Identification of host-specific Bacteroidales 16S rDNA sequences from human sewage and ruminant feces.

The need to identify the source of fecal contamination of water has led to the development of various fecal source identification methods, a field known as microbial source tracking (MST). One promising method of MST focuses on fecal members of the order Bacteroidales, some of which exhibit a high degree of host-specificity. In order to identify host-specific Bacteroidales genetic markers, a ∼1060 bp section of Bacteroidales 16S rDNA was amplified from human sewage (n = 6), and bovine (n = 6) and ovine fecal (n = 5) samples and used for the generation of three clone libraries.

Specificity and sensitivity evaluation of novel and existing Bacteroidales and Bifidobacteria-specific PCR assays on feces and sewage samples and their application for microbial source tracking in Ireland.

Three novel ruminant-specific PCR assays, an existing ruminant-specific PCR assay and five existing human-specific PCR assays, which target 16S rDNA from Bacteroidales or Bifidobacteria, were evaluated. The assays were tested on DNA extracted from ruminant (n=74), human (n=59) and non-ruminant animal (n=44) sewage/fecal samples collected in Ireland. The three novel PCR assays compared favourably to the existing ruminant-specific assay, exhibiting sensitivities of 91-100% and specificities of 95-100% as compared to a sensitivity of 95% and specificity of 94%, for the existing ruminant-specific assay.

Trophic status of experimental cutaway peatland lakes in ireland and implications for future lake creation.

Of the 80,000 hectares of Bord na Móna owned peatland coming out of industrial production in Ireland approximately the next 25 years, over 20,000 hectares has been designated for shallow lake creation. Four experimental lakes created by flooding areas of redundant cutaway peatland in Co. Offaly were monitored over a 3-year period in order to obtain baseline information on their water quality and trophic status.

Effect of influent COD/SO4(2-) ratios on mesophilic anaerobic reactor biomass populations: physico-chemical and microbiological properties.

The competitive and syntrophic interactions between different anaerobic bacterial trophic groups in sulphate limited expanded granular sludge bed (EGSB) reactors was investigated. The outcome of competition between the sulphate-reducing, methanogenic and syntrophic populations after development in reactors at varying influent COD/SO4 (2-) ratios was examined in batch activity tests with the inclusion of specific sulphate reducing bacteria (SRB) and methane producing archaea (MPA) inhibitors. SRB species could not out-compete MPA species for acetate at influent COD/SO4 (2-) ratios as low as 2.

Toxicity of nitrite toward mesophilic and thermophilic sulphate-reducing, methanogenic and syntrophic populations in anaerobic sludge.

The various problems associated with treating sulphate-containing wastewaters stem inherently from successful competitive interactions between sulphate reducing bacteria (SRB) and other bacteria involved in the process, resulting in the formation of H(2)S. Prevention of in-reactor sulphide generation by use of specific SRB inhibitors presents a potential solution. Nitrite has been reported to be a specific inhibitor of SRB but its possible toxicity to syntrophic and methanogenic members of the anaerobic consortium has not been investigated.

Long-term effects of operating temperature and sulphate addition on the methanogenic community structure of anaerobic hybrid reactors.

The diversity, population dynamics, and activity profiles of methanogens in anaerobic granular sludges from two anaerobic hybrid reactors treating a molasses wastewater both mesophilically (37 degrees C) and thermophilically (55 degrees C) during a 1081 day trial were determined. The influent to one of the reactors was supplemented with sulphate, after an acclimation period of 112 days, to determine the effect of competition with sulphate-reducing bacteria on the methanogenic community structure. Sludge samples were removed from the reactors at intervals throughout the operational period and examined by amplified ribosomal DNA (rDNA) restriction analysis (ARDRA) and partial sequencing of 16S rRNA genes.

Linezolid compared with eperezolid, vancomycin, and gentamicin in an in vitro model of antimicrobial lock therapy for Staphylococcus epidermidis central venous catheter-related biofilm infections.

Central venous catheter (CVC)-related infection (CVC-RI) is a common complication of CVC use. The most common etiological agents of CVC-RI are gram-positive organisms, in particular, staphylococci. An in vitro model for the formation of biofilms by Staphylococcus epidermidis ATCC 35984 on polyurethane coupons in a modified Robbins device was established.

Arsenical resistance in the IncHI2 plasmids.

The IncHI2 plasmid R478, like other arsenic resistance IncH plasmids, provides increased levels of resistance to sodium arsenate (up to 100mM) and sodium arsenite (up to 10mM) to the host cell. An arsenic resistance fragment of R478 was cloned and sequenced revealing four arsenic resistance associated gene homologues, arsR, arsB, arsC, and arsH. Two other open reading frames in the cloned fragment were found to be homologues of sulphate transport associated genes.

Characterization of two autoreplicative regions of the IncHI2 plasmid R478: RepHI2A and RepHI1A((R478)).

Plasmids of the incompatibility groups HI and HII (IncH plasmids) generally confer multiple antibiotic resistances upon their host pathogenic strain. IncHI group plasmids are distinguished by their property of optimal transfer by conjugation at temperatures below 30 degrees C, allowing for the spread of multiple antibiotic resistance outside their host natural environment, the gut. Plasmids of the IncHI1 subgroup encode multiple replicons.