Effect of volatiles from bacteria and yeast on the growth and pigmentation of sap-stain fungi
A Bruce, R E Wheatley, S Verrall
Sapstain fungi cause deterioration of wood due to colonisation by pigmented hyphae but without producing significant strength losses. This is due to the production of melanin in the fungal cell walls of the staining fungi. Any biological control strategy targeted against this type of deterioration would therefore be considered successful if it inhibited either fungal growth or pigment production. Previous work has established that specific bacterial and yeast isolates selected on the basis of agar screening studies could significantly reduce levels of staining in wood block tests. This paper presents the results of a study to examine the role of volatile organic compounds (VOCs) produced by three bacterial and three yeast isolates on the growth and pigment production by a range of five sap-stain fungi on three media types. Results were variable and dependent on media type. Of all combinations tested Sclerophoma pityophila showed greatest levels of inhibition when exposed to bacterial VOCs when grown on tryptone soya agar. On some occasions, although no significant inhibition of growth was produced, the level of pigmentation of the sapstain colony as measured using image analysis equipment was significantly reduced compared with corresponding controls. The implications of this work for the biological control of sapstain fungi are discussed.