral diversity. Wider sequencing efforts and method development are required to further explore soil RNA viromes and understand their ecological function; however, this study represents an important step towards the characterisation of soil viral communities and interactions with their microbial hosts, which will provide a more holistic view of the biology of economically and ecologically important soils.</p>
To assess faecal pollution in coastal waters, current monitoring is reliant on culture-based enumeration of bacterial indicators, which does not account for the presence of viable but non-culturable or sediment-associated micro-organisms, preventing effective quantitative microbial risk assessment (QMRA). Seasonal variability in viable but non-culturable or sediment associated bacteria challenge the use of faecal indicator organisms (FIOs) for water monitoring. We evaluated seasonal changes in FIOs and human enteric pathogen abundance in water and sediments from the Ribble and Conwy estuaries in the UK. Sediment provided greater bacterial abundance than the overlying water column, however, key pathogenic species (Shigella spp, Campylobacter jejuni, Salmonella spp, hepatitis A virus, hepatitis E virus and norovirus GI and GII) were not detected in sediments. Salmonella was detected in low levels in the Conwy water in spring/summer and norovirus GII was detected in the Ribble water in winter. The abundance of E. coli and Enterococcus spp. quantified by culture based methods, rarely matched the abundance of these species when measured by qPCR. The discrepancy between these methods was greatest in winter at both estuaries, due to low CFU's, coupled with higher gene copies (GC). Temperature accounted for 60% the variability in bacterial abundance in water in autumn, whilst in winter salinity explained 15% of the variance. Relationships between bacterial indicators/pathogens and physicochemical variables were inconsistent in sediments, no single indicator adequately described occurrence of all bacterial indicators/pathogens. However, important variables included grain size, porosity, clay content and concentrations of Zn, K and Al. Sediments with greater organic matter content and lower porosity harboured a greater proportion of non-culturable bacteria (including dead cells and extracellular DNA) in winter. Here, we show the link between physicochemical variables and season which govern culturability of human enteric pathogens and FIOs. Therefore, knowledge of these factors is critical for accurate microbial risk assessment. Future water quality management strategies could be improved through monitoring sediment-associated bacteria and non-culturable bacteria. This could facilitate source apportionment of human enteric pathogens and FIOs and direct remedial action to improve water quality.
The role of proteinaceous amino acids in rhizosphere nutrient mobilization was assessed both experimentally and theoretically. The degree of adsorption ont
