The culture supernatant of the enrichment culture was mixed with pentafluorobenzyl bromide and then analyzed. The mass

spectrum of the pentafluorobenzyl derivative showed a molecular ion at m/z 226 (M+). The GC retention time and MS spectrum of the derivatized compound agreed with those of formate derivatized by pentafluorobenzyl bromide. In the enrichment cultures grown on 2.12, 6.38, and 10.6 mM 4-aminopyridine for 10 days, 0.05 ± 0.012 mM formate accumulated in 10.6 mM 4-aminopyridine medium. Although the enrichment culture gradually degraded 4-aminopyridine with growth, 4-amino-3-hydroxypyridine accumulated in the culture to a final concentration of 6.4 × 10−3 BIX 1294 datasheet mM after 5 days of cultivation. When we cultivated the enrichment culture in basal medium containing 4-amino-3-hydroxypyridine or 3,4-dihydroxypyridine (final concentration, 0.05% wt/vol) with and without 4-aminopyridine, the culture completely degraded 3,4-dihydroxypyridine in both media in 4 days but did not degrade 4-amino-3-hydroxypyridine in either medium. Identification of the gene encoding 3-hydroxy-4-pyridine dioxygenase in the isolated strains We hypothesized that 4-aminopyridine is metabolized to 3,4-dihydroxypyridine, and that the pyridine ring is then cleaved by 3-hydroxy-4-pyridone dioxygenase, as described below. The fragment amplified

by pydA-specific primers was isolated and analyzed to determine whether some predominant strain in the enrichment culture carries the dioxygenase gene. The same sequence fragment https://www.selleckchem.com/products/AC-220.html was amplified from three different samples. The amino acid sequence deduced from the determined 801-bp sequence showed a high level of identity with sequences of the extradiol-dioxygenase-3B-like superfamily of proteins, especially with that of the putative PydA from Hyphomicrobium sp. MC1 (YP_004673996) (see Additional file 2: Figure S1). Isolation of culturable bacterial strains from

the enrichment culture The enrichment culture contained at least seven strains of dominant bacteria (designated as strains 4AP-A to 4AP-G) that could grow on nutrient agar. The physiological and learn more biochemical parameters of strains 4AP-A and 4AP-G were characterized, and their 16S rRNA genes were analyzed by sequencing. Strains 4AP-B, 4AP-C, 4AP-D, 4AP-E, and 4AP-F were classified by 16S rRNA gene analysis (Table 2, see Additional 3-mercaptopyruvate sulfurtransferase file 1: Tables S1 and S2). None of these strains could degrade 4-aminopyridine by itself or when combined with other strains, including all six of the other culturable dominant strains. Table 2 Identification of bacteria constituting the 4-aminopyridine-degrading enrichment culture Strain Genus or species affiliation (RDP II classifier) Best database match Identity (%) 4AP-A Pseudomonas nitroreducens P. nitroreducens IAM 1439 (AM088473) 1511/1523 (99.1%) 4AP-B Stenotrophomonas maltophilia S. maltophilia e-p13 (AJ293473) 1532/1537 (99.7%) 4AP-C Enterobacter agglomerans E.