scholarly journals Enumeration and Inoculation of Nitrifying Bacteria in Soilless Potting Media

1997 ◽  
Vol 122 (5) ◽  
pp. 709-714 ◽  
Author(s):  
Harvey J. Lang ◽  
George C. Elliott
Keyword(s):  
Counting Efficiency ◽  
Nitrifying Bacteria ◽  
Most Probable Number ◽  
Probable Number ◽  
Potting Medium ◽  
Pure Cultures ◽  
Potting Media ◽  
Nitrobacter Agilis ◽  
Inoculum Volume ◽  
Rate Limiting

Autotrophic nitrifying organisms were enumerated in soilless potting media using the most probable number (MPN) technique. Populations of NH4+ and NO2- oxidizing organisms varied widely between two soilless media—Metro-Mix 220 and 350. Estimates for NH4+ oxidizing organisms ranged from 0.7 to 7.8 × 105 organisms/cm3, while NO2- oxidizers ranged from 1.3 to 9.5 × 105 organisms/cm3. Population numbers were similar to those typically reported in soils. There was a significant effect of medium type, NH4+ N : NO3- N fertilizer ratio, and planting on MPN counts of both groups of organisms, with significant interaction between several of the factors. Estimates of NH4+ oxidizers were not linearly correlated with NH4+ oxidizing activity, implying low counting efficiency, heterotrophic nitrification, or rate-limiting substrate NH4+ level. In a separate study, a soilless potting medium was inoculated with pure cultures of either Nitrosomonas europaea or Nitrobacter agilis. Rates of NH4+ and NO2- oxidation increased, respectively, as inoculum volume increased. Inoculation with nitrifying bacteria may help in the overall management of N in the rhizosphere and be feasible alternatives for the prevention of either NH4+ or NO2- phytotoxicity with fertilizers containing urea or NH4+.

scholarly journals The Influence of Mineral Fertilizer Combined With a Nitrification Inhibitor on Microbial Populations and Activities in Calcareous Uzbekistanian Soil Under Cotton Cultivation

2001 ◽  
Vol 1 ◽  
pp. 108-113 ◽  
Author(s):  
Dilfuza Egamberdiyeva ◽  
Muhiddin Mamiev ◽  
Svetlana K. Poberejskaya
Keyword(s):  
Nitrification Inhibitor ◽  
Mineral Fertilizer ◽  
Denitrifying Bacteria ◽  
Nitrifying Bacteria ◽  
Most Probable Number ◽  
Nitrification Rate ◽  
Nitrification Inhibitors ◽  
Probable Number ◽  
Soil Microbial ◽  
Soil Microbial Population

Application of fertilizers combined with nitrification inhibitors affects soil microbial biomass and activity. The objective of this research was to determine the effects of fertilizer application combined with the nitrification inhibitor potassium oxalate (PO) on soil microbial population and activities in nitrogen-poor soil under cotton cultivation in Uzbekistan. Fertilizer treatments were N as urea, P as ammophos, and K as potassium chloride. The nitrification inhibitor PO was added to urea and ammophos at the rate of 2%. Three treatments—N200P140K60(T1), N200P140 POK60(T2), and N200P140 POK60(T3) mg kg-1soil—were applied for this study. The control (C) was without fertilizer and PO. The populations of oligotrophic bacteria, ammonifying bacteria, nitrifying bacteria, denitrifying bacteria, mineral assimilating bacteria, oligonitrophilic bacteria, and bacteria group Azotobacter were determined by the most probable number method. The treatments T2 and T3 increased the number of oligonitrophilic bacteria and utilization mineral forms of nitrogen on the background of reducing number of ammonifying bacteria. T2 and T3 also decreased the number of nitrifying bacteria, denitrifying bacteria, and net nitrification. In conclusion, our experiments showed that PO combined with mineral fertilizer is one of the most promising compounds for inhibiting nitrification rate, which was reflected in the increased availability and efficiency of fertilizer nitrogen to the cotton plants. PO combined with mineral fertilizer has no negative effects on nitrogen-fixing bacteria Azotobacter and oligo-nitrophilic bacteria.

