In vitro evaluation of dew-retting of flax by fungi from southern Europe

Summary Flax dew-retting is widely adopted in most flax-growing countries, but it does not represent a practical solution where dry weather conditions occur after harvest. A study of the local microbiological aspects was undertaken as a contribution to improve field-retting of flax under southern European climates. Fungi were isolated from soil and dew-retted flax in northern Italy, and 23 representative strains were chosen to test their ability to ret flax stems. Experiments were performed in vitro on flax stem pieces artificially inoculated with single fungal strains. Retting degree was assessed with a mechanical test, to evaluate the ease with which the bast was detached from the wood core, and by the analysis of the residual fibre pectins using uronic acid. Uronic acid dosage provided a better differentiation of the strains than the mechanical test. There was a large variability in retting ability among the species assayed and even among strains of the same species. The best results were obtained with all Aspergillus and Penicillium strains, while Mucor and Rhizopus strains showed a variable retting ability. Fusarium, Trichoderma strains and Epicoccum nigrum had the poorest retting abilities among all the fungal strains assayed.

[1]  N. Vertregt,et al.  The pectin content as a measure of the retting and rettability of flax , 1995 .

[2]  P. Mercer,et al.  Degradation of flax stems by Botrytis cinerea , 1988 .

[3]  N. Blumenkrantz,et al.  New method for quantitative determination of uronic acids. , 1973, Analytical biochemistry.

[4]  H. Sharma,et al.  Production of polysaccharide-degrading enzymes by saprophytic fungi from glyphosate-treated flax and their involvement in retting , 1984 .

[5]  P. E. Nelson,et al.  Fusarium species: an illustrated manual for identification. , 1983 .

[6]  J. D. Bilbro,et al.  Illustration of a Cluster Analysis Method for Mean Separation1 , 1978 .

[7]  Danny E. Akin,et al.  Production of highly efficient enzymes for flax retting by Rhizomucor pusillus , 1999 .

[8]  Averil E. Brown,et al.  Epicoccum nigrum, a primary saprophyte involved in the retting of flax , 1984 .

[9]  D. L. Black,et al.  Relationship between pectin content of stems of flax cultivars, fungal cell wall-degrading enzymes and pre-harvest retting , 1986 .

[10]  R. Hanlin,et al.  Identification and retting efficiencies of fungi isolated from dew-retted flax in the United States and europe , 1997, Applied and environmental microbiology.

[11]  T. Wood.  The cellulase of Fusarium solani. Purification and specificity of the -(1-4)-glucanase and the -D-glucosidase components. , 1971, The Biochemical journal.

[12]  H. Sharma.  An alternative method of flax retting during dry weather , 1986 .

[13]  D. Seaby,et al.  Development of a hand tool to test the degree of retting of flax straw , 1984 .

[14]  G. Henriksson,et al.  Structural Effects on Flax Stems of Three Potential Retting Fungi , 1998 .

[15]  P. R. van Weeren,et al.  A microtiter plate assay for the determination of uronic acids. , 1998, Analytical biochemistry.

[16]  P. C. Bargale.  Development and testing of a manual flax-scutching machine , 1990 .

[17]  C. Sams,et al.  Purification and characterization of a polygalacturonase produced by Penicillium expansum in apple fruit , 1996 .

[18]  J. Lewis,et al.  Liquid Fermentation Technology for Experimental Production of Biocontrol Fungi , 1984 .

[19]  L. Madden.  Considerations for the Use of Multiple Comparison Procedures in Phytopathological Investigations , 1982 .

[20]  F. de França,et al.  Retting of Flax by Aspergillus niger. , 1969, Applied microbiology.