ABSTRACT The objective of the present study was to use a test system for clustering and character... more ABSTRACT The objective of the present study was to use a test system for clustering and characterizing the bacterial populations in five wastewater infiltration systems ranging in size from 12 m2 to 1960 m2 (corresponding to the demand for 4–500 population equivalents). From each system two sand samples were taken and from each sample 88 bacterial isolates were collected. Every isolate was exposed to 52 physiological and biochemical tests. The resulting 880 objects × 52 variable data matrix was subjected to principal components analysis (PCA). After a variable reduction the PCA model revealed a scattered bacteria pattern (score plot) in parts of the sand filters expected to have high loading rates of wastewater, e.g. at the inlet of the filters. This indicates that a diverse bacterial population had developed in response to the carbon and energy source in the wastewater. In contrast to this pattern a more narrow bacteria pattern had developed in low loaded parts of the sand filter. The most important variables explaining the structure of the microbial biofilm at high wastewater load were the ability to ferment sugars and the capacity to sustain different pH levels. The potential to ammonify and grow on nutrient broth was also an important feature. In conclusion, the bacterial test system together with PCA seems to be a useful tool to evaluate the function of a bacterial sand-filter ecosystem.
Using consensus regions in gene sequences encoding the two forms of nitrite reductase (Nir), a ke... more Using consensus regions in gene sequences encoding the two forms of nitrite reductase (Nir), a key enzyme in the denitrification pathway, we designed two sets of PCR primers to amplify cd1- and Cu-nir. The primers were evaluated by screening defined denitrifying strains, denitrifying isolates from wastewater treatment plants, and extracts from activated sludge. Sequence relationships of nir genes were also established. The cd1 primers were designed to amplify a 778 to 799-bp region of cd1-nir in the six published sequences. Likewise, the Cu primers amplified a 473-bp region in seven of the eight published Cu-nir sequences. Together, the two sets of PCR primers amplified nir genes in nine species within four genera, as well as in four of the seven sludge isolates. The primers did not amplify genes of nondenitrifying strains. The Cu primers amplified the expected fragment in all 13 sludge samples, but cd1-nir fragments were only obtained in five samples. PCR products of the expected s...
ABSTRACT The objective of the present study was to use a test system for clustering and character... more ABSTRACT The objective of the present study was to use a test system for clustering and characterizing the bacterial populations in five wastewater infiltration systems ranging in size from 12 m2 to 1960 m2 (corresponding to the demand for 4–500 population equivalents). From each system two sand samples were taken and from each sample 88 bacterial isolates were collected. Every isolate was exposed to 52 physiological and biochemical tests. The resulting 880 objects × 52 variable data matrix was subjected to principal components analysis (PCA). After a variable reduction the PCA model revealed a scattered bacteria pattern (score plot) in parts of the sand filters expected to have high loading rates of wastewater, e.g. at the inlet of the filters. This indicates that a diverse bacterial population had developed in response to the carbon and energy source in the wastewater. In contrast to this pattern a more narrow bacteria pattern had developed in low loaded parts of the sand filter. The most important variables explaining the structure of the microbial biofilm at high wastewater load were the ability to ferment sugars and the capacity to sustain different pH levels. The potential to ammonify and grow on nutrient broth was also an important feature. In conclusion, the bacterial test system together with PCA seems to be a useful tool to evaluate the function of a bacterial sand-filter ecosystem.
Using consensus regions in gene sequences encoding the two forms of nitrite reductase (Nir), a ke... more Using consensus regions in gene sequences encoding the two forms of nitrite reductase (Nir), a key enzyme in the denitrification pathway, we designed two sets of PCR primers to amplify cd1- and Cu-nir. The primers were evaluated by screening defined denitrifying strains, denitrifying isolates from wastewater treatment plants, and extracts from activated sludge. Sequence relationships of nir genes were also established. The cd1 primers were designed to amplify a 778 to 799-bp region of cd1-nir in the six published sequences. Likewise, the Cu primers amplified a 473-bp region in seven of the eight published Cu-nir sequences. Together, the two sets of PCR primers amplified nir genes in nine species within four genera, as well as in four of the seven sludge isolates. The primers did not amplify genes of nondenitrifying strains. The Cu primers amplified the expected fragment in all 13 sludge samples, but cd1-nir fragments were only obtained in five samples. PCR products of the expected s...
Uploads
Papers by Sara Hallin