INDUCTION OF GERMINATION IN MYXOCOCCUS-XANTHUS FRUITING BODY SPORES

Myxococcus xanthus, when starved on a solid surface, undergoes a multicellular cycle of development that consists of fruiting and sporulation. Myxospore germination has been followed in CTT, a complex medium composed mainly of peptides, by monitoring the sequential disappearance of some characteristic spore properties. Loss of heat resistance, shortly after incubation was initiated, was followed by loss of resistance of SDS and finally, refractility and ovoid shape. Germination of a population of myxospores did not occur synchronously. However, in the presence of calcium, germination was activated, being more rapid and synchronous. Other spore activation treatments tested did not have the same stimulatory effect. We searched for specific nutrients or chemicals capable of inducing germination. Amino acids, unlike other potential carbon and energy sources for M. xanthus, or several sugars tested, were most effective in triggering germination. Continuous incubation in CTT and Casamino acids germinant solutions was not required for induction and completion of germination of a large proportion of spores in a population.