ES2841973B2 - BACTERIAL STRAINS AND THEIR USE FOR THE BIOREMEDIATION OF SOILS CONTAMINATED WITH BIPHENYL AND DIPHENYL OXIDE (HTF) - Google Patents

Description

DESCRIPTION

BACTERIAL STRAINS AND THEIR USE FOR SOIL BIOREMEDIATION

CONTAMINATED WITH BIPHENYL AND DIPHENYL OXIDE (HTF)

The present invention falls within the field of biotechnology applied to the environmental sector, and in particular refers to microorganisms useful for the in situ degradation (bioremediation) of surfaces, preferably soils, contaminated with the components of the heat transfer fluid HTF, biphenyl and diphenyl oxide (HTF).

BACKGROUND OF THE INVENTION

Solar thermal power plants are based on the capture and concentration of solar radiation. The capture takes place through mirrors and the concentration is carried out by means of heat transfer fluids. Basically, the function of the heat transfer fluid is to transfer the energy collected by the parabolic trough collectors (mirrors) to the power block through a heat exchange system. The steam produced in the exchangers is used in a steam turbine to generate rotational mechanical energy that will ultimately be transformed into electrical energy.

The heat transfer fluids that give the best results are organic fluids, which do not change state even if the temperature increases a lot. One of the most used is the eutectic mixture composed of 73.5% by weight of diphenyl ether (diphenyl oxide) and 26.5% of 1,1-Biphenyl (biphenyl). This fluid is usually called HTF (for its acronym in English "Heat Transfer Fluid"). Thus, most of the world's solar thermal power plants use the HTF heat transfer fluid to transfer heat from the parabolas to the turbines that generate electricity. This fluid is a highly toxic, viscous, colourless-yellowish liquid with a boiling point of 257 °C.

The HTF works at temperatures between about 290°C, at the entrance of the line where the radiation is concentrated, and 390°C at the exit. A higher outlet temperature would mean a higher overall performance of the plant, but the chemical characteristics of the fluid do not make it possible to use it above 400°C: the degradation reactions increase exponentially in speed, giving rise to volatile and heavy hydrocarbons that modify the behavior of the plant and which pose safety concerns. For this reason, solar thermal power plants have a limited maximum working temperature of the organic fluid at about 400°C. In addition, they require systems that eliminate the products originating from the degradation, normally using successive filtrations and distillations.

However, and despite the fact that there are many measures to control emissions into the air, soil and water in solar thermal plants, it is inevitable that certain types of unpredictable and uncontrollable discharges may occur, the magnitude of which can vary from a few liters at the joints to tons if a larger accident were to take place. In addition, sometimes the pipes of the power plants lose their tightness as a result of changes in temperature during the operation of the plant, producing leaks in the union elbows of the same that contaminate the floor of the power plants.

Therefore, in addition to air pollution due to the volatility of the HTF components, the receiving matrix that suffers the greatest impact is the soil.

HTF has high levels of ecotoxicity and toxicity in humans. Focusing on the environment, when a spill occurs, there are significant risks that HTF will affect the populations of organisms that live in the soil, and eventually also aquatic organisms, since a leak can lead to the contamination of a aquifer, for example.

The environmental impact of the HTF discharge is mainly due to biphenyl, with the ecotoxicity of diphenyl oxide being much lower.

Given the unpredictability of the losses, and the fact that spills can often be very delocalized, that is, be of little magnitude, but of great scope (drips in widely separated joints along the entire surface of the field of mirrors), the treatment options for contaminated soil must be flexible enough to be implemented in different locations and with moderate costs. Likewise, treatment alternatives must maintain the philosophy of solar thermal plants: sustainable energy and environmentally friendly solutions.

