Purification of a factor from two weeds stimulatory to Bradyrhizobium in broth culture
1991
Mallim, M.A.B.
The stimulatory effect of extracts of lambsquarters when heated to 100 deg. C for 30 minutes or autoclaved for 15 minutes was reduced by about 20% compared to untreated extracts. Extracts of green foxtail were less affected by higher temperature under similar conditions. Extracts of both green foxtail and lambsquarters completely lost their stimulatory effect following exposure to aerial microflora for 120 h. Water extract of lambsquarters shoots was more stimulatory than methanol extract, and neither of the two nor butanol extracts resulted in stimulation. Both shoots and roots of lambsquarters and green foxtail were sequentially extracted first by water followed by methanol and vice versa. The bioassay of these extracts indicated that there could be two components of the growth factor, one is soluble in water, the other is soluble in methanol. After fractionation the crude aqueous extract of lambsquarters shoot by four organic solvents, the residual aqueous extract retained the growth factor. Dialysis of the residual aqueous extract of lambsquarters shoots through a membrane indicated that the molecular weight of the growth factor was less than 1000 was separated by paper chromatography using 6% acetic acid as developer. The fraction with Rf0.91 showed the highest stimulation of the bacterium.
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