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Engineering of Nitrosomonas europaea to express Vitreoscilla hemoglobin enhances oxygen uptake and conversion of ammonia to nitrite.

Kunkel SA, Pagilla KR, Stark BC - AMB Express (2015)

Bottom Line: Vgb was maintained stably and appeared to be expressed in the transformants at VHb levels of about 0.75 nmol/g wet weight.Expression of VHb in the N. europaea transformants was correlated with an approximately 2 fold increase in oxygen uptake rate by whole cells at oxygen concentrations in the range of 75-100% saturation, but no change in oxygen uptake rate at oxygen concentrations below 25% saturation.VHb expression was also correlated with an increase of as much as about 30% in conversion of ammonia to nitrite by growing cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Illinois Institute of Technology, Chicago, IL, 60616, USA, skunkel@iit.edu.

ABSTRACT
Nitrosomonas europaea was transformed with a recombinant plasmid bearing the gene (vgb) encoding the hemoglobin (VHb) from the bacterium Vitreoscilla under control of the N. europaea amoC P1 promoter. Vgb was maintained stably and appeared to be expressed in the transformants at VHb levels of about 0.75 nmol/g wet weight. Expression of VHb in the N. europaea transformants was correlated with an approximately 2 fold increase in oxygen uptake rate by whole cells at oxygen concentrations in the range of 75-100% saturation, but no change in oxygen uptake rate at oxygen concentrations below 25% saturation. VHb expression was also correlated with an increase of as much as about 30% in conversion of ammonia to nitrite by growing cells. The results suggest that engineering of key aerobic wastewater bacteria to express bacterial hemoglobins may be a useful strategy to produce species with enhanced respiratory abilities.

No MeSH data available.


Related in: MedlinePlus

Oxygen uptake measurements for N. europaea[pSK2] (gray squares and gray line) and untransformed N. europaea (black diamonds and black line). a Measurements made starting with DO at 100% saturation. b Measurements made starting with DO at 25% saturation. All points are averages of five independent experiments; for every experiment at both initial oxygen concentrations and for both strains, the same mass of cells (0.06 OD600nm) was tested. Error bars indicate standard deviations (which in some cases are smaller than the diameter of the symbols).
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Fig4: Oxygen uptake measurements for N. europaea[pSK2] (gray squares and gray line) and untransformed N. europaea (black diamonds and black line). a Measurements made starting with DO at 100% saturation. b Measurements made starting with DO at 25% saturation. All points are averages of five independent experiments; for every experiment at both initial oxygen concentrations and for both strains, the same mass of cells (0.06 OD600nm) was tested. Error bars indicate standard deviations (which in some cases are smaller than the diameter of the symbols).

Mentions: The transformant was compared with the untransformed control strain regarding respiration (SOUR) at both high oxygen concentration (starting at 100% saturation) as well as low oxygen concentration (starting at 25% saturation) (Fig. 4). Starting at 100% DO the SOUR of the transformant was substantially greater than that of the untransformed strain (Fig. 4a), but starting at lower DO the SOUR of the two strains was essentially identical (Fig. 4b).Fig. 4


Engineering of Nitrosomonas europaea to express Vitreoscilla hemoglobin enhances oxygen uptake and conversion of ammonia to nitrite.

Kunkel SA, Pagilla KR, Stark BC - AMB Express (2015)

Oxygen uptake measurements for N. europaea[pSK2] (gray squares and gray line) and untransformed N. europaea (black diamonds and black line). a Measurements made starting with DO at 100% saturation. b Measurements made starting with DO at 25% saturation. All points are averages of five independent experiments; for every experiment at both initial oxygen concentrations and for both strains, the same mass of cells (0.06 OD600nm) was tested. Error bars indicate standard deviations (which in some cases are smaller than the diameter of the symbols).
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4522006&req=5

Fig4: Oxygen uptake measurements for N. europaea[pSK2] (gray squares and gray line) and untransformed N. europaea (black diamonds and black line). a Measurements made starting with DO at 100% saturation. b Measurements made starting with DO at 25% saturation. All points are averages of five independent experiments; for every experiment at both initial oxygen concentrations and for both strains, the same mass of cells (0.06 OD600nm) was tested. Error bars indicate standard deviations (which in some cases are smaller than the diameter of the symbols).
Mentions: The transformant was compared with the untransformed control strain regarding respiration (SOUR) at both high oxygen concentration (starting at 100% saturation) as well as low oxygen concentration (starting at 25% saturation) (Fig. 4). Starting at 100% DO the SOUR of the transformant was substantially greater than that of the untransformed strain (Fig. 4a), but starting at lower DO the SOUR of the two strains was essentially identical (Fig. 4b).Fig. 4

Bottom Line: Vgb was maintained stably and appeared to be expressed in the transformants at VHb levels of about 0.75 nmol/g wet weight.Expression of VHb in the N. europaea transformants was correlated with an approximately 2 fold increase in oxygen uptake rate by whole cells at oxygen concentrations in the range of 75-100% saturation, but no change in oxygen uptake rate at oxygen concentrations below 25% saturation.VHb expression was also correlated with an increase of as much as about 30% in conversion of ammonia to nitrite by growing cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Illinois Institute of Technology, Chicago, IL, 60616, USA, skunkel@iit.edu.

ABSTRACT
Nitrosomonas europaea was transformed with a recombinant plasmid bearing the gene (vgb) encoding the hemoglobin (VHb) from the bacterium Vitreoscilla under control of the N. europaea amoC P1 promoter. Vgb was maintained stably and appeared to be expressed in the transformants at VHb levels of about 0.75 nmol/g wet weight. Expression of VHb in the N. europaea transformants was correlated with an approximately 2 fold increase in oxygen uptake rate by whole cells at oxygen concentrations in the range of 75-100% saturation, but no change in oxygen uptake rate at oxygen concentrations below 25% saturation. VHb expression was also correlated with an increase of as much as about 30% in conversion of ammonia to nitrite by growing cells. The results suggest that engineering of key aerobic wastewater bacteria to express bacterial hemoglobins may be a useful strategy to produce species with enhanced respiratory abilities.

No MeSH data available.


Related in: MedlinePlus