However, there are very few studies regarding the biodegradation of HTF. Until now, these studies have focused on evaluating the degradation of one of the two components separately. Thus, Gibson (Gibson et al., 1973, Biochemical and Biophysical Research Communications, 50(2):211-219) studied the degradation of biphenyl by the bacteria Beijennckia ; Dodge used a fungus for the same compound (Dodge et al., 1979, Biodegra, 178(1):223-230) and Fugihara described the ability of Pseudomonas aeruginosa KF702 (NBRC110665) to degrade biphenyl (Fugihara et al., 2015; Genome Announc 3: e00517-15). Bacterial biodegradation of diphenyl ether by Pseudomonas putida, Sphingomonas sp. SS3 strain, and Cupriavidus sp. (Catelani et al., 1971, Experientia, 27(10): 1173-1174; Schmidt et al., 1992, Appl. Environ. Microbiol., 58(9):2744-2750; Wang et al., 2015, Environ Sci Pollut Res, DOI 10.1007/s11356-015-4854-3).

As for the mixture of both compounds, that is, the HTF fluid, up to now no microorganism has been described that can simultaneously and efficiently degrade the two organic compounds present in this eutectic mixture. There is very little progress with the prospect of looking at the effect of bacterial degrading activity on HTF itself. Only one bacterium of the genus Pseudomonas, in particular the strain P. oleovorans HBD2 CECT8969 (ES2641967), and one fungus, Phlebia lindtneri, have been described (Mori et al., 2002, FEMS Microbiol Lett, 213(1): 127-31 ), which are useful for the degradation of the HTF fluid.

Therefore, there is a need to identify microorganisms, or combinations thereof, resistant to the two components of HTF and their degradation products, which are effective in the simultaneous use and, therefore, elimination of both compounds. The application of these microorganisms would be an ecological, economical and efficient solution for the in situ treatment or bioremediation of soils contaminated with HTF, such as, for example, in solar thermal power plants and in the vicinity of them.

DESCRIPTION OF THE INVENTION

The present invention represents a solution to the aforementioned problem, by providing a bacterial strain of Enterococcus sp., isolated and characterized by the inventors, which is capable of efficiently degrading the two components of the HTF heat transfer fluid, that is, biphenyl and diphenyl oxide . Thus, said strain can be irrigated in contaminated areas where there have been spills of said fluid for bioremediation or degradation in situ.

The present invention also proposes the use of said strain of Enterococcus sp. in combination, that is, as a bacterial consortium, with an Achromobacter strain and a Pseudomonas aeruginosa strain, also isolated and characterized by the inventors, in the proportions 64.5%, 6.9% and 28.6%, respectively. This bacterial consortium enhances the ability of the Enterococcus sp. described in the present invention to degrade the components of HTF (biphenyl and diphenyl oxide), for which it also represents a very useful tool for the bioremediation of soils contaminated with it.

The tests shown below demonstrate that the strain of Enterococcus sp. of the present invention is capable of degrading biphenyl and diphenyl oxide, preferably diphenyl oxide, with greater efficiency than other bacteria, for example than the other two strains of Achromobacter and P. aeruginosa described in the present invention, when these are used individually. In addition, these tests show that the combination or consortium, in the specific percentages indicated here, of the three bacterial strains isolated in the present invention has a biphenyl and diphenyl oxide degradation capacity much higher than the degradation capacity of said compounds of each of these strains separately and even to the degradation capacity of said compounds by a combination of these same strains but in other proportions different from that indicated in the previous paragraph (see Table 1 of the examples).

With the aim of finding and designing those microorganisms and combinations thereof that are most efficient in the degradation of HTF, in the present invention the three bacterial strains described here were isolated from a soil contaminated with HTF in Spanish territory, subsequently they were cultivated in vitro by means of a procedure whose conditions have been optimized by the inventors in order to induce the HTF-degrading capacity in said strains and were finally characterized.

