Pseudomonas Strains Research Articles

Isolation and Characterization of Plant Growth-Promoting Bacteria from the Rhizosphere of Medicinal and Aromatic Plant Minthostachys verticillata.

This study aimed to isolate and characterize Pseudomonas native strains from the rhizospheric soil of Minthostachys verticillata plants to evaluate their potential as plant growth-promoting rhizobacteria (PGPR). A total of 22 bacterial isolates were obtained and subjected to various biochemical tests, as well as assessments of plant growth-promoting traits such as phosphate solubilization, hydrogen cyanide production, biocontrol properties through antibiosis, and indole acetic production. Genotypic analysis via 16S rRNA gene sequencing and phylogenetic tree construction identified the strains, with one particular strain named SM 33 showing significant growth-promoting effects on M. verticillata seedlings. This strain, SM 33, showed high similarity to Stutzerimonas stutzeri based on 16S rRNA gene sequencing and notably increased both shoot fresh weight and root dry weight of the plants. These findings underscore the potential application of native Pseudomonas strains in enhancing plant growth and health, offering promising avenues for sustainable agricultural practices.

Phenotypic and Genotypic Characterization of AmpC Beta-Lactamase in Clinical Isolates of Pseudomonas aeruginosa Findings From a Tertiary Care Hospital.

Background and aim Pseudomonas aeruginosa is an opportunistic pathogen responsible for various healthcare-related infections, which are difficult to treat due to intrinsic and acquired resistance. This study aimed to investigate AmpC β-lactamase production using phenotypic and genotypic methods in Pseudomonas aeruginosa strains isolated from a tertiary care hospital in Karad, Maharashtra, India. Material and methods Over one year, a descriptive cross-sectional study was conducted at the Department of Microbiology, Krishna Institute Medical Sciences, Krishna Vishwa Vidyapeeth, Karad. Phenotypic detection of AmpC beta-lactamase was performed using the Cefoxitin-Cloxacillin Double-Disc Synergy Test method, and genotypic detection was conducted using conventional polymerase chain reaction (PCR) targeting the bla Pseudomonas-derived cephalosporinases (PDC) and bla cephamycinase (CMY) genes. Results Out of 205 clinical isolates of Pseudomonas aeruginosa, 110 (53.66%) showed AmpC production phenotypically, while 86 (41.95%) were positive genotypically. The blaPDC gene was detected in 36.10% of isolates, and the blaCMY gene in 10.73% ofisolates. Conclusions The study findings indicate that AmpC-β-lactamase stands out as the primary resistance mechanism in strains of Pseudomonas aeruginosaisolated from the hospital. PCR study concluded that blaPDC (36.10 %) was the leading gene responsible for AmpC synthesis among study isolates. Early detection of AmpC beta-lactamase production by employing phenotypic and genotypic methods is crucial for detecting antibiotic resistance. This dual approach enables healthcare professionals to decide on the most effective antibiotics and mitigate the development of resistance.

Expanding the Pseudomonas diversity of the wheat rhizosphere: four novel species antagonizing fungal phytopathogens and with plant-beneficial properties.