Selective enumeration of aromatic and aliphatic hydrocarbon degrading bacteria by a most-probable-number procedure

1996 ◽  
Vol 42 (3) ◽  
pp. 252-258 ◽  
Author(s):  
Brian A. Wrenn ◽  
Albert D. Venosa
Keyword(s):  
Polycyclic Aromatic Hydrocarbon ◽  
Aromatic Hydrocarbon ◽  
Oxidation Products ◽  
Most Probable Number ◽  
Probable Number ◽  
Microtiter Plates ◽  
Degrading Bacteria ◽  
Polycyclic Aromatic ◽  
Pure Cultures ◽  
Plate Counts

A most-probable-number (MPN) procedure was developed to separately enumerate aliphatic and aromatic hydrocarbon degrading bacteria, because most of the currently available methods are unable to distinguish between these two groups. Separate 96-well microtiter plates are used to estimate the sizes of these two populations. The alkane-degrader MPN method uses hexadecane as the selective growth substrate and positive wells are detected by reduction of iodonitrotetrazolium violet, which is added after incubation for 2 weeks at 20 °C. Polycyclic aromatic hydrocarbon degraders are grown on a mixture of phenanthrene, anthracene, fluorene, and dibenzothiophene in a second plate. Positive wells turn yellow to greenish-brown from accumulation of the partial oxidation products of the aromatic substrates and they can be scored after a 3-week incubation period. These MPN procedures are accurate and selective. For pure cultures, heterotrophic plate counts on a nonselective medium and the appropriate MPN procedure provide similar estimates of the population density. Bacteria that cannot grow on the selective substrates do not produce false positive responses even when the inoculum density is very high. Thus, this method, which is simple enough for use in the field, provides reliable estimates for the density and composition of hydrocarbon-degrading microbial populations.Key words: most probable number, polycyclic aromatic hydrocarbon, alkane, hydrocarbon, bacteria.

Colony-Forming Unit Enumeration by a Plate-MPN Method

1983 ◽  
Vol 46 (10) ◽  
pp. 836-841 ◽  
Author(s):  
S-T. TAN ◽  
R. B. MAXCY ◽  
W. W. STROUP
Keyword(s):  
Standard Technique ◽  
Most Probable Number ◽  
Plate Method ◽  
Probable Number ◽  
Microbial Counts ◽  
Colony Forming Unit ◽  
Pure Cultures ◽  
Petri Plate ◽  
Mpn Test ◽  
Surface Plate

Concepts of the standard surface plate method and the most probable number method (MPN) were combined to provide a new enumeration technique (plate-MPN). Three discrete 0.01-ml samples of an appropriate decimal dilution were inoculated onto each quadrant of a pre-dried petri plate. The discrete spots from the inoculum were then observed for growth after incubation. Results were interpreted analogous to a 3-tube MPN test using presently available tables. Application of the test to pure cultures and mixed flora provided no evidence to indicate the plate-MPN technique to be any less accurate than the standard technique for microbial counts. The plate-MPN technique was less precise than the standard technique. However, the plate-MPN technique has many advantages over traditional methods.

A Method of Profiling Microbial Communities Based on a Most-Probable-Number Assay That Uses BIOLOG Plates and Multiple Sole Carbon Sources

1999 ◽  
Vol 65 (10) ◽  
pp. 4419-4424 ◽  
Author(s):  
Masashi Gamo ◽  
Tadashi Shoji
Keyword(s):  
Bacterial Communities ◽  
Carbon Sources ◽  
High Rate ◽  
Most Probable Number ◽  
Probable Number ◽  
New Approach ◽  
Mixing Ratios ◽  
Color Development ◽  
Assay Procedure ◽  
Pure Cultures

ABSTRACT A new approach to the community-level BIOLOG assay was proposed. This assay, which we call the BIOLOG-MPN assay, is a most-probable-number (MPN) assay that uses BIOLOG plates and multiple sole carbon sources, and the profiles obtained by this assay consist of MPNs estimated for the substrates in the BIOLOG plates. In order to demonstrate the performance of the BIOLOG-MPN assay, it was applied to pure cultures, model bacterial communities that contain two strains in different ratios, and microbial community samples. MPN estimation using BIOLOG plates worked well for the substrates on which utilizers can grow at a sufficiently high rate for color development under the conditions of the assay procedure. Furthermore, the results obtained using model communities showed that the MPNs obtained reflected the mixing ratios of pure cultures in the model communities. The profiles obtained using model communities and community samples were differentiated properly by statistical analyses. The results suggest that the BIOLOG-MPN assay is a promising procedure for obtaining a quantitative picture of the community structure.

