Culturing erosion bacteria: Procedures for obtaining purer cultures and pure strains

This paper describes procedures used in attempts to isolate pure strains of erosion bacteria from bacterial consortia obtained from decaying wood. The wood originated from archaeological waterlogged wood and foundation pilings. Kapok fibres were used as a substitute for wood in most experiments. Erosion bacteria attached firmly to the surface of kapok fibres and to cellophane. Intense washing of these substrates resulted in active cultures with a reduced number of associated secondary bacteria. This was not achieved with common dilution techniques. Pure strains obtained from streaking on cellulose or nutrient agar failed to attack kapok fibres and pine wood. Single erosion bacteria cells were separated from secondary bacteria by using laser techniques (optical tweezers). Molecular analyses of the most purified culture, obtained through washing of cellophane, and of laser separated bacteria, suggested that erosion bacteria belong to the CFB (Cytophaga-Flavobacterium-Bacteroides) complex.