Plant-beneficial Pseudomonas bacteria hold the potential to be used as inoculants in agriculture to promote plant growth and health through various mechanisms. The discovery of new strains tailored to specific agricultural needs remains an open area of research. In this study, we report the isolation and characterization of four novel Pseudomonas species associated with the wheat rhizosphere. Comparative genomic analysis with all available Pseudomonas type strains revealed species-level differences, substantiated by both digital DNA-DNA hybridization and average nucleotide identity, underscoring their status as novel species. This was further validated by the phenotypic differences observed when compared to their closest relatives. Three of the novel species belong to the P. fluorescens species complex, with two representing a novel lineage in the Pseudomonas phylogeny. Functional genome annotation revealed the presence of specific features contributing to rhizosphere colonization, including flagella and components for biofilm formation. The novel species have the genetic potential to solubilize nutrients by acidifying the environment, releasing alkaline phosphatases and their metabolism of nitrogen species, indicating potential as biofertilizers. Additionally, the novel species possess traits that may facilitate direct promotion of plant growth through the modulation of the plant hormone balance, including the ACC deaminase enzyme and auxin metabolism. The presence of biosynthetic clusters for toxins such as hydrogen cyanide and non-ribosomal peptides suggests their ability to compete with other microorganisms, including plant pathogens. Direct inoculation of wheat roots significantly enhanced plant growth, with two strains doubling shoot biomass. Three of the strains effectively antagonized fungal phytopathogens (Thielaviopsis basicola, Fusarium oxysporum, and Botrytis cinerea), demonstrating their potential as biocontrol agents. Based on the observed genetic and phenotypic differences from closely related species, we propose the following names for the four novel species: Pseudomonas grandcourensis sp. nov., type strain DGS24T ( = DSM 117501T = CECT 31011T), Pseudomonas purpurea sp. nov., type strain DGS26T ( = DSM 117502T = CECT 31012T), Pseudomonas helvetica sp. nov., type strain DGS28T ( = DSM 117503T = CECT 31013T) and Pseudomonas aestiva sp. nov., type strain DGS32T ( = DSM 117504T = CECT 31014T).

Siderophore interactions drive the ability of Pseudomonas spp. consortia to protect tomato against Ralstonia solanacearum.

The soil-borne bacterial pathogen Ralstonia solanacearum causes significant losses in Solanaceae crop production worldwide, including tomato, potato, and eggplant. To efficiently prevent outbreaks, it is essential to understand the complex interactions between pathogens and the microbiome. One promising mechanism for enhancing microbiome functionality is siderophore-mediated competition, which is shaped by the low iron availability in the rhizosphere. This study explores the critical role of iron competition in determining microbiome functionality and its potential for designing high-performance microbiome engineering strategies. We investigated the impact of siderophore-mediated interactions on the efficacy of Pseudomonas spp. consortia in suppressing R. solanacearum , both in vitro and in vivo. Our findings show that siderophore production significantly enhances the inhibitory effects of Pseudomonas strains on pathogen growth, while other metabolites are less effective under iron-limited conditions. Moreover, siderophores play a crucial role in shaping interactions within the consortia, ultimately determining the level of protection against bacterial wilt disease. This study highlights the key role of siderophores in mediating consortium interactions and their impact on tomato health. Our results also emphasize the limited efficacy of other secondary metabolites in iron-limited environments, underscoring the importance of siderophore-mediated competition in maintaining tomato health and suppressing disease.

Adsorption of Flavonoids in a Transcriptional Regulator TtgR: Relative Binding Free Energies and Intermolecular Interactions.

Antimicrobial resistance in bacteria often arises from their ability to actively identify and expel toxic compounds. The bacterium strain Pseudomonas putida DOT-T1E utilizes its TtgABC efflux pump to confer robust resistance against antibiotics, flavonoids, and organic solvents. This resistance mechanism is intricately regulated at the transcriptional level by the TtgR protein. Through molecular dynamics and alchemical free energy simulations, we systematically examine the binding of seven flavonoids and their derivatives with the TtgR transcriptional regulator. Our simulations reveal distinct binding geometries and free energies for the flavonoids in the active site of the protein, which are driven by a range of noncovalent forces encompassing van der Waals, electrostatic, and hydrogen bonding interactions. The interplay of molecular structures, substituent patterns, and intermolecular interactions effectively stabilizes the bound flavonoids, confining their movements within the TtgR binding pocket. These findings yield valuable insights into the molecular determinants that govern ligand recognition in TtgR and shed light on the mechanism of antimicrobial resistance in P. putida DOT-T1E.

The different effects of molybdate on Hg(II) bio-methylation in aerobic and anaerobic bacteria.

