The yeast Pichia sp. As a short-term biological control agent to fungal spoilage of sawn softwood timber
C Payne, H J Staines, A Bruce
Previous work has found isolates of the yeast Pichia to be a successful biological control agent toward moulding of fruits. An isolate was tested for the ability to protect sapwood of Pinus sylvestris timber against visual degrade by surface growth of moulds and staining fungi. Successful protection of autoclaved wood sprayed with a mixture of common wood moulding fungi was achieved when the yeast was applied at a rate of 6 x 10 8 cells/cm2. Yeast cells were sprayed onto the wood blocks at the same time as the fungi and blocks were incubated under conditions favourable to fungal development for 15 and 25 days before assessment using a visual scale. Limitation of the disfigurement of green wood required a similar cell application rate. Protection of blocks sprayed with Ophiostomatoid staining fungi following sterilisation required a lower concentration of yeast cells (2 x 10 6 cells/cm2). Survival and reproduction of Pichia cells on sterilised wood blocks was also determined across a range of relative humidity and temperature conditions previously found to support development of wood moulding and staining fungi. Following 16 weeks incubation at temperatures of 8-25°C at relative humidity 93-100%, between 46 and 473% of the number of colony forming units applied to the wood were recovered. Maximum increase in viable yeast cell count on wood blocks occurred at 100% relative humidity and 15°C.