Biological sciences/11. Bioengineering and Bioinformatics
c.b.s. Bekturova A.Zh., d.b.s. Khanturin M.R.
L.N. Gumilev Eurasian National University, Kazakhstan
Features of the bacteria Pseudomonas genomes
organization and their hydrocarbon activity
In the 50-60-th years of this century in the world and national literature
appeared a large amount of research on bacteria Pseudomonas.
Bacteria Pseudomonas are similar in morphology and very diverse in their cultural
and physiological characteristics.
The bacterial genome is represented by a single closed circular DNA
molecule (bacterial chromosome), its size and composition in different strains are
special. For example, the genome size of P. fluorescens Pf-5 is 7.1 m. bases pairs,
and
the
strainPseudomonas
fluorescens PfO-1
is
6.43841
m.b.p. [1]. Pseudomonas aeruginosa is the size of the genome - 6.3 m.b.p., which
contains 5570 genes on one chromosome [2].
Bacteria in addition to the main chromosome contain small extrachromosomal
DNA which called - plasmids. Sizes of plasmids ranged from several thousand to
hundreds of thousands of base pairs, and the number of copies per cell - from one
to several hundred.
Plasmids capable of autonomous (independent of the main chromosome)
replication and is stably inherited in a number of cell generations. Many plasmids
given host cell tangible selective advantage - resistance to antibiotics, heavy
metals, the ability to degrade various xenobiotics, etc. Members of the genus
Pseudomonas are most effective in combating various types of pollutants. They are
essentially the "omnivorous." The cells of these organisms contain a hydroxylase
and oxidoreductase, which can degrade a large number of molecules of
hydrocarbons and aromatic compounds such as benzene, xylene, and toluene.
Decomposition of aromatic acids can begin with non-oxidative decarboxylation,
leading to the formation of phenols, which are then oxidized in the linear
unsaturated dicarboxylic acid [3]. The genes encoding these enzymes are part of
the plasmids [4].
САМ and NAH plasmids provide their own transport, inducing hybridization
of bacterial cells, other plasmids can be transferred only if the bacteria have other
plasmids, to ensure cross. [5].
Chakrabarti [6] after a successful crossing was a strain containing the plasmid
XYL and NAH, as well as a hybrid plasmid obtained by recombination of parts of
the CAM and OCT plasmids (by themselves they are not compatible, then there
can not exist as a separate plasmid in a bacterial cell). This strain is able to grow
rapidly in the crude oil, as it metabolizes hydrocarbons are much more active than
any of the strains containing only one plasmid. The strain can be especially useful
in treatment ponds for wastewater, where we can control the temperature and other
external factors.
In the study of strains of Pseudomonas aeruginosa Belhaj. et al [7] reported
the presence of the genetic information of some alkane-monooxygenase. Many
strains have been found genes similar to genes alkB1 and alkB2, that found
in Pseudomonas putida. This suggests that in degradation of long chain alkanes
in Pseudomonas aeruginosa are responsible for at least two alkane-hydroxylase
complexes. Some strains were detected third hydroxylase complex encoded by the
gene alkB [8]. These strains were able to utilize a wider range of alkanes (С12С22 и С6-С22), and were also able to degrade toxic insoluble alkanes. In the
oxidation of alkanes involving membrane-bound monooxygenase encoded by the
gene alkB and electron-transport system consisting of two rubredoxin and NADHdependent reductase rubredoxin encoded by the genes respectively rubA,
rubA2 and rubB. [9]. These genes are part of the plasmid pUCP20 or strain
of Pseudomonas aeruginosa plasmid in the OST strain Pseudomonas putida
GPo1. [10].
Vetrova and others [11] reported a higher hydrocarbon activity in
strain Pseudomonas chlororaphis PCL1391, which contains a plasmid pBS216.
The most well described by way of degradation of alkanes encoded OCT
plasmid of the strain Pseudomonas putida Gpo1 (formerly Pseudomonas
oleovorans). Membrane-bound monooxygenase, soluble rubredoxin and
rubredoxin reductase serve to convert alkanes to alcohols. The alcohol is then
oxidized to aldehyde and the corresponding acid in the β-oxidation and the citric
acid cycle. It shown, that the stimulation of oil biodegradation in the presence
of Pseudomonas aeruginosabiosurfactant. [12]. Among the greatest positive effect
of biosurfactant shows ramnolipids.
Thus, because the ability to degradation of various pollutants depends on the
enzyme composition of microorganisms, the use of computer analysis of
nucleotide sequences of their genomes to evaluate and identify among them the
most efficient degraders.
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a
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Produced
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83
kilobase
naphthalene
degradation
plasmid
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