In nature, methylmercury (MeHg) is primarily generated through microbial metabolism, and the ability of bacteria to methylate Hg(II) depends on both bacterial properties and environmental factors. It is widely known that, as a metabolic analog, molybdate can inhibit the sulfate reduction process and affect the growth and methylation of sulfate-reducing bacteria (SRB). However, after it enters the cell, molybdate can be involved in various intracellular metabolic pathways as a molybdenum cofactor; whether fluctuations in its concentration affect the growth and methylation of aerobic mercury methylating strains remains unknown. To address this gap, aerobic γ-Proteobacteria strains Raoultella terrigena TGRB3 (B3) and Pseudomonas putida TGRB4 (B4), as well as an obligate anaerobic δ-Proteobacteria strain of the SRB Desulfomicrobium escambiense CGMCC 1.3481 (DE), were used as experimental strains. The growth and methylation ability of each strain were analyzed under conditions of 500 ng·L-1 Hg(II), 0 and 21% of oxygen, and 0, 0.25, 0.50, and 1 mM of MoO4 2-. In addition, in order to explore the metabolic specificity of aerobic strains, transcriptomic data of the facultative mercury-methylated strain B3 were further analyzed in an aerobic mercuric environment. The results indicated that: (a) molybdate significantly inhibited the growth of DE, while B3 and B4 exhibited normal growth. (b) Under anaerobic conditions, in DE, the MeHg content decreased significantly with increasing molybdate concentration, while in B3, MeHg production was unaffected. Furthermore, under aerobic conditions, the MeHg productions of B3 and B4 were not influenced by the molybdate concentration. (c) The transcriptomic analysis showed several genes that were annotated as members of the molybdenum oxidoreductase family of B3 and that exhibited significant differential expression. These findings suggest that the differential expression of molybdenum-binding proteins might be related to their involvement in energy metabolism pathways that utilize nitrate and dimethyl sulfoxide as electron acceptors. Aerobic bacteria, such as B3 and B4, might possess distinct Hg(II) biotransformation pathways from anaerobic SRB, rendering their growth and biomethylation abilities unaffected by molybdate.

REMEDIATION OF SOILS CONTAMINATED WITH HEAVY FRACTION HYDROCARBONS USING BIOSURFACTANTPRODUCED BYPSEUDOMONAS SP.

This study evaluated the effectiveness of the biosurfactant generated by a strain of Pseudomonas sp. in the removal of heavy fraction hydrocarbons from a soil contaminated with 28,000 mg/kg, by a washing process. The efficacy of the biosurfactant was compared to that of a chemical surfactant, used at a concentration of 0.1%. After five wash cycles, the biosurfactant reached a maximum removal efficiency of 42.71%, in contrast to that of the chemical surfactant, 32.31%. In addition, bioaugmentation with the culture medium used for the production of the biosurfactant was evaluated, with a removal of 38.29% of these hydrocarbons in 90 days.

Biofertilizer Production using Phosphate-solubilizing Pseudomonas spp. Isolated from Rhizosphere Soil: Towards Indigenous Biofertilizer for Enhanced Crop Productivity in Katsina, Nigeria