The advantages associated with the present invention are that it allows the bioremediation of surfaces, preferably soils, contaminated with any of the components of HTF (diphenyl ether or 1,1-Biphenyl) or with a mixture of both (HTF itself), in a effective, ecological and low-cost way. In addition, the strains described in the present invention are adapted to live in soils of a different nature contaminated with HTF or with any of its components, managing to degrade it in situ at low cost and through a simple procedure. The application of the strains of the invention for this purpose does not pose any complications at the infrastructure level, in particular, it is not necessary to restore or modify the existing facilities of the solar thermal plants, which allows the treatment to be implemented immediately in existing infrastructures, and the cost of maintenance is minimal. Also, in the bioremediation process here described, no toxic reagents or systems that consume energy are used, since it is the activity of the bacteria that allows the efficient degradation of HTF. Finally, the strains of the present invention allow great versatility in their applications in bioremediation of soils contaminated with HTF or with any of its components, being able to be applied both in small fluid spills (drips) and in larger contaminated areas.

For all these reasons, a first aspect of the invention relates to a bacterial strain of Enterococcus sp. isolated and deposited in the Spanish Collection of Type Cultures with deposit number CECT30012 (also called HTF1).

Another aspect of the invention relates to a bacterial strain of Achromobacter sp. isolated and deposited in the Spanish Collection of Type Cultures with deposit number CECT30013 (also called HTF2).

Another aspect of the invention refers to a bacterial strain of Pseudomonas aeruginosa isolated and deposited in the Spanish Collection of Type Cultures with deposit number CECT30014 (also called HTF3).

As indicated above, these three strains, from now on "bacterial strains of the invention" or "strains of the invention", have been isolated from soil contaminated with HTF in Spanish territory and deposited on November 19, 2019 under the Budapest Treaty on the Spanish Type Culture Collection as an International Depository Authority (headquartered in Building 3 CUE, Parc Científic Universitat de Valencia, C/ Catedrático Agustín Escardino, 9, 46980 Paterna (Valencia) SPAIN).

Within the scope of the present invention, those bacteria that derive from the bacterial strains of the invention are also contemplated and these can form part of the bacterial composition or consortium described later as an alternative to the specifically indicated strains, as long as they retain the ability to degrade HTF or any of its components. Examples of bacteria derived from the bacterial strains specifically indicated in the invention may be mutants and genetically modified organisms that have variations in their genome with respect to the genome of the strains described in the invention, but where said variations do not affect the ability of the strains to downgrade HTF or any of its components. The bacteria derived from Bacterial strains of the invention can be produced naturally or intentionally by mutagenesis methods known in the state of the art, such as, but not limited to, growth of the original strain in the presence of mutagenic or stress-causing agents or by genetic engineering targeting the desired mutation(s). Genetically modified organisms derived from the bacterial strains of the invention that retain their ability to degrade HTF or any of its components and, therefore, to be used in the treatment or bioremediation of surfaces, preferably soils, contaminated with said fluid are also contemplated. or with any of its components. An assay to check whether a microorganism has the ability to degrade HTF or any of its components is described in the examples that accompany this description.

On the other hand, within the present invention the cellular components, metabolites, bioactive compounds and/or molecules secreted by any of the bacterial strains of the invention or by their co-culture, as well as the compositions comprising said elements are also contemplated. and the uses thereof for the treatment or bioremediation of surfaces, preferably soils, contaminated with HTF or any of its components.

Another aspect of the invention relates to a pure bacterial culture comprising any of the bacterial strains of the invention, preferably the Enterococcus sp. CECT30012.

The “bioactive compounds are products obtained from the strains of the present invention, both their extracellular and intracellular components. Such bioactive compounds could include, but are not limited to, cell wall components (such as peptidoglycans), nucleic acids, organic and inorganic acids, membrane components or others, such as proteins, peptides, amino acids, enzymes. , lipids and carbohydrates and their combinations (such as lipoproteins, glycolipids or glycoproteins), vitamins, salts, minerals, etc. Also any molecule produced or modified by the bacterium, and/or secreted or released to the outside, as a consequence of its metabolic activity, during its growth, its use in technological processes or during its storage.

