-
Applied and Environmental Microbiology Feb 2021Diazotrophs can produce bioavailable nitrogen from inert N gas by bioelectrochemical nitrogen fixation (-BNF), which is emerging as an energy-saving and highly selective...
Diazotrophs can produce bioavailable nitrogen from inert N gas by bioelectrochemical nitrogen fixation (-BNF), which is emerging as an energy-saving and highly selective strategy for agriculture and industry. However, current -BNF technology is impeded by requirements for NH assimilation inhibitors to facilitate intracellular ammonia secretion and precious metal catalysts to generate H as the energy-carrying intermediate. Here, we initially demonstrate inhibitor- and catalystless extracellular NH production by the diazotroph Pseudomonas stutzeri A1501 using an electrode as the sole electron donor. Multiple lines of evidence revealed that P. stutzeri produced 2.32 ± 0.25 mg/liter extracellular NH at a poised potential of -0.3 V (versus standard hydrogen electrode [SHE]) without the addition of inhibitors or expensive catalysts. The electron uptake mechanism was attributed to the endogenous electron shuttle phenazine-1-carboxylic acid, which was excreted by P. stutzeri and mediated electron transfer from electrodes into cells to directly drive N fixation. The faradaic efficiency was 20% ± 3%, which was 2 to 4 times that of previous -BNF attempts using the H-mediated pathway. This study reports a diazotroph capable of producing secretable NH via extracellular electron uptake, which has important implications for optimizing the performance of -BNF systems and exploring the novel nitrogen-fixing mode of syntrophic microbial communities in the natural environment. Ammonia greatly affects global ecology, agriculture, and the food industry. Diazotrophs with an enhanced capacity of extracellular NH excretion have been proven to be more beneficial to the growth of microalgae and plants, whereas most previously reported diazotrophs produce intracellular organic nitrogen in the absence of chemical suppression and genetic manipulation. Here, we demonstrate that Pseudomonas stutzeri A1501 is capable of extracellular NH production without chemical suppression or genetic manipulation when the extracellular electrode is used as the sole electron donor. We also reveal the electron uptake pathway from the extracellular electron-donating partner to P. stutzeri A1501 via redox electron shuttle phenazines. Since both P. stutzeri A1501 and potential electron-donating partners (such as electroactive microbes and natural semiconductor minerals) are abundant in diverse soils and sediments, P. stutzeri A1501 has broader implications on the improvement of nitrogen fertilization in the natural environment.
Topics: Ammonia; Nitrogen Fixation; Pseudomonas stutzeri
PubMed: 33310714
DOI: 10.1128/AEM.01998-20 -
Indian Journal of Ophthalmology Jan 2020We report a rare case of Pseudomonas stutzeri endophthalmitis in an immunocompetent individual along with the review of the literature. A 39-year-old healthy lady... (Review)
Review
We report a rare case of Pseudomonas stutzeri endophthalmitis in an immunocompetent individual along with the review of the literature. A 39-year-old healthy lady presented with sudden painful loss of vision in her right eye. She was diagnosed with postcataract surgery acute endophthalmitis and underwent vitrectomy, intraocular lens explantation and intravitreal antibiotics. P. stutzeri was isolated from vitreous. Though the infection was controlled, the anatomy of the eye could not be salvaged and the right eye became phthisical. P. stutzeri is a rare cause of endophthalmitis with usually poor outcomes.
Topics: Adult; Cataract Extraction; Endophthalmitis; Eye Infections, Bacterial; Female; Humans; Pseudomonas Infections; Pseudomonas stutzeri
PubMed: 31856535
DOI: 10.4103/ijo.IJO_334_19 -
Frontiers in Microbiology 2023Soil salinization and acidification seriously damage soil health and restricts the sustainable development of planting. Excessive application of chemical fertilizer and...