Study’s Novelty/Excerpt This study offers an approach to sustainable agriculture by isolating and identifying phosphate-solubilizing Pseudomonas species from the rhizosphere soil of Wagini ward, Katsina state, for the production of biofertilizers. The research highlights the significant phosphate-solubilizing activity of these native strains, which enhances phosphorus availability to plants through the secretion of organic acids and enzymes. By demonstrating the positive effects of these Pseudomonas-based biofertilizers on maize, beans, and millet, this study provides valuable insights into the development of eco-friendly, cost-effective biofertilizers tailored to local agroecosystems, thereby promoting sustainable agricultural practices in Nigeria. Full Abstract The utilization of biofertilizers holds promise as a sustainable approach to enhance soil fertility and crop productivity while reducing reliance on chemical fertilizers. Beyond nitrogen, phosphorus is integral to various aspects of plant metabolism, including cell division, growth, development, sugar breakdown, and nuclear transport. The present study focuses on isolating Pseudomonas as phosphate-solubilizing bacteria from the rhizosphere soil to produce biofertilizer. Ten samples of rhizosphere soil samples were collected from agricultural fields in Wagini ward, Batsari Local Government area, Katsina state. The isolation and identification of Pseudomonas species from the soil samples were conducted using standard microbiological techniques, followed by screening for plant growth-promoting traits (phosphate solubilization). Subsequently, selected Pseudomonas species exhibiting robust phosphate solubilization were assessed for their efficacy in biofertilizer production, after which the produced biofertilizer was tested on maize, beans, and millet. The formulated biofertilizers demonstrated remarkable positive effects on the tested crops’ growth compared to those that were not treated with the Pseudomonas-based biofertilizer after seven days of cultivation under controlled conditions. The results of this study revealed that the isolated Pseudomonas strains exhibited significant phosphate-solubilizing activity. This indicates their potential to release phosphorus from insoluble forms, making it more accessible to plants. The solubilization activity was attributed to the secretion of organic acids and enzymes by the Pseudomonas strains, which can dissolve complex phosphates. This study underscores the importance of tacking native microbial resources for the development of eco-friendly and cost-effective biofertilizers tailored to local agroecosystems, thereby contributing to sustainable agricultural intensification and food security in Nigeria.

Bioprospecting of Fragrant Ginger (Zingiber aromaticum) Endophytic Bacteria from Enggano Island, Indonesia as Antimicrobial Compounds Producer

Fragrant Ginger or Lempuyang wangi (Zingiber aromaticum Val.) is one of the plants from the Zingiberaceae family that Indonesians widely use as traditional medicine. Endophytic bacteria living in the healthy plant are potentially carrying antimicrobial properties and good secondary metabolites. This study aims to determine the potential of endophytic bacteria from fragrant ginger plants from Enggano Island as antimicrobial. Antimicrobial activity was analyzed using the disc diffusion method from pallets and supernatant of bacteria. The results showed that five of 44 isolates consisting of Providencia strain LWERG 29, Stenotrophomonas strain LWERG 30, Bacillus strain LWEBG 39, Bacillus strain LWEBG 41, and Pseudomonas strain LWEBG 42 isolates were able to suppress pathogenic bacteria such as B. subtilis, P. aeruginosa, and E. coli. Interestingly, those selected species could show their ability to inhibit tested pathogens with a strong category. This is the first study that showed the potential of endophytic bacteria as antimicrobial agents isolated from fragrant ginger (Lempuyang Wangi) in Enggano Island, Indonesia.

A preliminary study on the interaction between Meloidogyne incognita and some strains of Pseudomonas spp. on growth performance of tomato under greenhouse conditions

The present study investigated the biological management of root-knot nematode (Meloidogyne incognita) in tomato plants using different strains of Pseudomonas spp. The experiment involved five treatments: a healthy control (T1), a nematode-inoculated control (T2), Pseudomonas fluorescens strain A (T3), P. fluorescens strain B (T4), and P. putida (T5). The results demonstrated significant differences in plant growth and root gall formation across treatments. The healthy control exhibited an average plant height of 12 cm and weight of 11 g. Nematode inoculation slightly reduced growth, with plants averaging 11 cm in height and 10 g in weight. Treatment with P. fluorescens strain A resulted in the highest growth, with plants reaching 13 cm in height and 12 g in weight. P. fluorescens strain B and P. putida treatments produced plants with average heights of 12 cm and 12.5 cm, and weights of 11 g and 10 g, respectively. Leaf and flower counts also varied, with T3, T4, and T5 treatments increasing leaf counts to 26, 40, and 33, respectively, compared to 15 in the nematode-inoculated control. The application of P. fluorescens strains A and B significantly reduced root galls to 8 and 15, respectively, compared to 29 in T2. P. putida treatment resulted in 21 root galls. These findings highlight the potential of Pseudomonas spp., especially P. fluorescens strains, in managing nematode infestation in tomato plants. Future studies should explore the mechanisms behind these microbial interactions and their long-term effects on plant health and yield.

