Mechanisms of ammonia, calcium and heavy metal removal from nutrient-poor water by Acinetobacter calcoaceticus strain HM12.

An Acinetobacter calcoaceticus strain HM12 capable of heterotrophic nitrification-aerobic denitrification (HN-AD) under nutrient-poor conditions was isolated, with an ammonia nitrogen (NH4+-N) removal efficiency of 98.53%. It can also remove heavy metals by microbial induced calcium precipitation (MICP) with a Ca2+ removal efficiency of 75.91%. Optimal conditions for HN-AD and mineralization of the strain were determined by kinetic analysis (pH = 7, C/N = 2.0, Ca2+ = 70.0 mg L-1, NH4+-N = 5.0 mg L-1). Growth curves and nitrogen balance elucidated nitrogen degradation pathways capable of converting NH4+-N to gaseous nitrogen. The analysis of the bioprecipitation showed that Zn2+ and Cd2+ were removed by the MICP process through co-precipitation and adsorption (maximum removal efficiencies of 93.39% and 80.70%, respectively), mainly ZnCO3, CdCO3, ZnHPO4, Zn3(PO4)2 and Cd3(PO4)2. Strain HM12 produces humic and fulvic acids to counteract the toxicity of pollutants, as well as aromatic proteins to increase extracellular polymers (EPS) and promote the biomineralization process. This study provides a experimental evidence for the simultaneous removal of multiple pollutants from nutrient-poor waters.

Nitrogen removal by a novel heterotrophic nitrification and aerobic denitrification bacterium Acinetobacter calcoaceticus TY1 under low temperatures.

A new bacterial strain, Acinetobacter calcoaceticus TY1, was identified in activated sludge. This strain efficiently metabolized nitrogen from ammonium at low temperatures, utilizing NH4+-N, NO3--N, and NO2--N as nitrogen sources. Of these, NH4+-N was superior in terms of both assimilation and heterotrophic nitrification at 8 °C. The nitrogen metabolism-associated genes amoA, nirK, and nosZ were identified in TY1. Optimal requirements for growth and nitrogen removal were pH 7, shaking speed of 90 rpm, a C/N ratio of 10, and sodium citrate for the carbon supply. The ability to denitrify at low temperature suggests TY1's potential for wastewater management.

Synergism of imipenem with fosfomycin associated with the active cell wall recycling and heteroresistance in Acinetobacter calcoaceticus-baumannii complex.

The carbapenem-resistant Acinetobacter calcoaceticus-baumannii (ACB) complex has become an urgent threat worldwide. Here, we determined antibiotic combinations and the feasible synergistic mechanisms against three couples of ACB (A. baumannii (AB250 and A10), A. pittii (AP1 and AP23), and A. nosocomialis (AN4 and AN12)). Imipenem with fosfomycin, the most effective in the time-killing assay, exhibited synergism to all strains except AB250. MurA, a fosfomycin target encoding the first enzyme in the de novo cell wall synthesis, was observed with the wild-type form in all isolates. Fosfomycin did not upregulate murA, indicating the MurA-independent pathway (cell wall recycling) presenting in all strains. Fosfomycin more upregulated the recycling route in synergistic strain (A10) than non-synergistic strain (AB250). Imipenem in the combination dramatically downregulated the recycling route in A10 but not in AB250, demonstrating the additional effect of imipenem on the recycling route, possibly resulting in synergism by the agitation of cell wall metabolism. Moreover, heteroresistance to imipenem was observed in only AB250. Our results indicate that unexpected activity of imipenem on the active cell wall recycling concurrently with the presence of heteroresistance subpopulation to imipenem may lead to the synergism of imipenem and fosfomycin against the ACB isolates.

Rhamnolipids from non-pathogenic Acinetobacter calcoaceticus: Bioreactor-scale production, characterization and wound healing potency.

