scholarly journals Comparative Genomics Provides Insights into the Taxonomy of Azoarcus and Reveals Separate Origins of Nif Genes in the Proposed Azoarcus and Aromatoleum Genera

Genes ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 71
Author(s):  
Roberto Tadeu Raittz ◽  
Camilla Reginatto De Pierri ◽  
Marta Maluk ◽  
Marcelo Bueno Batista ◽  
Manuel Carmona ◽  
...  
Keyword(s):  
Aromatic Compounds ◽  
Growth Promotion ◽  
Nitrogenase Activity ◽  
Full Length ◽  
Polluted Water ◽  
Nitrate Respiration ◽  
Nif Genes ◽  
Diverse Range ◽  
Single Strain ◽  
Group 2

Among other attributes, the Betaproteobacterial genus Azoarcus has biotechnological importance for plant growth-promotion and remediation of petroleum waste-polluted water and soils. It comprises at least two phylogenetically distinct groups. The “plant-associated” group includes strains that are isolated from the rhizosphere or root interior of the C4 plant Kallar Grass, but also strains from soil and/or water; all are considered to be obligate aerobes and all are diazotrophic. The other group (now partly incorporated into the new genus Aromatoleum) comprises a diverse range of species and strains that live in water or soil that is contaminated with petroleum and/or aromatic compounds; all are facultative or obligate anaerobes. Some are diazotrophs. A comparative genome analysis of 32 genomes from 30 Azoarcus-Aromatoleum strains was performed in order to delineate generic boundaries more precisely than the single gene, 16S rRNA, that has been commonly used in bacterial taxonomy. The origin of diazotrophy in Azoarcus-Aromatoleum was also investigated by comparing full-length sequences of nif genes, and by physiological measurements of nitrogenase activity using the acetylene reduction assay. Based on average nucleotide identity (ANI) and whole genome analyses, three major groups could be discerned: (i) Azoarcus comprising Az. communis, Az. indigens and Az. olearius, and two unnamed species complexes, (ii) Aromatoleum Group 1 comprising Ar. anaerobium, Ar. aromaticum, Ar. bremense, and Ar. buckelii, and (iii) Aromatoleum Group 2 comprising Ar. diolicum, Ar. evansii, Ar. petrolei, Ar. toluclasticum, Ar. tolulyticum, Ar. toluolicum, and Ar. toluvorans. Single strain lineages such as Azoarcus sp. KH32C, Az. pumilus, and Az. taiwanensis were also revealed. Full length sequences of nif-cluster genes revealed two groups of diazotrophs in Azoarcus-Aromatoleum with nif being derived from Dechloromonas in Azoarcus sensu stricto (and two Thauera strains) and from Azospira in Aromatoleum Group 2. Diazotrophy was confirmed in several strains, and for the first time in Az. communis LMG5514, Azoarcus sp. TTM-91 and Ar. toluolicum TT. In terms of ecology, with the exception of a few plant-associated strains in Azoarcus (s.s.), across the group, most strains/species are found in soil and water (often contaminated with petroleum or related aromatic compounds), sewage sludge, and seawater. The possession of nar, nap, nir, nor, and nos genes by most Azoarcus-Aromatoleum strains suggests that they have the potential to derive energy through anaerobic nitrate respiration, so this ability cannot be usefully used as a phenotypic marker to distinguish genera. However, the possession of bzd genes indicating the ability to degrade benzoate anaerobically plus the type of diazotrophy (aerobic vs. anaerobic) could, after confirmation of their functionality, be considered as distinguishing phenotypes in any new generic delineations. The taxonomy of the Azoarcus-Aromatoleum group should be revisited; retaining the generic name Azoarcus for its entirety, or creating additional genera are both possible outcomes.

scholarly journals Screening, Identification and Growth-Promotion Products of Multifunctional Bacteria in a Chinese Fir Plantation