New Insights into Pseudomonas spp.-Produced Antibiotics: Genetic Regulation of Biosynthesis and Implementation in Biotechnology.

Pseudomonas bacteria are renowned for their remarkable capacity to synthesize antibiotics, namely mupirocin, gluconic acid, pyrrolnitrin, and 2,4-diacetylphloroglucinol (DAPG). While these substances are extensively employed in agricultural biotechnology to safeguard plants against harmful bacteria and fungi, their potential for human medicine and healthcare remains highly promising for common science. However, the challenge of obtaining stable producers that yield higher quantities of these antibiotics continues to be a pertinent concern in modern biotechnology. Although the interest in antibiotics of Pseudomonas bacteria has persisted over the past century, many uncertainties still surround the regulation of the biosynthetic pathways of these compounds. Thus, the present review comprehensively studies the genetic organization and regulation of the biosynthesis of these antibiotics and provides a comprehensive summary of the genetic organization of antibiotic biosynthesis pathways in pseudomonas strains, appealing to both molecular biologists and biotechnologists. In addition, attention is also paid to the application of antibiotics in plant protection.

Characterization of cotinine degradation in a newly isolated Gram-negative strain Pseudomonas sp. JH-2.

Cotinine, the primary metabolite of nicotine in the human body, is an emerging pollutant in aquatic environments. It causes environmental problems and is harmful to the health of humans and other mammals; however, the mechanisms of its biodegradation have been elucidated incompletely. In this study, a novel Gram-negative strain that could degrade and utilize cotinine as a sole carbon source was isolated from municipal wastewater samples, and its cotinine degradation characteristics and kinetics were determined. Pseudomonas sp. JH-2 was able to degrade 100mg/L (0.56 mM) of cotinine with high efficiency within 5 days at 30 ℃, pH 7.0, and 1% NaCl. Two intermediates, 6-hydroxycotinine and 6-hydroxy-3-succinoylpyridine (HSP), were identified by high-performance liquid chromatography and liquid chromatograph mass spectrometer. The draft whole genome sequence of strain JH-2 was obtained and analyzed to determine genomic structure and function. No homologs of proteins predicted in Nocardioides sp. JQ2195 and reported in nicotine degradation Pyrrolidine pathway were found in strain JH-2, suggesting new enzymes that responsible for cotinine catabolism. These findings provide meaningful insights into the biodegradation of cotinine by Gram-negative bacteria.

Determination of soil phenanthrene degradation through a fungal-bacterial consortium.

