Evening star., 1939-01-10
Of Stars, Men
And Atoms
Notebook of Science Progress
In Field, Laboratory
And Study
BIZ Thomas r. Henri.

ana Stuoy
By Thomas r. Henry.
Various bacteria which live on plant
roots secrete into the soil a powerful
growth substance which may increase
crop yields by as much as 20 per cent.
Evidence of this has just been re-
ported to the Soviet Academy Of
Sciences by the academy's Institute Of
Microbiology. It long has been known
that various plant root bacteria, espe-
cially certain varieties which congre-
gated on the roots of legunfes, are an
important factor in soil fertility, but 1t
has been assumed that this was entirely
due to their ability to fix nitrogen from
the air, thus restoring to the soil an
indispensable element for plant growth.
The Russian experiments show that
there is another factor at work, that
the microorganisms actually produce q
stimulating substance of some sort quite
aside from their nitrogen-flxation ability.
Some Of the most effective nitrogen pro-
ducers completely lack this ability,
while others, which have no role in
restoring the soil nitrogen, produce 1t in
great quantities.
The two most notable producers of the
unidentified secretion are aZobacter
chroococcum and pseudomanas flu
orescens. They are about equal in their
effectiveness. The former is also a
nitrogen fixer. The latter is not, and
all of its stimulating properties must
belong to its secretions.
The experiments were conducted with
fax. In one of them fax seeds were
soaked for "a hours in a suspension OF
azobacter chroococcum in water-about
500,0O0000 of the organisms per cubic
centimeter. When these seeds were
planted they grew more quickly and
appeared to be more resistant to dis
ease. A similar experiment was carried
out with wheat seeds. At the end of 10
days more of the seedlings from the
treated seeds remained alive and their
weight was considerably greater.
In other experiments wheat seeds
were mixed with combination of bac-
terra and peat before sowing The grain
yield from those in which pseudomonas
f1uorescens had been mixed with the
peat was 20 per cent greater than for
those sown without any treatment
Almost exactly the same result was
obtained with fax seeds.
Maltese, the sugar in malt which
exists in very minute quantities under
natural conditions and may be con-
sidered a "cultivated sugar" is fer
mented by the action of variety of
yeast the strain of which has been
preserved from generation to genera
ton ever since man began to brew beer.
This yeast also does not occur in the
wild. Where did it come from? 1t is
very similar to yeast know as sac
charomyces paradoxus. which is abun-
dant in nature but which does not have
the ability to ferment maltese, although
1t is an effective fermenter of various
other sugars, such as glucose, fructose
and sachyrose. These are wild sugars,
with which the yeast has been in con-
tact for countless millions of years.
According to report just made to
the Soviet academy by DR.. V. I. Kudry-
avtsev of the Meteorological Institute. it
has been possible to duplicate expert
mentally what must have happened in
the distant past when beer brewing
started and bring a new microorganism
into the world. A mash was made up
containing variety of wild sugars and
a small quantity of maltese. The wild
yeast, saccharomyces paradoxus, was
turned loose in it.
The wild sugars fermented in the
usual time. The maltese remained un-
affected The yeast cells stopped multi
plying and began to die off, chiefly as
result OF starvation, DR.. Kudryavtsev
believes. But few days later the fermen-
tation process started again and the fer
mentation process effected the hitherto
untouched maltese. 1t was an excellent
example Of evolution at work under the
spur OF necessity. Out of the millions
OF wild yeast organisms few were able
to adapt themselves to the maltese and
thus save themselves from starvation.
They were the flttest to survive in this
crisis which had arisen in their world
These few surviving cells multiplied
rapidly and were transferred to other
maltese solutions. Some were unable to
maintain themselves for more than few
generations, but others have been con-
tlnued for 20 or more generations. They
appear indistinguishable in form and
way of life from the tame yeast used in
beer brewing, but they have not yet
attained the same efficiency. At best
they are able to form a ferment con-
tanning only from six to seven per cent
Of alcohol.