Magnetovibrio blakemorei gen. nov., sp. nov., a magnetotactic bacterium ( Alphaproteobacteria : Rhodospirillaceae ) isolated from a salt marsh

2013 ◽  
Vol 63 (Pt_5) ◽  
pp. 1824-1833 ◽  
Author(s):  
Dennis A. Bazylinski ◽  
Timothy J. Williams ◽  
Christopher T. Lefèvre ◽  
Denis Trubitsyn ◽  
Jiasong Fang ◽  
...  
Keyword(s):  
Salt Marsh ◽  
Electron Acceptor ◽  
Anaerobic Growth ◽  
Rrna Gene ◽  
Magnetotactic Bacterium ◽  
Single Chain ◽  
Circular Chromosome ◽  
Terminal Electron Acceptor ◽  
Content Type ◽  
Link Type

A magnetotactic bacterium, designated strain MV-1T, was isolated from sulfide-rich sediments in a salt marsh near Boston, MA, USA. Cells of strain MV-1T were Gram-negative, and vibrioid to helicoid in morphology. Cells were motile by means of a single polar flagellum. The cells appeared to display a transitional state between axial and polar magnetotaxis: cells swam in both directions, but generally had longer excursions in one direction than the other. Cells possessed a single chain of magnetosomes containing truncated hexaoctahedral crystals of magnetite, positioned along the long axis of the cell. Strain MV-1T was a microaerophile that was also capable of anaerobic growth on some nitrogen oxides. Salinities greater than 10 % seawater were required for growth. Strain MV-1T exhibited chemolithoautotrophic growth on thiosulfate and sulfide with oxygen as the terminal electron acceptor (microaerobic growth) and on thiosulfate using nitrous oxide (N2O) as the terminal electron acceptor (anaerobic growth). Chemo-organoautotrophic and methylotrophic growth was supported by formate under microaerobic conditions. Autotrophic growth occurred via the Calvin–Benson–Bassham cycle. Chemo-organoheterotrophic growth was supported by various organic acids and amino acids, under microaerobic and anaerobic conditions. Optimal growth occurred at pH 7.0 and 26–28 °C. The genome of strain MV-1T consisted of a single, circular chromosome, about 3.7 Mb in size, with a G+C content of 52.9–53.5 mol%.Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain MV-1T belongs to the family Rhodospirillaceae within the Alphaproteobacteria , but is not closely related to the genus Magnetospirillum . The name Magnetovibrio blakemorei gen. nov., sp. nov. is proposed for strain MV-1T. The type strain of Magnetovibrio blakemorei is MV-1T ( = ATCC BAA-1436T  = DSM 18854T).

scholarly journals Magnetospira thiophila gen. nov., sp. nov., a marine magnetotactic bacterium that represents a novel lineage within the Rhodospirillaceae ( Alphaproteobacteria )

2012 ◽  
Vol 62 (Pt_10) ◽  
pp. 2443-2450 ◽  
Author(s):  
Timothy J. Williams ◽  
Christopher T. Lefèvre ◽  
Weidong Zhao ◽  
Terry J. Beveridge ◽  
Dennis A. Bazylinski
Keyword(s):  
Carbon Fixation ◽  
Lima Bean ◽  
Optimal Growth ◽  
Rrna Gene ◽  
Magnetotactic Bacterium ◽  
Single Chain ◽  
Content Type ◽  
Link Type ◽  
The Family ◽  
Semi Solid

A marine, magnetotactic bacterium, designated strain MMS-1T, was isolated from mud and water from a salt marsh in Woods Hole, Massachusetts, USA, after enrichment in defined oxygen-concentration/redox-gradient medium. Strain MMS-1T is an obligate microaerophile capable of chemoorganoheterotrophic and chemolithoautotrophic growth. Optimal growth occurred at pH 7.0 and 24–26 °C. Chemolithoautotrophic growth occurred with thiosulfate as the electron donor and autotrophic carbon fixation was via the Calvin–Benson–Bassham cycle. The G+C content of the DNA of strain MMS-1T was 47.2 mol%. Cells were Gram-negative and morphologically variable, with shapes that ranged from that of a lima bean to fully helical. Cells were motile by means of a single flagellum at each end of the cell (amphitrichous). Regardless of whether grown in liquid or semi-solid cultures, strain MMS-1T displayed only polar magnetotaxis and possessed a single chain of magnetosomes containing elongated octahedral crystals of magnetite, positioned along the long axis of the cell. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain MMS-1T belongs to the family Rhodospirillaceae within the Alphaproteobacteria , and is distantly related to species of the genus Magnetospirillum . Strain MMS-1T is therefore considered to represent a novel species of a new genus, for which the name Magnetospira thiophila gen. nov., sp. nov. is proposed. The type strain of Magnetospira thiophila is MMS-1T ( = ATCC BAA-1438T = JCM 17960T).

