Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Microbial nitrogen utilization”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 289 records · Page 16Linked to original sources
PubMed2005

Screening of novel cellulose-degrading bacterium and its application to denitrification of groundwater.

To establish an environmentally friendly groundwater bioremediation process using a cellulose carrier combined with cellulose-utilizing, denitrifying microorganisms, a novel psychrophilic bacterium, designated CL-5, which can degrade a commercial-based cellulose carrier as the sole carbon source, was screened. Since the denitrification capability of CL-5 is low, complex microbial systems were constructed together with other denitrifying bacteria designated NR-1 and NR-2 that were also isolated from soil. The nitrate-reducing activities of mixed cultures were much higher than those of the pure cultures of CL-5, NR-1 and NR-2. The highest N(2)O and N(2) formation activities were observed in the mixed culture of CL-5+NR-2.

Biodegradation, Environmental↗
PubMed1997

Evaluation of the E test for fluconazole susceptibility testing of Candida albicans isolates from oropharyngeal candidiasis.

The aim of the present study was to evaluate the utility of the E test in determining the antifungal susceptibility of Candida albicans. Reproducibility of the E test was determined for amphotericin B, fluconazole, and itraconazole using three different solid media: RPMI 1640, Casitone, and yeast nitrogen base agar. Minimum inhibitory concentrations (MICs) were comparable (results at +/- 2 dilutions) in 92% of the tests for amphotericin B and in 100% for fluconazole and itraconazole. Determination of MIC endpoints was easiest on Casitone agar. Candida albicans isolates from 23 patients undergoing fluconazole therapy for oropharyngeal candidiasis were tested for fluconazole susceptibility. Good correlation was obtained between the MICs of fluconazole and clinical outcome. Clinical failure was associated with strains for which MICs were > or = 48 micrograms/ml. These results suggest that the E test has potential utility for fluconazole susceptibility testing of clinical yeast isolates.

Amphotericin B↗
PubMedDate not supplied

[Roseinatronobacter thiooxidans Gen. Nov., sp. Nov., a new alkaliphilic aerobic bacteriochlorophyll-alpha-containing bacteria from a soda lake].

Several samples of microbial mat obtained from soda lakes of the Kunkurskaya steppe (Chita oblast) abundantly populated by purple bacteria were screened for the presence of heterotrophic alkaliphiles capable of oxidizing sulfur compounds to sulfate. This capacity was found in only one pigmented strain, ALG 1, isolated on medium with acetate and thiosulfate at pH 10. The strain was found to be a strictly aerobic and obligately heterotrophic alkaliphile. Growth on medium with acetate was possible within a narrow pH range from 8.5 to 10.4. The strain formed a reddish orange carotenoid and bacteriochlorophyll a. Pigments were synthesized only at high concentrations of nitrogen-containing organic compounds (peptone or yeast extract). The production of bacteriochlorophyll a was maximal under microaerobic conditions in darkness. Strain ALG 1 could oxidize sulfide, thiosulfate, sulfite, and elemental sulfur to sulfate. In heterotrophically growing culture (pH 10), thiosulfate was not oxidized until the late logarithmic phase. The sulfur-oxidizing activity was maximal at the most alkaline pH values. The notable increase in the efficiency of organic carbon utilization observed in the presence of thiosulfate suggested that the bacterium was a sulfur-oxidizing lithoheterotroph. The phylogenetic analysis of the 16S rRNA gene showed strain ALG 1 to be a member of the alpha-3 subgroup of proteobacteria and to constitute a distinct branch located between nonsulfur purple bacteria Rhodobacter and Rhodovulum. Based on the unique phenotypic properties and the results of phylogenetic analysis, the alkaliphilic isolate ALG 1 was assigned to a new genus and species Roseinatronobacter thiooxidans with the type strain DSZM-13087.

Alkalies↗
PubMed2005

Enzymatic degradation of nitriles by Klebsiella oxytoca.

Klebsiella oxytoca, isolated from cyanide-containing wastewater, was able to utilize many nitriles as sole source of nitrogen. The major objective of this study was to explore the ability of K. oxytoca to utilize some nitriles and then further evaluate the pathways of transformation of cyanide compounds by K. oxytoca. Results from this study indicate that succinonitrile and valeronitrile were the most optimal sources of nitrogen for the growth of K. oxytoca. The biodegradation of acetonitrile proceeded with the formation of acetamide followed by acetic acid. The production of ammonia was also detected in this biodegradation experiment. Similar results were observed in the propionitrile biodegradation experiments. Collectively, this study suggests that the breakdown of acetonitrile or propionitrile by this bacterium was via a two-step enzymatic hydrolysis with amides as the intermediates and organic acids plus with ammonia as the end products.