Forests ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 120
Author(s):  
Guangyu Zhao ◽  
Yihui Wei ◽  
Jiaqi Chen ◽  
Yuhong Dong ◽  
Lingyu Hou ◽  
...  
Keyword(s):  
High Efficiency ◽  
Growth Promotion ◽  
Nitrogenase Activity ◽  
Acc Deaminase ◽  
Inorganic Phosphorus ◽  
Chinese Fir ◽  
Biochemical Tests ◽  
Growth Promoting ◽  
Chinese Fir Plantation ◽  
Physiological And Biochemical

Purpose: This research was aimed to screen and identify multifunctional phosphorus-dissolving bacteria of a Chinese fir (Cunninghamia lanceolata) plantation and study its phosphorus-dissolving characteristics in order to provide strain resources and a theoretical basis for developing the appropriate bacterial fertilizer of a Chinese fir plantation. Methods: First, phosphorus-dissolving bacteria were isolated from the woodland soil of a Chinese fir plantation by Pikovskava inorganic phosphorus medium (PVK). Then, some growth-promoting indicators of primary screening strains were determined, including the capacity of phosphorus-solubilized, nitrogenase activity, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity, production of indole-3-acetic acid (IAA), secretion of iron carrier and so on. Finally, the screening multifunctional phosphorus-dissolving bacteria were identified, which were combined with colony characteristics, physiological and biochemical tests and molecular biotechnology. Results: (1) Thirteen phosphorus-dissolving bacteria were isolated and screened in total, and P5 (195.61 mg·L−1) had the strongest capacity of phosphorus-solubilized. Five phosphorus-dissolving bacteria were provided with nitrogenase activity, and the highest activity of nitrogenase was P10 and P5 (71.90 C2H4 nmol·mL−1·h−1 and 71.00 C2H4 nmol·mL−1·h−1, respectively). Four strains were provided with ACC deaminase activity, and the highest activity of ACC deaminase was P5 and P9, (0.74 μmol·mg−1·h−1 and 0.54 μmol·mg−1·h−1, respectively). Most strains could secrete IAA, and three strains of bacteria had a strong secretory ability, which could secrete IAA with a concentration greater than 15 mg·mL−1, and P5 was 18.00, P2 was 17.30, P6 was 15.59 (mg·mL−1). P5 produced carriers of iron better than others, and the ratio of the diameter of the iron production carrier ring to the diameter of the colony was 1.80, respectively, which was significantly higher than other strains. Combining all kinds of factors, P5 multifunctional phosphorus-dissolving bacteria were screened for eventual further study. (2) Strain P5 was identified as Burkholderia ubonensis, based on the colony characteristics, physiological and biochemical tests, 16SrDNA sequence analysis and phylogenetic tree construction. Conclusion: P5 has a variety of high-efficiency growth-promoting capabilities, and the ability to produce IAA, ACC deaminase activity and siderophore performance are significantly higher than other strains, which had great potential in the development of microbial fertilizer.

scholarly journals SCREENING OF SOIL BACTERIA FOR PLANT GROWTH PROMOTION ACTIVITIES IN VITRO

2016 ◽  
Vol 4 (1) ◽  
pp. 27 ◽  
Author(s):  
Edi Husen
Keyword(s):  
Plant Growth ◽  
Soil Bacteria ◽  
Phosphate Solubilization ◽  
Azotobacter Vinelandii ◽  
Growth Promotion ◽  
Nitrogenase Activity ◽  
Chelating Agent ◽  
Plant Growth Promoting Rhizobacteria ◽  
Iaa Production

Fourteen isolates of soil bacteria, including two known plant growth promoting rhizobacteria (PGPR) strains, Azotobacter vinelandii Mac 259 and Bacillus cereus UW 85, were tested in vitro. Parameters assessed were indoleacetic acid (IAA) production, phosphate solubilization, dinitrogen fixation, and siderophore (Fe-III chelating agent) production. IAA production was assayed colorimetrically using ferric chlorideperchloric acid reagent. Phosphate-solubilization and siderophore production were tested qualitatively by plating the bacteria in Pikovskaya and chrome azurol S agar, respectively. The ability to fix dinitrogen was measured based on nitrogenase activity of the bacteria by gas chromatography. The results showed that twelve isolates produced IAA, ranged from 2.09 to 33.28 µmol ml-1. The ability to solubilize precipitated phosphate was positively exhibited by four isolates (BS 58, BTS, TCaR 61, and BTCaRe 65). Seven isolates including Mac 259 positively produced siderophore. None of the isolates showed nitrogenase activity. Only one isolate (TS 3) did not exhibit any of the traits tested. Isolate TCeRe 60 and reference strain Mac 259 were found to have IAA- and siderophore-producing traits. Four P-solubilizing bacteria (BS 58, BTS, TCaR 61, and BTCaRe 65) were also IAA- and siderophore-producing bacteria. Potential use of these PGPR isolates needs further test in enhancing plant growth.