Another aspect of the invention relates to a composition, hereinafter "composition of the invention”, which comprises any of the bacterial strains of the invention, preferably the strain of Enterococcus sp. CECT30012, or the pure bacterial culture comprising any of the bacterial strains of the invention, preferably the Enterococcus sp. CECT30012.

In a preferred embodiment, this composition of the invention further comprises a biologically acceptable carrier and/or excipient.

The biologically acceptable vehicle or excipient can be of natural or artificial origin, and must be compatible with the in vitro maintenance and storage of the bacterial strains of the invention, that is, it must not compromise their viability and functionality. Preferably, the biologically acceptable excipient is alginate.

In another preferred embodiment, the composition of the invention comprises the strain of Enterococcus sp. CECT30012, or the pure bacterial culture comprising said strain, and further the bacterial strain of Achromobacter sp. CECT30013 and the bacterial strain of Pseudomonas aeruginosa CECT30014, where the proportion of each of the strains in the composition, with respect to the total amount of bacterial strains present in the composition, is 6.9% of Achromobacter sp. CECT30013, 64.5% Enterococcus sp. CECT30012 and 28.6% Pseudomonas aeruginosa CECT30014.

The composition of the invention comprising the strains of Achromobacter sp. CECT30013, Enterococcus sp. CECT30012 and P. aeruginosa CECT30014 in the aforementioned percentages has shown to be the most efficient in the degradation of the two components of the HTF heat transfer fluid among all the strains tested individually and among all the combinations of said strains tested in different percentages (see Table 1 of the examples shown below).

Another aspect of the invention refers to the use of any of the bacterial strains of the invention, preferably the Enterococcus sp. CECT30012, from the pure bacterial culture comprising any of the bacterial strains of the invention, preferably the Enterococcus sp. CECT30012, or the composition of the invention, for the degradation, preferably in situ, of biphenyl (1, 1-Biphenyl), diphenyl oxide (diphenyl ether) or both (HTF).

By "HTF degradation" is meant the simultaneous degradation of the two organic compounds present in this eutectic mixture (biphenyl and diphenyl oxide).

Another aspect of the invention refers to the use of any of the bacterial strains of the invention, preferably the Enterococcus sp. CECT30012, from the pure bacterial culture comprising any of the bacterial strains of the invention, preferably the Enterococcus sp. CECT30012, or the composition of the invention, for the bioremediation, treatment or decontamination of surfaces, preferably soils or water, more preferably soils, contaminated with biphenyl (1, 1-Biphenyl), diphenyl oxide (diphenyl ether) or both ( HTF).

By "surface" is meant any liquid medium, for example, water, or solid, for example, soil, contaminated with HTF or with any of its chemical components (biphenyl and diphenyl oxide).

"Bioremediation" or "biocorrection" means the use of living organisms, in the context of the present invention the strains of the invention alone or in combination, or their pure cultures, to eliminate, degrade or neutralize contaminants from soil or water. . It refers to the use of these elements directly at the source of the contamination, by inoculating them into the contaminated environment that is intended to be treated.

Another aspect of the invention refers to a method or procedure, from now on "first method of the invention", for the bioremediation, treatment or decontamination of surfaces, preferably soils or water, more preferably soils, contaminated with biphenyl (1, 1-Biphenyl), diphenyl oxide (diphenyl ether) or both (HTF), comprising the following steps:

a. cultivate any of the bacterial strains of the invention, preferably the strain Enterococcus sp. CECT30012, the pure bacterial culture comprising any of the bacterial strains of the invention, preferably the Enterococcus sp. CECT30012, or the composition of the invention, preferably until reaching a density of at least 0.2 x 109 CFU/ml, more preferably between 0.5 x 109 and 1 x 109 CFU/ml, and

b. Dispense, preferably by irrigation, on the surface, preferably soil, contaminated to be treated, the culture obtained after step (a).