Biodegradation, Environmental↗
PubMed1990

Cefotaxime-resistant Nocardia asteroides strains are isolates of the controversial species Nocardia farcinica.

A recent study of Nocardia asteroides revealed that 95% of clinical strains had one of five antibiotic resistance patterns. We found the pattern of resistance to cefotaxime and cefamandole in 19% of 200 clinical N. asteroides isolates. Isolates with this drug resistance pattern were from numerous geographic sources and were associated with significant clinical disease (56% of patients had disseminated infections). Phenotypic studies revealed that these isolates were relatively homogeneous and matched previous descriptions and reference strains of the controversial species N. farcinica. Growth at 45 degrees C, acid production from rhamnose, ability to utilize acetamide as a nitrogen and carbon source, and resistance to tobramycin and cefamandole were features of N. farcinica that could be tested in the clinical laboratory and allowed their distinction from N. asteroides. The serious nature of disease due to N. farcinica and its resistance to the newer cephalosporins suggest a clinical need for laboratory identification of this species. (Current tests used in clinical laboratories do not distinguish N. farcinica from N. asteroides.) This is the first recognition that N. farcinica has a specific drug resistance pattern and confirms the previously described concept that drug resistance patterns of N. asteroides may be associated with specific taxonomic groups.

Cefotaxime↗
PubMed2004

Modified colorimetric assay for susceptibility testing of azole antifungal drugs against Candida species.

We modified a rapid susceptibility assay (RSA) for antifungal susceptibility testing of azoles based upon glucose utilization. This modified RSA method provides quantitative endpoint readings in 6 h. In this study, the modified RSA and the National Committee for Clinical Laboratory Standards M27-A methods were used to determine the MICs of fluconazole and itraconazole for 118 Candida isolates. Yeast nitrogen base containing 0.12 g of glucose per liter was used for the modified RSA method. For fluconazole, agreement among assays within one or two twofold dilutions was 72.9 and 88.1%, respectively; for itraconazole, agreement within one or two twofold dilutions was 82.2 and 89.8%, respectively. These data suggest that the modified RSA method is a reliable and rapid method for azole antifungal susceptibility testing against Candida species.

Antifungal Agents↗
PubMed1995

Development of a microbial community of bacterial and yeast antagonists to control wound-invading postharvest pathogens of fruits.

Two antagonists, the bacterium Pseudomonas syringae and the pink yeast Sporobolomyces roseus, against blue mold (caused by Penicillium expansum) on apple controlled this disease more effectively when combined at approximately equal biomass (50:50 of the same turbidity) than in individual applications. Addition of L-asparagine enhanced the biocontrol effectiveness of P. syringae but decreased that of S. roseus and had no significant effect when the antagonists were combined. Populations of both antagonists increased in apple wounds and were further stimulated by the addition of L-asparagine. The carrying capacity of wounds for P. syringae was not affected by S. roseus. Populations of P. syringae in wounds inoculated individually or in a 50:50 mixture with S. roseus reached the same level after 3 days at 22 degrees C. However, populations of S. roseus recovered after applications of the mixture were consistently lower than those recovered after individual applications. Similar effects were observed in in vitro tests in which populations of S. roseus grown in mixtures with P. syringae were consistently lower than those grown alone, while the populations of P. syringae were not affected by the presence of S. roseus. A total of 36 carbon and 35 nitrogen compounds were tested for utilization by both antagonists. Fourteen nitrogenous compounds were utilized by both P. syringae and S. roseus, and an additional nine compounds were utilized by P. syringae. S. roseus and P. syringae utilized 17 and 13 carbon sources, respectively; 9 sources were common to both antagonists. Populations of these antagonists in apple wounds appear to form a relatively stable community dominated by P. syringae.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomass↗
PubMed2001

Anaerobic degradation and dehalogenation of chlorosalicylates and salicylate under four reducing conditions.

