Fungi colonising wood in the cooling tower water system at the Madras Fertilizer Company, Madras, India

A cooling tower water system at the Madras Fertilizers Company, Madras, India was investigated for the occurrence of microfungi over a period of 108 weeks from March 1978 to April 1980. The make-up water, cooling tower water and effluent were baited with pine (Pinus patula Schl. & Cham.) and beech (Fagus rhamnifolia A. DC.) wooden test blocks. Observations were made at 6-weekly interval for the qualitative and quantitative changes in the species composition. The study showed that a cooling tower water system in the tropics provides a suitable environment for the growth and development of a variety of microfungi. Differences in the physical and chemical factors (e.g. temperature, effluent concentration, etc.) in cooling tower water systems have a profound effect on the composition of the mycoflora. Generally beech test blocks attracted a greater variety of fungi than pine. A total of 106 species belonging to 65 genera were isolated from the cooling tower water system, which were classified into ‘primary’, ‘secondary’ and ‘sporadic’ colonisers on the basis of the sequence and frequency of their appearance on the test blocks. Further, based on the percentage frequency the fungi were categorised into ‘dominant’, ‘common’, ‘frequent’, ‘occasional’ and ‘rare’ forms. Some of them reported in this study are already known for their potency to cause soft rot and white rot in wood.