Development of a recombinant ureolytic Lactococcus lactis for urea removal.
Kidney failure is a common disease with high frequency. Food-grade recombinant bacteria that can effectively remove urea has great potential for treatment of renal failure. A nonpathogenic strain, L. lactis MG1363, was transformed with plasmid pMG36eure, which carries urease gene. The expression of transgene urease in genetically modified L. lactis MG1363 and the urease activity in removal of urea were investigated. It was found that the removal of urea by recombinant L. lactis MG1363 was pH- and nickel-dependent. At pH 6.5 and in the presence of 250 microM of NiSO4, 50 approximately 60% of urea could be removed in 24 hours. The urea removal activity was also evaluated in imitative gastroenteric environment. After being exposed to acidic solution (pH2.5-4.0) for 2 hours, the cells were then grown in a medium containing 0.1 cfu/ml bile acid salt, 30 mg/dl urea, and 250 microM NiSO4 at pH 6.8. The concentration of urea decreased over time, and the removal was about 30% at 10 hours and 65% at 24 hours, respectively. The safety tests were performed by feeding normal rats with either L. lactis MG1363 or recombinant L. lactis MG1363. The two materials did not cause any changes in blood cells and blood biochemical indexes. There were no differences in terms of body weight and water/food consumption between the two materials. These results indicate the safety, feasibility, and capacity of urease gene modified Lactococcus Lactis in removal of urea under the gastroenteric circumstances. Further investigation may generate a food-grade strain for treatment of chronic renal failure.
Zhang
Suai
S
Key Laboratory of Bioactive Materials, Ministry of Education, College of Life Science, Nankai University, Tianjin, China.
Li
Dongxia
D
Tian
Kai
K
Bai
Yu
Y
Zhang
Hongkai
H
Song
Cunjiang
C
Qiao
Mingqiang
M
Kong
Deling
D
Yu
Yaoting
Y
D000818:Animals; D001691:Biological Therapy / Q000379:methods*; D005818:Genetic Engineering; D006863:Hydrogen-Ion Concentration; D007674:Kidney Diseases / Q000628:therapy; D013294:Lactococcus lactis / Q000235:genetics*; D009532:Nickel / Q000494:pharmacology; D051381:Rats; D011994:Recombinant Proteins; D014169:Transformation, Bacterial; D019076:Transgenes; D016896:Treatment Outcome; D014508:Urea / Q000378:metabolism*; D014510:Urease / Q000008:administration & dosage / Q000235:genetics / Q000378:metabolism* / Q000627:therapeutic use
D011994:Recombinant Proteins; D009532:Nickel; D014508:Urea; D014510:Urease