Rhamnolipids are predominantly produced from the opportunistic pathogen Pseudomonas aeruginosa, which restricts their scaled-up production and biomedical applications. Moreover, the wound healing property of rhamnolipids is mainly focused on either mono- or di-rhamnolipid congeners, which are obtained after extensive and costly purification procedures. Here, crude rhamnolipids from non-pathogenic Acinetobacter calcoaceticus BU-03 have been prepared and characterized and their wound healing potency evaluated in vitro and in vivo. Rhamnolipid extract was produced in a bioreactor by batch fermentation at a concentration of 12.7 ± 1.4 g/L. Characterization of the extract by Fourier Transform Infrared spectroscopy and mass spectrometry revealed characteristic rhamnolipid peaks. Rha-C10-C10 and Rha-Rha-C10-C10 appeared as the predominant congeners along with minor quantities of six more congeners. The rhamnolipid extract obtained from A. calcoaceticus had no toxicity against mouse fibroblast L929 cells and accelerated their migration. Transforming growth factor beta 1 (TGF-ß1) has been shown to promote fibroblast migration by activating Smad3. It was found that the rhamnolipid extract enhanced Smad3 phosphorylation in L929 cells. In vivo studies showed that it promoted wound healing in mice with excisional wounds. The protein levels of TGF-ß1 and alpha smooth muscle actin (α-SMA), a highly contractile protein, were significantly increased by 2.56- and 1.51-fold, respectively, in extract-treated compared with vehicle control-treated wounds, indicating that the activation of TGF-ß1 signaling is possibly involved in the wound healing effect. These results suggest that a rhamnolipid extract obtained from A. calcoaceticus has potential as a wound healing material for topical application in cutaneous wound treatment.

Characterization and genomic analysis of a diesel-degrading bacterium, Acinetobacter calcoaceticus CA16, isolated from Canadian soil.

BACKGROUND: With the high demand for diesel across the world, environmental decontamination from its improper usage, storage and accidental spills becomes necessary. One highly environmentally friendly and cost-effective decontamination method is to utilize diesel-degrading microbes as a means for bioremediation. Here, we present a newly isolated and identified strain of Acinetobacter calcoaceticus ('CA16') as a candidate for the bioremediation of diesel-contaminated areas. RESULTS: Acinetobacter calcoaceticus CA16 was able to survive and grow in minimal medium with diesel as the only source of carbon. We determined through metabolomics that A. calcoaceticus CA16 appears to be efficient at diesel degradation. Specifically, CA16 is able to degrade 82 to 92% of aliphatic alkane hydrocarbons (CnHn + 2; where n = 12-18) in 28 days. Several diesel-degrading genes (such as alkM and xcpR) that are present in other microbes were also found to be activated in CA16. CONCLUSIONS: The results presented here suggest that Acinetobacter strain CA16 has good potential in the bioremediation of diesel-polluted environments.

Highly efficient removal of victoria blue R and bioelectricity generation from textile wastewater using a novel combined dual microbial fuel cell system.

A novel combined dual microbial fuel cell (MFC) system was developed for the continuous removal of Victoria Blue R (VBR) and electricity generation. Anaerobic and aerobic VBR-degrading bacteria, Shewanella putrefaciens and Acinetobacter calcoaceticus, respectively, were applied simultaneously. The effects of various factors on the performance of the novel system in the continuous mode were investigated, and optimal operating parameters for the system were determined. The optimal liquid retention time for continuous treatment was 36 h. The optimal external resistances of connected MFCs were 390 Ω and 1300 Ω. When artificial wastewater containing 1000 mg/l of VBR was fed continuously into the system, the VBR removal efficiency achieved was 98.7%. In addition, the acute toxicity of the effluent was decreased by a factor of 21.1-22.3, indicating that the system could detoxify VBR intermediates. VBR degradation involved a stepwise demethylation process, which occurred mainly in the first MFC, whereas aromatic ring opening, sequential deamination reaction, and carbon oxidation occurred mainly in the second MFC. When actual VBR-containing wastewater (75-262 mg/l) was introduced, the removal efficiencies of VBR, chemical oxygen demand, colority, NH3, and bioelectricity generation were >99.8%, >96.6%, >88.0%, 100%, and >194.8 mW/m2, respectively and the original inoculated strains remained dominant. Therefore, the combined dual MFC system could be applied to the treatment of actual VBR-containing wastewater.

