|
|
|
|
|
|
Salinity Decreases Nitrite Reductase Gene Diversity in Denitrifying Bacteria of Wastewater Treatment Systems. Sachiko Yoshie, 2004. Genomic Comparison of Salmonella enterica Serovars and Salmonella bongori by Use of an S . enterica Serovar Typhimurium DNA Microarray. Kaman Chan, 2003.The genus Salmonella consists of over 2,200 serovars that differ in their host range and ability to cause disease despite their close genetic relatedness . The genetic factors that influence each serovar's level of host adaptation, how they evolved or were acquired, their influence on the evolution of each serovar, and the phylogenic relationships between the serovars are of great interest as they provide insight into the mechanisms behind these differences in host range and disease progression . We have used an Salmonella enterica serovar Typhimurium spotted DNA microarray to perform genomic hybridizations of various serovars and strains of both S . enterica (subspecies I and IIIa) and Salmonella bongori to gain insight into the genetic organization of the serovars . Our results are generally consistent with previously published DNA association and multilocus enzyme electrophoresis data . Our findings also reveal novel information . We observe a more distant relationship of serovar Arizona (subspecies IIIa) from the subspecies I serovars than previously measured . We also observe variability in the Arizona SPI-2 pathogenicity island, indicating that it has evolved in a manner distinct from the other serovars . In addition, we identify shared genetic features of S . enterica serovars Typhi, Paratyphi A, and Sendai that parallel their unique ability to cause enteric fever in humans . Therefore, whereas the taxonomic organization of Salmonella into serogroups provides a good first approximation of genetic relatedness, we show that it does not account for genomic changes that contribute to a serovar's degree of host adaptation . Growth of Rhodosporidium toruloides Strain DBVPG 6662 on Dibenzothiophene Crystals and Orimulsion. Franco Baldi, 2003.Strains DBVPG 6662 and DBVPG 6739 of Rhodosporidium toruloides, a basidiomycete yeast, grew on thiosulfate as a sulfur source and glucose (2 g liter-1 or 10.75 mM) as a carbon source . DBVPG 6662 has a defective sulfate transport system, whereas DBVPG 6739 barely grew on sulfate . They were compared for the ability to use dibenzothiophene (DBT) and related organic sulfur compounds as sulfur sources . In the presence of glucose as a carbon source and DBT as a sulfur source, strain DBVPG 6662 grew better than DBVPG 6739 . In the presence of thiosulfate as a sulfur source, the two yeast strains did not use DBT, DBT-sulfone, benzenesulfonic acid, biphenyl, and fluorene . When the two strains were grown in the presence of glucose, strain DBVPG 6662 transformed 27% of the DBT present (10 µM) at a rate of 0.023 µmol liter-1 h-1 in 36 h . Traces of 2,2'-dihydroxylated biphenyl were transiently accumulated under these conditions . When the same strain was grown on glucose in the presence of a higher concentration of DBT (0.5 g liter-1), mainly in an insoluble form, the whole surface of the DBT crystals was colonized by a thick mycelium . This adherent structure was imaged by confocal microscopy with fluorescent concanavalin A, a lectin that specifically binds glucose and mannose residues . When DBVPG 6662 was grown on glucose in the presence of a commercial emulsion of bitumen, i.e., orimulsion, 68% of the benzo- and dibenzothiophenes and DBTs was removed after 15 days of incubation . The fungus adhered by hyphae to orimulsion droplets . When cultivated in the presence of commercial emulsifier-free fuel oil containing alkylated benzothiophenes and DBTs and having a composition similar to that of orimulsion, strain DBVPG 6662 removed only 11% of the total organic sulfur that occurs in the medium and did not adhere to the oil droplets . These results indicate that strain DBVPG 6662 is able to utilize the organic sulfur of DBT and a large variety of thiophenic compounds that occur extensively in commercial fuel oils by physically adhering to the organic sulfur source .
|
© 2005
Transgalactic Ltd (manufacturer of Bioscreen C software) |
Privacy Statement | P.O. Box
1393, 00101 Helsinki, Finland,
Last modified: May 25, 2005
| ||||||