Comparison of the plant growth-promotion performance of a consortium of Bacilli inoculated as endospores or as vegetative cells

2019 ◽  
Vol 95 (11) ◽  
Author(s):  
Isha Hashmi ◽  
Christophe Paul ◽  
Andrej Al-Dourobi ◽  
Frederic Sandoz ◽  
Priscilla Deschamps ◽  
...  
Keyword(s):  
Seed Germination ◽  
Plant Growth ◽  
Positive Impact ◽  
Growth Promotion ◽  
Soil Microbial Communities ◽  
Vegetative Cells ◽  
Single Strain ◽  
Positive Effects ◽  
Pot Experiments

ABSTRACT The effect of three plant growth-promoting Bacillus strains inoculated either alone or as a consortium was tested on oat (Avena sativa) growth. The bioinoculants were applied as vegetative cells or endospores at low cell densities on the seeds and their effect was tested in sterile in vitro conditions, pot experiments, and a field trial. The in vitro seed germination assay showed that both individual bacterial inocula and bacterial consortia had positive effects on seed germination. Greenhouse pot experiments with sterile and non-sterile soil showed that consortia increased the total dry biomass of oat plants as compared to single strain inoculation and uninoculated controls. However, the positive impact on plant growth was less prominent when the bioinoculated strains had to compete with native soil microbes. Finally, the field experiment demonstrated that the consortium of vegetative cells was more efficient in promoting oat growth than the endospore consortium and the uninoculated control. Moreover, both consortia successfully colonized the roots and the rhizosphere of oat plants, without modifying the overall structure of the autochthonous soil microbial communities.

scholarly journals Plant Growth Promoting Abilities of Novel Burkholderia-Related Genera and Their Interactions With Some Economically Important Tree Species

2021 ◽  
Vol 5 ◽  
Author(s):  
Munusamy Madhaiyan ◽  
Govindan Selvakumar ◽  
Tan HianHwee Alex ◽  
Lin Cai ◽  
Lianghui Ji
Keyword(s):  
Plant Growth ◽  
Oil Palm ◽  
Tree Species ◽  
Growth Promotion ◽  
Nitrogenase Activity ◽  
Acc Deaminase ◽  
Bacterial Strains ◽  
Pgp Traits ◽  
Plant Growth Promoting ◽  
Promote Plant Growth

A survey of bacterial endophytes associated with the leaves of oil palm and acacias resulted in the isolation of 19 bacterial strains belonging to the genera Paraburkholderia, Caballeronia, and Chitinasiproducens, which are now regarded as distinctively different from the parent genus Burkholderia. Most strains possessed one or more plant growth promotion (PGP) traits although nitrogenase activity was present in only a subset of the isolates. The diazotrophic Paraburkholderia tropica strain S39-2 with multiple PGP traits and the non-diazotrophic Chitinasiproducens palmae strain JS23T with a significant level of 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity were selected to investigate the influence of bacterial inoculation on some economically important tree species. Microscopic examination revealed that P. tropica S39-2 was rhizospheric as well as endophytic while C. palmae JS23T was endophytic. P. tropica strain S39-2 significantly promoted the growth of oil palm, eucalyptus, and Jatropha curcas. Interestingly, the non-diazotrophic, non-auxin producing C. palmae JS23T strain also significantly promoted the growth of oil palm and eucalyptus although it showed negligible effect on J. curcas. Our results suggest that strains belonging to the novel Burkholderia-related genera widely promote plant growth via both N-independent and N-dependent mechanisms. Our results also suggest that the induction of defense response may prevent the colonization of an endophyte in plants.