Bioconversion of 5-Hydroxymethylfurfural (HMF) to 2,5-Furandicarboxylic Acid (FDCA) by a Native Obligate Aerobic Bacterium, Acinetobacter calcoaceticus NL14.

2,5-Furandicarboxylic acid (FDCA), one of the top biomass-based platform chemical, is highly promising for resins and polymers, and it can be prepared from the bio-oxidation of hydroxymethyl furfural (HMF), which can be obtained mainly from lignocellulosic glucose that has a high production potential from not edible biomass.A native strain, Acinetobacter calcoaceticus NL14, that could convert HMF into FDCA is used for combining degradation and fermentation by consolidated bioprocessing (CBP). In this study, it was observed that the initial HMF concentration and pH neutralizer played important roles in the bioconversion of HMF, 5 g/L of HMF could be converted by 100% within 48 h with 0.5 g/L sodium carbonate (Na2CO3) with the production of 0.31 g/L FDCA. Extra glucose and hydrogen peroxide (H2O2) addition could further promote the production of FDCA to 0.54 g/L with 100% HMF conversion and a higher conversion rate. This report could provide a potential native bacterium for furan chemicals bioconversion and bioelimination, especially for FDCA bioproduction.

Enhanced biomass production and nutrient removal capacity of duckweed via two-step cultivation process with a plant growth-promoting bacterium, Acinetobacter calcoaceticus P23.

Plant growth-promoting bacteria (PGPB) are considered a promising tool to improve biomass production and water remediation by the aquatic plant, duckweed; however, no effective methodology is available to utilize PGPB in large hydroponic systems. In this study, we proposed a two-step cultivation process, which comprised of a "colonization step" and a "mass cultivation step," and examined its efficacy in both bucket-scale and flask-scale cultivation experiments. We showed that in the outdoor bucket-scale experiments using three kinds of environmental water, plants cultured through the two-step cultivation method with the PGPB strain, Acinetobacter calcoaceticus P23, yielded 1.9 to 2.3 times more biomass than the control (without PGPB inoculation). The greater nitrogen and phosphorus removals compared to control were also attained, indicating that this strategy is useful for accelerating nutrient removal by duckweed. Flask-scale experiments using non-sterile pond water revealed that inoculation of strain P23 altered duckweed surface microbial community structures, and the beneficial effects of the inoculated strain P23 could last for 5-10 d. The loss of the duckweed growth-promoting effect was noticeable when the colonization of strain P23 decreased in the plant. These observations suggest that the stable colonization of the plant with PGPB is the key for maintaining the accelerated duckweed growth and nutrient removal in this cultivation method. Overall, our results suggest the possibility of an improved duckweed production using a two-step cultivation process with PGPB.

Cytokine profiles of umbilical cord blood mononuclear cells upon in vitro stimulation with lipopolysaccharides of different vaginal gram-negative bacteria.

Inflammatory immune responses induced by lipopolysaccharides (LPS) of gram-negative bacteria play an important role in the pathogenesis of preterm labor and delivery, and in neonatal disorders. To better characterize LPS-induced inflammatory response, we determined the cytokine profile of umbilical cord blood mononuclear cells (UBMC) stimulated with LPS of seven vaginal gram-negative bacteria commonly found in pregnant women with preterm labor and preterm rupture of membrane. UBMC from ten newborns of healthy volunteer mothers were stimulated with purified LPS of Escherichia coli, Enterobacter aerogenes, Klebsiella pneumoniae, Proteus mirabilis, Acinetobacter calcoaceticus, Citrobacter freundii, and Pseudomonas aeruginosa. UBMC supernatants were tested for the presence of secreted pro-inflammatory cytokines (IL-6, IL-1ß, TNF), anti-inflammatory cytokine (IL-10), TH1-type cytokines (IL-12, IFN-γ), and chemokines (IL-8, MIP-1α, MIP-1ß, MCP-1) by Luminex technology. The ten cytokines were differentially induced by the LPS variants. LPS of E. coli and E. aerogenes showed the strongest stimulatory activity and P. aeruginosa the lowest. Interestingly, the ability of UBMC to respond to LPS varied greatly among donors, suggesting a strong individual heterogeneity in LPS-triggered inflammatory response.

