at 3000 rpm for ten minutes 0 5 ml of supernatant was layered on a stepwise sucrose density gradient with a range of density of 1 25 to 1 05 gm ml in a polyethylene tube for a beckman sw 56 rotor the tube was centrifuged for two hours at 35 000 rpm at 4 u00b0 c then the tube was pierced at the bottom and the around 22 30 fractions were collected in polypropylene tubes aliquot from some fractions were taken to measure density using an abbe refractometer aliquots of all fractions were precipitated with tca in order to measure incorporation of tritiated uracil into soluble material radioactivity of each precipitate was measured in a scintillation counter as shown in fig1 a 1 c superoxide dismutase sod from a vegetal source has a significant decreasing effect on mycoplasma growth sod was included in the medium at the first of the five day experiment the sod was purified from melon plant material the control shown in fig1 a had a peak of about 1200 counts the experimental treated with 50 u03bcg ml sod had a peak of around 500 counts while the experimental treated with 100 u03bcg ml sod had a peak of around 250 counts these results are assumed to represent the ability of the.