In stage (a) of this procedure, the culture must be carried out in a suitable nutrient medium that has the HTF components, that is, biphenyl and diphenyl oxide, as the only carbon source, and in conditions that favor the growth of the bacteria of the invention. Thus, preferably the conditions for said culture are between a temperature of 20-30°C, more preferably 22°C, with constant orbital agitation between 120 and 250 rpm, and the presence of a culture medium consisting of a minimum concentration of salts and HTF in a proportion of at least 10% (vol/vol).

This procedure can be applied directly to, for example, contaminated surfaces in solar thermal power plants where HTF is used as a heat transfer fluid (most of the solar thermal power plants in the world).

In another preferred embodiment of this procedure, the irrigation of step (b) is carried out in a ratio of 5 ml of culture per gram of soil.

As explained above, the bacterial strains of the invention, after their isolation, were cultivated under conditions that favor the degrading activity of HTF. Thus, another aspect of the invention refers to a method or procedure, hereinafter "second method of the invention", for the production of microorganisms, preferably bacteria, useful for the degradation of biphenyl, diphenyl oxide or both. (HTF), which includes the following stages:

a. isolate a sample of water or soil, preferably from 1g of soil, contaminated with biphenyl, diphenyl oxide or both,

b. cultivate the sample isolated in step (a) in a culture medium in the presence of biphenyl, diphenyl oxide or both, at a temperature between 20 and 30°C and with orbital agitation between 120 and 250 rpm, preferably 120 rpm,

c. carry out one or more transfers of the culture from step (b) to fresh media in which the amount of culture medium is progressively reduced, preferably replacing it with a minimum salt medium, and the amount of biphenyl, diphenyl oxide is maintained or both, in order to obtain microorganisms that are able to grow in these components and use them as the only source of carbon,

d. repeat step (c) until the culture medium is completely removed, e. inoculate the culture obtained after step (d) in a medium, preferably in a soil sample, comprising a known concentration of biphenyl, diphenyl oxide, or both, and

F. analyzing what concentration of biphenyl, diphenyl oxide or both has disappeared after step (e).

In a preferred embodiment of this second procedure, the culture medium of step (b) is Luria Bertani (LB medium).

In a more preferred embodiment, the culture medium of step (b) comprises biphenyl and diphenyl oxide at a concentration of at least 10% with respect to the total volume of the medium (vol/vol).

In another preferred embodiment, the culture transfers in step (c) are carried out weekly.

In another preferred embodiment, the progressive reduction of the amount of culture medium in step (c) is achieved by eliminating 10% of the culture medium in each transfer and replacing it with a minimum salt medium.

Steps (e) and (f) are intended to verify that the microorganism(s) present in the culture obtained after step (d) are not only resistant to the components of 1HTF but are also capable of degrading it. To do this, preferably, the percentage of biodegradation in media contaminated with HTF and inoculated with the culture resulting from step (d) is compared to a control (medium contaminated with the same amount of HTF, but without the inoculation of said culture) and the concentration of the two HTF components is analyzed at the beginning of the experiment (t=0) and at time t (t being between 7-15 days).

In another preferred embodiment, the analysis of step (f) is carried out between 7 and 15 days after the inoculum of step (e), preferably 15 days.

In another preferred embodiment of the second method of the invention, one or more negative controls consisting of media, preferably soil samples, comprising the same concentration of biphenyl, diphenyl oxide or both as the medium used in step (e) are performed in parallel. , but where the culture obtained after step (d) is not inoculated. Subsequently, the concentration of biphenyl, diphenyl oxide or both that has disappeared in these negative controls is analyzed and compared with that obtained in the stage (f).

If it is finally verified that the concentration of HTF in the inoculated experiments is significantly lower than that obtained in the negative control, it is concluded that the culture used and obtained after step (d) comprises microorganisms capable of degrading HTF and will proceed to the isolation and identification of them.