Enzyme cocktail containing NADH regeneration system for efficient bioremediation of oil sludge contamination.

Oil sludge is one kind of toxic and persistent contamination to ecology system from petroleum industry. In order to recycle contaminated sands and reduce environmental impacts at a lower operating cost, enzyme cocktail 21/CbFDH including NADH regeneration system for oily sludge bioremediation was constructed for the first time. The intracellular enzymes of oil-degrading strain Acinetobacter calcoaceticus 21 were prepared and the formate dehydrogenase gene Cbfdh from Candida boidinii was cloned and functionally expressed in E.coli BL21 induced by lactose. The activity and stability of CbFDH was enhanced through self-induction medium optimization using Box-Behnken design. The CbFDH activity was 12.2 times increased and was only decreased 3.9% upon storage at 30 °C for 5 d. The CbFDH increased the degradation rate of oil in high concentration. For the sludge with 10% oil (w/w), the degradation rate achieved 35.6% after 12 h using enzyme 21/CbFDH with the protein ratio of 1:4. The results will provide novel perspectives for creation and operation of petroleum-degrading enzymes involving formate dehydrogenase with higher efficiency and lower cost comparing to current microbial strains or consortium.

Butylbenzene and tert-Butylbenzene-Sorption on Sand Particles and Biodegradation in the Presence of Plant Natural Surfactants.

The effects of hydrocarbons sorption on sand and saponins presence in the system on butylbenzene and tert-butylbenzene biological degradation was investigated. Additionally, the impact of saponins-containing plant extracts on environmental microorganisms was studied. Results of cell surface property measurements in samples with saponins only revealed changes in cell surface hydrophobicity, electrokinetic potential and membrane permeability when compared to corresponding values for glucose-grown microbes. Subsequently, in sorption experiments, the hydrocarbon adsorption kinetics in bacteria-free samples were better explained with the pseudo-second order kinetic model as compared to the pseudo-first order and intraparticular diffusion models. Moreover, the equilibrium data fitted better to the Freundlich isotherm for both benzene derivatives. In the samples combining hydrocarbons sorption and biological degradation in the presence of saponins, alkane-substituted hydrocarbons removal was accelerated from 40% to 90% after 14 days and the best surfactant in this aspect was S. officinalis extract.

Isolation and Characterization of Fipronil Degrading Acinetobacter calcoaceticus and Acinetobacter oleivorans from Rhizospheric Zone of Zea mays.

An enrichment culture technique was used for the isolation of bacteria capable of utilizing fipronil as a sole source of carbon and energy. Based on morphological, biochemical characteristics and phylogenetic analysis of 16S rRNA sequence, the bacterial strains were identified as Acinetobacter calcoaceticus and Acinetobacter oleivorans. Biodegradation experiments were conducted in loamy sand soil samples fortified with fipronil (50 µg kg(-1)) and inoculated with Acinetobacter sp. cells (45 × 10(7) CFU mL(-1)) for 90 days. Soil samples were periodically analyzed by gas liquid chromatography equipped with electron capture detector. Biodegradation of fipronil fitted well with the pseudo first-order kinetics, with rate constant value between 0.041 and 0.051 days(-1). In pot experiments, fipronil and its metabolites fipronil sulfide, fipronil sulfone and fipronil amide were found below quantifiable limit in soil and root, shoot and leaves of Zea mays. These results demonstrated that A. calcoaceticus and A. oleivorans may serve as promising strains in the bioremediation of fipronil-contaminated soils.

Biodegradation of Phenol by Bacteria Strain Acinetobacter Calcoaceticus PA Isolated from Phenolic Wastewater.

