7 research outputs found
Biofilm Community Dynamics in Bench-Scale Annular Reactors Simulating Arrestment of Chloraminated Drinking Water Nitrification
Annular
reactors (ARs) were used to study biofilm community succession and
provide ecological insight during nitrification arrestment through
simultaneously increasing monochloramine (NH<sub>2</sub>Cl) and chlorine
to nitrogen mass ratios, resulting in four operational periods (I–IV).
Analysis of 16S rRNA-encoding gene sequence reads (454-pyrosequencing)
examined viable and total biofilm communities and found total samples
were representative of the underlying viable community. Bacterial
community structure showed dynamic changes corresponding with AR operational
parameters. Period I (complete nitrification and no NH<sub>2</sub>Cl residual) was dominated by <i>Bradyrhizobium</i> (total
cumulative distribution: 38%), while environmental <i>Legionella</i>-like phylotypes peaked (19%) during Period II (complete nitrification
and minimal NH<sub>2</sub>Cl residual). <i>Nitrospira moscoviensis</i> (nitrite-oxidizing bacteria) was detected in early periods (2%)
but decreased to <0.02% in later periods, corresponding to nitrite
accumulation. <i>Methylobacterium</i> (19%) and members
of <i>Nitrosomonadaceae</i> (42%) dominated Period III (complete
ammonia and partial nitrite oxidation and low NH<sub>2</sub>Cl residual).
An increase in <i>Afipia</i> (haloacetic acid-degrading
bacteria) relative abundance (<2% to 42%) occurred during Period
IV (minimal nitrification and moderate to high NH<sub>2</sub>Cl residual).
Microbial community and operational data provided no evidence of taxa-time
relationship, but rapid community transitions indicated that the system
had experienced ecological regime shifts to alternative stable states
The Impact of Silver Nanoparticles on the Composting of Municipal Solid Waste
The
study evaluates the impact of polyvinylpyrrolidone (PVP) coated
silver nanoparticles (PVP-AgNPs) on the composting of municipal solid
waste. The results suggest that there was no statistically significant
difference in the leachate, gas, and solid quality parameters and
overall composting performance between the treatments containing the
AgNPs, Ag<sup>+</sup>, and negative control. Nonetheless, taxonomical
analyses of 25 Illumina 16S rDNA barcoded libraries containing 2 393 504
sequences indicated that the bacterial communities in composted samples
were highly diverse and primarily dominated by Clostridia (48.5%),
Bacilli (27.9%), and beta-Proteobacteria (13.4%). Bacterial diversity
studies showed that the overall bacterial community structure in the
composters changed in response to the Ag-based treatments. However,
the data suggest that functional performance was not significantly
affected due to potential bacterial functional redundancy within the
compost samples. The data also indicate that while the surface transformation
of AgNPs to AgCl and Ag<sub>2</sub>S can reduce the toxicity, complexation
with organic matter may also play a major role. The results of this
study further suggest that at relatively low concentrations, the organically
rich waste management systems’ functionality may not be influenced
by the presence of AgNPs
The Univariate and multivariate results for individual risk factors and the generalized additive model risk ratios with the spatial term of a waterborne outbreak in Vuorela, July 2012.
<p>The Univariate and multivariate results for individual risk factors and the generalized additive model risk ratios with the spatial term of a waterborne outbreak in Vuorela, July 2012.</p
Categorized distance and proportion of cases within those groups in a waterborne outbreak in Vuorela, July 2012.
<p>Categorized distance and proportion of cases within those groups in a waterborne outbreak in Vuorela, July 2012.</p
Epidemic curve of a waterborne outbreak in Vuorela, July 2012 based on the reported onset date of illness of the cases, and <i>E. coli</i> bacteria counts and chlorine levels in the point 7 (See Fig. 1) of the water distribution network.
<p>Epidemic curve of a waterborne outbreak in Vuorela, July 2012 based on the reported onset date of illness of the cases, and <i>E. coli</i> bacteria counts and chlorine levels in the point 7 (See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0104713#pone-0104713-g001" target="_blank">Fig. 1</a>) of the water distribution network.</p
Microbiological results of faecal samples from symptomatic patients of a waterborne outbreak in Vuorela, July 2012.
<p>Methods used were cultivation<sup>1</sup>, PCR/RT-PCR<sup>2</sup> (polymerase chain reaction/reverse transcripition-PCR), EM<sup>3</sup> (electron microscopy) and/or EIA<sup>4</sup> (Enzyme Immunoassay). <sup>5</sup><i>Campylobacter jejuni</i> and <sup>6</sup>EHEC O157:H7 (from one sample) and <sup>7</sup>sapovirus GII.P3 were isolated from the samples.</p
Phylogenetic relationships among OTUs (•) of the genus <i>Arcobacter</i> in a waterborne outbreak in Vuorela, July 2012.
<p>The tree was inferred from a maximum likelihood analysis of aligned 16S rRNA gene sequence (≈255 bp) and nodes with a bootstrap value ≥50% of 1 000 replicates are identified. <i>Sulfurospirillum deleyianum</i> (NR_074378) and <i>Campylobacter fetus</i> (L04314) were used as outgroup. Number in bracket represents the total amount of DNA/RNA reads identified in samples from A) the upper storage reservoir before cleaning, B) tap water during contamination and C) the upper storage reservoir after cleaning. *<i>A. butzleri</i>, <i>A. cryaerophilus</i> and <i>A. skirrowii</i> have been associated with gastrointestinal diseases <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0104713#pone.0104713-Collado1" target="_blank">[76]</a>.</p