Studies on mycorrhizal associations in Harvard Forest, Massachusetts

1989 ◽  
Vol 67 (8) ◽  
pp. 2245-2251 ◽  
Author(s):  
Ruhama Berliner ◽  
John G. Torrey
Keyword(s):  
Plant Species ◽  
Most Probable Number ◽  
Probable Number ◽  
Harvard Forest ◽  
Mycorrhizal Associations ◽  
Monotropoid Mycorrhiza ◽  
Vesicular Arbuscular ◽  
Low Diversity ◽  
Different Types ◽  
Good Proportion

An estimate was made of the abundance of different types of mycorrhizal associations in two plant communities of conifers and hardwoods in the Harvard Forest. Lists of plant species, the coverage of their foliage in the canopy and understorey layers, and the types of mycorrhizal associations for 45 species common in these communities are presented. Of the species examined, 91 % were mycorrhizal, representing most of the known major types, viz. ectomycorrhiza, vesicular–arbuscular mycorrhiza (VAM), ericoid, and monotropoid mycorrhiza. Of the 45 species studied, 22% of the species showed ectomycorrhizal, and 71 % VAM associations. A direct spore count was a more reliable method than the most probable number method for determining VAM occurrence in the soil. Spore numbers ranged from 4.4 to 11.8 spores/g oven-dried soil. In conifer stands, ectomycorrhizae were most common, although VAM were also observed in the conifer species. In hardwood stands, VAM were more frequent than in conifer stands, but mycorrhizae were heterogeneous and included a good proportion of the ericoid type. Ectomycorrhizae were more common in communities of low diversity; VAM occurred more frequently in communities of high plant species diversity.

Vesicular – arbuscular mycorrhizae in disturbed and revegetated sites from La Gran Sabana, Venezuela

1992 ◽  
Vol 70 (1) ◽  
pp. 73-79 ◽  
Author(s):  
Gisela Cuenca ◽  
Milagros Lovera
Keyword(s):  
Arbuscular Mycorrhizae ◽  
Plant Cover ◽  
Ground Cover ◽  
Arbuscular Mycorrhizal ◽  
Most Probable Number ◽  
Probable Number ◽  
Organic Layers ◽  
Vesicular Arbuscular Mycorrhizae ◽  
Disturbed Areas ◽  
Vesicular Arbuscular

Savannas growing on stony, old and nutrient-poor soils of southern Venezuela were severely disturbed by removal of the soil organic layers with bulldozers for road building. Introduced species Brachiaria decumbens, Brachiaria humidicola, Pueraria phaseoloides, and Calopogonium sp. were sown. The substrate was fertilized and limed. Plant cover, vesicular – arbuscular mycorrhizae colonization, spore number, and most probable number of propagulels in undisturbed savanna, disturbed nonrevegetated savanna, and six revegetated savannas were assessed. The perturbation reduced the mycorrhizal propagule number in comparison with the undisturbed savanna. In the nonrevegetated areas the mean percent ground cover 2 years after disturbance was low (0.04%). In revegetated areas an increase in mycorrhizal propagule number occurred and the mycorrhizal colonization of the sown species was high. In restored areas there was an increase in species of nonmycotrophic Amaranthaceae. The results support other predictions on the mycorrhizae in successional biomes, because in the extremely nutrient-poor soils studied the colonizing species were mainly mycotrophic. The reclamation program applied in disturbed areas was useful because it has allowed the recovery of vesicular – arbuscular mycorrhizal inoculum and there was an increase in the recolonization of native plants. Key words: disturbance, endomycorrhizae, revegetation, savanna, vesicular – arbuscular mycorrhizae.

scholarly journals Molecular Methods for Assessement the Bacterial Communities from Different Type of Soils in Romania

2011 ◽  
Vol 39 (1) ◽  
pp. 64 ◽  
Author(s):  
Călina Petruţa CORNEA ◽  
Cătălina VOAIDEŞ ◽  
Matilda CIUCA ◽  
Vasilica STAN ◽  
Eugenia GAMENT ◽  
...  
Keyword(s):  
Plant Species ◽  
Host Plants ◽  
Root Nodules ◽  
Indigenous Populations ◽  
Most Probable Number ◽  
Organic Carbon Content ◽  
Bacterial Strains ◽  
Probable Number ◽  
Plate Counts ◽  
Fertilization Level