Bacillus thermotolerans sp. nov., a thermophilic bacterium capable of reducing humus

2013 ◽  
Vol 63 (Pt_10) ◽  
pp. 3672-3678 ◽  
Author(s):  
Guiqin Yang ◽  
Xuemei Zhou ◽  
Shungui Zhou ◽  
Dehui Yang ◽  
Yueqiang Wang ◽  
...  
Keyword(s):  
Gene Sequence ◽  
Cellular Fatty Acid ◽  
Thermophilic Bacterium ◽  
Anaerobic Growth ◽  
Rrna Gene ◽  
Biochemical Tests ◽  
Unidentified Phospholipid ◽  
Content Type ◽  
Link Type ◽  
Gram Staining

A novel thermotolerant bacterium, designated SgZ-8T, was isolated from a compost sample. Cells were non-motile, endospore-forming, Gram-staining positive, oxidase-negative and catalase-positive. The isolate was able to grow at 20–65 °C (optimum 50 °C) and pH 6.0–9.0 (optimum 6.5–7.0), and tolerate up to 9.0 % NaCl (w/v) under aerobic conditions. Anaerobic growth occurred with anthraquinone-2,6-disulphonate (AQDS), fumarate and NO3 - as electron acceptors. Phylogenetic analysis based on the16S rRNA and gyrB genes grouped strain SgZ-8T into the genus Bacillus , with the highest similarity to Bacillus badius JCM 12228T (96.2 % for 16S rRNA gene sequence and 83.5 % for gyrB gene sequence) among all recognized species in the genus Bacillus . The G+C content of the genomic DNA was 49.3 mol%. The major isoprenoid quinone was menaquinone 7 (MK-7) and the polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and an unidentified phospholipid. The major cellular fatty acid was iso-C16 : 0. On the basis of its phenotypic and phylogenetic properties, chemotaxonomic analysis and the results of physiological and biochemical tests, strain SgZ-8T ( = CCTCC AB 2012108T = KACC 16706T) was designated the type strain of a novel species of the genus Bacillus , for which the name Bacillus thermotolerans sp. nov. is proposed.

scholarly journals Caldichromatium japonicum gen. nov., sp. nov., a novel thermophilic phototrophic purple sulphur bacterium of the Chromatiaceae isolated from Nakabusa hot springs, Japan

2020 ◽  
Vol 70 (11) ◽  
pp. 5701-5710 ◽  
Author(s):  
Mohit Kumar Saini ◽  
Weng ChihChe ◽  
Nathan Soulier ◽  
Aswathy Sebastian ◽  
Istvan Albert ◽  
...  
Keyword(s):  
Type Species ◽  
Microbial Mats ◽  
Hot Springs ◽  
Phylogenetic Position ◽  
Rrna Gene ◽  
Sequence Comparisons ◽  
Circular Chromosome ◽  
Content Type ◽  
Link Type ◽  
Purple Sulphur Bacterium