Fungal-bacterial consortia enhance organic pollutant removal, but the underlying mechanisms are unclear. We used stable isotope probing (SIP) to explore the mechanism of bioaugmentation involved in polycyclic aromatic hydrocarbon (PAH) biodegradation in petroleum-contaminated soil by introducing the indigenous fungal strain Aspergillus sp. LJD-29 and the bacterial strain Pseudomonas XH-1. While each strain alone increased phenanthrene (PHE) degradation, the simultaneous addition of both strains showed no significant enhancement compared to treatment with XH-1 alone. Nonetheless, the assimilation effect of microorganisms on PHE was significantly enhanced. SIP revealed a role of XH-1 in PHE degradation, while the absence of LJD-29 in 13C-DNA indicated a supporting role. The correlations between fungal abundance, degradation efficiency, and soil extracellular enzyme activity indicated that LJD-29, while not directly involved in PHE assimilation, played a crucial role in the breakdown of PHE through extracellular enzymes, facilitating the assimilation of metabolites by bacteria. This observation was substantiated by the results of metabolite analysis. Furthermore, the combination of fungus and bacterium significantly influenced the diversity of PHE degraders. Taken together, this study highlighted the synergistic effects of fungi and bacteria in PAH degradation, revealed a new fungal-bacterial bioaugmentation mechanism and diversity of PAH-degrading microorganisms, and provided insights for in situ bioremediation of PAH-contaminated soil.IMPORTANCEThis study was performed to explore the mechanism of bioaugmentation by a fungal-bacterial consortium for phenanthrene (PHE) degradation in petroleum-contaminated soil. Using the indigenous fungal strain Aspergillus sp. LJD-29 and bacterial strain Pseudomonas XH-1, we performed stable isotope probing (SIP) to trace active PHE-degrading microorganisms. While inoculation of either organism alone significantly enhanced PHE degradation, the simultaneous addition of both strains revealed complex interactions. The efficiency plateaued, highlighting the nuanced microbial interactions. SIP identified XH-1 as the primary contributor to in situ PHE degradation, in contrast to the limited role of LJD-29. Correlations between fungal abundance, degradation efficiency, and extracellular enzyme activity underscored the pivotal role of LJD-29 in enzymatically facilitating PHE breakdown and enriching bacterial assimilation. Metabolite analysis validated this synergy, unveiling distinct biodegradation mechanisms. Furthermore, this fungal-bacterial alliance significantly impacted PHE-degrading microorganism diversity. These findings advance our understanding of fungal-bacterial bioaugmentation and microorganism diversity in polycyclic aromatic hydrocarbon (PAH) degradation as well as providing insights for theoretical guidance in the in situ bioremediation of PAH-contaminated soil.

A phage tail-like bacteriocin suppresses competitors in metapopulations of pathogenic bacteria.

Bacteria can repurpose their own bacteriophage viruses (phage) to kill competing bacteria. Phage-derived elements are frequently strain specific in their killing activity, although there is limited evidence that this specificity drives bacterial population dynamics. Here, we identified intact phage and their derived elements in a metapopulation of wild plant-associated Pseudomonas genomes. We discovered that the most abundant viral cluster encodes a phage remnant resembling a phage tail called a tailocin, which bacteria have co-opted to kill bacterial competitors. Each pathogenic Pseudomonas strain carries one of a few distinct tailocin variants that target the variable polysaccharides in the outer membrane of co-occurring pathogenic Pseudomonas strains. Analysis of herbarium samples from the past 170 years revealed that the same tailocin and bacterial receptor variants have persisted in Pseudomonas populations. These results suggest that tailocin genetic diversity can be mined to develop targeted "tailocin cocktails" for microbial control.

Antagonistic potential and biological control mechanisms of Pseudomonas strains against banded leaf and sheath blight disease of maize

Rhizoctonia solani, the causal agent of banded leaf and sheath blight (BL&SB), poses a significant threat to maize and various crops globally. The increasing concerns surrounding the environmental and health impacts of chemical fungicides have encouraged intensified concern in the development of biological control agents (BCAs) as eco-friendly alternatives. In this study, we explored the potential of 22 rhizobacteria strains (AS1–AS22) isolates, recovered from the grasslands of the Pithoragarh region in the Central Himalayas, as effective BCAs against BL&SB disease. Among these strains, two Pseudomonas isolates, AS19 and AS21, exhibited pronounced inhibition of fungal mycelium growth in vitro, with respective inhibition rates of 57.04% and 54.15% in cell cultures and 66.56% and 65.60% in cell-free culture filtrates. Additionally, both strains demonstrated effective suppression of sclerotium growth. The strains AS19 and AS21 were identified as Pseudomonas sp. by 16S rDNA phylogeny and deposited under accession numbers NAIMCC-B-02303 and NAIMCC-B-02304, respectively. Further investigations revealed the mechanisms of action of AS19 and AS21, demonstrating their ability to induce systemic resistance (ISR) and exhibit broad-spectrum antifungal activity against Alternaria triticina, Bipolaris sorokiniana, Rhizoctonia maydis, and Fusarium oxysporum f. sp. lentis. Pot trials demonstrated significant reductions in BL&SB disease incidence (DI) following foliar applications of AS19 and AS21, with reductions ranging from 25 to 38.33% compared to control treatments. Scanning electron microscopy revealed substantial degradation of fungal mycelium by the strains, accompanied by the production of hydrolytic enzymes. These findings suggest the potential of Pseudomonas strains AS19 and AS21 as promising BCAs against BL&SB and other fungal pathogens. However, further field trials are warranted to validate their efficacy under natural conditions and elucidate the specific bacterial metabolites responsible for inducing systemic resistance. This study contributes to the advancement of sustainable disease management strategies and emphasizes the potential of Pseudomonas strains AS19 and AS21 in combating BL&SB and other fungal diseases affecting agricultural crops.