Bacillus cereus UW85 inoculation effects on growth, nodulation, and N accumulation in grain legumes: Field studies

2002 ◽  
Vol 82 (2) ◽  
pp. 291-298 ◽  
Author(s):  
W. John Bullied ◽  
Terry J. Buss ◽  
J. Kevin Vessey
Keyword(s):  
Bacillus Cereus ◽  
Common Bean ◽  
Growth Promotion ◽  
Nitrogenase Activity ◽  
Dry Weight ◽  
Field Studies ◽  
Grain Legumes ◽  
N Accumulation ◽  
N Content ◽  
Stimulation Of

Bacillus cereus strain UW85 was assessed for growth-promotion effects on soybean and common bean in the presence and absence of rhizobial inoculation at two field sites in Manitoba in 1994. Growth promotions due to B. cereus UW85 occurred for soybean only, and only at one site. Promotions in plant emergence in soybean were apparent at 60 d after planting (DAP), but stimulations in shoot dry weight (DW), N concentration, and N content were not apparent until 90 DAP. At maturity (120 DAP), inoculation with UW85 resulted in stimulation of seed yield by 9% and seed N content by 14%. However, stimulation in growth and N parameters by UW85 treatment was proportionally greater in the absence of B. japonicum inoculation than in the presence of the rhizobial inoculant. These observations, in combination with the observations that nitrogenase activity was not stimulated by UW85 treatment, clearly indicate that the UW85-mediated stimulation of growth and N accumulation of soybean is via a generalized stimulation of plant growth, and not via a stimulation in the soybean-B. japonicum symbiosis per se. Overall, our study indicates that inoculation with UW85 has the potential of increasing soybean production in western Canada, but these effects are site specific and are not seen in common bean. Key words: Bacillus cereus UW85, common bean, Glycine max, growth-promotion, Phaseolus vulgaris, soybean

Nodulation and Nitrogenase Activity of Peanuts Inoculated with Single Strain Isolates of Rhizobium1

1980 ◽  
Vol 7 (2) ◽  
pp. 95-97 ◽  
Author(s):  
G. H. Elkan ◽  
J. C. Wynne ◽  
T. J. Schneeweis ◽  
T. G. Isleib
Keyword(s):  
North Carolina ◽  
Host Plants ◽  
Nitrogenase Activity ◽  
Field Site ◽  
Single Strain ◽  
Greenhouse Study ◽  
Naturally Occurring ◽  
Greenhouse Evaluation ◽  
Arachis Hypogaea L ◽  
Rhizobial Population

Abstract Nodulation and nitrogenase activity (μM C2H4/plant/hr) for 48 diverse peanut (Arachis hypogaea L.2) genotypes were determined in a field site where the soil supported high populations of endemic rhizobia. These same rhizobia and peanut genotypes had previously been evaluated in a greenhouse study. Both host genotypes and rhizobial strains significantly influenced nodulation and nitrogenase activity. Roots of Virginia-type host plants were better nodulated and exhibited higher nitrogenase activity than genotypes of the fastigiate type. Florigiant, the predominant cultivar in the Virginia-North Carolina area, produced the most nodules and had the greatest nitrogenase activity. Variation in nodulation and nitrogenase activity for the single strain isolates in the presence of naturally occurring field populations indicated that the strains were able to compete for nodule sites. Strains both less and more effective than the naturally occurring rhizobial population were observed. Nitrogenase activity of the strains was correlated with previous greenhouse results suggesting that greenhouse evaluation of rhizobial strains for peanuts is useful as a preliminary screen before evaluation in the field.

scholarly journals Eradication of a Large Outbreak of a Single Strain of vanB Vancomycin-ResistantEnterococcus faeciumat a Major Australian Teaching Hospital

2004 ◽  
Vol 25 (5) ◽  
pp. 384-390 ◽  
Author(s):  
Keryn J. Christiansen ◽  
Patricia A. Tibbett ◽  
William Beresford ◽  
John W. Pearman ◽  
Rosie C. Lee ◽  
...  
Keyword(s):  
Tertiary Care ◽  
Care Facility ◽  
Control Measures ◽  
Epidemic Strain ◽  
Single Strain ◽  
Large Outbreak ◽  
Vancomycin Resistant ◽  
Executive Group ◽  
Group 2 ◽  
Widespread Dissemination

