Phyllosphere <i>E</i>. <i>coli</i> O157:H7 bioluminescence (A) and colonisation (B) of epiphytic and loosely bound cells (black bars) and endophytic and tightly bound cells (white bars) of seedlings 23 days after sowing in soil 96 days after contamination with <i>E. coli</i> O157.

<p>Data points are the mean of 4 replicates + SEM.</p

Rhizosphere <i>E</i>. <i>coli</i> O157:H7 bioluminescence (A) and colonisation (B) of the lettuce cultivars Vaila (open circle) and Dazzle (filled circle).

<p>Data points are the mean of 4 replicates + SEM.</p

Bioluminescence of <i>E</i>. <i>coli</i> O157:H7 colonizing the shoot (A and C) and the root (B and D) of different lettuce cultivars.

<p>Bars with different letter codes differ significantly from each other (one-way ANOVA, <i>P</i><0.001; Tukey multiple comparison test, <i>P</i><0.01). Data points are the mean of 4 replicates + SEM.</p

The relationship between CFU and bioluminescence of <i>E</i>. <i>coli</i> O157:H7 colonizing different cultivars of lettuce.

<p>Epiphytic and loosely bound colonization of shoots (A) and roots (B) and colonization by endophytic and tightly bound cells of shoots (C) and roots (D). Lettuce cultivars: Vaila (filled triangle); Rosetta (open triangle); Regina (filled circle); Lakeland (open circle); Marshall (filled square); Webbs (open square); Unrivalled (cross); Lollo Rossa (star); Little Gem (closed diamond); Dazzle (open diamond); Green (filled inverted triangle); Set (open inverted triangle). Data points are the mean of 4 replicates ± SEM.</p

Lettuce cultivars used in this study.

<p>Lettuce cultivars used in this study.</p

Phyllosphere <i>E</i>. <i>coli</i> O157:H7 bioluminescence (A and B) and colonisation (C and D) of the lettuce cultivars Vaila (open circle) and Dazzle (filled circle) Data points are the mean of 4 replicates + SEM.

<p>Phyllosphere <i>E</i>. <i>coli</i> O157:H7 bioluminescence (A and B) and colonisation (C and D) of the lettuce cultivars Vaila (open circle) and Dazzle (filled circle) Data points are the mean of 4 replicates + SEM.</p

Free Cu in in soil solutions.

<p>The relationship between Cu concentration in soil solution and the application rate of nano-CuO (panels A, D), bulk-CuO (panels B, E) and CuSO₄ (panels C, F) in mineral (panels A, B, C) and organic (D, E, F) soils. Note the broken y-axis scales (panels C, F). Datapoints are the mean of three replicate analyses ±1 SE. Sometimes error bars are hidden by symbols.</p

Zn toxicity to bacterial communities in mineral (panels A, B, C) and organic (panels D, E, F) soils.

<p>The effects of nano-sized (i.e. ENPs; panels A, D) and macroparticulate ‘bulk-sized’ (i.e. non-ENP) oxide (panels B, E) and as well as sulfate forms of Zn (panels C, F) on soil bacterial community growth rate are contrasted. The relationship between the relative bacterial growth (normalized relative to the bacterial growth rate in unamended soils) and rate of Zn application are described with a sigmoidal curve to establish the concentration response relationship (presented as lines). Datapoints represent the mean of two independent replicates ±1 SE. Sometimes error bars are hidden by symbols.</p

Sediment Composition Influences Spatial Variation in the Abundance of Human Pathogen Indicator Bacteria within an Estuarine Environment

<div><p>Faecal contamination of estuarine and coastal waters can pose a risk to human health, particularly in areas used for shellfish production or recreation. Routine microbiological water quality testing highlights areas of faecal indicator bacteria (FIB) contamination within the water column, but fails to consider the abundance of FIB in sediments, which under certain hydrodynamic conditions can become resuspended. Sediments can enhance the survival of FIB in estuarine environments, but the influence of sediment composition on the ecology and abundance of FIB is poorly understood. To determine the relationship between sediment composition (grain size and organic matter) and the abundance of pathogen indicator bacteria (PIB), sediments were collected from four transverse transects of the Conwy estuary, UK. The abundance of culturable <i>Escherichia coli</i>, total coliforms, enterococci, <i>Campylobacter</i>, <i>Salmonella</i> and <i>Vibrio</i> spp. in sediments was determined in relation to sediment grain size, organic matter content, salinity, depth and temperature. Sediments that contained higher proportions of silt and/or clay and associated organic matter content showed significant positive correlations with the abundance of PIB. Furthermore, the abundance of each bacterial group was positively correlated with the presence of all other groups enumerated. <i>Campylobacter</i> spp. were not isolated from estuarine sediments. Comparisons of the number of culturable <i>E. coli</i>, total coliforms and <i>Vibrio</i> spp. in sediments and the water column revealed that their abundance was 281, 433 and 58-fold greater in sediments (colony forming units (CFU)/100<b> </b>g) when compared with the water column (CFU/100<b> </b>ml), respectively. These data provide important insights into sediment compositions that promote the abundance of PIB in estuarine environments, with important implications for the modelling and prediction of public health risk based on sediment resuspension and transport.</p></div

Bacterial abundance (CFU/100 g wet weight) compared to sediment grain size, organic matter content in sediments and bacterial abundance in the water column (CFU/100 ml), across four transverse transects.

<p>(A) Transect 1, (B) Transect 2, (C) Transect 3, (D) Transect 4. The X-axis represents sample points (n = 3 replicate samples for A, B, C and D except for sediment samples site 13, n = 2), mean values are plotted and error bars represent the SEM).</p