Bacteria
EA-Plant Sciences
BACTERIA
CONTENTS
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Page
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Bacteria of Air
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2
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Bacteria of Water
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3
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Bacteria of Soil
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5
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Bacteria in Intestinal Tracts of Animals
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7
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Bibliography
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10
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EA-Plant Sciences
(C. D. Kelly)
BACTERIA
Only a few short years passed from the time Pasteur made his first
studies of bacteria until bacteriologists were included with the scientists
on arctic expeditions. In 1860, Pasteur demonstrated the presence of bac–
teria in air drawn into previously sterilized and sealed flasks of broth by
breaking the narrow necks of the flasks and drawing air in by the partial
vacuum. The bacteria caused fermentation of the broth. Eight years later,
Nystrom (13) carried out similar experiments in Spitsbergen and found the
fermentation of the broth to be slower there than in temperate regions; this
he interpreted as being due to the existence of fewer bacteria in the Arctic.
From that time onward, studies were carried out on many arctic as well as
Antarctic expeditions — studies that involved not only the bacteria in air,
sea, and soil, but also those in the intestinal tracts of birds, mammals, and
fishes.
On most arctic expeditions, the work of the bacteriologist was but a
minor part of the scientific studies on the expedition, and therefore these
investigations have been sporadic and in many respects seem to lack purpose.
Because of the conditions imposed by nature, where, on an expedition, the facil–
ities for study were often primitive, and supplies of necessity reduced to a
minimum, the results have not always been conclusive. However, when all the
pieces of evidence are put together, they make an interesting whole which
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requires further research to make the picture complete. No doubt, as time
toes on, further investigations will be carried out, but because they seemingly
have no utilitarian value, these remaining parts of the picture, through lack
of support, may be slow in coming.
The bacteria found in the Arctic seem not to be different from those in
temperate regions, though always fewer in number. It is felt by some that
these bacteria have come into the Arctic from more temperate zones and have
adapted themselves to the rigorous conditions of temperature, light, and soil.
This is not necessarily the case, however, as it has never been shown that bac–
teria which are found in countries that are definitely not even subarctic and
yet have extremely cold winters require any special adaptation to exist under
these conditions.
It would seem desirable to deal with the subject of arctic bacteriology
in its separate parts by discussing the bacteria of the air, water, soil, and
intestinal tracts of arctic animals independently. On many expeditions all
these various materials were examined for bacteria simultaneously, but for
clarity they will be dealt with separately here.
Bacteria of Air
As previously mentioned, Nystrom (13), using a crude qualitative method,
established the fact that there were bacteria in the air of Spitsbergen,
though they appeared to be few in number. This would seem to be the first
study of bacteria in the arctic air, and probably the earliest arctic bac–
teriology.
The first quantitative examinations of arctic air for bacteria were
made on the Nathorst expedition in 1898. Samples were taken at some twenty
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different places including Bear Island, Spitsbergen, and King Charles Land.
Levin (9) on this expedition used the method of Petri, modified by Miguel,
in which the air was filtered through powdered sugar, granulated sugar, salt,
and glass wool. One thousand liters of air were run through the filter as
one sample, the operation taking four to five hours. All these samples proved
free from bacteria except at one place on Bear Island where three colonies
were isolated.
Hesse (4), while studying the bacteria of sea water from the Norwegian
coast by way of Iceland to Spitsbergen, exposed agar plates to the air and
found such small numbers of organisms developing as to consider the air sterile.
Lindbergh in 1933 exposed Vaseline-coated slides from an airplane over
Greenland for Meier (11). Owing to the death of Meier no complete report was
published, and whether or not bacteria were present on these slides is not
known.
During August and September of 1947, while botanizing in northern Canada
and the Canadian Arctic Islands, Polunin exposed agar plates to the air (15).
After incubation, these plates yielded a rich harvest of bacteria and fungi.
The bacteria were typical air-borne types of soil origin. These plates were
exposed by hand from the window of an aircraft.