Rhizobia are soil bacteria that are capable to form nitrogen-fixing symbiosis with leguminous plants. This ability, as well as the diversity of microbial populations in the soil, and in the rhizosphere of host plants and non-host plants is influenced by several factors, including crop management. The aim of this work was the examination of the influence of some factors on indigenous populations of rhizobia in soils under different crop managements. The genetic diversity of rhizobial strains isolated directly from soil (free-living state) or from root nodules of three herbaceous perennial legumes was examined. The study was conducted in the experimental fields located in Moara Domnească area (South of Romania) and in the Brașov County. The characteristics of brown reddish soil were determined (nitrogen content, organic carbon content and pH). Counting of the rhizobia populations was done by most probable number estimation and by viable plate counts. Bacterial strains were isolated directly from soil samples or from root nodules of different plant species (Trifolium repens, T. pratense and Lotus corniculatus). The characterization of rhizobia was performed by DNA fingerprinting (ERIC PCR and BOX PCR) and the bacterial diversity of soils was examined by DGGE technique. The results revealed that the rhizobial diversity was significantly lower in soils under increased fertilization with N. A reduced intraspecific polymorphism was observed in the strains recovered from the same plant species (Trifolium spp.), whatever the origin of the plant (Moara Domnească or Brașov) but clear differences appeared to be related to the origin of nodules (red or white clover) as revealed by DNA fingerprints. However, various amplicon profiles were observed by DGGE when total DNA isolated from soils was examined, the differences being associated with the fertilization level.

Evaluation of the Compact Dry VP Method for Screening Raw Seafood for Total Vibrio parahaemolyticus

2009 ◽  
Vol 72 (1) ◽  
pp. 169-173 ◽  
Author(s):  
HIDEMASA KODAKA ◽  
HAJIME TERAMURA ◽  
SHINGO MIZUOCHI ◽  
MIKAKO SAITO ◽  
HIDEAKI MATSUOKA
Keyword(s):  
Vibrio Parahaemolyticus ◽  
Cold Water ◽  
Correlation Coefficients ◽  
Water Soluble ◽  
Coliform Bacteria ◽  
Most Probable Number ◽  
Probable Number ◽  
Different Types ◽  
Phosphate Buffered Saline ◽  
Vibrio Spp

Compact Dry VP (CDVP) is a ready-to-use method for enumerating Vibrio parahaemolyticus in food. The presterilized plates contain a culture medium comprising peptone, NaCl, bile salts, antibiotics, chromogenic substrates, and polysaccharide gum as a cold water–soluble gelling. After diluting raw seafood samples in a phosphate-buffered saline solution, a 1-ml aliquot was inoculated onto the center of the plate and allowed to diffuse by capillary action. Blue-green colonies forming on the plates were counted after 18 to 20 h of incubation at 35°C. A total of 85 V. parahaemolyticus strains (62 tdh+ strains and 23 tdh− strains) were studied for inclusivity, 81 (95.3 %) of which produced blue-green colonies. When 97 strains (14 strains of Vibrio spp., 33 strains of coliform bacteria, and 50 strains of noncoliform bacteria) were assessed for exclusivity, 10 strains of Vibrio spp. produced non–blue-green colonies, and 87 strains failed to grow. The CDVP and U.S. Food and Drug Administration Bacteriological Analytical Manual (FDA-BAM) methods were compared with the use of four different types of raw seafood that were inoculated with four different V. parahaemolyticus strains. For raw tuna and oysters, the FDA-BAM colony lift method was used, whereas the FDA-BAM most-probable-number method was used for salmon and scallop. The linear correlation coefficients between the CDVP and FDA-BAM methods were 0.99 for fresh raw tuna, 0.95 for fresh raw oysters, 0.95 for frozen raw salmon, and 0.95 for frozen raw scallops. These results suggest that the CDVP method is useful for screening raw seafood for V. parahaemolyticus.