Soil salinization and acidification seriously damage soil health and restricts the sustainable development of planting. Excessive application of chemical fertilizer and other reasons will lead to soil acidification and salinization. This study focus on acid and salinized soil, investigated the effect of phosphate-solubilizing bacteria, MJ1 combined with nitrogen-fixing bacteria DSM4166 or mutant CHA0- on crop quality, soil physicochemical properties, and microbial communities. A total of 5 treatments were set: regular fertilization (T1), regular fertilization with MJ1 and DSM4166 (T2), regular fertilization with MJ1 and CHA0- (T3), 30%-reducing fertilization with MJ1 and DSM4166 (T4), and 30%-reducing fertilization with MJ1 and CHA0- (T5). It was found that the soil properties (OM, HN, TN, AP, AK, and SS) and crop quality of cucumber (yield production, protein, and vitamin C) and lettuce (yield production, vitamin C, nitrate, soluble protein, and crude fiber) showed a significant response to the inoculated strains. The combination of MJ1 with DSM4166 or CHA0- influenced the diversity and richness of bacterial community in the lettuce-grown soil. The organismal system-, cellular process-, and metabolism-correlated bacteria and saprophytic fungi were enriched, which were speculated to mediate the response to inoculated strains. pH, OM, HN, and TN were identified to be the major factors correlated with the soil microbial community. The inoculation of MJ1 with DSM4166 and CHA0- could meet the requirement of lettuce and cucumber growth after reducing fertilization in acid and salinized soil, which provides a novel candidate for the eco-friendly technique to meet the carbon-neutral topic.
PubMed: 36819023
DOI: 10.3389/fmicb.2023.1064358 -
Synthetic and Systems Biotechnology Jun 2023The biological treatment of wastewater with high concentrations of ammonia nitrogen has become a hot research issue, but there are limited reports on the mechanism of...
The biological treatment of wastewater with high concentrations of ammonia nitrogen has become a hot research issue, but there are limited reports on the mechanism of ammonia nitrogen utilization by microorganisms. In this paper, a transcriptomic approach was used to investigate the differences in gene expression at 500.0 mg/L (Amo 500) and 100.0 mg/L (Amo 100) ammonium concentrations to reveal the mechanism of ammonia nitrogen removal from water by F2. The transcriptome data showed 1015 (459 up-regulated and 556 down-regulated) differentially expressed genes with functional gene annotation related to nitrogen source metabolism, glycolysis, tricarboxylic acid cycle, extracellular polysaccharide synthesis, energy conversion and transmembrane transport, revealing the metabolic process of ammonium nitrogen conversion to biological nitrogen in F2 through assimilation. To verify the effect of ammonium transporter protein (AmtB) of cell membrane on assimilation, a F2-Δ mutant strain was obtained by constructing a knockout plasmid (pK18mobsacB-Δ), and it was found that the growth characteristics and ammonium removal rate of the mutant strain were significantly reduced at high ammonium concentration. The carbon source components and dissolved oxygen conditions were optimized after analyzing the transcriptome data, and the ammonium removal rate was increased from 41.23% to 94.92% with 500.0 mg/L ammonium concentration. The study of F2 transcript level reveals the mechanism of ammonia nitrogen influence on microbial assimilation process and improvement strategy, which provides a new strategy for the treatment of ammonia nitrogen wastewater.
PubMed: 37033292
DOI: 10.1016/j.synbio.2023.03.002 -
Frontiers in Bioscience (Landmark... Jan 2023wilt and blight are the most important diseases of chickpea. The current study was designed to investigate the individual and combined effect of salicylic acid (SA)...
BACKGROUND
wilt and blight are the most important diseases of chickpea. The current study was designed to investigate the individual and combined effect of salicylic acid (SA) with and to suppress wilt and promote growth of chickpea varieties: Thal-2006 and Punjab-2008.
METHODS
At the time of sowing, inoculum of was applied to the soil and the incidence of wilt was recorded after 60 days. The seeds were inoculated with and prior to sowing. Chickpea plants were treated with salicylic acid at seedling stage.