Bacteria of Water
Bacteriological studies of water have included fresh water in lakes,
small pools from melting snow on ice floes, as well as sea water. The
organisms found were fewer in number and their total activity was greatly
reduced as compared with those from water in more temperate zones, but no ap–
parent difference in types was found.
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Nansen (12) made microscopic observations of fresh water from pools of
melting snow on ice floes on the Arctic Sea and found bacteria, diatoms, algae,
and Infusoria. It was estimated that one bacterium was present in eleven cubic
centimeters of water. The types were not determined so little can be said
about them.
Gran (3) found nitrifying bacteria in the Arctic Sea. These were bacteria
that could oxidize ammonia to nitrites and those that oxidized the nitrites
to nitrates.
Hesse (4) examined sea water at various points from the coast of Norway to
Iceland and over to Spitsbergen and back to Norway, and in these samples he
found nitrifying and denitrifying bacteria.
In 1914 Isachenko published a monograph on his investigations of bacteria
of the Barents Sea (5). This study was designed to obtain a broad picture of
the biochemical processes taking place in the open sea and of the bacteria in–
volved. The aerobic nitrogen-fixing bacterium
Azotobacter chroococcum
and the
anaerobic nitrogen-fixing bacterium
Clostridium pasteurianum
were found as well
as one other nitrogen-fixing bacterium that was not satisfactorily determined.
Bacteria that oxidize ammonia to nitrites and those oxidizing nitrites to
nitrates were found in the water as well as in the mud, not only near the shore,
but also at depths of 65 to 100 meters where the Gulf Stream flows into the
Arctic Sea. These organisms were considered by the author to be permanent
inhabitants of the sea and not mere casual bacteria from the land. Fourteen
species of denitrifying bacteria, capable of reducing nitrates to nitrites and
nitrites to ammonia, were found near the shore and in the open sea. These
species were of two types: those reducing nitrates in the absence of proteins,
and those requiring peptone for denitrification. Only a few were able to carry
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the denitrification on to atmospheric nitrogen. Several organisms were
described that were capable of producing hydrogen sulfide from proteins or
from the reduction of sulfates.
Butkevich (2) examined the water of Barents Sea and also mud from the
bottom by a direct count method. The numbers were low except where there
was mixing with water from the Gulf Stream. In the water he found bacteria
to be present in numbers from 1,000 to 500,000 per milliliter, while in the
upper layers of the mud he observed numbers up to 500 million per gram. Some
bacteria were observed growing at −3° to −7°C.
Much of the information on the bacteria of the Arctic Sea comes from
that area north of Europe which may be modified, to some extent at least, by
the Gulf Stream. Whether bacterial activity would be the same in other parts
of the Arctic Sea is not entirely clear. It would seem, however, that the
bacteria of water in the Arctic are the same as those found in other parts
of the world where activity is reduced by low temperatures.
Bacteria of Soil
The bacteria in the soil of the Arctic have been studied by a number of
men and quite a large amount of information has been accumulated in this field.
The general impression of all these workers is that the organisms in arctic
soils are the same as those found in soils of regions having a more temperate
climate. In most cases the impression would seem to be that these organisms
had adapted themselves to growing at a lower temperature. Also, as one would
expect, the numbers are not high owing to the lowness of the temperature and
the shortness of the period in which they can be active.
During 1916, while on the second expedition to Thule in Greenland,
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Thorild Wulff collected samples of soil, and faecal material from arctic ani
0
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mals, which he sent to Denmark for bacterial examination by Bartel (1). These
samples were collected in the area along the west coast of Greenland, inhabited
by Eskimos, between the island of Disko and Cape York. While this material
yielded some interesting results, at least a year elapsed before they could
be examined, so the results were not as complete as if the examination had
been on fresh material. All the material was held below freezing while in
Greenland. The soil samples contained the usual soil bacteria, including
nitrifying and denitrifying types, urea fermenters, butyric acid bacteria,
and nonsymbiotic nitrogen-fixing bacteria.
