A positive ecological role for tropical myxomycetes in association with bacteria

Through several separate studies made in our laboratory we have found that in rou- tine cultures myxomycete plasmodia are invariably associated - closely and tenaciously - with one bacterial species, and thus monoxenic. The association is not species-specific, but the bacte- ria in most cases belong to the Enterobacteriaceae. The bacteria can be easily isolated and grown in pure culture, but this is not always true for the plasmodium. From parallel studies con- ducted with monoxenic plasmodial structures and pure cultures of the bacterial associate, we find that the monoxenic plasmodia can fix atmospheric nitrogen, produce extracellular enzymes and degrade certain types of wood and litter, and also tolerate high concentrations of various chemical pollutants, while the bacterial associates in pure culture exhibit none of these proper- ties. Thus the association confers on the organism certain properties not manifest in the individ- ual partners. As a result of some of our natural observations we presume this to occur in nature, and ascribe to the myxomycetes a positive role in the recycling of nutrients on the forestfloor. The ideas expressed in this paper are the outcome of the results of the work done by several of my research students over the last twenty years. One of the most enthusiastic of these was S. Balaji, who died an untimely death in April this year, in a drowning accident at Freiburg, Germany where he was a Post-doctoral Fellow. I dedicate this paper to S. Balaji. Details of these experiments are being published elsewhere.