We found a match
Your institution may have rights to this item. Sign in to continue.
- Title
N<sub>2</sub>-FIXING CYANOBACTERIA HARNESSED FOR BIOSOLAR PRODUCTION OF NITROFERTILIZER.
- Authors
Shengni Tian; Huilan Zhu; Liping Gu; Ruanbao Zhou
- Abstract
Nitrogen fertilizer is a primary driver in agricultural productivity, and thus impacts food, feed, fiber, and fuel production. Unfortunately, current fossil fuel-dependent ammonia production is energy intensive and damaging to the environment. Economic and eco-friendly methods to produce ammonia are urgently needed. Fortunately, N2-fixation by cyanobacterial heterocysts offers such a unique opportunity. When combined nitrogen becomes limiting, the cyanobacterium Anabaena species responds by the formation of terminally differentiated, specialized nitrogen-fixing cells called heterocysts. However, mankind has largely ignored its potential application for this solar-powered, oxic N2-fixation in heterocysts. Normally, the amount of ammonia produced by the heterocysts of Anabaena is tightly regulated to be just sufficient to support the growth of vegetative cells, with little or no excess of ammonia to secrete. However, reducing glutamine synthetase (GlnA) activity in vivo could lead to ammonia secretion (Qin et al. 1999. Current Microbiology 46(6):423-31; Healy et al. 2003. Acta Botanica Sinica 41(1):65-70.). We hypothesized that genetically knocking down the GlnA activity would increase the secreting rate of ammonia produced by the nitrogenase. Therefore, this project is to create ammonia secreting Anabaena mutant strains by both knocking out and knocking down the glnA gene. Three independent glnA-knockout mutants have been created through inactivating the glnA (alr2328) in Anabaena sp. PCC 7120. These mutants were capable of secreting 5, 3 and 20-fold more ammonia than the wild-type strain during 26h, 48h and 72h of N2-fixing, respectively. The average secretion rates of ammonia were 6.6, 44.2 and 254 µg/ml/OD700/h, respectively. Three independent glnA-knockdown mutants created through overexpressing an anti-sense of glnA secreted 108, 16, 13-fold more ammonia than the wild-type strain during 26, 48 and 72h of N2-fixing, respectively. The average secretion rates of ammonia during 26h, 48h and 72h were 145, 220 and 154 µg/ml/OD700/h, respectively.
- Subjects
NITROGEN-fixing bacteria; CYANOBACTERIA
- Publication
Proceedings of the South Dakota Academy of Science, 2018, Vol 97, p257
- ISSN
0096-378X
- Publication type
Article