A novel thermophilic phototrophic purple sulphur bacterium was isolated from microbial mats (56 °C) at Nakabusa hot springs, Nagano prefecture, Japan. Cells were motile, rod-shaped, stain Gram-negative and stored sulphur globules intracellularly. Bacteriochlorophyll a and carotenoids of the normal spirilloxanthin series were the major pigments. Dense liquid cultures were red in colour. Strain No.7T was able to grow photoautotrophically using sulfide, thiosulfate, sulfite and hydrogen (in the presence of sulfide) as electron donors and bicarbonate as the sole carbon source. Optimum growth occurred under anaerobic conditions in the light at 50 °C (range, 40–56 °C) and pH 7.2 (range, pH 7–8). Major fatty acids were C16 : 0 (46.8 %), C16 : 1 ω7c (19.9 %), C18 : 1 ω7c (21.1 %), C14 : 0 (4.6 %) and C18 : 0 (2.4 %). The polar lipid profile showed phosphatidylglycerol and unidentified aminophospholipids to be the major lipids. The only quinone detected was ubiquinone-8. 16S rRNA gene sequence comparisons indicated that the novel bacterium is only distantly related to Thermochromatium tepidum with a nucleotide identity of 90.4 %. The phylogenetic analysis supported the high novelty of strain No.7T with a long-branching phylogenetic position within the Chromatiaceae next to Thermochromatium tepidum . The genome comprised a circular chromosome of 2.99 Mbp (2 989 870 bp), included no plasmids and had a DNA G+C content of 61.2 mol%. Polyphasic taxonomic analyses of the isolate suggested strain No.7T is a novel genus within the Chromatiaceae . The proposed genus name of the second truly thermophilic purple sulphur bacterium is Caldichromatium gen. nov. with the type species Caldichromatium japonicum sp. nov. (DSM 110881=JCM 39101).

Mariniplasma anaerobium gen. nov., sp. nov., a novel anaerobic marine mollicute, and proposal of three novel genera to reclassify members of Acholeplasma clusters II–IV

2021 ◽  
Vol 71 (12) ◽  
Author(s):  
Miho Watanabe ◽  
Hisaya Kojima ◽  
Kunihiro Okano ◽  
Manabu Fukui
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Genome Sequence ◽  
Sequence Similarity ◽  
Rrna Gene ◽  
Strictly Anaerobic ◽  
Optimum Growth ◽  
Circular Chromosome ◽  
Content Type ◽  
Link Type

A novel strictly anaerobic chemoorganotrophic bacterium, designated Mahy22T, was isolated from sulfidic bottom water of a shallow brackish meromictic lake in Japan. Cells of the strain were Gram-stain-negative, non-motile and coccoid in shape with diameters of about 600–800 nm. The temperature range for growth was 15–37 °C, with optimum growth at 30–32 °C. The pH range for growth was pH 6.2–8.9, with optimum growth at pH 7.2–7.4. The strain grew with NaCl concentrations of 5% or below (optimum, 2–3%). Growth of the strain was enhanced by the addition of thiosulfate. The major cellular fatty acids were C16:0 and anteiso-C15:0. Respiratory quinones were not detected. The complete genome sequence of strain Mahy22T possessed a 1 885 846 bp circular chromosome and a 12 782 bp circular genetic element. The G+C content of the genome sequence was 30.1 mol%. Phylogenetic analysis based on the 16S rRNA gene revealed that the novel strain belonged to the family Acholeplasmataceae , class Mollicutes . The closest relative of strain Mahy22T with a validly published name was Acholeplasma palmae J233T with a 16S rRNA gene sequence similarity of 90.5%. Based on the results of polyphasic analysis, the name Mariniplasma anaerobium gen. nov., sp. nov. is proposed to accommodate strain Mahy22T, along with reclassification of some Acholeplasma species into Alteracholeplasma gen. nov., Haploplasma gen. nov. and Paracholeplasma gen. nov.

Pontivivens ytuae sp. nov., isolated from deep sea sediment of the Mariana Trench

2021 ◽  
Vol 71 (9) ◽  
Author(s):  
Zhen Wang ◽  
Rong-bin Du ◽  
Qing-lei Sun ◽  
Yuan-yuan Sun ◽  
Jian Zhang ◽  
...  
Keyword(s):  
Deep Sea ◽  
Type Species ◽  
Sequence Similarity ◽  
Rrna Gene ◽  
Phenotypic Properties ◽  
Circular Chromosome ◽  
Mariana Trench ◽  
Content Type ◽  
Deep Sea Sediment ◽  
Link Type