scholarly journals Enhanced Mineralization of [U-14C]2,4-Dichlorophenoxyacetic Acid in Soil from the Rhizosphere of Trifolium pratense

2004 ◽  
Vol 70 (8) ◽  
pp. 4766-4774 ◽  
Author(s):  
Liz J. Shaw ◽  
Richard G. Burns
Keyword(s):  
Plant Species ◽  
Trifolium Pratense ◽  
Rhizosphere Soil ◽  
Most Probable Number ◽  
Dichlorophenoxyacetic Acid ◽  
Polymorphism Analysis ◽  
Alternative Mechanism ◽  
Probable Number ◽  
Enhanced Biodegradation ◽  
2,4 Dichlorophenoxyacetic Acid

ABSTRACT Enhanced biodegradation in the rhizosphere has been reported for many organic xenobiotic compounds, although the mechanisms are not fully understood. The purpose of this study was to discover whether rhizosphere-enhanced biodegradation is due to selective enrichment of degraders through growth on compounds produced by rhizodeposition. We monitored the mineralization of [U-14C]2,4-dichlorophenoxyacetic acid (2,4-D) in rhizosphere soil with no history of herbicide application collected over a period of 0 to 116 days after sowing of Lolium perenne and Trifolium pratense. The relationships between the mineralization kinetics, the number of 2,4-D degraders, and the diversity of genes encoding 2,4-D/α-ketoglutarate dioxygenase (tfdA) were investigated. The rhizosphere effect on [14C]2,4-D mineralization (50 μg g−1) was shown to be plant species and plant age specific. In comparison with nonplanted soil, there were significant (P < 0.05) reductions in the lag phase and enhancements of the maximum mineralization rate for 25- and 60-day T. pratense soil but not for 116-day T. pratense rhizosphere soil or for L. perenne rhizosphere soil of any age. Numbers of 2,4-D degraders in planted and nonplanted soil were low (most probable number, <100 g−1) and were not related to plant species or age. Single-strand conformational polymorphism analysis showed that plant species had no impact on the diversity of α-Proteobacteria tfdA-like genes, although an impact of 2,4-D application was recorded. Our results indicate that enhanced mineralization in T. pratense rhizosphere soil is not due to enrichment of 2,4-D-degrading microorganisms by rhizodeposits. We suggest an alternative mechanism in which one or more components of the rhizodeposits induce the 2,4-D pathway.

ICMSF Methods Studies. XI. Collaborative/Comparative Studies on Determination of Coliforms Using the Most Probable Number Procedure1

1979 ◽  
Vol 42 (8) ◽  
pp. 638-644 ◽  
Author(s):  
J. H. SILLIKER ◽  
D. A. GABIS ◽  
A. MAY
Keyword(s):  
Comparative Studies ◽  
Confidence Limit ◽  
Collaborative Study ◽  
The Other ◽  
Most Probable Number ◽  
Probable Number ◽  
Collaborative Studies ◽  
Different Types ◽  
Confirmatory Tests

Results of two international collaborative studies on the MPN technique for determination of coliforms in foods are reported. Three methods involving use of different presumptive and confirmatory media were compared. Results of one collaborative study conducted among 15 laboratories using eight different types of inoculated foods showed differences among the laboratories as great as 3.3 log units. The greatest difference between confirmatory tests using different media was 0.5 log units. Results of the other collaborative study conducted among five laboratories using three types of naturally contaminated foods showed differences among the laboratories as great as 1.4 log units. The greatest difference between tests using different media was 0.2 log unit. Both studies showed that the 95% confidence limit for a single value reported by a given laboratory was ± 1 log unit or ± 0.45 log unit for a mean of five values. The second study showed that a major source of variation within laboratories was between replicate aliquots. The findings are discussed in terms of their significance with respect to the monitoring of microbiological specifications for food.

