Isolation from Urine of Two Serratia marcescens Strains Excreting a Diffusible Yellow Pigment

Abstract

Two bacterial strains excreting a yellow pigment were isolated from human urine and identified as Serratia marcescens. The pigment was produced in the late exponential and early stationary phases of growth. Minimal media supplemented with tyrosine, phenylalanine, 3,4-dihydroxyphenylacetate or tryptophan, as well as complex media, induced pigment production. UVvisible spectra of the extracted pigment had peaks characteristic of 2-hydroxy-5-carboxymethylmuconate semialdehyde, produced from meta-cleavage of 3,4-dihydroxyphenylacetate by the enzyme 3,4-dihydroxyphenylacetate 2,3-dioxygenase (EC 1 .13.11.15). This enzyme was active when the bacteria were grown under conditions promoting pigment production. The kinetics and factors affecting pigment production are also reported.

Brown pigmentation in Serratia marcescens cultures associated with tyrosine metabolism

“…Among bacteria, eurnelanins have been demonstrated in Actinomycetes (Kiister 1976) and factors than pigmented ones, which could be an advantage in clinical environments (Ding and Williams 1983;Platt and Sommerville 1981 ;Quian et al 1982). Recently, we described two S. marcescens strains that excreted a yellow diffusible pigment, 2-hydroxy-5-carboxymethylmuconic acid semialdehyde, which is related to the catabolism of tyrosine in this species (Trias et al 1987a(Trias et al , 1988. While studying the induction of the yellow pigment in nonpigmented strains of S. marcescens isolated from human infections, we found that sometimes brown pigmentation appears in the culture medium.…”

“…Mutant enrichment was performed by a modification of the azthreonam mutant enrichment method (Trias et al 1987b). The mutagenized cells were pelleted and resuspended in Erlenmeyer flasks with 50 mL of M70 medium (Grimont and Grimont 1984), with tyrosine as the sole carbon and energy source.…”

“…Mutagenesis with N-methyl-N-nitro-N-nitrosoguanidine was carried out as previously described (Trias et al 1987b). Mutant enrichment was performed by a modification of the azthreonam mutant enrichment method (Trias et al 1987b).…”

“…Strain CW551 (Trias et al 1987b) was used in the studies of the kinetics of pigment production, as well as in enzyme assays and mutagenesis. Strain ATCC 274 was used as a control.…”

“…A mineral medium (GL) for S. marcescens was prepared as previously described (Lorkn and Guinea 1978;Trias et al 1987a). Tyrosine was added to GL to give a final concentration of l g/L (GLT medium).…”