A Gram-stain-negative, light pink-coloured, rod-shaped, flagellated and facultative anaerobic bacterial strain, designated MT2928T, was isolated from deep-sea sediment collected from the Mariana Trench. Growth of strain MT2928T occurred optimally at 28 °C, pH 8.0–9.0 and in the presence of 1.0–2.0 % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain MT2928T belongs to the genus Pontivivens and has the highest sequence similarity to Pontivivens insulae GYSW-23T (96.6 %). Genomic analysis indicated that strain MT2928T contains a circular chromosome of 4 199 362 bp with G+C content of 67.2 mol%. The strain did not produce bacteriochlorophyll a, but produced carotenoid. The predominant respiratory quinone of MT2928T was ubiquinone-10. The polar lipids of MT2928T contained diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, two unidentified lipids and two unidentified phospholipids. The major fatty acids of strain MT2928T contained summed feature 8 (C18 : 1  ω7c or/and C18 : 1  ω6c), C18 : 0 and summed feature 2 (iso-C16 : 1 I and/or C14 : 0 3-OH). On the basis of phylogenetic, physiological, biochemical and other phenotypic properties, strain MT2928T represents a novel species of the genus Pontivivens , and the name Pontivivens ytuae sp. nov. is proposed with the type species MT2928T (=MCCC 1K05575T=JCM 34320T).

Desulfotomaculum peckii sp. nov., a moderately thermophilic member of the genus Desulfotomaculum , isolated from an upflow anaerobic filter treating abattoir wastewaters

2013 ◽  
Vol 63 (Pt_6) ◽  
pp. 2082-2087 ◽  
Author(s):  
Linda Jabari ◽  
Hana Gannoun ◽  
Jean-Luc Cayol ◽  
Moktar Hamdi ◽  
Bernard Ollivier ◽  
...  
Keyword(s):  
Type Species ◽  
Small Subunit ◽  
Rrna Gene ◽  
Small Subunit Rrna ◽  
Terminal Electron Acceptor ◽  
Content Type ◽  
Moderately Thermophilic ◽  
Sulfate Reducing ◽  
Link Type ◽  
Nitrate And Nitrite

A novel anaerobic thermophilic sulfate-reducing bacterium designated strain LINDBHT1T was isolated from an anaerobic digester treating abattoir wastewaters in Tunisia. Strain LINDBHT1T grew at temperatures between 50 and 65 °C (optimum 55–60 °C), and at pH between 5.9 and 9.2 (optimum pH 6.0–6.8). Strain LINDBHT1T required salt for growth (1–40 g NaCl l−1), with an optimum of 20–30 g l−1. In the presence of sulfate as terminal electron acceptor, strain LINDBHT1T used H2/CO2, propanol, butanol and ethanol as carbon and energy sources but fumarate, formate, lactate and pyruvate were not utilized. Butanol was converted to butyrate, while propanol and ethanol were oxidized to propionate and acetate, respectively. Sulfate, sulfite and thiosulfate were utilized as terminal electron acceptors but elemental sulfur, iron (III), fumarate, nitrate and nitrite were not used. The G+C content of the genomic DNA was 44.4 mol%. Phylogenetic analysis of the small-subunit rRNA gene sequence indicated that strain LINDBHT1T was affiliated to the genus Desulfotomaculum with the type strains of Desulfotomaculum halophilum and Desulfotomaculum alkaliphilum as its closest phylogenetic relatives (about 89 % similarity). This strain represents a novel species of the genus Desulfotomaculum , Desulfotomaculum peckii sp. nov.; the type strain is LINDBHT1T ( = DSM 23769T = JCM 17209T).

scholarly journals Urechidicola croceus gen. nov., sp. nov., a member of the family Flavobacteriaceae

2020 ◽  
Vol 70 (3) ◽  
pp. 1751-1757 ◽  
Author(s):  
Su-Kyoung Shin ◽  
Hana Yi
Keyword(s):  
Sequence Similarity ◽  
Polar Lipids ◽  
Rrna Gene ◽  
Phenotypic Properties ◽  
Urechis Unicinctus ◽  
Circular Chromosome ◽  
Protein Coding ◽  
Content Type ◽  
Link Type ◽  
The Family