Vesicular-arbuscular mycorrhiza in semi-arid pastures of south-west Queensland and their effect on growth responses to phosphorus fertilizers by grasses

1992 ◽  
Vol 43 (5) ◽  
pp. 1143 ◽  
Author(s):  
RD Armstrong ◽  
KR Helyar ◽  
EK Christie
Keyword(s):  
Growth Response ◽  
Grass Species ◽  
Most Probable Number ◽  
Growth Responses ◽  
Differential Growth ◽  
Probable Number ◽  
Vesicular Arbuscular ◽  
Phosphorus Fertilizers ◽  
Native Pasture ◽  
P Fertilizer

Field and controlled environment studies were undertaken to determine the seasonal variation in vesicular-arbuscular mycorrhizal (VAM) propagules under different types of vegetation in the mulga (Acacia aneura) shrublands of south-western Queensland and how inoculation with VAM affects the growth and response to phosphorus fertilizers of several grasses common to this region. A most probable number (MPN) technique was used to estimate the number of viable VAM propagules under mulga shrubland and native pasture. There was a pronounced rise in MPN at a native pasture site from June to November, peaking at 1 propagule/g soil, before declining between November and May to non detectable concentrations. In the mulga shrubland site, MPN remained very low (less than 0.2 propagules/g soil) throughout the study. Pasture species in the field were screened for VAM infection in both winter and summer. Only three of the 14 species sampled were infected with VAM in winter (June) after a long drought. In contrast, 10 of the 14 species sampled in December possessed VAM-infected roots. A pot experiment was conducted to examine the influence of VAM inoculation on growth and the response to phosphate fertilizer of several important pasture grasses in pastures derived from mulga shrublands. The treatments comprised a factorial combination of inoculation or non-inoculation with VAM, four grass species (Aristida armata, Cenchms ciliaris cv. USA, Digitaria ammophilla, and Thyridolepis mitchelliana), and four rates of P fertilizer designed to range over very deficient to non-limiting for each species. All species except D. ammophilla produced growth responses to VAM inoculation. Though C. ciliaris and T. mitchelliana responded to VAM inoculation only in soil unamended with P fertilizer, A. amata showed growth responses across all P rates examined, suggesting some factor other than P was limiting this species. The growth response of the grasses to VAM inoculation was poorly correlated with the percentage of root infected with VAM. D. ammophilla had the highest levels of root infection (32%) despite producing no growth response to VAM. In contrast, T. mitchelliana had less than 2% of the root infected with VAM. All species had thin fibrous roots with long (0.35-0.47 mm), frequent root hairs. The differential growth responses to VAM inoculation of A. armata compared with the other grasses may provide a management strategy to control Aristida ingress into pastures established from mulga shrublands.

Mycorrhizal Associations of Plant-Species in a Semiarid Community

1986 ◽  
Vol 34 (5) ◽  
pp. 585 ◽  
Author(s):  
P Mcgee
Keyword(s):  
Plant Species ◽  
South Australia ◽  
Growing Season ◽  
Arbuscular Mycorrhizas ◽  
Mycorrhizal Associations ◽  
Vesicular Arbuscular ◽  
Ectomycorrhizal Association

Of 93 species in 37 families occurring in a semiarid open mallee community near Murray Bridge, South Australia, 85 species were mycorrhizal. Vesicular-arbuscular mycorrhizas (VAM) were more common than other types of mycorrhizas observed. Genera not previously known to form ectomycorrhizas include Astroloma (Epacridaceae), Comesperma (Polygalaceae), Thysanotus (Asphodelaceae: Liliflorae), Baeckea and Calytrix (Myrtaceae), Dampiera (Goodeniaceae), Podotheca and Toxanthes (Inulae: Asteraceae). Many species were found with both ectomycorrhizas and VAM, with annuals having both VAM and ectomycorrhizas for the whole growing season and perennials usually exhibiting either a predominantly VAM or ectomycorrhizal association. Vesicles were present in plant species not commonly thought of as mycorrhizal hosts.