Cross-regulation and cross-talk of conserved and accessory two-component regulatory systems orchestrate Pseudomonas copper resistance.

Bacteria use diverse strategies and molecular machinery to maintain copper homeostasis and to cope with its toxic effects. Some genetic elements providing copper resistance are acquired by horizontal gene transfer; however, little is known about how they are controlled and integrated into the central regulatory network. Here, we studied two copper-responsive systems in a clinical isolate of Pseudomonas paraeruginosa and deciphered the regulatory and cross-regulation mechanisms. To do so, we combined mutagenesis, transcriptional fusion analyses and copper sensitivity phenotypes. Our results showed that the accessory CusRS two-component system (TCS) responds to copper and activates both its own expression and that of the adjacent nine-gene operon (the pcoA2 operon) to provide resistance to elevated levels of extracellular copper. The same locus was also found to be regulated by two core-genome-encoded TCSs-the copper-responsive CopRS and the zinc-responsive CzcRS. Although the target palindromic sequence-ATTCATnnATGTAAT-is the same for the three response regulators, transcriptional outcomes differ. Thus, depending on the operon/regulator pair, binding can result in different activation levels (from none to high), with the systems demonstrating considerable plasticity. Unexpectedly, although the classical CusRS and the noncanonical CopRS TCSs rely on distinct signaling mechanisms (kinase-based vs. phosphatase-based), we discovered cross-talk in the absence of the cognate sensory kinases. This cross-talk occurred between the proteins of these two otherwise independent systems. The cusRS-pcoA2 locus is part of an Integrative and Conjugative Element and was found in other Pseudomonas strains where its expression could provide copper resistance under appropriate conditions. The results presented here illustrate how acquired genetic elements can become part of endogenous regulatory networks, providing a physiological advantage. They also highlight the potential for broader effects of accessory regulatory proteins through interference with core regulatory proteins.

Draft genome sequences of Streptomyces virginiae strain CMAA1738, Paenibacillus ottowii strain CMAA1739 and Pseudomonas inefficax strain CMAA1741, isolated from rhizosphere of wheat landraces.

In this study, we have identified and characterized three genomes from bacteria isolated from the rhizosphere of Triticum aestivum. Streptomyces virginiae CMAA1738 and Paenibacillus ottowii CMAA1739 were obtained from the wheat landrace Iran 1-29-11334, and Pseudomonas inefficax CMAA1741 was isolated from the wheat landrace Karakilcik.

