14.12 “Die Bacterien der Papilionaceen-Knöllchen” by
Martinus Beijerinck (1888)
Martinus Willem Beijerinck (1888) began his publication with a brief review of the
literature on root nodules of legumes (family Fabaceae). Beijerinck then described
the results from his efforts at isolating a bacterial species that was associated with
legume root nodules. Beijerinck used gelatin plates on which he was able to grow the
bacteria from those nodules, after first grinding the nodules on cleaned glass plates.
Instructions easily still can be found for preparing gelatin plates to culture microorganisms (Merten 2020). Beijerinck assigned the name Bacillus Radicicola to his
newly found bacteria. Beijerinck capitalized both the genus and species names
which he assigned to his discovered bacteria.
The concepts presented by Beijerinck included a belief that the bacteroids found
inside of root nodules were shaped protein bodies which the plant cultivates from
Bacillus Radicicola, and Bacillus Radicicola was a species of metamorphic bacteria
which migrates into the roots from the outside. He concluded that these bacteria must
penetrate into the plant cell lumen by an existence of pores in the cell wall, that this
process represents an infection of living cells of the root pericambium, and the
produced nodules then serve for the purpose of local protein accumulation.
Beijerinck believed the bacteroids are stored within the cytoplasm where the bacteroids are better served with a lower than ordinary oxygen tension and also that juices
of the papilionaceae cells were their favorite food for the bacteroids.
Beijerinck had found that germinating Papilionaceae (leguminous plants whose
flowers have butterfly-shaped corollas) seeds placed between the Bacillus
Radicicola colonies on gelatin plates greatly promote growth of the bacterial colonies. He believed that tissues of the Papilionaceae roots must be exerting a strong
attraction on the Bacillus Radicicola, and he regarded these roots as bacterial traps.
Beijerinck specifically mentioned the well-known fact that there are either none or
very few root nodules on legume plants that have been grown in humus-rich soil.
Beijerinck suggested that the papilionacea roots probably release substances into the
soil that attract Bacillus Radicicola, and if there is no nodule formation as in the case
mentioned, then this secretion of attractive substances may have been either abnormal or completely absent.
Beijerinck defined the interactions of Bacillus radicicola with plants belonging to
numerous genera of the family Fabaceae, those genera were Caragana, Cytisus,
Ervum (which now seems to be synonymous with Vicia), Lotus (that is not a
reference to the water plant Nelumbo nucifera which commonly is called Lotus),
Lupinus, Ornithopus, Phaseolus, Pisum, Robinia, Trifolium, and Vicia. He found
that the bacteria cultivated from different Papilionaceae species are very similar, but
not always completely identical. Although the external appearance of root nodules
differed depending upon the species of legume being examined, Beijerinck assessed
the fact that the inner structure reveals the same level of microbial training was not to
be surprising for, and I translate his words directly, “ ... educations that are obviously
as old as the legume group itself”.
228
C. J. Hurst
Martinus Beijerinck (1888)
Martinus Willem Beijerinck (1888) began his publication with a brief review of the
literature on root nodules of legumes (family Fabaceae). Beijerinck then described
the results from his efforts at isolating a bacterial species that was associated with
legume root nodules. Beijerinck used gelatin plates on which he was able to grow the
bacteria from those nodules, after first grinding the nodules on cleaned glass plates.
Instructions easily still can be found for preparing gelatin plates to culture microorganisms (Merten 2020). Beijerinck assigned the name Bacillus Radicicola to his
newly found bacteria. Beijerinck capitalized both the genus and species names
which he assigned to his discovered bacteria.
The concepts presented by Beijerinck included a belief that the bacteroids found
inside of root nodules were shaped protein bodies which the plant cultivates from
Bacillus Radicicola, and Bacillus Radicicola was a species of metamorphic bacteria
which migrates into the roots from the outside. He concluded that these bacteria must
penetrate into the plant cell lumen by an existence of pores in the cell wall, that this
process represents an infection of living cells of the root pericambium, and the
produced nodules then serve for the purpose of local protein accumulation.
Beijerinck believed the bacteroids are stored within the cytoplasm where the bacteroids are better served with a lower than ordinary oxygen tension and also that juices
of the papilionaceae cells were their favorite food for the bacteroids.
Beijerinck had found that germinating Papilionaceae (leguminous plants whose
flowers have butterfly-shaped corollas) seeds placed between the Bacillus
Radicicola colonies on gelatin plates greatly promote growth of the bacterial colonies. He believed that tissues of the Papilionaceae roots must be exerting a strong
attraction on the Bacillus Radicicola, and he regarded these roots as bacterial traps.
Beijerinck specifically mentioned the well-known fact that there are either none or
very few root nodules on legume plants that have been grown in humus-rich soil.
Beijerinck suggested that the papilionacea roots probably release substances into the
soil that attract Bacillus Radicicola, and if there is no nodule formation as in the case
mentioned, then this secretion of attractive substances may have been either abnormal or completely absent.
Beijerinck defined the interactions of Bacillus radicicola with plants belonging to
numerous genera of the family Fabaceae, those genera were Caragana, Cytisus,
Ervum (which now seems to be synonymous with Vicia), Lotus (that is not a
reference to the water plant Nelumbo nucifera which commonly is called Lotus),
Lupinus, Ornithopus, Phaseolus, Pisum, Robinia, Trifolium, and Vicia. He found
that the bacteria cultivated from different Papilionaceae species are very similar, but
not always completely identical. Although the external appearance of root nodules
differed depending upon the species of legume being examined, Beijerinck assessed
the fact that the inner structure reveals the same level of microbial training was not to
be surprising for, and I translate his words directly, “ ... educations that are obviously
as old as the legume group itself”.
228
C. J. Hurst