Microbiology. — “Chemosynthesis at denitrification with sulfur as 
source of energy.” By Prof. M. W. Beijerinck. 
(Communicated at the meeting of February 28, 1920). 
In photosynthesis organic matter results from the reduction of 
carbonic acid by light as source of energy; the same takes place 
in chemosynthesis by chemical energy. Organisms with photo- or 
chemosynthesis are called autotrophes; those which feed on other 
organic substances are heterotrophes. The product of chemosynthesis 
is the body substance of the producers, always spore-free bacteria. 
1 described chemosynthesis at denitrification with sulfur as source 
of energy, on 16 April 1903 at the 9 Dutch Congress of Natural 
and Medical Science’). I then thought that in the process a facul- 
tatively anaerobic bacterium was concerned difficult to isolate by the 
plate-culture method. It was further presumed, that this species pro- 
duced so much organic substance by chemosynthesis that the many 
directly visible bacteria, denitrifying with organic food, might live 
thereon. This supposition has proved to be erroneous; the latter 
themselves are in fact the operators of the sulfur denitrification as 
well as of the chemosynthesis. They are easily cultivated on broth- 
agar or broth-gelatin, but then they lose, and this is the new view, 
their autotrophy together with the power of sulfur denitrification, 
whilst preserving this power with organic food. The loss is caused 
by the growth with organic food and this less being hereditarily 
constant, we have a case here similar to that which I described 
earlier for the nitrate ferment, and which I called “physiological 
species formation’’). Just as I then distinguished the oligotrophic 
from the polytrophie state we may in this case speak of the auto- 
trophic and the heterotrophic condition of the operators*). The hetero- 
trophic form is thus some common denitrifying bacterium. 
On account of the little acquaintance with chemosynthesis acquired 
until now, [ will begin with describing once more the original 
experiment *). 
9 Phénomènes de réduction produits par les microbes. Archives Néerland. 
Sér. 2. T. 9, Pag. 158, 1904 
*) These Proceedings. Vol. 23, Pag 1163, March 28 (10 April) 1914. 
% As the existence of chemosynthesis is proved with certainty for the sulfur 
denitrification, but not for the nitration, the same nomenclature could not be 
followed in the two cases. 
*) An enumeration of the chief processes accompanied with chemosynthesis is 
to be found in my paper: Bildung und Verbrauch von Stickstoffoxydul durch Bakteriën. 
Centralbl. f. Bakteriologie 2te Abt. Bd. 25, Pag. 30, 1910, 