Transformation of nitrogen and distribution of nitrogen-related bacteria in a polluted urban stream

2009 ◽  
Vol 60 (6) ◽  
pp. 1597-1605 ◽  
Author(s):  
Y. Jiao ◽  
W. B. Jin ◽  
Q. L. Zhao ◽  
G. D. Zhang ◽  
Y. Yan ◽  
...  
Keyword(s):  
Nitrate Concentration ◽  
Denitrifying Bacteria ◽  
Nitrogen Transformation ◽  
Nitrifying Bacteria ◽  
Urban Stream ◽  
Sediment Surface ◽  
Most Probable Number ◽  
Nitrogen Species ◽  
Probable Number ◽  
Selection Of

Most researchers focused on either nitrogen species or microbial community for polluted urban stream while ignoring the interaction between them and its effect on nitrogen transformation, which restricted the rational selection of an effective and feasible remediation technology. Taking Buji stream in Shenzhen (China) as target stream, the distribution of nitrogen-related bacteria was investigated by most probable number (MPN) besides analysis of nitrogen species etc. The nitrogen-related bacteria in sediment were 102 times richer than those in water. Owing to their faster growth, the MPN of ammonifying bacteria and denitrifying bacteria were 105 and 102 times higher than those of nitrifying bacteria, respectively. The ammonifying bacteria numbers were significantly related to BOD5 in water, while nitrifying bacteria in sediment correlated well with nitrate in water. Thus, nitrification occurred mainly in sediment surface and was limited by low proportion of nitrifying bacteria. The denitrifying bacteria in sediment had good relationship with BOD5 and nitrite and nitrate in water. Low DO and rich organic compounds were beneficial to denitrification but unfavourable to nitrification. Denitrification was restricted by low nitrite and nitrate concentration. These results could be served as a reference for implementing the remediation scheme of nitrogen polluted urban stream.

scholarly journals Rapid and Simple Method for the Most-Probable-Number Estimation of Arsenic-Reducing Bacteria

2001 ◽  
Vol 67 (7) ◽  
pp. 3168-3173 ◽  
Author(s):  
Linping Kuai ◽  
Arjun A. Nair ◽  
Martin F. Polz
Keyword(s):  
Dry Weight ◽  
Environmental Water ◽  
Microtiter Plate ◽  
Most Probable Number ◽  
Precipitation Reaction ◽  
Simple Method ◽  
Probable Number ◽  
Cell Counts ◽  
Pure Cultures ◽  
Reducing Bacteria

ABSTRACT A rapid and simple most-probable-number (MPN) procedure for the enumeration of dissimilatory arsenic-reducing bacteria (DARB) is presented. The method is based on the specific detection of arsenite, the end product of anaerobic arsenate respiration, by a precipitation reaction with sulfide. After 4 weeks of incubation, the medium for the MPN method is acidified to pH 6 and sulfide is added to a final concentration of about 1 mM. The brightly yellow arsenic trisulfide precipitates immediately and can easily be scored at arsenite concentrations as low as 0.05 mM. Abiotic reduction of arsenate upon sulfide addition, which could yield false positives, apparently produces a soluble As-S intermediate, which does not precipitate until about 1 h after sulfide addition. Using the new MPN method, population estimates of pure cultures of DARB were similar to direct cell counts. MPNs of environmental water and sediment samples yielded DARB numbers between 101 and 105 cells per ml or gram (dry weight), respectively. Poisoned and sterilized controls showed that potential abiotic reductants in environmental samples did not interfere with the MPN estimates. A major advantage is that the assay can be easily scaled to a microtiter plate format, enabling analysis of large numbers of samples by use of multichannel pipettors. Overall, the MPN method provides a rapid and simple means for estimating population sizes of DARB, a diverse group of organisms for which no comprehensive molecular markers have been developed yet.

scholarly journals Comparison of Nitrification Rates in Blueberry and Forest Soils

2002 ◽  
Vol 127 (1) ◽  
pp. 136-142 ◽  
Author(s):  
Eric J. Hanson ◽  
Philip A. Throop ◽  
Sedat Serce ◽  
John Ravenscroft ◽  
Eldor A. Paul
Keyword(s):  
Forest Soils ◽  
Vaccinium Corymbosum ◽  
Nitrifying Bacteria ◽  
Most Probable Number ◽  
Acidic Soils ◽  
Probable Number ◽  
Net Nitrification ◽  
Nitrification Potential ◽  
Plastic Bags ◽  
Highbush Blueberries

