Use of coumarin by soil fungi

Abstract

Use of coumarin by soil fungi has been studied. The route of coumarin degradation was suggested to proceed first by reduction to dihydrocoumarin and then by hydration to melilotic acid.

Biodegradation of 7-Hydroxycoumarin in Pseudomonas mandelii 7HK4 via ipso-Hydroxylation of 3-(2,4-Dihydroxyphenyl)-propionic Acid

“…After the completion of bioconversions, there were no visible spectra observed for the residual aromatic compound in the reaction mixtures with 7-hydroxycoumarin, except for the reactions with 6-hydroxycoumarin, 6,7-dihydroxycoumarin, and coumarin, which had non-disappearing UV absorption maxima at 260–270 nm wavelengths. These spectra are similar to that of 3-phenylpropionic acid (data not shown), suggesting that 7-hydroxycoumarin-induced 7HK4 strain can only catalyze the hydrolysis and reduction of lactone moiety of coumarin, 6-hydroxycoumarin, and 6,7-dihydroxycoumarin producing 3-(2-hydroxyphenyl)-propionic, 3-(2,5-dihydroxyphenyl)-propionic, and 3-(2,4,5-trihydroxyphenyl)-propionic acids, respectively, comparable to similar biotransformations in other microorganisms [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 ]. In addition, uninduced Pseudomonas sp.…”

“…It has been shown previously that 3-(2-hydroxyphenyl)-2-propenoic and 3-(2-hydroxyphenyl)-propionic acids, as shown in Figure 1 B, are the intermediates in a known coumarin metabolic pathway in several microorganisms [ 9 , 10 , 11 , 14 , 16 ]. By analogy, it was suggested that 3-(2,4-dihydroxyphenyl)-propionic acid may be an intermediate metabolite in 7-hydroxycoumarin catabolism, as shown in Figure 1 B.…”

“…Furthermore, 3-(2,4-dihydroxyphenyl)-propionic acid has been identified as an intermediate metabolite during biotransformations of 7-hydroxycoumarin. This finding agrees with the data published for the conversion of coumarin by Pseudomonas spp., Arthrobacter spp., and Aspergillus spp., which all catalyze the hydrolysis and reduction of coumarin producing 3-(2-hydroxyphenyl)-propionic acid as the main intermediate [ 9 , 10 , 11 , 14 ]. However, compared with P. mandelii 7HK described in this study, little is known about the bioconversion of other coumarin derivatives as well as further conversions of 3-(2-hydroxyphenyl)-propionic acid in bacteria listed above.…”

“…It has been shown previously that a number of soil microorganisms, such as Pseudomonas , Arthrobacter , Aspergillus , Penicillium , and Fusarium spp. can grow on coumarin ( 1 ) as a sole source of carbon [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 ]. The key intermediate during coumarin catabolism in bacteria is 3-(2-hydroxyphenyl)-propionic acid ( 4 ) [ 10 , 11 , 16 ].…”

“…In the case of Pseudomonas sp. 30-1 and Aspergillus niger ATCC 11394 cells, coumarin is initially reduced to dihydrocoumarin ( 3 ) by a NADH-dependent oxidoreductase and only then enzymatically hydrolyzed [ 9 , 10 , 14 ]. Arthrobacter and Pseudomonas species are capable of oxidizing 3-(2-hydroxyphenyl)-propionic acid to 3-(2,3-dihydroxyphenyl)-propionic acid by using specific flavin-binding aromatic hydroxylases [ 16 ].…”