Nitrogen Incorporation into Lignite Humic Acids during Microbial Degradation

• Published in: Geomicrobiology journal 2009-10, Vol.26 (7), p.484-490
• Main Authors: Dong, LianHua, Yuan, HongLi
• Format: Article
• Language: English
• Subjects: 01 COAL, LIGNITE, AND PEAT; AGRICULTURE; AMMONIUM SULFATES; BIODEGRADATION; HUMIC ACIDS; LIGNITE; microbial degradation; NITROGEN; nitrogen incorporation; USES
• ISSN: 0149-0451; 1521-0529
• DOI: 10.1080/01490450903061085

Previous study showed that nitrogen content in lignite humic acids (HA) increased significantly during lignite biodegradation. In this paper we evaluated the factors responsible for the increased level of N in HA and the formation of new nitrogen compound following microbial degradation. When the ammonium sulfate concentration in lignite medium was < 0.5%, the N-content in HA was higher than that in the crude lignite humic acid (cHA); when the ammonium sulfate concentration was ≥ 0.5%, both the biodegraded humic acid (bHA) N-content and the content of bHA in lignite increased significantly, but at 2.0% no increase was observed. This indicated that HA incorporated N existing in the lignite medium, and more HA can incorporate more N with the increase of bHA amount in lignite during microbial degradation. CP/MAS 15 N NMR analysis showed that the N incorporated into HA during biotransformation was in the form of free or ionized NH 2 -groups in amino acids and sugars, as well as NH 4 + . We propose nitrogen can be incorporated into HA biotically and abiotically. The high N content bHA has a potential application in agriculture since N is essential for plant growth.