The anaerobic biodegradability and transformation of the mono-and dichlorinated salicylates (2-hydroxybenzoates) was examined under denitrifying, Fe (III) reducing, sulfate reducing and methanogenic conditions. 3,6-Dichlorosalicylate and 6-chlorosalicylate are anaerobic microbial metabolites of dicamba, a widely used herbicide. Anaerobic microcosms were established with dicamba treated soil from Wyoming, and golf course drainage stream sediments from New Jersey, which were each spiked with salicylate, 3,6-dichlorosalicylate or one of the four monochlorosalicylate isomers. Salicylate was degraded under denitrifying, sulfidogenic and methanogenic conditions. In methanogenic enrichments 5-chlorosalicylate and 3-chlorosalicylate were reductively dehalogenated to salicylate which was then utilized. Dehalogenation of monochlorinated salicylates to salicylate was also observed in denitrifying chlorosalicylate degrading cultures. The study revealed that the position of the chlorine substituent as well as the predominant electron accepting process affect the rate and extent of chlorosalicylate degradation in anoxic environments.

Anaerobiosis↗
PubMed1999

Growth of Azospirillum irakense KBC1 on the aryl beta-glucoside salicin requires either salA or salB.

The rhizosphere nitrogen-fixing bacterium Azospirillum irakense KBC1 is able to grow on pectin and beta-glucosides such as cellobiose, arbutin, and salicin. Two adjacent genes, salA and salB, conferring beta-glucosidase activity to Escherichia coli, have been identified in a cosmid library of A. irakense DNA. The SalA and SalB enzymes preferentially hydrolyzed aryl beta-glucosides. A Delta(salA-salB) A. irakense mutant was not able to grow on salicin but could still utilize arbutin, cellobiose, and glucose for growth. This mutant could be complemented by either salA or salB, suggesting functional redundancy of these genes in salicin utilization. In contrast to this functional homology, the SalA and SalB proteins, members of family 3 of the glycosyl hydrolases, show a low degree of amino acid similarity. Unlike SalA, the SalB protein exhibits an atypical truncated C-terminal region. We propose that SalA and SalB are representatives of the AB and AB' subfamilies, respectively, in glycosyl hydrolase family 3. This is the first genetic implication of this beta-glucosidase family in the utilization of beta-glucosides for microbial growth.

Amino Acid Sequence↗
PubMed1975

Morphology and physiology of Spirochaeta aurantia strains isolated from aquatic habitats.

1. Seven strains of Spirochaeta aurantia were isolated from pond and swamp water by means of a selective technique which utilized the ability of these organisms to move through bacterial filters and to diffuse through agar media. Although most of the isolations were accomplished when enrichment media low in carbohydrates were used, all seven strains were found to be exclusively saccharolytic. 2. The isolates could be divided into two groups on the basis of cell morphology: a loosely coiled group, and a tightly coiled group with markedly smaller wave length and wave apmlitude. Spirochetes of the latter group possessed a slightly lower GC content in their DNA. The isolates were facultative anaerobes, synthesized carotenoid pigments which conferred an orange color to aerobic colonies, and utilized a variety of carbohydrates--but not amino acids--as energy sources. Exogenous thiamine was required by six isolates tested, riboflavin by four, and biotin by one. The major products of glucose fermentation were acetate, ethanol, CO2 and H2. Growth of the isolates was inhibited by a variety of antibiotics. Determinations of GC contents of DNA showed that strains of S. aurantia are phylogenetically distant from spirochetes classified in the genera Treponema and Leptospira. 3. S. aurantia populations inoculated in the center of agar medium plates migrated in the form of growth rings toward the periphery of the plates. The rate of migration of glucose-utilizing rings was greatest at low glucose concentrations (e.g., 0.02 g/100 ml). It was concluded that migration of cells present in these rings was mainly due to a chemotactic response to glucose which served both as the attractant and the substrate. Chemotaxis of S. aurantia toward glucose may be used as a selective factor in isolating this bacterium from natural environments. 4. The subspecific epithet stricta is proposed to recognize, taxonomically, the tightly coiled strains of S. aurantia.

Aerobiosis↗
PubMed1993

Recombinational inactivation of the gene encoding nitrate reductase in Aspergillus parasiticus.