A Gram-stain-negative, rod-shaped, non-flagellated, non-gliding, aerobic bacterial strain, designated LPB0138T, was isolated from a marine spoon worm (Urechis unicinctus). The strain LPB0138T contains a circular chromosome of 3.43 Mb with a DNA G+C content of 30.4 mol%. The genome includes 2987 protein-coding genes and two copies of rRNA operons. The 16S rRNA gene sequence analysis showed that the isolate occurred within a clade containing only members of the family Flavobacteriaceae . The highest sequence similarity was observed with the genus Lutibacter (93.0–94.3 %), but the phylogenetic leaf of the new isolate did not belong to any of the genera known in the family Flavobacteriaceae . The low sequence similarity and the phylogenetic tree topology implied the novel generic status of the new isolate. The phenotypic properties of the strain LPB0138T also differentiated this isolate from its neighbour genera by showing a distinctive fatty acid composition, unique polar lipids profile, and low DNA G+C content. The LPB0138T strain contained menaquinone 6 as the isoprenoid quinone; iso-C15 : 1 G, iso-C15 : 0, iso-C15 : 0 3-OH, and iso-C17 : 0 3-OH as the major fatty acids; and phosphatidylethanolamine, unidentified aminophospholipids, unidentified aminolipids, and unidentified lipids as the major polar lipids. Based on the polyphasic taxonomic data obtained, the LPB0138T strain is considered to represent a novel species in a novel genus of the family Flavobacteriaceae, for which the name Urechidicola croceus gen. nov., sp. nov. was proposed. The type strain is LPB0138T (=KACC 18889T;=JCM 31563T).

scholarly journals Kushneria phosphatilytica sp. nov., a phosphate-solubilizing bacterium isolated from a solar saltern

2020 ◽  
Author(s):  
Guang-Xun Du ◽  
Ling-Yun Qu ◽  
Xu-Guang Hong ◽  
Cheng-Hua Li ◽  
De-Wen Ding ◽  
...  
Keyword(s):  
Phylogenetic Analysis ◽  
Type Species ◽  
Sequence Similarity ◽  
23S Rrna ◽  
Phylogenetic Position ◽  
Rrna Gene ◽  
Circular Chromosome ◽  
Content Type ◽  
Link Type ◽  
A Genome

A Gram-stain-negative, motile, rod-shaped, non-endospore-forming, aerobic and halophilic bacterium, designated strain YCWA18T, was isolated from the sediment of Jimo-Daqiao saltern in China. This strain was able to grow at NaCl concentrations in the range 0.5–20 % (w/v) with optimum growth at 6 % (w/v) NaCl. Growth occurred at temperatures of 4–40 °C (optimum 28 °C) and pH 4.0–9.0 (optimum 7.0). Phylogenetic analysis based on 16S rRNA gene sequences showed that strain YCWA18T belonged to the genus Kushneria and shared the highest sequence similarity of 98.7 % with Kushneria sinocarnis DSM 23229T. Moreover, the phylogenetic analysis based on the 23S rRNA gene sequence also confirmed the phylogenetic position of this novel strain. The predominant fatty acids were C16 : 0, C17 : 0 cyclo and C12 : 0 3-OH. The major isoprenoid quinone was Q-9 (94.2 %) and the polar lipids were diphosphatidylglycerol (DPG), phosphatidylglycerol (PG), phosphatidylethanolamine (PE), an unidentified aminolipid (AL), an unidentified phospholipids (PL) and two unidentified lipids (L). The complete genome of strain YCWA18T consisted of a single, circular chromosome of 3 624 619 bp, with an average G+C content of 59.1 mol%. A genome-based phylogenetic tree constructed using an up-to-date bacterial core gene set (UBCG) showed that strain YCWA18T formed a clade with K. sinocarnis DSM 23229T. However, the level of the ANI and dDDH values between strain YCWA18T and K. sinocarnis DSM 23229T were 82.3 and 24.6 %, respectively, which were low enough to distinguish strain YCWA18T from K. sinocarnis DSM 23229T. Overall, based on the phenotypic, chemotaxonomic, phylogenetic and genomic analyses, strain YCWA18T represents a novel species of genus Kushneria . The name Kushneria phosphatilytica sp. nov. is proposed, with the type strain YCWA18T (=CGMCC 1.9149T=NCCB 100306T).

scholarly journals Desulfobotulus mexicanus sp. nov., a novel sulfate-reducing bacterium isolated from the sediment of an alkaline crater lake in Mexico

2020 ◽  
Vol 70 (5) ◽  
pp. 3219-3225 ◽  
Author(s):  
Maria Fernanda Pérez-Bernal ◽  
Elcia M. S. Brito ◽  
Manon Bartoli ◽  
Johanne Aubé ◽  
Bernard Ollivier ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Type Species ◽  
Crater Lake ◽  
Rrna Gene ◽  
16S Rrna Gene Sequences ◽  
Terminal Electron Acceptor ◽  
Content Type ◽  
Sulfate Reducing ◽  
Link Type ◽  
Optimum Ph

