RESUMO
Ten strains which were characterized by the formation of ballistoconidia, the absence of xylose in whole-cell hydrolysates, the presence of Q-9 as the major ubiquinone isoprenologue, the inability to ferment sugars and positive diazonium blue B and urease reactions were isolated from plant samples collected in Thailand. These isolates were closely related to Bensingtonia phyllada based on the analysis of 18S rDNA sequences. On the basis of the morphological, physiological and chemotaxonomic properties, the 10 isolates were assigned to the genus Bensingtonia. DNA complementarity showed that these isolates were genetically distinct from known species of the genus Bensingtonia. The isolates are described as Bensingtonia thailandica sp. nov. The type strain is strain TY-138T (= JCM 10651T).
Assuntos
Basidiomycota/classificação , Filogenia , Folhas de Planta/microbiologia , Basidiomycota/genética , Basidiomycota/isolamento & purificação , Metabolismo dos Carboidratos , DNA Fúngico/genética , DNA Ribossômico/genética , Dados de Sequência Molecular , RNA Ribossômico 16S/genética , Tailândia , Clima TropicalRESUMO
The extracellular acidic polysaccharides of the manganese-oxidizing bacterium Pedomicrobium manganicum were able to bind preformed colloidal MnO(2). The capacity of the cells to bind MnO(2) was pH dependent. Enhanced binding capacity below pH 5 suggests that ionic bonding forces are involved in the binding mechanism and that there is a charge reversal on the acidic polysaccharides between pH 5 and 4 that is due to increased protonation of carboxyl groups.
RESUMO
The deposition of manganese in a water distribution system with manganese-related "dirty water" problems was studied over a 1-year period. Four monitoring laboratories with Robbins biofilm sampling devices fitted to the water mains were used to correlate the relationship among manganese deposition, the level of manganese in the water, and the chlorination conditions. Manganese deposition occurred by both chemical and microbial processes. Chemical deposition occurred when Mn(II) not removed during water treatment penetrated the filters and entered the distribution system, where it was oxidized by chlorine and chlorine dioxide used for disinfection. Microbial deposition occurred in areas with insufficient chlorination to control the growth of manganese-depositing biofilm. At 0.05 mg of Mn(II) per liter, the chemical deposition rate was much greater than microbial deposition. Significant deposition occurred at 0.03 mg of manganese per liter, and dirty water complaints were not eliminated until manganese levels were continuously less than 0.02 mg/liter and chlorination levels were greater than 0.2 mg/liter. A guideline level of 0.01 mg of manganese per liter is recommended.