Functional disruption of the gene encoding nitrate reductase (niaD) in Aspergillus parasiticus was conducted by two strategies, one-step gene replacement and the integrative disruption. Plasmid pPN-1, in which an internal DNA fragment of the niaD gene was replaced by a functional gene encoding orotidine monophosphate decarboxylase (pyrG), was constructed. Plasmid pPN-1 was introduced in linear form into A. parasiticus CS10 (ver-1 wh-1 pyrG) by transformation. Approximately 25% of the uridine prototrophic transformants (pyrG+) were chlorate resistant (Chlr), demonstrating their inability to utilize nitrate as a sole nitrogen source. The genetic block in nitrate utilization was confirmed to occur in the niaD gene by the absence of growth of the A. parasiticus CS10 transformants on medium containing nitrate as the sole nitrogen source and the ability to grow on several alternative nitrogen sources. Southern hybridization analysis of Chlr transformants demonstrated that the resident niaD locus was replaced by the nonfunctional allele in pPN-1. To generate an integrative disruption vector (pSKPYRG), an internal fragment of the niaD gene was subcloned into a plasmid containing the pyrG gene as a selectable marker. Circular pSKPYRG was transformed into A. parasiticus CS10. Chlr pyrG+ transformants were screened for nitrate utilization and by Southern hybridization analysis. Integrative disruption of the genomic niaD gene occurred in less than 2% of the transformants. Three gene replacement disruption transformants and two integrative disruption transformants were tested for mitotic stability after growth under nonselective conditions. All five transformants were found to stably retain the Chlr phenotype after growth on nonselective medium.(ABSTRACT TRUNCATED AT 250 WORDS)

Aflatoxins↗
PubMed2005

Effects of selected pharmaceuticals on riverine biofilm communities.

Although pharmaceutical and therapeutic products are widely found in the natural environment, there is limited understanding of their ecological effects. Here we used rotating annular bioreactors to assess the impact of 10 microg.L(-1) of the selected pharmaceuticals ibuprofen, carbamazepine, furosemide, and caffeine on riverine biofilms. After 8 weeks of development, community structure was assessed using in situ microscopic analyses, fluor-conjugated lectin binding, standard plate counts, fluorescent in situ hybridization, carbon utilization spectra, and stable carbon isotope analyses. The biofilm communities varied markedly in architecture although only caffeine treated biofilms were significantly thicker. Cyanobacteria were suppressed by all 4 compounds, whereas the nitrogen containing caffeine, furosemide, and carbamazepine increased algal biomass. Ibuprofen and carbamazepine reduced bacterial biomass, while caffeine and furosemide increased it. Exopolymer content and composition of the biofilms was also influenced. Significant positive and negative effects were observed in carbon utilization spectra. In situ hybridization analyses indicated all treatments significantly decreased the gamma-proteobacterial populations and increased beta-proteobacteria. Ibuprofen in particular increased the alpha-proteobacteria, beta-proteobacteria, cytophaga-flavobacteria, and SRB385 probe positive populations. Caffeine and carbamazepine additions resulted in significant increases in the high GC354c and low GC69a probe positive cells. Live-dead analyses of the biofilms indicated that all treatments influenced the ratio of live-to-dead cells with controls having a ratio of 2.4, carbamazepine and ibuprofen being 3.2 and 3.5, respectively, and furosemide and caffeine being 1.9 and 1.7, respectively. Stable isotope analyses of the biofilms indicated delta 13C values shifted to more negative values relative to control biofilms. This shift may be consistent with proportional loss of cyanobacteria and relative increase in algal biomass rather than incorporation of pharmaceutical carbon into microbial biofilm. Thus, at 10 microg.L(-1) levels pharmaceuticals exhibit both nutrient-like and toxic effects on riverine microbial communities.

Bacteria↗
PubMed2004

Microscale and molecular assessment of impacts of nickel, nutrients, and oxygen level on structure and function of river biofilm communities.