Inoculation of citrus with root fragments containing chlamydospores of the mycorrhizal fungus Glomus intraradices

1986 ◽  
Vol 64 (8) ◽  
pp. 1739-1744 ◽  
Author(s):  
J. H. Graham ◽  
D. Fardelmann
Keyword(s):  
Arbuscular Mycorrhizae ◽  
Glomus Intraradices ◽  
Mycorrhizal Fungus ◽  
Arbuscular Mycorrhizal ◽  
Most Probable Number ◽  
Probable Number ◽  
Vesicular Arbuscular ◽  
Grass Root ◽  
Colonization Potential ◽  
Potting Media

The vesicular–arbuscular mycorrhizal fungus, Glomus intraradices, was found sporulating in citrus roots in an orchard soil. Dead root fragments of citrus accounted for a high proportion of the propagules in soil as measured by the most probable number technique. Sudan grass root fragments from pot cultures containing 7 and 94 chlamydospores of G. intraradices per milligram dry root had 11 and 184 (most probable number) propagules per milligram dry root, respectively. Inoculum densities of 20–40 mg of root fragments per 100 cm3 of potting media resulted in 100% inoculation success of Carrizo citrange grown from seed. A decrease in root fragment density to as low as 2.5 mg per 100 cm3 of medium reduced inoculation success and root colonization, but did not reduce growth and nutrient uptake by inoculated seedlings. The growth of vesicular–arbuscular mycorrhizal plants in a soilless medium amended with relatively insoluble rock phosphate was less than that of nonmycorrhizal plants fertilized with soluble phosphorus; copper uptake, however, was significantly increased by vesicular–arbuscular mycorrhizae. Root fragments stored up to 1 year under moist conditions did not lose colonization potential, whereas drying reduced colonization potential to near zero after 9 months.

The 'most probable number' method for enumerating infective propagules of vesicular arbuscular mycorrhizal fungi in soil

Soil Research ◽  
1979 ◽  
Vol 17 (3) ◽  
pp. 515 ◽  
Author(s):  
WM Porter
Keyword(s):  
Arbuscular Mycorrhizal Fungi ◽  
Mycorrhizal Fungi ◽  
Large Population ◽  
Arbuscular Mycorrhizal ◽  
Most Probable Number ◽  
Probable Number ◽  
Vesicular Arbuscular ◽  
Field Soils ◽  
Wet Sieving ◽  
Good Agreement

Estimates of the number of infective propagules of vesicular-arbuscular (VA) endophytes in two soils were obtained using a most probable number (MPN) method. These estimates were compared with counts of the number of spores in the same soils obtained using a conventional wet sieving method. In one soil, there was good agreement between the number of coarse endophyte propagules, estimated by the MPN technique, and the number of germinable spores extracted using the wet sieving technique. However, a large population of fine endophyte propagules (more than 230 per 50 g soil) could only be enumerated using the MPN technique. In the second soil, fewer coarse endophyte propagules were found using the wet sieving technique than when using the MPN technique. The MPN technique appears to give a more realistic estimate of the number of infective propagules of VA endophytes in field soils than the conventional method.

scholarly journals Escherichia coli contamination of groundwater in Metro City, Lampung

2021 ◽  
Vol 277 ◽  
pp. 04001
Author(s):  
Qanza Nurul Jannah ◽  
Gita Lestari Putri
Keyword(s):  
Escherichia Coli ◽  
Water Source ◽  
Water Sources ◽  
Most Probable Number ◽  
Probable Number ◽  
E Coli ◽  
Groundwater Samples ◽  
Who Standards ◽  
Different Types ◽  
Very High

Groundwater sources are widely used to supply water for drinking and other domestic purposes in Metro City, Indonesia. The presence of Escherichia coli (E. coli) is an indicator of fecal contamination in the water source. Therefore, this study was conducted to assess the level of E. coli contamination in groundwater at Metro City. The analysis was conducted on 253 households in 5 sub-districts using groundwater samples from different types of wells such as boreholes, protected wells, and unprotected wells. The E. coli concentrations were determined using the Colilert-18 method with IDEXX Quanti-Tray 2000 and the results showed the highest levels of contamination were in unprotected wells. E. coli was detected in 71% of water sources with 36% classified as very high risk or above 100 MPN (Most Probable Number)/100ml based on WHO standards. The findings, showed that the protection of water sources has the ability to reduce the risk of contamination.

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