A phenol-degrading bacterium strain PA was successfully isolated from the effluent of petrochemical wastewater. Based on its morphological, physiological and biochemical characteristics, the strain PA was characterized as a Gram-negative, strictly aerobic, nonmotile and short rod-shaped bacterium that utilizes phenol as a sole carbon and energy source. 16S rDNA sequence analysis revealed that this strain is affiliated to Acinetobacter calcoaceticus in the group of Gammaproteobacteria. The strain was efficient in removing 91.6% of the initial 800 mg ∙ L(-1) phenol within 48 h, and had a tolerance of phenol concentration as high as 1700 mg ∙ L(-1). These results indicated that A. calcoaceticus possesses a promising potential in treating phenolic wastewater.

[Antimicrobial Properties Surfactants Synthesized under Different Cultivation Conditions of Acinetobacter calcoaceticus EMV B-7241].

Aim: To study the antimicrobial properties of the surface-active agents (surfactants) Acinetobacter calcoaceticus IMV B-7241 depending on the availability of yeast autolysate and trace elements in the composition of ethanol-, n-hexadecane- and glycerol-containing media. Methods: Antimicrobial against bacteria (Escherichia coli IEM-1, Bacillus subtilis BT-2), and yeast (Candida albicans D-6) properties of the surfactant was determined by index of the minimum inhibitory concentration (MIC). Surfactants were extracted from supernatant of cultural liquid by mixture of chloroform and methanol (2:1). Results: The removal from cultivation medium yeast autolysate and trace element mix and replacing them by copper sulfate and iron sulphate in the medium with ethanol and n-hexadecane, and in the medium with glycerol - by potassium chloride, zinc sulfate and copper sulfate accompanied by decreasing antimicrobial properties of surfactants. The most effective antimicrobial agents were surfactant synthesized on ethanol in the presence of yeast autolysate and trace elements (MIC 9-20 µ/ml), whereas the surfactant obtained under similar cultivation conditions on glycerol and n-hexadecane, inhibited growth of tested bacteria and yeast at higher (9-68 and 27-54 µ/ml, respectively) concentrations. The minimum inhibitory concentration of surfactant, synthesized in a medium with ethanol (glycerol, n-hexadecane), yeast autolysate and trace elements, correlated with the activity of NADP+-dependent glutamate dehydrogenase - a key enzyme of aminolipids biosynthesis (610 ± 30, 395 ± 24, 397 ± 24 nM min-1·mg-1 protein, respectively). Conclusions: The higher activity of NADP+-dependent glutamate dehydrogenase when growing the strain IMV B-7241 in a medium with ethanol (n-hexadecane), yeast autolysates and trace elements compared to that in a medium with copper sulfate and iron sulfate, as well as an increase enzyme activity in the presence of zinc cations suggests the possibility of increasing synthesis aminolipids by introducing Zn2+ in the medium with ethanol and n-hexadecan. The obtained data indicate the need for studies depending on biological properties of surfactants of the cultivation conditions of producer.

[EFFECT OF Zn²âº ON SYNTHESIS OFACINETOBACTER CALCOACETICUS IMV B-7241 SURFACTANTS WITH ANTIMICROBIAL AND ANTIADHESIVE PROPERTIES].

