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Contrasting Effects of Horse Serum and Fresh Yeast Extract on Growth of Spiroplasma citri and Corn Stunt Spiroplasma. E. C. K. Igwegbe, Department of Biology, Alabama State University, Montgomery, AL., Present address: Department of Crop Science, University of Nigeria, Nsukka, Nigeria; Phytopathology 68:1530-1534. Accepted for publication 24 April 1978. Copyright © 1978 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-68-1530.

Both Spiroplasma citri (SS) and corn stunt spiroplasma (CSS) grew faster and attained higher titers in liquid or agar medium supplemented with 5% horse serum than in medium with 20% horse serum. When growth was initiated with a low concentration of inoculum, CSS failed to reproduce but SS achieved excellent growth in a medium containing 20% horse serum. Spiroplasma citri grew in more agar medium variations and was less affected by high concentrations of fresh yeast extract than was CSS. These results suggest that CSS and SS differ in their responses to the presence of similar concentrations of horse serum or fresh yeast extract.