A novel Gram-negative, non-spore-forming, vibrio-shaped, anaerobic, alkaliphilic, sulfate-reducing bacterium, designated strain PAR22NT, was isolated from sediment samples collected at an alkaline crater lake in Guanajuato (Mexico). Strain PAR22NT grew at temperatures between 15 and 37 °C (optimum, 32 °C), at pH between pH 8.3 and 10.1 (optimum, pH 9.0–9.6), and in the presence of NaCl up to 10 %. Pyruvate, 2-methylbutyrate and fatty acids (4–18 carbon atoms) were used as electron donors in the presence of sulfate as a terminal electron acceptor and were incompletely oxidized to acetate and CO2. Besides sulfate, both sulfite and elemental sulfur were also used as terminal electron acceptors and were reduced to sulfide. The predominant fatty acids were summed feature 10 (C18 : 1  ω7c and/or C18 : 1 ω9t and/or C18 : 1 ω12t), C18 : 1  ω9c and C16 : 0. The genome size of strain PAR22NT was 3.8 Mb including 3391 predicted genes. The genomic DNA G+C content was 49.0 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that it belongs to the genus Desulfobotulus within the class Deltaproteobacteria . Its closest phylogenetic relatives are Desulfobotulus alkaliphilus (98.4 % similarity) and Desulfobotulus sapovorans (97.9 % similarity). Based on phylogenetic, phenotypic and chemotaxonomic characteristics, we propose that the isolate represents a novel species of the genus Desulfobotulus with the name Desulfobotulus mexicanus sp. nov. The type strain is PAR22NT (=DSM 105758T=JCM 32146T).

scholarly journals Phenazines Regulate Nap-Dependent Denitrification inPseudomonas aeruginosaBiofilms

2018 ◽  
Vol 200 (9) ◽  
Author(s):  
Yu-Cheng Lin ◽  
Matthew D. Sekedat ◽  
William Cole Cornell ◽  
Gustavo M. Silva ◽  
Chinweike Okegbe ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Nitrate Reductase ◽  
Electron Acceptor ◽  
Bacterial Infections ◽  
Redox State ◽  
Reductase Activity ◽  
Anaerobic Growth ◽  
Bet Hedging ◽  
Terminal Electron Acceptor ◽  
Content Type

ABSTRACTMicrobes in biofilms face the challenge of substrate limitation. In particular, oxygen often becomes limited for cells inPseudomonas aeruginosabiofilms growing in the laboratory or during host colonization. Previously we found that phenazines, antibiotics produced byP. aeruginosa, balance the intracellular redox state of cells in biofilms. Here, we show that genes involved in denitrification are induced in phenazine-null (Δphz) mutant biofilms grown under an aerobic atmosphere, even in the absence of nitrate. This finding suggests that resident cells employ a bet-hedging strategy to anticipate the potential availability of nitrate and counterbalance their highly reduced redox state. Consistent with our previous characterization of aerobically grown colonies supplemented with nitrate, we found that the pathway that is induced in Δphzmutant colonies combines the nitrate reductase activity of the periplasmic enzyme Nap with the downstream reduction of nitrite to nitrogen gas catalyzed by the enzymes Nir, Nor, and Nos. This regulatory relationship differs from the denitrification pathway that functions under anaerobic growth, with nitrate as the terminal electron acceptor, which depends on the membrane-associated nitrate reductase Nar. We identified the sequences in the promoter regions of thenapandniroperons that are required for the effects of phenazines on expression. We also show that specific phenazines have differential effects onnapgene expression. Finally, we provide evidence that individual steps of the denitrification pathway are catalyzed at different depths within aerobically grown biofilms, suggesting metabolic cross-feeding between community subpopulations.IMPORTANCEAn understanding of the unique physiology of cells in biofilms is critical to our ability to treat fungal and bacterial infections. Colony biofilms of the opportunistic pathogenPseudomonas aeruginosagrown under an aerobic atmosphere but without nitrate express a denitrification pathway that differs from that used for anaerobic growth. We report that the components of this pathway are induced by electron acceptor limitation and that they are differentially expressed over the biofilm depth. These observations suggest that (i)P. aeruginosaexhibits “bet hedging,” in that it expends energy and resources to prepare for nitrate availability when other electron acceptors are absent, and (ii) cells in distinct biofilm microniches may be able to exchange substrates to catalyze full denitrification.

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