Does siderophore production influence the relative abundance of Rhizobium meliloti in two field populations?

1993 ◽  
Vol 39 (3) ◽  
pp. 348-351 ◽  
Author(s):  
L. R. Barran ◽  
E. S. P. Bromfield
Keyword(s):  
Soil Ph ◽  
Relative Abundance ◽  
Iron Content ◽  
Direct Relationship ◽  
Rhizobium Meliloti ◽  
Siderophore Production ◽  
Frequency Of Occurrence ◽  
Apparent Absence ◽  
Phage Types ◽  
Phage Sensitivity

Populations of indigenous Rhizobium meliloti isolated from nodules of alfalfa grown at sites A and B (soil pH, 7.0 and 6.1, respectively) were previously characterized on the basis of phage sensitivity and divided into 55 and 65 phage types. The available iron content of soil at site B was significantly higher than that at site A. Isolates representing the phage types comprising each of these populations were tested for the production of siderophores. The frequency of siderophore-producing (sid+) phage types of R. meliloti, estimated from the distribution of types in the two field populations, was significantly higher at site A (54%), where iron was less available, than at site B (18%). The distributions of frequency for sid+ and sid− phage types were similar at site A but differed (P < 0.005) at site B, where the soil was slightly acidic and contained more available iron. The apparent absence of a direct relationship between siderophore production and frequency of occurrence suggests that siderophore production may not influence the relative abundance of R. meliloti in these populations at sites differing in iron availability.Key words: siderophore, iron, Rhizobium meliloti, populations.

Denitrification activity of phage types representative of two populations of indigenous Rhizobium meliloti

1989 ◽  
Vol 35 (7) ◽  
pp. 737-740 ◽  
Author(s):  
Y.-K. Chan ◽  
L. R. Barran ◽  
E. S. P. Bromfield
Keyword(s):  
Medicago Sativa ◽  
Rhizobium Meliloti ◽  
Previous History ◽  
Indigenous Populations ◽  
Frequency Of Occurrence ◽  
Phage Types ◽  
Denitrification Activity ◽  
History Of ◽  
Phage Sensitivity ◽  
Two Populations

Isolates of Rhizobium meliloti from indigenous populations at two sites were previously characterized according to phage sensitivity. Isolates representative of the 55 and 65 phage types comprising these two populations, respectively, were tested for denitrification activity with nitrate or nitrite as substrate. Fifty-seven of 120 isolates were capable of denitrification with activities varying considerably between phage types. Only one isolate was able to denitrify nitrite but not nitrate, indicating the presence of a truncated denitrification pathway. Each of five phage types showed variation in denitrification ability between isolates from different sites, indicating possible adaptation of indigenous R. meliloti to their respective environments. The estimated frequency of occurrence of denitrifiers in the two indigenous populations of R. meliloti (9 and 13%) differed significantly between sites with and without a previous history of Medicago sativa cultivation, respectively.Key words: Rhizobium, denitrification, populations, phage.

A cryptic plasmid of indigenous Rhizobium meliloti possesses reiterated nodC and nifE genes and undergoes DNA rearrangement

1992 ◽  
Vol 38 (6) ◽  
pp. 563-568 ◽  
Author(s):  
V. K. Rastogi ◽  
E. S. P. Bromfield ◽  
S. T. Whitwill ◽  
L. R. Barran
Keyword(s):  
Genomic Dna ◽  
Rhizobium Meliloti ◽  
Phage Type ◽  
Cryptic Plasmid ◽  
Dna Rearrangement ◽  
Homologous Sequences ◽  
Phage Types ◽  
Phage Sensitivity ◽  
Cryptic Plasmids ◽  
Free Strain

