Microbiological transformation of pyridine derivatives (review)

Isolation of a 3-hydroxypyridine degrading bacterium, Agrobacterium sp. DW-1, and its proposed degradation pathway

A 3-hydroxypyridine degrading bacterium, designated strain DW-1, was isolated from petroleum contaminated soil in Liao River China. 16S rRNA-based phylogenetic analysis indicates that strain DW-1 belongs to genus Agrobacterium. The optimal cultivation temperature and pH for strain DW-1 with 3-hydroxypyridine were 30 °C and 8.0, respectively. Under optimal conditions, strain DW-1 could completely degrade up to 1500 mg/L of 3-hydroxypyridine in 66 h. The 3-hydroxypyridine degradation pathway of strain DW-1 was suggested by HPLC and LC-MS analysis. The first reaction of 3-hydroxypyridine degradation in strain DW-1 was α-hydroxylation so that the major metabolite 2,5-dihydroxypyridine was produced, and then 2,5-dihydroxypyridine was transformed by a Fe2+-dependent dioxygenase to form N-formylmaleamic acid. N-Formylmaleamic acid will be transformed to maleic acid and fumaric acid through maleamic acid. This is the first report of the 3-hydroxypyridine degradation pathway and the utilization of 3-hydroxypyridine by a Agrobacterium sp. It may be potentially used for the bioremediation of environments polluted with 3-hydroxypyridine.

Microbial degradation and metabolic pathway of pyridine by a Paracoccus sp. strain BW001

A bacterial strain using pyridine as sole carbon, nitrogen and energy source was isolated from the activated sludge of a coking wastewater treatment plant. By means of morphologic observation, physiological characteristics study and 16S rRNA gene sequence analysis, the strain was identified as the species of Paracoccus. The strain could degrade 2,614 mg l(-1) of pyridine completely within 49.5 h. Experiment designed to track the metabolic pathway showed that pyridine ring was cleaved between the C2 and N, then the mineralization of the carbonous intermediate products may comply with the early proposed pathway and the transformation of the nitrogen may proceed on a new pathway of simultaneous heterotrophic nitrification and aerobic denitrification. During the degradation, NH3-N occurred and increased along with the decrease of pyridine in the solution; but the total nitrogen decreased steadily and equaled to the quantity of NH3-N when pyridine was degraded completely. Adding glucose into the medium as the extra carbon source would expedite the biodegradation of pyridine and the transformation of the nitrogen. The fragments of nirS gene and nosZ gene were amplified which implied that the BW001 had the potential abilities to reduce NO2- to NO and/or N2O, and then to N2.

Microbial degradation of pyridine using Pseudomonas sp. and isolation of plasmid responsible for degradation

Pseudomonas (PI2) capable of degrading pyridine was isolated from the mixed population of the activated sludge unit which was being used for treating complex effluents, the strain was characterized. Aerobic degradation of pyridine was studied with the isolated strain and the growth parameters were evaluated. Pyridine degradation was further conformed by chromatography (HPLC) analysis. The process parameters like biomass growth and dissolved oxygen consumption were monitored during pyridine degradation. In order to conform with the plasmid capability to degrade pyridine, the requisite plasmid was isolated and transferred to DH 5alpha Escherichia coli. The subsequent biodegradation studies revealed the ability of the transformed plasmid capability to degrade the pyridine.