AbstractObjective:To demonstrate that nosocomial transmission of vancomycin-resistant enterococci (VRE) can be terminated and endemicity prevented despite widespread dissemination of an epidemic strain in a large tertiary-care referral hospital.Interventions:Two months after the index case was detected in the intensive care unit, 68 patients became either infected or colonized with an epidemic strain of vanB vancomycin-resistantEnterococcus faeciumdespite standard infection control procedures. The following additional interventions were then introduced to control the outbreak: (1) formation of a VRE executive group; (2) rapid laboratory identification (30 to 48 hours) using culture and polymerase chain reaction detection ofvanA andvanBresistance genes; (3) mass screening of all hospitalized patients with isolation of carriers and cohorting of contacts; (4) environmental screening and increased cleaning; (5) electronic flagging of medical records of contacts; and (6) antibiotic restrictions (third-generation cephalosporins and vancomycin).Results:A total of 19,658 patient and 24,396 environmental swabs were processed between July and December 2001. One hundred sixty-nine patients in 23 wards were colonized with a single strain of vanB vancomycin-resistantE. faecium.Introducing additional control measures rapidly brought the outbreak under control. Hospital-wide screening found 39 previously unidentified colonized patients, with only 7 more nonsegregat-ed patients being detected in the next 2 months. The outbreak was terminated within 3 months at a cost of $2.7 million (Australian dollars).Conclusion:Despite widespread dissemination of VRE in a large acute care facility, eradication was achievable by a well-resourced, coordinated, multifaceted approach and was in accordance with good clinical governance.

Bacillus cereus UW85 inoculation effects on growth, nodulation, and N accumulation in grain legumes: Controlled-environment studies

2002 ◽  
Vol 82 (2) ◽  
pp. 282-290 ◽  
Author(s):  
J. Kevin Vessey ◽  
Terry J. Buss
Keyword(s):  
Bacillus Cereus ◽  
Common Bean ◽  
Temperature Regime ◽  
Growth Promotion ◽  
Nitrogenase Activity ◽  
Controlled Environment ◽  
N Accumulation ◽  
Positive Effects ◽  
Whole Plant ◽  
Single Temperature

Treating seed with Bacillus cereus strain UW85 stimulates nodulation in soybean, but the underlying mechanisms of this stimulation are poorly understood. In this study we assessed the effects of inoculation on nodulation, nitrogenase activity and dry matter partitioning in soybean (cv. Maple Ridge), common bean (cv. OAC Rico) and pea (cv. Express) under controlled, gnotobiotic conditions. Plants were grown for 34 d under controlled-environment conditions without a mineral N source, at low two levels of (brady)rhizobia inoculation. Soybean and common bean were grown at a single temperature regime and pea was grown at two temperature regimes. Each trial consisted of five treatments (noninoculated control, low (brady)rhizobia inoculation, low (brady)rhizobia plus UW85 inoculation, high (brady)rhizobia inoculation, and high (brady)rhizobia plus UW85 inoculation) with six plants as replicates per treatment in a completely randomized design. Inoculation of soybean with UW85 increased growth of roots, shoots, and nodules across both levels of bradyrhizobia inoculation and increased plant N accumulation by 12%. In oculation with UW85 also increased whole-plant nodulation (nodules plant-1) by 16%, but there were no effects on specific nodulation [nodules g-1 root dry weight (DW)], individual nodule DW, nitrogenase activity (μmol H2 g-1 nodule DW h-1) or N2 fixation efficiency (g plant-N g-1 nodule DW). Inoculation of pea with UW85 at the low temperature regime increased whole-plant nodulation by 19%, but had no positive effects on any other growth parameters. Inoculation of common bean with UW85 had no positive effects on any aspects of growth, nodulation or nitrogenase activity. Our data indicate that under gnotobiotic conditions, UW85 inoculation increases nodulation in soybean indirectly by increasing root growth and not stimulating the nodulation process per se. The bacterium had little to no positive effects on pea and common bean symbioses. Key words: Bacillus cereus UW85, Glycine max, growth-promotion, nodulation, Phaseolus vulgaris, Pisum sativum

scholarly journals Examining the Effects of the Nitrogen Environment on Growth and N2-Fixation of Endophytic Herbaspirillum seropedicae in Maize Seedlings by Applying 11C Radiotracing