Kazanski (8) studied the soil of Novaya Zemlya and identified seven dif–
ferent soil types. He examined the profiles of the soils by a microscopic
method and found bacteria as deep as the soil itself went. Cultural methods
demonstrated the presence of many types of bacteria; aerobic and anaerobic
cellulose decomposers, nitrifiers and denitrifiers, nodule bacteria, and
anaerobic, nonsymbiotic nitrogen-fixing bacteria. He was not able to find
Azotobacter
.
Isachenko and Simokova in 1934, reported on the bacteria of the soil of
the Soviet Arctic (6). They isolated several groups of bacteria common to
temperate zones and though they represented specific strains developed at
low temperatures.
A report was published in 1936 by Levinskaia and Mamincheva on the soils
of Murmansk where peat, sand, and sand-clay types were examined (10). Samples
were taken at intervals of two months from one-meter holes dug in the soil.
They obtained counts around 100,000 and 157,000 per gram, with the highest
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count in sand-clay soil. The highest counts were found in the winter, which
is a common experience in frozen soil due to break up of bacterial clumps.
Physiological processes were extremely slow and weak in intensity, but showed
some increase in winter and autumn. The authors attributed the low activity
to low pH (pH 5.2 to 6.4) and the prolonged low temperature. They did not
find
Azotobacter
, members of the
Escherichia coli
group or urea-decomposing
group. The absence of the last two groups they considered to be an index of
virgin soil, free from infection from animals. The organisms found were con–
sidered to be truly soil organisms of common types which had adapted themselves
to these conditions of temperature, light, and soil.
James and Sutherland (7), in 1942, made studies of permanently frozen
soil at Churchill on Hudson Bay, at the edge of the tree line. They did not
obtain very conclusive results in clay soils but found bacteria as deep as nine
feet in gravel, and concluded that these might have been carried into the soil
by seepage. In the soil above that which was permanently frozen, they found
anaerobic bacteria and cellulose-decomposing bacteria, and, in sulfur dioxide
media, they found motile rods.
Bacteria in Intestinal Tracts of Animals
Levin (9) states that previous studies in the Arctic and Antarctic had
shown that the intestinal tracts of polar bears, seals, sharks, eider ducks,
penguins, frigate birds, black gulls, guillemots, sea urchins, and shrimps
were sterile. As this work had been carried out previous to 1899, when methods
were still somewhat primitive, there is some doubt as to its reliability. In
any case, it would indicate very low numbers in the intestinal tract. Lavin
reports finding a single species,
Bacterium coli communior
, in the intestines
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of a polar bear and two seals. The same was true of white-winged gulls and
lower marine animals. In the majority of mammals and birds, however, the
intestines were completely sterile.
Hesse (4) considered it necessary in a study of this problem with birds
to be sure that they were truly arctic and had not received food from any
other source. He eliminated birds that could fly long distances or might have
received food from the ship in which he traveled. He examined a guillemot and
two snipe and though the other two showed sterile intestines, one snipe had a
single species of bacteria present. This organism was a Gran-positive, motile,
short coccoid rod, occurring in pairs, and growing best under anaerobic con–
ditions and at 37°C.
Bartel (1) studied the intestinal contents of birds and animals collected
by Wulff in 1916, and found many of the usual intestinal types present including
some twenty species of bacteria, torula, actinomycetes, and molds. The animals
examined were: blue fox, arctic hare, crow, seal, polar bear, lemming, and
partridge. Unfortunately, this material had to be kept for a year before exam–
ination, which made it impossible to determine original numbers or types. This
work contributed little to the problem as to whether or not the intestinal con–
tents of truly arctic animals are sterile or nearly so. By holding the specimens
a year some organisms may have died while others may have multiplied. Also the
area where the samples were taken had long been inhabited by Eskimos.
