In the first isolation of the bacteria infecting the roots of the Leguminosae, Beijerinck found that the common meat-peptone gelatin substrate is not well adapted to their growth; but that a medium, very suitable for their culture, consists of a water extract of legume leaves, 0.25 per cent asparagin; 5 per cent sucrose and 7 per cent gelatin. Later he modified this medium by making a more concentrated legume extract from pea seedlings and omitting the asparagin. At about the same time Breal found that a water extract of the roots of legumes also favors the growth of these organisms. Hiltner and Störmer suggested a medium with asparagin as the only source of nitrogen. Later a neutral water extract of pressed yeast was advocated by Fred and this is in general use at the present time. However, extracts of some nonleguminous plants have been used with apparently equally good results. Müller and Stapp obtained excellent growth of the various cultures of the root nodule bacteria on an extract of carrots; and very recently Carroll reports that an aqueous extract of asparagus promotes the growth of these organisms just as well as yeast extract.
Proceedings of the Iowa Academy of Science
©1934 Iowa Academy of Science, Inc.
Thorne, D. Wynne and Walker, R. H.
"Some Factors Influencing the Respiration of Rhizobium,"
Proceedings of the Iowa Academy of Science, 41(1), 63-70.
Available at: https://scholarworks.uni.edu/pias/vol41/iss1/7