2021 ◽  
Vol 9 (8) ◽  
pp. 1582
Author(s):  
Spenser Waller ◽  
Stacy L. Wilder ◽  
Michael J. Schueller ◽  
Alexandra B. Housh ◽  
Stephanie Scott ◽  
...  
Keyword(s):  
Plant Growth ◽  
Root Colonization ◽  
Growth Promotion ◽  
Nitrogenase Activity ◽  
Growth Conditions ◽  
Significant Inhibition ◽  
Cereal Crops ◽  
Herbaspirillum Seropedicae ◽  
Promote Plant Growth ◽  
Biological Nitrogen

Herbaspirillum seropedicae, as an endophyte and prolific root colonizer of numerous cereal crops, occupies an important ecological niche in agriculture because of its ability to promote plant growth and potentially improve crop yield. More importantly, there exists the untapped potential to harness its ability, as a diazotroph, to fix atmospheric N2 as an alternative nitrogen resource to synthetic fertilizers. While mechanisms for plant growth promotion remain controversial, especially in cereal crops, one irrefutable fact is these microorganisms rely heavily on plant-borne carbon as their main energy source in support of their own growth and biological functions. Biological nitrogen fixation (BNF), a microbial function that is reliant on nitrogenase enzyme activity, is extremely sensitive to the localized nitrogen environment of the microorganism. However, whether internal root colonization can serve to shield the microorganisms and de-sensitize nitrogenase activity to changes in the soil nitrogen status remains unanswered. We used RAM10, a GFP-reporting strain of H. seropedicae, and administered radioactive 11CO2 tracer to intact 3-week-old maize leaves and followed 11C-photosynthates to sites within intact roots where actively fluorescing microbial colonies assimilated the tracer. We examined the influence of administering either 1 mM or 10 mM nitrate during plant growth on microbial demands for plant-borne 11C. Nitrogenase activity was also examined under the same growth conditions using the acetylene reduction assay. We found that plant growth under low nitrate resulted in higher nitrogenase activity as well as higher microbial demands for plant-borne carbon than plant growth under high nitrate. However, carbon availability was significantly diminished under low nitrate growth due to reduced host CO2 fixation and reduced allocation of carbon resources to the roots. This response of the host caused significant inhibition of microbial growth. In summary, internal root colonization did little to shield these endophytic microorganisms from the nitrogen environment.

Respiratory nitrogen metabolism and nitrosative stress defence in ϵ-proteobacteria: the role of NssR-type transcription regulators

2011 ◽  
Vol 39 (1) ◽  
pp. 299-302 ◽  
Author(s):  
Melanie Kern ◽  
Christine Winkler ◽  
Jörg Simon
Keyword(s):  
Nitrogen Metabolism ◽  
Nitrosative Stress ◽  
Dominant Role ◽  
Nitrogen Compound ◽  
Anaerobic Respiration ◽  
Model Organisms ◽  
Nitrate Respiration ◽  
Diverse Range ◽  
Transcription Regulators

ϵ-Proteobacteria form a globally ubiquitous group of ecologically significant organisms and comprise a diverse range of host-associated and free-living species. To grow by anaerobic respiration, many ϵ-proteobacteria reduce nitrate to nitrite followed by either nitrite ammonification or denitrification. Using the ammonifying model organisms Wolinella succinogenes and Campylobacter jejuni, the electron transport chains of nitrate respiration, respiratory nitrite ammonification and even N2O (nitrous oxide) respiration have been characterized in recent years, but knowledge on nitrosative stress defence, nitrogen compound-sensing and corresponding signal transduction pathways is limited. The potentially dominant role of NssR (nitrosative stress-sensing regulator)-type transcription regulators in ϵ-proteobacterial nitrogen metabolism is discussed.

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