ABSTRACT
Enhancement of the desulfurization activities of Paenibacillus strains 32O-W and 32O-Y were investigated using dibenzothiophene (DBT) and DBT sulfone (DBTS) as sources of sulphur in growth experiments. Strains 32O-W, 32O-Y and their co-culture (32O-W plus 32O-Y), and Vitreoscilla hemoglobin (VHb) expressing recombinant strain 32O-Yvgb and its co-culture with strain 32O-W were grown at varying concentrations (0·1-2 mmol l-1 ) of DBT or DBTS for 96 h, and desulfurization measured by production of 2-hydroxybiphenyl (2-HBP) and disappearance of DBT or DBTS. Of the four cultures grown with DBT as sulphur source, the best growth occurred for the 32O-Yvgb plus 32O-W co-culture at 0·1 and 0·5 mmol l-1 DBT. Although the presence of vgb provided no consistent advantage regarding growth on DBTS, strain 32O-W, as predicted by previous work, was shown to contain a partial 4S desulfurization pathway allowing it to metabolize this 4S pathway intermediate.
Subject(s)
Biodegradation, Environmental , Paenibacillus/metabolism , Thiophenes/metabolism , Vitreoscilla/metabolism , Bacterial Proteins/metabolism , Coculture Techniques , Paenibacillus/growth & development , Sulfur/metabolism , Truncated Hemoglobins/metabolism , Vitreoscilla/growth & developmentABSTRACT
The hemoglobins found in unicellular organisms show a greater chemical reactivity, protect cells against oxidative stress and hence have been implicated in a wider variety of potential functions than those traditionally associated with animal and plant hemoglobins. There are well-documented studies showing that bacteria expressing Vitreoscilla hemoglobin (VHb), the first prokaryotic hemoglobin characterized, have better growth and oxygen uptake rates than VHb counterparts.
Subject(s)
Hemoglobins/genetics , Vitreoscilla/genetics , Bacterial Proteins/genetics , Catalase/analysis , Catalase/metabolism , Cloning, Molecular , Enterobacter aerogenes/genetics , Enterobacter aerogenes/growth & development , Enterobacter aerogenes/metabolism , Gene Expression , Hemeproteins/genetics , Hemoglobins/analysis , Hemoglobins/biosynthesis , Oxygen/analysis , Oxygen Consumption , Recombinant Proteins/biosynthesis , Superoxide Dismutase/analysis , Superoxide Dismutase/metabolism , Vitreoscilla/growth & development , Vitreoscilla/metabolismABSTRACT
Strains of the filamentous gliding bacterium Vitreoscilla, LB13 and C1, are shown to be highly sensitive to UV-A (320-400 nm), with an LD50 of less than 20 kJ m(-2). Vitreoscilla LB13 can be protected from UV-A by including superoxide dismutase and catalase, separately or in combination, during the exposure, indicating an involvement of reactive oxygen species. LB13A, a photo-insensitive strain derived from LB13, is described.