Anaerobic bacteria are spread in nature. They are met in great number, for example, in marshes, where the organic substance is separated from oxygen of air by the layer of water and silt.

The same phenomenon may takes place in caves. We showed, that in caves, containing organic substance the carbon dioxide gas settles in the lowest part of caves, from the bottom up to 1,5 meter height. The same data were received in the process of the work [25]. The phenomenon is comprehensive: the carbon dioxide gas is heavier than air and settles on the bottom of a cave, separating the organic substance from air oxygen. On the other hand, the upper layers of the organic substance, play the role of a separator for the lower layers.

As the world's experience for obtaining of biogas from urban places of garbage shows [93], that that kind of separation is quite enough for receiving the anaerobic environment, and the methane origin with the help of microbes. So as to say, the hypothesis, that "methanic " caves serve as the reactors of biogas, is right. With the goal to clarify the existence of anaerobic bacteria in caves, we chose, as the object of research one of the most well - known caves of Armenia - the cave of Bears [20].

The cave of Bears is situated in Yegeknadzor region. It is three million years old. The total length of the cave is 4 km. It is considered to be in the number of the world's most beautiful caves because it is rich with stalactites and stalagmites.

The cave was discovered by me and Vardan Shaldgyan in 1980, December 2.

The cave is dry , there are insignificant drops in some places. There are not high plants, among the representations of the animal world flying mousses are met, insects are discovered. Till 1980 the first hall of the cave used to be bear den. In one of the halls the backbone of a bear was discovered.

The cave has the same temperature constantly. So in 21 of July 1996 at 2 o'clock, when it was + 37 OC outdoors, the inner temperature of the cave was +9 OC in the depth of 20 m from the entrance of the cave, +9,5 OC in the depth of 40 m from the entrance, +10,5 OC in the depth of 80 m, +12 OC in the depth of 120 m.

In October 13, 1996, at the same time, in the same parts it was +17 OC outdoors and indoors +9 OC, +10,5 OC, +10 OC, +11,5 OC respectfully.

Samples of the soil were taken from five different places for bacteriological analysis. The sample #1 was taken from the front part of the cave, #2 in the depth of 20 m from entrance of the cave, #3 in the depth of 40 m from entrance of the cave, #4 in the depth of 80m from the entrance of the cave, #5 in the depth of 120m from the entrance of the cave.

The bacteriolobiological analysis was hold on five different agar media due to the separate physiological groups. The results, which were got, are given in Table 15.

Table 15. The results of microbiological analysis of the cave of Bears.

Samples

Microflora

1

2

3

4

5

Total number of microbes in 1 g. of a sample

2,2.105

1,0.105

o,8.105

1,2.105

0,95.105

Anaerobic bacteria

( % )

51.5

17,3

21

20,8

23,8

Sporeforming bacteria

( % )

15

23

12

14

19

Intestinal bacteria ( coli form bacteria) ( % )

21

25

16,7

19

8,7

Actinomycetes

( % )

3

5,7

3,1

0

1,4

Penicillium and aspergillus ( % )

9

18

24

28

18

Ferment mushroom insects ( % )

1,5

2

0

1,5

3,1

Not sporeforming bacteria ( % )

30

19

23

16,7

26

As it is seen from the Table 15, in all samples exist appreciable quantities of anaerobic bacteria. Consequently, in caves methane and carbon dioxide gas occur through the anaerobic fermentation of organic substraktes.