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48 
STUDY OF MICROBIAL COMMUNITY OF COTTON RHIZOSPHERE 
Zakiryaeva S.I.
1
, Sherbekova N.A.
1,2
, AtadjanovaS.Sh.
1 
1
 Institute of Microbiology of the Academy of Sciences of the Republic of 
Uzbekistan.,
2
 National University of Uzbekistan named after Mirzo 
Ulugbek. 

[e-mail]
 
The soil as a habitat for microorganisms provides for their development a 
variety of microenvironments, often diametrically opposed in their properties. 
The totality of the root system with the soil is a complex ecological niche 
inhabited by beneficial, harmful and neutral microorganisms for plants. Active 
secretion of various substances by the root cells provides nutrient substrates for 
microorganisms that form strong associations with it both inside the root tissues 
and on the root surface, as well as in the rhizosphere. 
The rhizosphere was originally defined as the soil habitat of 
microorganisms, which is directly under the influence of the vital activity of the 
root system of the host plant. Microbial communities formed in the rhizosphere 
have a significant impact on the growth and development of plants. Gram-
negative bacteria of the genera Pseudomonas, Klebsiella, Enterobacter, 
Alcaligenes make up the main part of the rhizosphere microbial community. 
Microorganisms living in this zone are represented by species that intensively 
produce vitamins, amino acids, heteroauxins and enzymes and therefore have a 
certain influence on the development of the host organism. 
In this regard, the purpose of the study was to study the microbial 
community of the cotton rhizosphere and their species composition. 
The object of the study was microorganisms isolated from the rhizosphere 
of cotton grown on moderately saline soils of the Syrdarya. Samples were taken 
in spring, summer and autumn. The isolated bacteria were identified based on 
the study of morphological, cultural, and physiological properties and by 
MALDI TOF mass spectrometry. 
We have studied the qualitative and quantitative composition of the cotton 
rhizosphere. During the study, more than 30 bacteria were isolated that form the 
microbiocenosis of the cotton rhizosphere. The results of the study showed that 
the rhizosphere is more densely populated with bacteria. The microbial 
community of the cotton rhizosphere is represented by such bacterial species as 
Enterobacter cloacae,Bacillus cereus, B. wakoensis, B.subtilis, B.megaterium, 
B.simplex, B.endophyticus, Lactobacillus malefermentansand Cedecea davisae.
In the spring, bacteria of the genus Enterobacter developed in the greatest 
amount in the rhizosphere of cotton, and bacteria of the genus Bacillus 
developed in summer and autumn. 

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49 
We have studied the abundance of the main agronomically important 
groups of soil microorganisms in the cotton rhizosphere. Ammonification is of 
great importance for plant nutrition. In spring, the number of ammonifiers in the 
rhizosphere was 2.5x107 CFU/g soil, in summer their number was an order of 
magnitude higher (1.0x108 CFU/g soil), and in autumn it was 2 orders of 
magnitude higher (1.9x109 CFU/g soil), compared with spring. Microorganisms 
that use mineral forms of nitrogen are oligonitrophils. The number of 
oligonitrophilic microorganisms in the rhizosphere was the best in all seasons, 
in spring - 8.1x105 CFU/g soil, in summer and autumn - 1.3x106 CFU/g soil. 
The number of micromycetes in the rhizosphere was the same in all seasons and 
amounted to 3x103 CFU/g soil. 
Thus, during the study, more than 30 species of rhizobacteria were 
isolated. The microbiocenosis of the cotton rhizosphere was represented by such 
bacterial genera as Enterobacter, Bacillus and Lactobacillus. Gram-positive 
bacteria of the genus Bacillus dominated in the rhizosphere in summer and 
autumn. The dominant species of the cotton root zone were E.cloacae and 
B.endophyticus.