Indigenous Rhizobium meliloti were previously characterized on the basis of plasmid profiles and phage sensitivity patterns (phage types). Rhizobium meliloti 1076, which contained two cryptic plasmids, was one of four isolates comprising phage type 23. In this study, the large cryptic plasmid pVS1(size >500 b) was transferred from isolate 1076 into the plasmid-free strain of Agrobacterium tumefaciens UBAPF1. This plasmid contained nucleotide sequences homologous to genes for nodulation (nodB, nodC) and nitrogen fixation (nifH, nifD, nifK, nifE). Cosmid clones possessing the nod and nif homologous sequences, which had been selected from a genomic bank of A. tumefaciens UBAPF1 containing pVS1, complemented R. meliloti nodC and nifE mutants, respectively. These results demonstrate that the nodC and nifE homologous sequences are functionally expressed. Three of four isolates comprising phage type 23 possessed a megaplasmid band in agarose gels characteristic of R. meliloti, as well as two cryptic plasmids. The fourth isolate (No. 323) lacked the large cryptic plasmid corresponding to pVS1, but instead showed a band of lesser mobility than that of the megaplasmids. Nevertheless, its restricted genomic DNA retained the nodC and nifE hybridizing fragments characteristic of pVS1, indicating that the cryptic plasmid has undergone DNA rearrangement. Key words: Rhizobium, plasmid, reiteration, genes, rearrangement.

EFFECTS OF SOIL ACIDITY ON RHIZOBIA NUMBERS, NODULATION AND NITROGEN FIXATION BY ALFALFA AND RED CLOVER

1977 ◽  
Vol 57 (2) ◽  
pp. 197-203 ◽  
Author(s):  
W. A. RICE ◽  
D. C. PENNEY ◽  
M. NYBORG
Keyword(s):  
Nitrogen Fixation ◽  
Soil Ph ◽  
Soil Acidity ◽  
Field Experiments ◽  
Rhizobium Meliloti ◽  
Acid Soils ◽  
Red Clover ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration ◽  
Greenhouse Experiments

The effects of soil acidity on nitrogen fixation by alfalfa (Medicago sativa L.) and red clover (Trifolium pratense L.) were investigated in field experiments at 28 locations, and in greenhouse experiments using soils from these locations. The pH of the soils (limed and unlimed) varied from 4.5 to 7.2. Rhizobia populations in the soil, nodulation, and relative forage yields (yield without N/yield with N) were measured in both the field and greenhouse experiments. Rhizobium meliloti numbers, nodulation scores, and relative yields of alfalfa decreased sharply as the pH of the soils decreased below 6.0. For soils with pH 6.0 or greater, there was very little effect of pH on any of the above factors for alfalfa. Soil pH in the range studied had no effect on nodulation scores and relative yields of red clover. However, R. trifolii numbers were reduced when the pH of the soil was less than 4.9. These results demonstrate that hydrogen ion concentration is an important factor limiting alfalfa growth on acid soils of Alberta and northeastern British Columbia, but it is less important for red clover. This supports the continued use of measurements of soil pH, as well as plant-available Al and Mn for predicting crop response to lime.

Historical Changes in Large River Fish Assemblages of the Americas

2005 ◽  
Keyword(s):  
Relative Abundance ◽  
Mississippi River ◽  
Largemouth Bass ◽  
Fish Assemblage ◽  
Fish Assemblages ◽  
Micropterus Salmoides ◽  
Lepomis Macrochirus ◽  
Large River ◽  
Frequency Of Occurrence ◽  
Abundance And Distribution

<em>Abstract.</em>—An investigation of historical fisheries information for pools 4–13 of the upper Mississippi River (UMR) was conducted to 1) determine the pre-1938 relative abundance and distribution of bluegill <em>Lepomis macrochirus </em>and largemouth bass <em>Micropterus salmoides, </em>2) determine the composition and relative abundance of the preimpoundment fish assemblage, and 3) determine if a shift in frequency of occurrence and relative abundance has occurred due to impoundment.