Studies were carried out to assess the influence of nutrients, dissolved oxygen (DO) concentration, and nickel (Ni) on river biofilm development, structure, function, and community composition. Biofilms were cultivated in rotating annular reactors with river water at a DO concentration of 0.5 or 7.5 mg liter(-1), with or without a combination of carbon, nitrogen, and phosphorus (CNP) and with or without Ni at 0.5 mg liter(-1). The effects of Ni were apparent in the elimination of cyanobacterial populations and reduced photosynthetic biomass in the biofilm. Application of lectin-binding analyses indicated changes in exopolymer abundance and a shift in the glycoconjugate makeup of the biofilms, as well as in the response to all treatments. Application of the fluorescent live-dead staining (BacLight Live-Dead staining kit; Molecular Probes, Eugene, Oreg.) indicated an increase in the ratio of live to dead cells under low-oxygen conditions. Nickel treatments had 50 to 75% fewer 'live' cells than their corresponding controls. Nickel at 0.5 mg liter(-1) corresponding to the industrial release rate concentration for nickel resulted in reductions in carbon utilization spectra relative to control and CNP treatments without nickel. In these cases, the presence of nickel eliminated the positive influence of nutrients on the biofilm. Other culture-dependent analyses (plate counts and most probable number) revealed no significant treatment effect on the biofilm communities. In the presence of CNP and at both DO levels, Ni negatively affected denitrification but had no effect on hexadecane mineralization or sulfate reduction. Analysis of total community DNA indicated abundant eubacterial 16S ribosomal DNA (rDNA), whereas Archaea were not detected. Amplification of the alkB gene indicated a positive effect of CNP and a negative effect of Ni. The nirS gene was not detected in samples treated with Ni at 0.5 mg liter(-1), indicating a negative effect on specific populations of bacteria, such as denitrifiers, resulting in a reduction in diversity. Denaturing gradient gel electrophoresis revealed that CNP had a beneficial impact on biofilm bacterial diversity at high DO concentrations, but none at low DO concentrations, and that the negative effect of Ni on diversity was similar at both DO concentrations. Notably, Ni resulted in the appearance of unique bands in 16S rDNA from Ni, DO, and CNP treatments. Sequencing results confirmed that the bands belonged to bacteria originating from freshwater and marine environments or from agricultural soils and industrial effluents. The observations indicate that significant interactions occur between Ni, oxygen, and nutrients and that Ni at 0.5 mg liter(-1) may have significant impacts on river microbial community diversity and function.

Biofilms↗
PubMed1985

Precision and sensitivity of the measurement of 15N enrichment in D-alanine from bacterial cell walls using positive/negative ion mass spectrometry.

Sensitive detection of cellular components from specific groups of microbes can be utilized as 'signatures' in the examination of microbial consortia from soils, sediments or biofilms. Utilizing capillary gas chromatography/mass spectrometry and stereospecific derivatizing agents, D-alanine, a component localized in the prokaryotic (bacterial) cell wall, can be detected reproducibly. Enrichments of D-[15N]alanine determined in E. coli grown with [15N]ammonia can be determined with precision at 1.0 atom%. Chemical ionization with methane gas and the detection of negative ions (M - HF)- and (M - F or M + H - HF)- formed from the heptafluorobutyryl D-2 butanol ester of D-alanine allowed as little as 8 pg (90 fmol) to be detected reproducibly. This method can be utilized to define the metabolic activity in terms of 15N incorporation at the level of 10(3)-10(4) cells, as a function of the 15N-14N ratio.

Alanine↗
PubMed1998

Physiology of organic nitrogen acquisition by ectomycorrhizal fungi and ectomycorrhizas.

Ectomycorrhizal fungi are symbiotically associated microorganisms which ecological importance has been repeatedly demonstrated. There has been a considerable amount of research aimed at assessing the ability of ectomycorrhizal fungi and ectomycorrhizas to utilize organic nitrogen sources. The fate of soil proteins, peptides and amino acids has been studied from a number of perspectives. Exocellular hydrolytic enzymes have been detected and characterized in a number of ectomycorrhizal and ericoid fungi. Studies on amino acid transport through the plasma membrane have demonstrated the ability of ectomycorrhizal fungi to take up the products of proteolytic activities. Investigations on intracellular metabolism of amino acids have allowed the identification of the metabolic pathways involved. Possible intracellular compartmentation of amino acids will be examined by immunocytochemistry. Further translocation of amino acids in symbiotic tissues has been established by experiments using isotopic tracers, although the exact nature of the nitrogenous compounds transferred at the symbiotic interface remained unclear. One of the main future challenges in the physiology of organic nitrogen acquisition is to determine the nature, the regulation and the location of N-compound transporters at the soil-fungus and fungus-plant interfaces. The molecular approach which is just emerging in this particular research area will greatly improve our knowledge. Future research should also address the extent of competition between different ectomycorrhizal species and between different microbial populations for organic nitrogen.

Amino Acids↗
PubMed2001

Impact of heating-degree-day accumulation during bermudagrass hay storage on nutrient utilization by lambs.