Though these studies are far from conclusive, it would seem that the intes–
tinal canals of birds and mammals may often be sterile, and that, where bacteria
are present, they may be few in numbers and species.
From such bacteriological studies as have been made in the Arctic, it would
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seem that there are no distinct arctic bacteria. The bacterial types are
similar to those found in other parts of the world, though they may have
adapted themselves to growing under the adverse conditions imposed by the
climate of the Arctic. It does seem surprising, however, that the intestinal
tracts of warm-blooded animals, where conditions are satisfactory for growth,
should be sterile or nearly so.
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BIBLIOGRAPHY
1. Bartel, Chr. “Recherches bacteriologiques sur le sol et sur les matieres
fecales des animaux polaires du Groënland septentrional,”
Meddel
–
elser om Grønland
. København, vol.64, pp.1-76, 1922.
2. Butkevich, V.S. Metodika bacteriologicheskogo issledovaniia i nekotorye
dannye po raspredeleniiu bakterii v vode i gruntakh Barentsova
moria. (Methods of bacteriological investigation and some dis–
tributional data onbottom and water bacteria of the Barents Sea.)
Trudy Gossudarstvennogo Okeanograficheskogo Instituta
, vol.2(2),
pp.5-39, 1932. (Oceanagraphic Inst. (Moscow)).
3. Gran, H.H. Studien über Meeresbacterien i Reduction von nitraten und
nitriten. Burgens Museums,
Aarbog
. No.10, 190.
4. Hesse, E. Bakteriologische Untersuchungen auf einer Fehrt nach Island, Spitz–
bergen, und Norwegen im Juli 1913.
Cent.f.Bakt
. I. Abt. Orgin.
vol.72, pp.454-77, 1914.
5. Isachenko, B.L. Izsliedovania nad Bakteriani Sievernavo Liedovitavo Okeana.
(Investigations on the Bacteria of the Arctic Ocean.) Petrograd.
1914. (Abstr. of Bact. 7, Abstr. No.1181, 1923.)
6. Isachenko, B.L. and Simokova, T.L. Bacteriologicheskiye issoledovaniya pochv
Arktiki. (Bacteriological Investigation of Arctic Soil.)
Trudy
Arkt. Inst
. vol.9, pp.107-24, 1934.
7. James, N. and Sutherland, M.L. “Are there Living Bacteria in Permanently
Frozen Subsoils?”
Can.J.Res
., vol.20, pp.228-35, 1942.
8. Kazanski, A.F. K Microflora Novoy Zemli. (The Microflora of Nova Zembla.)
Trudy polyarnoy Kommssii
, vol.7, pp.79-108, 1932.
9. Levin, M. “Les Microbes dans les regions artiques.”
Ann. d l’Inst. Pasteur
,
vol.13, pp.558-67, 1899.
10. Levinskaia, T.B. and Mamitcheva, I.S. K Kharakteristike Mikrobiologicheskikh
Processov Protekajuschikh v pochvakh Murmanska. (Characteristics
of microbiological processes taking place in soils of Murmansk.)
Arkiv. Biologicheskikh Nauk
, vol.43, pp.145-60, 1936.
11. Meier, F.C. and Lindbergh, C.A. “Collecting microorganisms from the arctic
atmosphere,”
Sci.Mon
., vol.40, pp.5-20, Jan. 1935.
12. Nansen, F.
Farthest North
. Constable and Co. London, 1897.
13. Nystrom, C. Om fasnings och forruttnelseprocesserna pa Spetsbergen. Upsala
Lakarafören Förh, 1868.
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14. Pady, S.M., Kelly, C.D., and Polunin, N. Arctic Aerobiology II. Pre–
liminary report on fungi and bacteria isolated from the air
in 1947.
Nature
, vol.162, p.379, 1948.
15. Polunin, N., Pady, S.M., and Kelly, C.D.
Nature,
vol.160, p.876, 1947.
C. D. Kelly