EFFECTS OF SEED INOCULATION METHODS WITH PEAT-BASED RHIZOBIUM MELILOTI ON ALFALFA

1975 ◽  
Vol 55 (2) ◽  
pp. 555-563 ◽  
Author(s):  
H. T. KUNELIUS ◽  
UMESH C. GUPTA
Keyword(s):  
Soil Ph ◽  
Dry Matter ◽  
Rhizobium Meliloti ◽  
Sandy Loam ◽  
Good Growth ◽  
Seed Treatments ◽  
Fine Sandy Loam ◽  
Seed Inoculation ◽  
Medicago Sativa L ◽  
Uniform Manner

Saranac alfalfa (Medicago sativa L.) was grown on Charlottetown fine sandy loam (CHFSL) and Culloden sandy loam (CSL) in the greenhouse and field. Uninoculated, inoculated with peat-based rhizobia (I), inoculated and molybdenum-treated (IMo), inoculated and lime-coated (ILC), and inoculated, lime-coated and Mo-treated (ILCMo) seeds were included. At soil pH 5.0 and 5.3 in the greenhouse, the dry weights of alfalfa ranged from 214 to 727 mg/plant in the four cuttings from the ILC and ILCMo seed. The dry weights of alfalfa from the I and IMo seed were 1.3 to 99.7% of those from the ILCMo seed. Alfalfa from the ILC and ILCMo seed was well nodulated, whereas I and IMo seed resulted in poor nodulation. The 1973 field experiment showed that ILC and ILCMo seed at soil pH 5.5 and 5.6 resulted in alfalfa dry matter (DM) yields of 4,050 and 4,830 kg/ha which were equal to DM yields from plots with a pH of 6.0 and 6.1 seeded with inoculated seed. In plots with pH 5.5 and 5.6, total DM yields from I and IMo seed were 26.0–49.7% lower than those from ILCMo seed. In 1972, seed treatments on CHFSL at pH 5.6 did not influence the DM yields of alfalfa, whereas on CSL at pH 5.2 the crop failed to establish except from ILC and ILCMo seed and in limed plots at pH 5.9. In the first cutting, high N concentrations of alfalfa tissue coincided with good growth and good nodulation. The Mo concentrations of alfalfa tissue were not influenced in a uniform manner by seed treatments and varied from 0.11 to 0.49 ppm in the first cut tissue.

scholarly journals Use of bacteriophage typing to distinguish Propionibacterium acne types I and II

1978 ◽  
Vol 7 (1) ◽  
pp. 84-90
Author(s):  
G F Webster ◽  
C S Cummins
Keyword(s):  
Phage Type ◽  
Bacterial Strains ◽  
Propionibacterium Acne ◽  
Bacteriophage Typing ◽  
Phage Types ◽  
Phage Sensitivity ◽  
Selective Lysis

Strains of serotypes I and II of Propionibacterium were compared for phage sensitivity. The two serotypes could be distinguished by using a typing set consisting of 16 bacteriophages at concentrations that demonstrated selective lysis of serotype I or II bacterial strains. Seven phage types were found; three were composed exclusively of serotype I, and four were exclusively composed of serotype II organisms. Generally, serotype I strains were more sensitive to phage lysis than were serotype II strains. No correlation was found between phage type and site of isolation.

scholarly journals Some correlations between the occurrence frequency of keratinophilic fungi and selected soil properties

2014 ◽  
Vol 37 (1-2) ◽  
pp. 101-116 ◽  
Author(s):  
Teresa Korniłłowicz-Kowalska ◽  
Justyna Bohacz
Keyword(s):  
Soil Properties ◽  
Soil Ph ◽  
Ecological Factors ◽  
Keratinophilic Fungi ◽  
Occurrence Frequency ◽  
Frequency Of Occurrence ◽  
Geophilic Dermatophytes

The results of studies on the correlation between the occurrence frequency of keratinophilic fungi, including geophilic dermatophytes and chrysosporium, and soil properties are presented and discussed in the article. The fraction with 0 &lt; 0.02 mm content and the soil pH were the most significant ecological factors that determined the frequency of occurrence and the distribution of these fungi in the soil

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