Subsequently, it will be possible to optionally proceed to determine what number of cells, or culture volume, is necessary to add per gram or kg or liter of contaminated surface for efficient bioremediation. The size of the inocula, that is, the relationship between the number of cells (or colony-forming units -CFU-) per unit weight of soil (for example, number of cells/g soil) or liter of water, will vary depending on the depending on the degree of contamination of the surface to be treated.

Throughout the description and claims the word "comprise" and its variants are not intended to exclude other technical characteristics, additives, components or steps. Other objects, advantages and features of the invention will be apparent to those skilled in the art in part from the description and in part from the practice of the invention. The following examples are provided by way of illustration, and are not intended to be limiting of the present invention.

EXAMPLES

Next, the invention will be illustrated by means of tests carried out by the inventors that show the effectiveness of the strains of the invention and their combination (consortium) in the degradation of HTF.

EXAMPLE 1. OBTAINING BACTERIA RESISTANT TO BIPHENYL AND DIPHENYL OXIDE (HTF).

The first part of the invention consisted in obtaining bacteria resistant to biphenyl and diphenyl oxide (HTF). To do this, a sample of around 1 g of soil contaminated with HTF was taken and transferred to 100 ml of a culture medium prepared with LB medium (Luria Bertani medium), which is a general medium for the growth of heterotrophic bacteria whose composition is: 10 g/l of peptone; 5 g/l of yeast extract and 10 g/l of NaCl, at pH 7.

In addition, 10% (vol/vol) of HTF was added. This culture was kept in orbital shaking at 120 r.p.m. and room temperature (approximately 22°C).

When it was verified, after approximately one week, that there had been growth of bacteria resistant to HTF components under these conditions, 10% of this culture was transferred to a new medium in which the proportion of LB had been reduced by 10%, again allowing the crop to prosper. The volume of LB removed was replaced by minimal salt medium. This process was repeated successively until the LB was eliminated and the final culture was prepared with a minimum salt medium and 10% HTF, exclusively.

Next, it was found that the bacteria thus obtained were capable of degrading the HTF components and transforming biphenyl and diphenyl oxide into simple carbon compounds (CO ² ) and compounds that bacteria can assimilate. To verify this biodegradation capacity, cultures of known concentration of HTF were prepared and the concentration of HTF that had disappeared in inoculated cultures after a period of between 7-15 days compared to controls without inoculum was analyzed. In the event that the degradation is not effective, it should begin again with the obtaining of new soil samples.

EXAMPLE 2. BIOREMEDIATION TEST OF CONTAMINATION BY HTF.

A solution prepared with 10% HTF was inoculated with the final culture obtained in Example 1. The initial inoculum size was 1,000,000 cells/ml. In parallel, another similar solution was prepared but without bacteria. Samples of each of the solutions were taken and frozen pending further analysis.

After 15 days, culture and control samples were taken and the concentration of biphenyl and diphenyl oxide in these cultures and in those preserved by freezing (representative of time t = 0) were analyzed. Thus, it was found that the culture was capable of eliminating the concentration of biphenyl and diphenyl oxide with an efficiency of 95 and 92%, respectively.

Once the capacity of the culture to resist and degrade HTF was verified, the bacterial species present in it were identified by means of sequencing. of the 16S rRNA gene, resulting in the culture being made up of strains of Achromobacter sp., Enterococcus sp. and Pseudomonas aeruginosa, which were deposited under the Budapest Treaty as indicated above.

Subsequently, an inoculum was made with the culture of the invention in soil artificially contaminated with 20,000 mg/l of HTF. The simulation was done in a volume of 1 m3 of soil. 5 ml of culture/g of soil containing 109 CFU/g soil were added through an irrigation system. A soil sample was taken before making the inoculum and once it was added, the bacteria were allowed to act for a period of 15 days, after which a soil sample was taken again, finding that the percentage of elimination of biphenyl and diphenyl oxide was 97 and 94%, respectively.

