Nutritional Requirements for Growth in Vitro of the Mycoplasmalike Organism Associated with Citrus Stubborn Disease’

Abstract

The most suitable culture conditions for the mycoplasmalike organism, isolated frequently from stubborn-diseased citrus plants, were investigated. The requirements for PPLO broth, serum, fructose, glucose, sucrose, tryptone, and yeast extract for promoting growth were studied. No growth occurred when PPLO broth and horse serum were excluded. Growth was optimal with 2% PPLO broth, less with 4%, and very slight with 6%. Colonies were normal on media containingO.0,0.5, and 1% tryptone, but were small at the 1.5% level. No growth occurred on media with 1.5% fructose. Only a few small colonies grew on media containing 1.5% glucose. Levels of 0.0-0.5% fructose or glucose gave optimal growth. Similar results were obtained with sucrose concentrations of 0.06-0.12 M as well as with a concentration ofO.25 M with no other added sugars. However, 1 M sucrose prevented growth. Growth was progressively stimulated by adding fresh yeast extract up to 8-10%.