Nitrogen microorganism metabolism

A83. Nicholas, D.J.D. Role of trace elements in the nitrogen 20A100. metabolism of plants with special reference to microorganisms J. Sci. Food Agric. 8 (1957), (Supplemental) sl5-s25. 20A101. 

It was specifically stated that the proposed metabolic pathway, which suggest C—N bond cleaving and so, a N-specific mechanism, was found when PTA-806 was employed as the biocatalyst. However, when the quinoline-adapted microorganisms, initially isolated from the chemostats (the native P. ayucida), were tested, they were found to fully degrade quinoline, utilizing it as both, a carbon as well as a nitrogen source. 

In summary, two general pathways are now accepted as the reaction basis of pyridine degradation by bacteria. One involves (i) hydroxylation reactions, followed by reduction, e.g., on Bacillus strain 4 and the other (ii) (aerobic) reductive pathway(s) not initiated by hydroxylations, e.g., on Nocardia strain Zl [348], Two review articles, one by Kaiser [320] and the other by Fetzner [326] gave the complete microbial metabolic pathways for several nitrogen compounds carried out in the presence of a variety of microorganisms, some of them previously studied by Professor Lingens [349], The complete degradation pathways of pyridine are shown in Fig. 29. 

A particular feature of phytoremediation is its suitability for the removal of common gaseous pollutants, such as CO2, NO2, CO and O3, which is difficult to achieve by physical methods. Since CO2 is a nutritional requirement for plant growth, elevated levels are favourable. Up to 10% of assimilated nitrogen is provided by the uptake of NO2 in certain plant species (Morikawa at el. 1999). CO is metabolized mainly by microorganisms, but to some extent also by plants (Orcutt and Nilsen 2000). Finally, O3 is taken up and removed from the environment by certain plants which have a high capacity to scavenge hydroxyl radicals, and these are the species commonly recommended for cultivation in urban areas, where this pollutant is common. 

---