Free-Living Bacteria

Knowles, Roger

doi:10.1007/978-1-4615-8957-0_4

Cited by 9 publications

(3 citation statements)

References 76 publications

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“…The nitrogen-fixing activity of the isolates was determined using the acetylene reduction assay 15) . Individual isolates were inoculated into an air-tight vial containing semisolid Rennie's medium 25) .…”

Section: Characterization Of the Isolatesmentioning

confidence: 99%

Predominant Culturable Bacillus Species in Japanese Arable Soils and Their Potential as Biocontrol Agents

2005

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To reveal predominant culturable Bacillus species in Japanese arable soils, aerobic spore-forming bacteria were isolated from different soils in Japan and their phylogenic positions were estimated from the 16S rDNA sequences. Bacillus species were also isolated from tomato roots grown in soils for 4 weeks to estimate the difference in phylogenic positions between soil and root isolates. The number of culturable Bacillus species ranged from 6.4 to 7.4 log cfu g-1 soil and 4.7 to 6.7 log cfu g-1 root in soils and tomato roots, respectively, and the proportion of Bacillus species among total culturable bacteria ranged from 3.8% to 17.9% and 0.1% to 6.7% in soils and roots, respectively. The differences in the number and percentage of culturable Bacillus species between the soils and roots were highly significant (P=0.0000 and 0.0023, respectively), indicating that Bacillus species were more predominant in soil than in root. A total of 108 isolates were characterized using the restriction fragment length polymorphism (RFLP) method and partial 16S rDNA sequences. They affiliated to 22 species including the genus Bacillus, Brevibacillus and Paenibacillus. No nitrogen fixers were isolated. The predominant species was Bacillus megaterium to which 42 isolates (39%) belonged. Some of the species, such as Bacillus luciferensis and Brevibacillus agri, were isolated only from the tomato roots and considered to be more adapted to the rhizosphere than soil. Among 108 isolates, only one strain, N2S6, belonging to Bacillus megaterium, showed consistent antagonistic activity against the bacterial wilt of tomato caused by Ralstonia solanacearum.

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Section: Characterization Of the Isolatesmentioning

confidence: 99%

Predominant Culturable Bacillus Species in Japanese Arable Soils and Their Potential as Biocontrol Agents

2005

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“…2 Moore (1966) in Greenland (1977): 30 kg· ha-'·yr-1 ; Tjepkema and van Berkum (1977): I; Singh and Balasubramanian (1980a): 10;Steyn and Delwiche (1970) in Bums and Hardy (1975): 4; Barberet a!. (1976) in Knowles (1978): 0.9; Balandreau (1975) in Knowles (1978) (1977) (Weber 1966, Lynch 1968, Hashimoto 1971, Vest 1971in Vest et al 1973, Pal and Saxena 1975 and solution culture (Alios and Bartholomew 1959); estimate assumes unfertilized crops grown on soils of low fertility (E. Kuinen, personal communication). t Eaglesham et al (1977).…”

