Search results for "microorganism"

Estimation of the density of the protocatechuate-degrading bacterial community in soil by real-time PCR

2008

Summary The β-ketoadipate pathway is the major route for degradation of aromatic compounds by various soil microorganisms. Protocatechuate 3,4-dioxygenase, a key enzyme of this pathway and which is encoded by pcaGH genes, catalyses the ring cleavage of protocatechuate. Microorganisms harbouring pcaGH genes are widely distributed in the environment but little is known about their relative abundance within the total microflora. Hence, this paper reports the development of a real-time PCR assay to quantify the bacterial pcaH sequence that encodes the β sub-unit of the protocatechuate 3,4-dioxygenase. This real-time PCR assay was linear over seven orders of magnitude with a calculated efficienc…

Influence of Bacteria <i>Pseudomonas fluorescens</i> on the Properties of Latvian Clay

2014

Wide varieties of bacteria are able to produce extracellular polymeric substances (EPS) which are mostly composed of polysaccharides. It is suggested that EPS substances can alter certain clay soil properties due to their ability to adhere to the surface of mineral particles. Most common used microorganisms by the researchers for this purpose are of either genus Bacillus or genus Pseudomonas. In this study growth of bacteria P. fluorescens AM PS11 culture in locally obtained clay is studied for the purpose of establishing their influence on rheological properties of clay. An attempt to evaluate it has been made using FT-IR and XRD. Change in plasticity of clay using Atterberg limits method …

Design of the Biotechnological System for the Cultivation of a Polysaccharide-Producing Microorganism and Metabolites Separation

1970

This paper presents a design of the biotechnological system established for the cultivation of a polysaccharide-producing microorganism and the separation of the polysaccharide together with other metabolites. The strain used is a halophilic archaeon called Haloferax mediterranei (Mironescu et al., 2003). On designing the biotechnological system, some requirements are important: The recipients and the pipes must be resistant to the corrosion action of the cultivation substrate very rich in NaCl (125 to 150 g/l); A command and control system for pH, temperature and substrate and inoculum feeding is necessary; A system for monitoring dissolved oxygen and gases evacuated from the bioreactor (O…

Inorganic Polyphosphate in Eukaryotes: Enzymes, Metabolism and Function

1999

Inorganic polyphosphates (polyP) are linear polymers of orthophosphate (Pi) residues linked by high-energy phosphoanhydride bonds. These polymers are widely distributed in nature, from archaebacteria, eubacteria, fungi, algae, and protozoa to higher plants and animals (for reviews, see Kulaev 1979; Wood and Clark 1988; Kornberg 1994, 1995). PolyP molecules are stable in neutral aqueous solutions, but are hydrolyzed by heat-treatment, and under acidic or alkaline conditions. The chain length of polyP may range from 3 to more than 1000 Pi residues; it can be analyzed on urea/polyacrylamide gels (Clark and Wood 1987; Lorenz et al. 1994a). In contrast to the linear polymer, branched inorganic p…

Shedding light on biogas: a transparent reactor triggers the development of a biofilm dominated by Rhodopseudomonas faecalis that holds potential for…

2019

AbstractConventional anaerobic digesters intended for the production of biogas usually operate in complete darkness. Therefore, little is known about the effect of light on microbial communities operating in anaerobic digesters. In the present work, we have studied through 16S rRNA gene amplicon Nanopore sequencing and shotgun metagenomic sequencing the taxonomic and functional structure of the microbial community forming a biofilm on the inner wall of a lab-scale transparent anaerobic biodigester illuminated with natural sunlight. The biofilm was composed of microorganisms involved in the four metabolic processes needed for biogas production. The biofilm proved surprisingly rich in Rhodops…

Phenazine antibiotics produced by fluorescent pseudomonads contribute to natural soil suppressiveness to Fusarium wilt

2009

Natural disease-suppressive soils provide an untapped resource for the discovery of novel beneficial microorganisms and traits. For most suppressive soils, however, the consortia of microorganisms and mechanisms involved in pathogen control are unknown. To date, soil suppressiveness to Fusarium wilt disease has been ascribed to carbon and iron competition between pathogenic Fusarium oxysporum and resident non-pathogenic F. oxysporum and fluorescent pseudomonads. In this study, the role of bacterial antibiosis in Fusarium wilt suppressiveness was assessed by comparing the densities, diversity and activity of fluorescent Pseudomonas species producing 2,4-diacetylphloroglucinol (DAPG) (phlD+) …

Impact of various factors on the diversity of soil microorganisms in agricultural and forest soils

2014

Elektroniskā versija nesatur pielikumus

Presence of endophytic bacteria in Vitis vinifera leaves as detected by Fluorescence in situ hybridization

2010

Fluorescence in situ hybridization (FISH) in combination with confocal laser scanning microscopy (CLSM) was applied to detect and localize bacterial colonies in leaf tissues of Vitis vinifera. Leaves were cleared to minimize the autofluorescence of plant fragments. The use of fluorescently labeled bacterial probe EUB338 on discolored grapevine leaf disks allowed the estimation of the spatial distribution of different bacterial colonies. In particular, bacterial colonies were found in veins, cells, hairs, intercellular spaces, and in cut edges of leaf disks of both non-Acremonium byssoides-colonized and A. byssoides-colonized leaves of five different cultivars. Furthermore, CLSM confirmed th…

Réponses de la plante et des microorganismes du sol aux changements environnementaux

2015

Functional stability of the nitrate-reducing community in grassland soils towards high nitrate supply

2006

Abstract To study the effects of short-term fluctuation of nitrate concentrations on the nitrate-reducing community, repacked soil cores were amended with 0, 100 and 300 μ g NO 3 - ‐ N g - 1 soil and incubated for 3, 7 and 14 days, respectively. The nitrate reductase activity was determined in a laboratory-based enzyme assay. In parallel, the community structure of nitrate-reducing microorganisms was characterised by RFLP-PCR using the functional gene narG , which encodes the catalytic site of the membrane-bound nitrate reductase. The community structure remained constant over the experimental period indicating that this functional community is characterised by a high resistance towards flu…