EXAMPLE 3. TEST TO IDENTIFY THE MOST EFFECTIVE BACTERIA IN THE BIOREMEDIATION OF HTF CONTAMINATION.

Finally, a test was carried out to evaluate the degradation percentage of the 1,1'-Biphenyl and diphenyl ether compounds using:

- Only the strain of Enterococcus sp. obtained in the previous examples and deposited in the CECT under the access number CECT30012.

- Only the strain of Achromobacter sp. obtained in the previous examples and deposited in the CECT under the access number CECT30013.

- Only the strain of Pseudomonas aeruginosa obtained in the previous examples and deposited in the CECT under the access number CECT30014.

- Bacterial consortium comprising Achromobacter sp. CECT30013, Pseudomonas aeruginosa CECT30014 and Enterococcus sp. CECT30012 in different proportions to determine which of the combinations was the most effective.

For the experiments, a medium (the same as that used in the previous examples) was started, comprising a minimum medium of salts and a concentration of HTF at 10% (vol/vol). Subsequently, the cultures indicated in Table 1 below were prepared (all with 100 ml of this medium and an inoculum of 1,000,000 cells/ml). The cultures were kept in orbital shaking at 120 rpm and at 30°C. The results shown in Table 1 correspond to the biodegradation of HTF at 15 days.

Table 1:

It was found that the monoculture formed exclusively by Enterococcus sp. CECT30012 is the one that provided the best results among all the monocultures tested, and that the consortium that worked best was the one that was formed by the combination of Achromobacter sp. CECT30013, Enterococcus sp. CECT30012 and Pseudomonas aeruginosa CECT30014 in proportions of 6.9%; 64.5% and 28.6%, respectively, that is, a consortium in which the presence of Enterococcus sp. CECT30012.

The worst-performing consortium was the one in which the Achromobacter species predominated. When the predominant species was Pseudomonas , intermediate yields were obtained.

Claims (9)

1. A bacterial strain of Enterococcus sp. isolated and deposited in the Spanish Collection of Type Cultures with deposit number CECT30012. 2. A pure bacterial culture comprising the strain according to claim 1. 3. A composition comprising the strain according to claim 1, or the pure bacterial culture according to claim 2. 4. The composition according to claim 3, further comprising a biologically acceptable carrier and/or excipient. 5. The composition according to any of claims 3 or 4, further comprising a bacterial strain of Achromobacter sp. deposited in the Spanish Type Culture Collection with deposit number CECT30013 and a bacterial strain of Pseudomonas aeruginosa deposited in the Spanish Type Culture Collection with deposit number CECT30014, where the proportion of each of the strains in the composition, with Regarding the total amount of bacterial strains present in the composition, it is 6.9% of Achromobacter sp. CECT30013, 64.5% Enterococcus sp. CECT30012 and 28.6% Pseudomonas aeruginosa CECT30014. 6. Use of the strain according to claim 1, of the pure bacterial culture according to claim 2 or of the composition according to any of claims 3 to 5 for the degradation of biphenyl, diphenyl oxide or both. 7. Use of the strain according to claim 1, of the pure bacterial culture according to claim 2 or of the composition according to any of claims 3 to 5 for the bioremediation of soils contaminated with biphenyl, diphenyl oxide or both. 8. Method for the bioremediation of soils contaminated with biphenyl, diphenyl oxide or both, comprising the following stages: a. cultivating the strain according to claim 1, the pure bacterial culture according to claim 2 or the composition according to any of claims 3 to 5, preferably until reaching a density of at least 0.2 x 109 CFU/ml, and b. irrigating the surface of the contaminated soil to be treated with the crop obtained after step (a). 9. The method according to claim 8, wherein the irrigation of step (b) is carried out in a ratio of 5 ml of culture per gram of soil.