Spontaneous heating in stored alfalfa (Medicago sativa) has reduced forage quality and DM and N digestibility through microbial respiration and Maillard polymer formation. The impact of heating-degree-day (HDD) accumulation in stored bermudagrass (Cynodon dactylon [L.] Pers.) was evaluated for its effect on nutrient utilization by lambs. Twenty Rambouillet wether lambs (53.1 +/- 0.74 kg) were used in a completely randomized total collection experiment. The hays selected for this study had previously undergone spontaneous heating, producing either 5, 119, 201, 273, or 401 HDD (> 35 degrees C) during a 60-d storage period. Lambs were offered diets of these hays at 1.5% of BW. Dry matter intake did not differ (P = 0.59) among hays. Linear relationships were detected between HDD and apparent digestibilities of DM (y = 59.1 - 0.016x; P < 0.01; R2 = 0.37), OM (y = 59.3 - 0.017x; P < 0.01; R2 = 0.43), NDF (y = 66.4 - 0.012x; P = 0.01; R2 = 0.30), and hemicellulose (y = 74.0 - 0.012x; P = 0.02; R2 = 0.27). Similarly, significant regressions were observed for fecal N excretion (g/d; y = 4.70 + 0.004x; P < 0.01; R2 = 0.68), apparent N absorbed (g/d; y = 7.4 - 0.005x; P < 0.01; R2 = 0.50), apparent N absorption (%; y = 61.2 - 0.038x; P < 0.01; R2 = 0.71), apparent neutral detergent insoluble nitrogen digestibility (%; y = 85.8 - 0.026x; P = 0.01; R2 = 0.73), and apparent acid detergent insoluble nitrogen digestibility (%; y = 1.5 + 0.101x; P < 0.01; R2 = 0.62). Therefore, spontaneous heating during the storage of bermudagrass hay has a negative effect on dry matter and fiber digestion and nitrogen absorption by lambs.

Animal Feed↗
PubMed1995

Influence of processing supplemental alfalfa on intake and digestion of dormant bluestem-range forage by steers.

Four ruminally and duodenally fistulated, 2-yr-old Angus x Hereford steers (average initial BW = 370 kg) were used to evaluate the effect of method of processing supplemental alfalfa on intake and digestion of dormant bluestem-range forage (2.8% CP, 78% NDF). Treatments (4 x 4 Latin square) were 1) control, no supplement; 2) ground and pelleted alfalfa hay (PELLET; 21% CP, 37% NDF); 3) ground and pelleted dehydrated alfalfa (DEHY; 21% CP, 44% NDF); and 4) longstem alfalfa hay (HAY; 20% CP, 37% NDF). All supplements were from a single cutting of alfalfa and fed at .5% BW (as-fed basis). Supplementing steers with alfalfa increased (P < or = .07) bluestem forage OM intake (FOMI); total OM intake (TOMI); true ruminal OM digestibility; total tract OM digestibility (TTOMD); total N, microbial N, and nonammonia-nonmicrobial N (NANM) flows to the duodenum; ruminal OM and fluid fill; fluid dilution rates; dietary DE concentration; and ruminal total VFA and NH3 N concentrations. Because of the enhanced FOMI and TOMI associated with alfalfa supplementation and the concomitant improvement in TTOMD, digestible OM intake (DOMI) also increased (P < .01) when supplemental alfalfa was fed. Method of processing alfalfa had little impact on forage utilization, except FOMI (P = .11), TOMI (P = .10), and ruminal OM fill (P = .09) tended to be greater when supplemental alfalfa pellets were dehydrated. Similarly, processing method tended to alter the molar proportions of some minor VFA. In conclusion, alfalfa supplementation exerted a dramatic impact on utilization of low-quality forage.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed2004

Response of saprotrophic microfungi degrading the fulvic fraction of soil organic matter to different N fertilization intensities, different plant species cover and elevated atmospheric CO2 concentration.

The response of the cenosis composition of soil saprotrophic microfungi able to utilize the fulvic fraction of soil organic matter to increased concentration of atmospheric carbon dioxide, plant species cover quality and different levels of nitrogen fertilization was determined under field conditions in a free-air carbon dioxide enrichment experiment. Twenty-nine species of microfungi were isolated from the tested soil. The effects of CO2 enrichment and plant species cover were not significant. Nitrogen fertilization was identified as the only significant factor inducing changes in the abundance of soil microorganisms. This was reflected in a relatively low value of quantitative Sørensen similarity index on comparing fertilized and unfertilized treatments and in 2-way ANOVA of total CFU counts. Some differences were observed in species diversity between the two variants of all treatments. No association between microfungi and the factors under study was found by using the Monte Carlo Permutation test in redundancy analysis.

Base Sequence↗