1887

Abstract

The kinetics of carboxylic acid methylation by chloromethane (CHCl) in mycelia of the fungus were examined. Substantial incorporation of CH-into ester was observed within 5 min of addition of CHCl to washed mycelia in the presence of the non-physiological acceptor butyric acid, rendering it unlikely that CHCl was converted to a diffusible intermediate before acting as methyl donor. The rate of methyl butyrate biosynthesis attained a maximum of 0·14 mol g h at 1·5 m-butyric acid, with higher concentrations causing increasing inhibition. Exogenous CHCl did not affect methyl butyrate production implying that the rate of CHCl biosynthesis did not limit methylation. However, CH,-incorporation from exogenous CHCl into methyl butyrate rose sharply from 20 to 60% between 15 and 4 m-butyric acid, suggesting inhibition of CHCl biosynthesis by the acid, an interpretation supported by the rapid decline in gaseous CHCl release by mycelia between 1·5 and 2 m-butyric acid. With the natural acceptor benzoic acid as substrate a significant increase in the rate of ester biosynthesis was obtained in the presence of exogenous CHCl. Ester biosynthesis was maximal (0·18 μmol g h) at 0·5 m-benzoic acid but fell extremely rapidly with increasing concentration. As with butyric acid supraoptimal concentrations halted CHCl release and increased CH-incorporation from exogenous CHCl. Studies on CH-incorporation from exogenous CHCl into ester revealed a linear relationship between the logarithm of the percentage CH-incorporation and the logarithm of CHCl concentration with both butyric and benzoic acids as substrate, suggesting that exogenous CHCl competed with endogenously synthesized CHCl for adsorption at a solid interface, possibly a membrane within the cell, prior to reaction of the compound at the active site. When mycelia were grown in the presence of different halide ions, greater methylating activity was found in Br- and I-grown mycelia. The system had a higher affinity for CHBr and CHI as methyl donors than CHCl. Fluoromethane was not a substrate for the methylating system nor did it act as a competitive inhibitor.

Loading

Article metrics loading...

/content/journal/micro/10.1099/00221287-136-8-1509
1990-08-01
2021-10-18
Loading full text...

Full text loading...

/deliver/fulltext/micro/136/8/mic-136-8-1509.html?itemId=/content/journal/micro/10.1099/00221287-136-8-1509&mimeType=html&fmt=ahah

References

  1. Collins R.P., Halim A.F. 1972; An analysis of odorous constituents produced by various species of Phellinus. . Canadian Journal of Microbiology 18:65–66
    [Google Scholar]
  2. Cowan M.I., Glen A.T., Hutchinson S.A., Macartney M.E., Mackintosh J.M., Moss A.M. 1973; Production of volatile metabolites by species of Fomes. . Transactions of the British Mycological Society 60:347–360
    [Google Scholar]
  3. Glasstone S., Lewis D. 1960 Elements of Physical Chemistry,, 2nd edn.. pp 558–567 London:: MacMillan.;
    [Google Scholar]
  4. Harper D.B. 1985; Halomethane from halide ion - a highly efficient fungal conversion of environmental significance. Nature; London: 31555–57
    [Google Scholar]
  5. Harper D.B., Hamilton J.T.G. 1988; Biosynthesis of chloromethane in Phellinus pomaceus. . Journal of General Microbiology 134:2831–2839
    [Google Scholar]
  6. Harper D.B., Kennedy J.T. 1986; Effect of growth conditions on halomethane production by Phellinus species: biological and environmental implications. Journal of General Microbiology 132:1231–1246
    [Google Scholar]
  7. Harper D.B., Kennedy J.T., Hamilton J.T.G. 1988; Chloromethane biosynthesis in poroid fungi. Phytochemistry 27:3147–3153
    [Google Scholar]
  8. Harper D.B., Hamilton J.T.G., Kennedy J.T., McNally K.J. 1989; Chloromethane, a novel methyl donor for biosynthesis of esters and anisoles in Phellinus pomaceus. . Applied and Environmental Microbiology 55:1981–1989
    [Google Scholar]
http://instance.metastore.ingenta.com/content/journal/micro/10.1099/00221287-136-8-1509
Loading
/content/journal/micro/10.1099/00221287-136-8-1509
Loading

Data & Media loading...

Most cited this month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error