RESULTS
The combination of and SA significantly increased root length (166% and 145%), shoot height (50% and 47%) and shoot biomass (300% and 233%) in cv. Thal-2006 and cv. Punjab-2008, respectively, in infected plants. Similarly, the combined treatment of + SA, also enhanced the plant growth parameters of chickpea varieties. Maximum reduction in disease severity was observed in both + SA (90% and 84%) and + SA (79% and 77%) treatments in cv. Thal-2006 and Punjab-2008, respectively. Both + SA and + SA treatments resulted in increased leaf relative water and total protein content, peroxidase, superoxide dismutase, phenylalanine ammonia-lyase and polyphenol oxidase activities in both resistant (cv. Thal-2006) and susceptible (cv. Punjab-2008) cultivars. Both treatments also significantly reduced malondialdehyde (MDA) and proline content in cv. Thal-2006 and Punjab-2008. Cultivar Thal-2006 was more effective than cv. Punjab-2008.
CONCLUSIONS
The results suggested that, in combination, salicylic acid and may play an important role in controlling wilt diseases by inducing systemic resistance in chickpea.
Topics: Biomass; Cicer; Combined Modality Therapy; Fusarium; Malondialdehyde; Plant Diseases; Salicylic Acid; Pseudomonas; Agricultural Inoculants
PubMed: 36722276
DOI: 10.31083/j.fbl2801020 -
Case Reports in Ophthalmology 2020A patient presented with complaints of a sudden decrease in vision, ocular redness, and pain in the right eye. The patient had a history of clear lens extraction with...
A patient presented with complaints of a sudden decrease in vision, ocular redness, and pain in the right eye. The patient had a history of clear lens extraction with intraocular lens (IOL) implantation for myopia 2 years previously. He had been prescribed topical steroids for episodes of inflammation that occurred repeatedly every 1-2 months. With a presumptive diagnosis of chronic endophthalmitis, a 23-G transconjunctival sutureless pars plana vitrectomy (PPV) with delivery of intravitreal antibiotics was performed the next day. Culture sensitivity testing of the vitreous sample indicated that was sensitive to ceftazidime and gentamicin. Two weeks later, the patient presented with sudden loss of vision and all the signs of recurrent endophthalmitis. 23-G transconjunctival sutureless PPV was performed along with removal of the posterior chamber IOL through a corneal incision. Complete resolution was only achieved after removal of the IOL, resulting in excellent visual recovery. Due to its chronic and fulminating nature, can induce endophthalmitis and should be considered in the differential diagnosis. Aseptic measures are the best prevention.
PubMed: 33437233
DOI: 10.1159/000510129 -
Scientific Reports Feb 2020Biological ammonium removal via heterotrophic nitrification/aerobic denitrification (HN/AD) presents several advantages in relation to conventional removal processes,...
Physicochemical characterization of Pseudomonas stutzeri UFV5 and analysis of its transcriptome under heterotrophic nitrification/aerobic denitrification pathway induction condition.
Biological ammonium removal via heterotrophic nitrification/aerobic denitrification (HN/AD) presents several advantages in relation to conventional removal processes, but little is known about the microorganisms and metabolic pathways involved in this process. In this study, Pseudomonas stutzeri UFV5 was isolated from an activated sludge sample from oil wastewater treatment station and its ammonium removal via HN/AD was investigated by physicochemical and molecular approaches to better understand this process and optimize the biological ammonium removal in wastewater treatment plants. Results showed that P. stutzeri UFV5 removed all the ammonium in 48-72 hours using pyruvate, acetate, citrate or sodium succinate as carbon sources, C/N ratios 6, 8, 10 and 12, 3-6% salinities, pH 7-9 and temperatures of 20-40 °C. Comparative genomics and PCR revealed that genes encoding the enzymes involved in anaerobic denitrification process are present in P. stutzeri genome, but no gene that encodes enzymes involved in autotrophic nitrification was found. Furthermore, transcriptomics showed that none of the known enzymes of autotrophic nitrification and anaerobic denitrification had their expression differentiated and an upregulation of the biosynthesis machinery and protein translation was observed, besides several genes with unknown function, indicating a non-conventional mechanism involved in HN/AD process.
Topics: Aerobiosis; Ammonium Compounds; Bacterial Proteins; Biodegradation, Environmental; Denitrification; Gene Expression Regulation, Bacterial; Heterotrophic Processes; Nitrification; Pseudomonas stutzeri; Sewage; Transcriptome; Wastewater
PubMed: 32042029
DOI: 10.1038/s41598-020-59279-7 -
Materials (Basel, Switzerland) Apr 2023Microbiologically influenced corrosion (MIC) is a common phenomenon in water treatment, shipping, construction, marine and other industries. Sulfate-reducing bacteria...