AIM: To study the effect of zinc cations in the composition of ethanol and n-hexadecane containing medium on the antiadhesive and antimicrobial activity of Acinetobacter calcoaceticus IMV B-7241 surfactants. METHODS: Surfactants were extracted from supernatant of cultural liquid by mixture of chloroform and methanol (2:1). The number of attached cells was determined spectrophotometrically, antimicrobial properties - by index of the minimum inhibitory concentration (MIC). RESULTS: Adding Zn²âº (38 mmol/l) into medium with ethanol and n-hexadecane containing copper sulphate and iron sulphate, was accompanied by the formation of surfactant with higher antimicrobial and antiadhesive activity, as well as increasing activity of NADP⁺-dependent glutamate dehydrogenase - a key enzyme of aminolipids biosynthesis. The minimum inhibitory concentration against Escherichia coli IEM- 1, Enterobacter cloaceae C-8, Staphylococcus aureus EMC- 1 and Proteus vulgaris IIA- 12 of surfactants, synthesized in the presence of Zn²âº, and the adhesion of E. coli IEM-1 on abiotic surfaces treated with such surfactants, were respectively in 1.6-3.3 times and 10-19 % lower than those of the preparations obtained under cultivation of IMV B-7241 strain in medium without zinc cations. The activity of NADP⁺-dependent glutamate dehydrogenase at the end of exponential phase of A. calcoaceticus IMV B-7241 growth in medium with ethanol (n-hexadecane), copper, zinc and iron sulfate; was 1739±87 (8333±416) nmol-min⁻¹ mg⁻¹ protein that in 2 and 15 times higher than under the same conditions cultivation on ethanol and n-hexadecane without Zn²âº. CONCLUSIONS: The obtained data suggest the possibility of biosynthesis regulation of A. calcoaceticus IMV B-7241 surfactants with antimicrobial and antiadhesive properties, when zinc cations (activator NADP⁺-dependent glutamate dehydrogenase - a key enzyme of aminolipids synthesis) were added into medium with ethanol (n-hexadecane), as well as the possibility of regulating the biological properties of the surfactants during cultivation of producer.

[EFFECT OF CULTIVATION CONDITION OF ACINETOBACTER CAL COACETICUS IMV B-7241 ON ANTIADHESIVE PROPERTIES OF SURFACTANTS].

AIM: To study the effect of growth factors and microelements in composition of ethanol-, n-hexadecane- and glycerol-containing media on antiadhesive properties of A cinetobacter calcoaceticus IMV B-7241 surfactants. METHODS: Surfactants were extracted from supernatant of cultural liquid by mixture of chloroform and methanol (2:1). The number (%) of attached cells (adhesion) was determined as a ratio of the optical density of the suspension obtained from the materials treated with surfactants to the optical density of the control samples (100 %). RESULTS: Dependence of surfactants antiadhesive properties on presence in the medium of A. calcoaceticus IMB B-7241 cultivation of growth factors and certain microelements, as well as the nature of the carbon source was established. Adhesion of bacteria (Escherichia coli IEM- 1, Bacillus subtilis BT-2) and yeast (Candida albicans D-6) on plastic, dutch tile, linoleum, and steel was a minimal (25-35 %) after surface treatment with surfactant (0.005 mg/ml) synthesized on ethanol in the presence of yeast autolysate and microelements. Replacement the yeast autolysate and microelement mixture in the composition of ethanol- and n-hexadecane-containing media by copper sulfate and iron sulfate and in the medium with glycerol by KCl, zinc sulfate and copper sulfate accompanied by decreasing antiadhesive properties of synthesized surfactants. CONCLUSIONS: The obtained data indicate that the increasing surfactant synthesis does not always the accompanied by the formation of product with the required biological properties and indicate the need for studies depending on biological properties of surfactants of the cultivation conditions of producer.

An endophytic bacterium Acinetobacter calcoaceticus Sasm3-enhanced phytoremediation of nitrate-cadmium compound polluted soil by intercropping Sedum alfredii with oilseed rape.

Intensive agricultural system with high input of fertilizer results in high agricultural output. However, excessive fertilization in intensive agricultural system has great potential to cause nitrate and heavy metal accumulation in soil, which is adverse to human health. The main objective of the present study was to observe the effects of intercropping and inoculation of endophytic bacterium Acinetobacter calcoaceticus Sasm3 on phytoremediation of combined contaminated soil in oilseed rape (Brassica napus L.). The results showed that with Sasm3 inoculation, the biomass of rape was increased by 10-20% for shoot, 64% for root, and 23-29% for seeds while the nitrate accumulation in rape was decreased by 14% in root and by 12% in shoot. The cadmium concentration in rape increased significantly with mono-inoculating treatment, whereas it decreased significantly after intercropping treatment. By denaturing gradient gel electrophoresis (DGGE) and real-time quantitative PCR analysis, the diversity of bacterial community and the number of nirS and nirK gene copies increased significantly with inoculation or/and intercropping treatment. In conclusion, the endophytic bacterium Sasm3-inoculated intercropping system not only improved the efficiency of clearing cadmium from soil without obstructing crop production, but also improved the quality of crop.

