Bacteria, yeasts and fungi suspended in a dextran solution were added to ampoules containing strips of filter paper which were dried without vacuum conditions. The ampoules were sealed and stored in the dark at room temperature. Viability counts were made of the original suspension immediately after drying and after storage periods of 3-48 months. Although bacterial cultures of many general did not show much resistance against dry conditions, bacteria of 13 other general had survived well or moderately after 4 years of storage. Most of the dried yeast cultures had survived after this period. Of the 16 fungal genera tested, species of 6 genera exhibited growth after 4 years. Results of this study were compared with those of two other preservation methods by which the same microorganisms were used.
The survival rate of cells of the genera Arthrobacter, Pseudomonas, Mycobacterium, Escherichia, Micrococcus and Saccharomyces when counted immediately after fast or slow drying (20 minutes and 24 hours, respectively) was rather similar. However, after prolonged periods of dry storage, the number of viable cells after slow drying was much higher as compared with the rapidly dried cells. Investigations with Escherichia coli demonstrated this phenomenon only when more than about 8 mg of water per 10(8) cells was available on a filter paper disc. In order to obtain optimum resistance to water loss the dessication period of 0.025 ml of suspension of E. coli must be longer than 13 hours.
The influence of pH, temperature and organic matter on the degradation of the lignin-cellulose complex of coconut fibres was studied. Many fungi (deuteromycetes and ascomycetes) and bacteria were isolated from partly decayed coir. The decomposition of the coconut fibres by these isolates was estimated, imitating field conditions. Some fungi of the genera tested were able to partly decompose the coconut fibres after long incubation periods. However, the quick and total decay of the coir wrapper around drain pipes seems to be caused by basidiomycetes only.Wrappers of coconut fibres around plastic drain pipes are used in the Netherlands on a large scale. After having functioned for one or two years, however, the filter capacity may be reduced owing to decay of the coir. Although the decay of wood by soft rot fungi has frequently been investigated (1-3), the degradation of coconut fibres, with its lignin percentage of nearly 40 %, has hardly been studied, In this study different soil types with pH values ranging from 4.3 to 8.2 were tested in 2-liter jars, imitating field conditions. The influence of temperature on the rate of fibre decomposition was also investigated.Many fungi and bacteria, isolated from partly decayed fibres, were incubated aerobically in sterile Erlenmeyer flasks containing unattacked coconut fibres, soil, and water. After different incubation periods, the loss of tensile strength and elasticity of the fibres was estimated.
MATERIALS AND METHODSInfluence of soil type, pH and temperature on the rate of fibre degradation. The experiments were carried out with 2-liter glass jars in which the field conditions of the coir wrapper were imitated (4). Tensile strength and elasticity of the coconut fibres were estimated according to ANTHEUNISSE (5). The pH of the soil was measured after suspending 10 g of soil in 25 ml distilled water and shaking for 30 min.
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