Highbush blueberries (Vaccinium corymbosum L.) are long lived perennial plants that are grown on acidic soils. The goal of this study was to determine how blueberry cultivation might influence the nitrification capacity of acidic soils by comparing the nitrification potential of blueberry soils to adjacent noncultivated forest soils. The net nitrification potential of blueberry and forest soils was compared by treating soils with 15N enriched (NH4)2SO4, and monitoring nitrate (NO3--N) production during a 34-day incubation period in plastic bags at 18 °C. Net nitrification was also compared by an aerobic slurry method. Autotrophic nitrifiers were quantified by the most probable number method. Nitrate production from labeled ammonium (15NH4+) indicated that nitrification was more rapid in blueberry soils than in forest soils from six of the seven study sites. Slurry nitrification assays provided similar results. Blueberry soils also contained higher numbers of nitrifying bacteria compared to forest soils. Nitrification in forest soils did not appear to be limited by availability of NH4+ substrate. Results suggest that blueberry production practices lead to greater numbers of autotrophic nitrifying bacteria and increased nitrification capacity, possibly resulting from annual application of ammonium containing fertilizers.

Determination of the number of root nodule bacteria in the presence of other organisms

1962 ◽  
Vol 2 (4) ◽  
pp. 5 ◽  
Author(s):  
RA Date ◽  
JM Vincent
Keyword(s):  
Root Nodule ◽  
Plate Count ◽  
Most Probable Number ◽  
Dilution Method ◽  
Nodule Bacteria ◽  
Probable Number ◽  
Root Nodule Bacteria ◽  
Carrier Materials ◽  
Pure Cultures

Use of the plant-dilution method for the determination of the number of root-nodule bacteria in nonsterile carrier materials has been described for both small and large-seeded legume hosts. Calculation of the most probable number of rhizobia is described using values based on the appropriate tables of Fisher and Yates, and approximate factors of error for 95 per cent fiducial limits are stated. It was found that the plant-dilution method was likely to underestimate the number of rhizobia by a factor not greater than 2, when comparisons were made with pure cultures. However for non-sterile peat the tendency was for the plate count to give the lower estimate. This latter effect was no doubt due to the presence of other organisms and therefore the plant-dilution method is to be preferred in such cases.

Effects of Electrolyzed Oxidizing Water Treatment on Reducing Vibrio parahaemolyticus and Vibrio vulnificus in Raw Oysters

2006 ◽  
Vol 69 (8) ◽  
pp. 1829-1834 ◽  
Author(s):  
TINGTING REN ◽  
YI-CHENG SU
Keyword(s):  
Water Treatment ◽  
Vibrio Parahaemolyticus ◽  
Vibrio Vulnificus ◽  
Safety Concern ◽  
Most Probable Number ◽  
Probable Number ◽  
Pacific Oysters ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Pure Cultures

Contamination of Vibrio parahaemolyticus and Vibrio vulnificus in oysters is a food safety concern. This study investigated effects of electrolyzed oxidizing (EO) water treatment on reducing V. parahaemolyticus and V. vulnificus in laboratory-contaminated oysters. EO water exhibited strong antibacterial activity against V. parahaemolyticus and V. vulnificus in pure cultures. Populations of V. parahaemolyticus (8.74 × 107 CFU/ml) and V. vulnificus (8.69 × 107 CFU/ml) decreased quickly in EO water containing 0.5% NaCl to nondetectable levels (>6.6 log reductions) within 15 s. Freshly harvested Pacific oysters were inoculated with a five-strain cocktail of V. parahaemolyticus or V. vulnificus at levels of 104 and 106 most probable number (MPN)/g and treated with EO water (chlorine, 30 ppm; pH 2.82; oxidation-reduction potential, 1131 mV) containing 1% NaCl at room temperature. Reductions of V. parahaemolyticus and V. vulnificus in oysters were determined at 0 (before treatment), 2, 4, 6, and8hof treatment. Holding oysters inoculated with V. parahaemolyticus or V. vulnificus in the EO water containing 1% NaCl for 4 to 6 h resulted in significant (P < 0.05) reductions of V. parahaemolyticus and V. vulnificus by 1.13 and 1.05 log MPN/g, respectively. Extended exposure (>12 h) of oysters in EO water containing high levels of chlorine (>30 ppm) was found to be detrimental to oysters. EO water could be used as a postharvest treatment to reduce Vibrio contamination in oysters. However, treatment should be limited to 4 to6hto avoid death of oysters. Further studies are needed to determine effects of EO water treatment on sensory characteristics of oysters.

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