Section: Regional Nitrogen Inputsmentioning

confidence: 99%

Nitrogen in West Africa: The Regional Cycle

Robertson¹,

Rosswall²

1986

Ecological Monographs

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We have calculated a nitrogen cycle budget for West Africa south of the northern Sahara that quantifies biologically important pools of nitrogen in the region and major fluxes associated with these pools. Major compartments of our model include noncultivated systems broken down by vegetation zone, successional status, and plant components; annual and perennial crops each broken down by crop species and plant and harvest components; wetlands; anthropic systems; and soils and sediments. Base reference year is 1978. Biological nitrogen fixation and precipitation fluxes dominated nitrogen inputs to West Africa in 1978. Approximately 12 × 109 kg were fixed in noncultivated systems; about half of this was fixed in early successional (0—6 yr) rain forests, and much of the rest in grazed or fallow savanna grasslands and woodlands. Less than 0.7 × 109 kg were fixed in cultivated systems; legumes accounted for ≈25% of this. Total anthropic sources (fossil fuel combustion, fertilizer production, and agricultural commodity imports) were minor (<0.3 × 109 kg). Precipitation inputs to the region were ≈0.4 × 109 kg. Most nitrogen leaving West Africa did so volatilized by fire (≈8.3 × 109 kg), principally in non—cropped systems. Major losses also occurred via hydrologic export to the Atlantic Ocean (1.5 × 109 kg) and via denitrification (1.1 × 109 kg). Total N losses from West Africa exceeded 11.0 × 109 kg. The nitrogen immobilized in growing woody vegetation appeared to have amounted to ≈5.6 × 109 kg. Most was immobilized in forested regions by vegetation regrowth during the fallow phase of the bush fallow crop rotation cycle, the dominant cropping system in West Africa. A very small amount was immobilized by perennial crops such as cacao and rubber. Net immobilization in soil was not estimated; total soil N was assumed to be in steady state for the region as a whole. Our overall budget balances within 1%, despite independent calculations of all major fluxes. The balance portrays a nitrogen cycle dominated by pools and fluxes in noncropped systems. In contrast to N balances in developed regions, direct anthropic fluxes are a minor part of the West Africa cycle. Indirect human influences, however, mainly through effects on vegetation cover, appear to be a major determinant of both the rates at which nitrogen is cycled in West Africa and the relative importance of most pools and fluxes.

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“…The diverse habitats of the N2-fixing bacteria include soil, aquatic, plant and animal ecosystems (Knowles, 1977(Knowles, , 1978. In such diverse environments different physiological requirements for optimal N2 fixation, such as adjustment to energy source and oxygen concentration, have been evolved by these bacteria.…”

Section: Introductionmentioning

confidence: 99%

Physiological and Genetic Characterization of a Diazotrophic Pseudomonad

Chan¹,

Wheatcroft²,

Watson³

1986

Microbiology

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A soil isolate, 4B, which had been previously assigned to the genus Pseudomonas and shown to be capable of reducing C2H2 with simple phenolic compounds as sole carbon source, was further characterized in comparison with two other diazotrophs which were identified as pseudomonads. The DNA base composition of 4B was 60.2 mol% G + C. Plasmid DNA was not detected in Y.-K. C H A N A N D OTHERS METHODS Bacterial strains, plasmids and DNA.Strain 4B, which has been tentatively assigned to the genus Pseudomonas, was originally isolated from a forest soil (Chan, 1986) and was recently deposited in the American Type Culture Collection (ATCC 43038). P. delafieldii (ATCC 17505) and P . putida (ATCC 33015) were obtained from the ATCC. Pseudomonas strain H8 (ATCC 35402) was a gift from W. ). Pseudomonas strain DC, originally isolated from the roots of the grass Deschampsia caespitosa (Haahtela et al., 1983), was kindly sent to us by K. Haahtela (University of Helsinki, Finland). Klebsiella pneumoniae M5A1 was obtained from V. N. Iyer, (Carleton University, Ottawa, Canada); Escherichia coli 553 (proA metF A) carrying plasmid RP4 (AprKmr NmrTcr) was from the Plasmid Referencecenter, Stanford University, USA ; E. coli B was from the Department of Microbiology, University of Manitoba, Canada; and E. coli HBlOl(pSA30) was from D. R. Helinski, (University of California, USA).Reference DNAs of Clostridiumperfringens, E. coli B and Micrococcus lysodeikticus were purchased from Sigma.Culture media. The maintenance agar used for the diazotrophic species consisted of 0.1 % (w/v) Difco tryptic soy broth solidified with 1.6% (w/v) Difco Bacto-agar; P. delafieldii was maintained on nutrient agar. Tests for autotrophic growth with Hz, O2 and C 0 2 were done in the defined medium described by De Bont & Leijten (1976).

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Free-Living Bacteria

Cited by 9 publications

References 76 publications

Predominant Culturable Bacillus Species in Japanese Arable Soils and Their Potential as Biocontrol Agents

Predominant Culturable Bacillus Species in Japanese Arable Soils and Their Potential as Biocontrol Agents

Nitrogen in West Africa: The Regional Cycle

Physiological and Genetic Characterization of a Diazotrophic Pseudomonad

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