Actinoplanetes in soil and on plant litter from freshwater habitats

An isolation method for actinoplanetes is described which uses the ability of the sporangium to withstand desiccation and release motile spores when subsequently rehydrated. The desiccation stage reduces the number of associated Gram negative bacteria which cause problems when attempts are made to isolate species on agar plates from natural substrates. The method has enabled the isolation of actinoplanetes directly from soil and plant litter and indirectly from soil with the aid of baits such as pollen and hair. Actinoplanetes appear to be common in dry soils collected from arid areas and sand dune systems. They are normally present on leaves submerged for a time in rivers, streams and lakes and subsequently deposited in heaps on shores or as debris on overhanging vegetation. An actinomycete resembling the ‘spore-dome’ organism recovered from leaves and twigs by Willoughby (1969) was frequently isolated during the course of these studies. Preliminary work suggests that different species can be recognized and could constitute a new genus within the family Streptomycetaceae.