Fungi and bacteria associated with the wet and brown wood in trunk of Betula pendula trees

Bacteria and fungi were isolated from external and internal zone of brown and water saturated wood of trunk of Betula pendula trees aged 44-46. Quantitative and qualitative differences in the bacterial and fungal populations were found between both the zones. Populations of bacteria increased towards the internal sapwood, contrary to the fungi which more frequently colonised the external zone. The most common bacteria were Pseudomonas spp. (mainly P.fluorescens biovar I) whereas Bacillus macerans, B. alvei and Erwinia heibicola were able to degrade the polygalacturonic acid and pectin gels. In case of the fungi population, the most common (more than 3%) colonising the external zone were successively: Phialophora fastigiata, Trichoderma harzianum, Alternaria alternata, Mortierella isabellina, Cladosporium herbarum, T. viride, C. cladosporioides and Melanconium betulinum. In the community of fungi occurring in the internal zone, the most common (more than 6.5%) were:Cladosporium herbarum, Phialophora lagerbergii and Ph.fastigiata