Role of Quinones in Electron Transfer of PQQ-Glucose Dehydrogenase Anodes­Mediation or Orientation Effect.

In this study, the influence of two quinones (1,2- and 1,4-benzoquinone) on the operation and mechanism of electron transfer in PQQ-dependent glucose dehydrogenase (PQQ-sGDH) anodes has been determined. Benzoquinones were experimentally explored as mediators present in the electrolyte. The electrochemical performance of the PQQ-sGDH anodes with and without the mediators was examined and for the first time molecular docking simulations were used to gain a fundamental understanding to explain the role of the mediator molecules in the design and operation of the enzymatic electrodes. It was proposed that the higher performance of the PQQ-sGDH anodes in the presence of 1,2- and 1,4-benzoquinones introduced in the solution is due to the shorter distance between these molecules and PQQ in the enzymatic molecule. It was also hypothesized that when 1,4-benzoquinone is adsorbed on a carbon support, it would play the dual role of a mediator and an orienting agent. At the same time, when 1,2-benzoquinone and ubiquinone are adsorbed on the electrode surface, the enzyme would transfer the electrons directly to the support, and these molecules would primarily play the role of an orienting agent.

[Destruction of oil in the presence of Cu2+ and surfactants of Acinetobacter calcoaceticus IMV B-7241, Rhodococcus erythropolis IMV Ac-5017 and Nocardia vaccinii IMV B-7405].

The effect of copper cations (0.01-1.0 mM) and surface-active agents (surfactants) of Acinetobacter calcoaceticus IMV B-7241, Rhodococcus erythropolis IMV Alc-5017 and Nocardia vaccinii IMV B-7405 in the form of culture liquid on the destruction of oil in water (3.0-6.0 g/L) and soil (20 g/kg), including in the presence of Cd2+ and Pb2+ (0.01-0.5 mM), was investigated. It was shown that the degree of oil degradation in water and soil after 20 days in the presence of low concentrations of Cu2+ (0.01-0.05 mM) and culture liquid of strains IMV B-7241, IMV Ac-5017, and IMV B-7405 was 15 - 25% higher than without copper cations. The activating effect of Cu2+ on the decomposition of complex oil and Cd2+ and Pb2+ pollution was established: after treatment with surfactant of A. calcoacelicus IMV B-7241 and R. erythropolis IMV Ac-5017 destruction of oil in water and soil was 85-95%, and after removal of the copper cations decreased to 45-70%. Intensification of oil destruction in the presence of copper cations may be due to their stimulating effect on the activity of alkane hydroxylases as in surfactant-producing strains, and natural (autochthonous) oxidizing microbiota.

Molecular identification of phosphate-solubilizing native bacteria isolated from the rhizosphere of Prosopis glandulosa in Mexicali valley.

One of the main limitations in intensive crop production in Northwestern Mexico is the dependence on the use of phosphate fertilizer. In this study, we isolated indigenous microorganisms with phosphate solubilization capacities from mesquite (Prosopis glandulosa) present in the Mexicali valley. In total, 4 bacteria were isolated from the rhizosphere of mesquite, including ICA01, ICA02Ba, ICA03Bs, and ICA04Ma. The bacterial isolates were identified based on their phenotypic and 16S rRNA gene sequencing data to be Acinetobacter calcoaceticus. The results showed that ICA01 was the most efficient in solubilizing phosphate, followed by ICA02Ba and ICA03Bs, while ICA04Ma showed the lowest phosphate-solubilizing activity. The pH value of the culture medium decreased with bacterial growth, suggesting that these strains produce organic acids that solubilize phosphorus. These results will be useful for biotechnological studies and A. calcoaceticus may be employed for biofertilization programs in northwest Mexico.