Eight of these Luminespib cell line isolates were found to grow poorly, or not at all, on phenylacetic acid as a sole carbon source in 96 well plates with liquid minimal salts media, (results not shown). Subsequent attempts to cultivate these eight isolates on similar media with styrene as a sole carbon source revealed only one mutant as being capable of growth, D7, achieving wild type biomass levels after a 12 hour period, Figure 2(a). The ability of D7 to grow on styrene indicated that catabolism

of the phenylacetic acid intermediate was functional in this mutant. Indeed, subsequent assays of a key enzyme in the process, phenylacetyl-CoA (PACoA) ligase, revealed almost identical activities in styrene grown wild type and D7 mutant cells, (1.8 ± 0.2 and 2.0 ± 0.19 nmol.min-1.mg-1 cell dry weight, respectively). However, D7 failed to grow when inoculated into liquid minimal salts media with phenylacetic acid as the sole carbon source, Figure 2(b). The ability of D7 to grow on styrene, (reflecting intracellular phenylacetic acid formation and degradation), but not on extracellular phenylacetic acid as supplied in the media, suggested the potential https://www.selleckchem.com/EGFR(HER).html mini-Tn5 disruption of a gene(s) involved in phenylacetic acid uptake. Growth of D7 on a non catabolon related substrate, citrate, produced GSK2126458 mw a similar profile to growth on styrene, Figure 2(a) and 2(c), suggesting core metabolism was intact. Figure

2 Growth analyses of wild type and D7 mutant strains. Growth analyses of P. putida CA-3 wild type (WT), rpoN disrupted mutant (D7) and RpoN complemented mutant (D7-RpoN+) grown on; (a) styrene, (b) phenylacetic acid and, (c) citrate, respectively. Identification and complementation of the rpoN gene disruption The insertion site of the mini-Tn5 transposon was mapped using Olopatadine two consecutive rounds of arbitrary PCR and the resulting amplicons sequenced and analysed using the GenBank, BLASTn algorithm. The chromosomal region immediately downstream of the Tn5

insertion displayed over 98% sequence similarity to rpoN genes from other P. putida strains, suggesting the gene was disrupted in mutant D7. The nucleotide sequence of the full gene was subsequently generated and submitted to Genbank under the accession number HM756586. In P. putida KT2440 the rpoN gene forms part of an operon with 4 putative downstream genes encoding members of the phosphotransferase system, including ptsN and ptsO [19]. While such an operonic structure has not been demonstrated for P. putida CA-3, the possibility existed that the observed phenylacetic acid negative phenotype of the D7 mutant may in fact have been as a result of downstream pleiotropic effects of the Tn5 insertion in rpoN. However, complementation of the disrupted rpoN with the cloned, full length wild type gene, (D7-RpoN+), was found to completely restore the strain’s ability to grow on styrene and phenylacetic acid, respectively, Figure 2(a) and 2(b).