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KMID : 0545120100200081251
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Journal of Microbiology and Biotechnology
2010 Volume.20 No. 8 p.1251 ~ p.1258
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Ammonium Production During the Nitrogen-Fixing Process by Wild Paenibacillus Strains and Cell-Free Extract Adsorbed on Nano TiO2 Particles
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Dariush Shokri0090036
Giti Emtiazi
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Abstract
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During the nitrogen-fixing process, ammonia (NH3) is incorporated into glutamate to yield glutamine and is generally not secreted. However, in this study, NH3- excreting strains of nitrogen-fixing Paenibacillus were isolated from soil. The ammonium production by the Paenibacillus strains was assayed in different experiments (dry biomass, wet biomass, cell-free extract, and cell-free extract adsorbed on nano TiO2 particles) inside an innovative bioreactor containing capsules of N2 and H2. In addition, the effects of different N2 and H2 treatments on the formation of NH3 were assayed. The results showed that the dry biomass of the strains produced the most NH3. The dry biomass of the Paenibacillus strain E produced the most NH3 at 1.50, 0.34, and 0.27 μM NH3/mg biomass/h in the presence of N2 + H2, N2, and H2, respectively, indicating that a combined effluent of N2 and H2 was vital for NH3 production. Notwithstanding, a cell-free extract (CFE) adsorbed on nano TiO2 particles produced the most NH3 and preserved the enzyme activities for a longer period of time, where the NH3 production was 2.45 μM/mg CFE/h over 17 h. Therefore, the present study provides a new, simple, and inexpensive method of NH3 production.
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KEYWORD
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ammonium, Paenibacillus, nano TiO2 particles, nitrogenase, nitrogen-fixing process
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