Transport and distribution of Salmonella enterica serovar Typhimurium in loamy and sandy soil monoliths with applied liquid manure.

A leaching experiment, where liquid manure spiked with Salmonella enterica serovar Typhimurium (Tet(+)) DSM554 was applied to soil surfaces, was conducted on intact soil monoliths (60 cm in diameter and 100 cm long). A total of 6.5 x 10(10) CFU was applied to each column.

The presence of embedded bacterial pure cultures in agar plates stimulate the culturability of soil bacteria.

Traditional methods for bacterial cultivation recover only a small fraction of bacteria from all sorts of natural environments, and attempts have been made to improve the bacterial culturability. Here we describe the development of a cultivation method, based on the embedment of pure bacterial cultures in between two layers of agar. Plates containing either embedded Pseudomonas putida or Arthrobacter globiformis resulted in higher numbers of CFUs of soil bacteria (21% and 38%, respectively) after 833 h of incubation, compared to plates with no embedded strain.

The microbiota of pigs influenced by diet texture and severity of Lawsonia intracellularis infection.

Pigs with and without naturally occurring Lawsonia intracellularis infection were fed diets with different texture. In a previous study from 79 pig herds using a similar feeding on pelleted or non-pelleted form showed that the non-pelleted diet was associated with a reduced prevalence of L. intracellularis.

Freezing at -800 degrees C distorts the DNA composition of bacterial communities in intestinal samples.

Terminal-restriction fragment length polymorphism (T-RFLP) was used to evaluate how to store intestinal specimens for bacterial community analysis. Bacterial communities are increasingly often described by means of DNA-based methods and it is common practice to store intestinal or faecal specimens either at -20 degrees C or -80 degrees C. In this study, samples of intestines from five different pigs were stored at -80 degrees C and -20 degrees C, respectively and a thawing and freezing procedure was carried out three times for each intestinal per pig per temperature.

Functional characteristics of culturable bacterioplankton from marine and estuarine environments.

Information on the structure of bacterioplankton communities is continuously increasing, while knowledge of their metabolic capabilities remains limited. In this study, the metabolic capacity of bacterioplankton was investigated, as such information is necessary to fully understand carbon cycling and other biogeochemical processes. The diversity of dominant culturable chemoorganotrophic bacteria from one estuarine and three marine environments was analyzed by random isolation of colony-forming units on solid media, taxonomical identification by partial 16S rRNA gene sequence analysis, and functional characterization of the isolates.

Bacterial diversity and community structure of a sub-surface aquifer exposed to realistic low herbicide concentrations.

An increasing number of herbicides are found in our groundwater environments. This underlines the need for examining the effects of herbicide exposure on the indigenous groundwater microbial communities, as microbial degradation is the major process responsible for the complete removal of most contaminants. We examined the effect of in situ exposure to realistic low concentrations of herbicides on the microbial diversity and community structure of sub-surface sediments from a shallow aquifer near Vejen (Denmark).

In situ exposure to low herbicide concentrations affects microbial population composition and catabolic gene frequency in an aerobic shallow aquifer.

The aim of this study was to evaluate how the in situ exposure of a Danish subsurface aquifer to phenoxy acid herbicides at low concentrations (<40 micro g l(-1)) changes the microbial community composition. Sediment and groundwater samples were collected inside and outside the herbicide-exposed area and were analyzed for the presence of general microbial populations, Pseudomonas bacteria, and specific phenoxy acid degraders. Both culture-dependent and culture-independent methods were applied.

Quantification of the atrazine-degrading Pseudomonas sp. strain ADP in aquifer sediment by quantitative competitive polymerase chain reaction.

The widely used herbicide atrazine and some of its degradation products are among the most commonly found xenobiotics in groundwater in Europe as well as in the USA. The bacterium Pseudomonas sp. strain ADP (P.

Soil microbial toxicity of eight polycyclic aromatic compounds: effects on nitrification, the genetic diversity of bacteria, and the total number of protozoans.

Eight polycyclic aromatic compounds (PACs) were tested for their toxic effect on the soil nitrification process, bacterial genetic diversity, and the total number of protozoans (naked amoebae and heterotrophic flagellates). After four weeks of exposure in a well-characterized agricultural soil, toxic effects were evaluated by comparison to uncontaminated control soils. All PACs affected the nitrification process, and the calculated no-observed-effect concentrations (NOECs) for nitrification were 79 mg/kg for pyrene, 24 mg/kg for fluoranthene, 26 mg/kg for phenanthrene, 72 mg/kg for fluorene, 23 mg/kg for carbazole, 22 mg/kg for dibenzothiophene, 75 mg/kg for dibenzofuran, and 1,100 mg/kg for acridine.