Evaluating the effectiveness of rhizobacteria producing 1-aminocyclopropane-1-carboxylic acid deaminase in inhibiting tumor formation by Agrobacterium tumefaciens

Crown gall is one of the most dangerous bacterial diseases affecting the production of fruit tree nurseries in Egypt and many countries of the world. In the present study, ten isolates of 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase-producing rhizobacteria were isolated from the rhizosphere of apricot (Prunus armeniaca L.) and plum (Prunus domestica L.) trees to evaluate their ability to decrease tumor formation by Agrobacterium tumefaciens (synonym Rhizobium radiobacter). The ten isolates were identified as Pseudomonas strains based on 16S rRNA gene sequence analysis and deduced protein sequences obtained from a partial ACC deaminase structural gene (acdS) sequence. Co-inoculating castor bean (Ricinus communis L.) and kalanchoe (Kalanchoe sp.) plants with A. tumefaciens and four ACC deaminase-producing Pseudomonas isolates decreased tumor formation. However, six ACC deaminase-producing Pseudomonas isolates produced varying results in these two plant species. The results showed that isolates of Pseudomonas vancouverensis reduced tumor formation when co-inoculated with A. tumefaciens in castor bean and kalanchoe plants. However, the isolate P. putida inhibited tumor formation in castor bean plants but did not achieve the same effect in kalanchoe plants. Additionally, isolates of P. frederiksbergensis and P. kilonensis decreased tumor formation in kalanchoe plants while increasing tumor formation in castor bean plants. The results showed that ACC deaminase-producing P. vancouverensis is a promising biocontrol agent against A. tumefaciens.

Secretion of 2,4 di-tertbutylphenol by a new Pseudomonas strain SBMCH11: A tert-butyl substituted phenolic compound displayed antibacterial efficacy

Pseudomonas sp. SBMCH11 was newly isolated from maritime soil samples which was identified by morphological, biochemical, and 16S rRNA gene sequencing. The isolated Pseudomonas sp. SBMCH11 had significant antibacterial activity against clinical bacterial strains including Pseudomonas aeruginosa and Staphylococcus aureus. Subsequently, high concentrations of antibacterial substances were achieved by optimizing the following parameters: pH (7.0), carbon (1 %), nitrogen sources (casein 0.2 %), NaCl (10 %), and incubation time (120 hrs). Furthermore, the extracted component from the Pseudomonas sp. SBMCH11 was shown to have a significant inhibitory effect on tested clinical pathogens. On the other hand, the extracted compound was confirmed as 2,4 di-tertbutylphenol (2,4 DTBP) by GC–MS with a molecular weight of 206.5 Daltons. Based on these findings, the isolated 2,4 DTBP could be recognized as a promising bioactive molecule for further antibacterial medication development. Compounds identified in the maritime environment from microorganisms, especially Pseudomonas sp. SBMCH11 could be regarded as a potential bio-factory for the synthesis of antibacterial compounds to suppress large numbers of pathogenic bacteria in the natural environment.

Phylogenetic analysis on 16S rRNA of Pseudomonas Species isolated from clinical specimens in Nigeria and other Regions

This project was to study the clinical isolates of Pseudomonas organisms in Nigeria in comparison with those of other regions of the world, to understand their evolutional relationship, using phylogenetic analysis of 16SrRNA. A total of 51 sequence data files of Pseudomonas species from different countries were selected based on 16S rRNA, using the National Centre for Biotechnology Information (NCBI) webpage. Geneious software (V9.0.5) was employed for sequence alignment. Tamura- Nei was used as the genetic distant model, while the tree build method was Neighbor-Joining with a bootstrap value of 1000 and 100 numbers of replicates to indicate the revolutionary process analyzed over time. Majority of the strains from Nigeria (7) have very little or no mutations in the sequences. These strains with other strains from the other countries were clustered at the 2nd branch of the tree, with a bootstrap value of 96%. Generally, there is similarity in diversity of the Pseudomonas species across the globe. Much diversity was seen in all the strains from Saudi Arabia, as all were found on the 10th branch of the tree. Two Pseudomonas strains previously identified as belonging to other species than aeruginosa were seen to be Pseudomonas aeruginosa strains. The low diversity shown by the strain isolates from Nigeria implies high fidelity to genetic stability with regard to the ancestral origin. The high mutation observed in all the strains from Saudi-Arabia indicates high diversity from the common ancestor and this may likely result to increased virulence and multi-drug resistance.