Microbiologically influenced corrosion (MIC) is a common phenomenon in water treatment, shipping, construction, marine and other industries. Sulfate-reducing bacteria (SRB) often lead to MIC. In this paper, a strain of () with the ability to inhibit SRB corrosion is isolated from the soil through enrichment culture. is a short, rod-shaped, white and transparent colony with denitrification ability. Our 16SrDNA sequencing results verify the properties of strains. The growth conditions of bacteria and SRB are similar, and the optimal culture conditions are about 30 °C, pH 7, and the stable stage is reached in about seven days. The bacteria can coexist in the same growth environment. Using the weight loss method, electrochemical experiments and composition analysis techniques we found that can inhibit the corrosion of X70 steel by SRB at 20~40 °C, pH 6~8. Furthermore, long-term tests at 3, 6 and 9 months reveal that can effectively inhibit the corrosion of X70 steel caused by SRB.
PubMed: 37049190
DOI: 10.3390/ma16072896 -
Bioresource Technology Feb 2021A novel denitrifying phosphorus-accumulating bacterium was isolated from contaminated sediment and identified as Pseudomonas stutzeri ADP-19. Bio-safety assays...
A novel denitrifying phosphorus-accumulating bacterium was isolated from contaminated sediment and identified as Pseudomonas stutzeri ADP-19. Bio-safety assays demonstrated that the strain was γ-hemolytic, antibiotic-sensitive, and had no decarboxylase activity. It removed 96.5% of NH-N and 73.3% of PO-P (at initial concentrations of 100 mg/L and 20 mg/L) under aerobic conditions, and the corresponding maximum removal rates were 3.44 and 0.41 mg/L/h, respectively. Nitrogen removal was achieved through a fully nitrification-denitrification pathway [NH-N → NHOH → NO-N → NO-N → NO-N → (NO) → N], while phosphorus removal mainly depended on the phosphate assimilation and the excessive poly-P accumulation. Strain ADP-19 also showed a strong salt tolerance within a wide salinity range of 0-5%. The enhanced biological treatment of anaerobic-digested wastewater in a sequencing batch reactor (SBR) indicated that the strain improved the microbial diversity of the activated sludge and significantly enhanced the nitrogen and phosphorus removal efficiency.
Topics: Adenosine Diphosphate; Bioreactors; Denitrification; Nitrification; Nitrogen; Phosphorus; Pseudomonas stutzeri; Sewage; Waste Disposal, Fluid; Wastewater
PubMed: 33276210
DOI: 10.1016/j.biortech.2020.124445 -
Frontiers in Bioengineering and... 2023Acetate is a low-cost feedstock for the production of different bio-chemicals. Electrochemical reduction of CO into acetate and subsequent acetate fermentation is a...
Acetate is a low-cost feedstock for the production of different bio-chemicals. Electrochemical reduction of CO into acetate and subsequent acetate fermentation is a promising method for transforming CO into value-added chemicals. However, the significant inhibitory effect of acetate on microbial growth remains a barrier for acetate-based biorefinery. In this study, the deletion of genes involved in L-leucine degradation was found to be beneficial for the growth of A1501 in acetate. (Δ), in which the hydroxymethylglutaryl-CoA lyase catalyzing -hydroxy--methylglutaryl-CoA into acetyl-CoA and acetoacetate was deleted, grew faster than other mutants and exhibited increased tolerance to acetate. Then, the genes from H16 for poly-3-hydroxybutyrate (PHB) biosynthesis were overexpressed in (∆) and the recombinant strain (∆-) can accumulate 0.11 g L PHB from commercial acetate. Importantly, (∆-) can also use CO-derived acetate to produce PHB and the accumulated PHB accounted for 5.42% (w/w) of dried cell weight of (∆-).
PubMed: 38026858
DOI: 10.3389/fbioe.2023.1297431