Biofilm dynamics studied with microsensors and molecular techniques

1998 ◽  
Vol 37 (4-5) ◽  
pp. 125-129 ◽  
Author(s):  
Cecilia M. Santegoeds ◽  
Gerard Muyzer ◽  
Dirk de Beer

Here we present preliminary data on the development of a biofilm from a wastewater treatment plant studied with microsensors and molecular techniques. The development during biofilm growth of oxygen, sulfide and pH profiles was measured with microsensors. Anoxic zones developed within one week and further increased during the following weeks. However, sulfide production was delayed and was first detected in a six-week-old biofilm. With denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S rRNA gene fragments the sequence of the bacterial community was followed showing an increasing complexity of the biofilm community during development. In a mature biofilm the influence of nitrate on sulfide production was studied by measuring oxygen, sulfide, pH, nitrite and nitrate profiles with microsensors. Sulfide production was detected deeper in the biofilm and in lower concentrations, when nitrate was added to the medium. The DGGE pattern of the mature biofilm showed both differences and similarities with the DGGE pattern of the 12-week-old biofilm. In particular the RNA pattern changed when nitrate was added to the medium, indicating a change in activity of certain strains.

2001 ◽  
Vol 67 (7) ◽  
pp. 2942-2951 ◽  
Author(s):  
Beatriz Dı́ez ◽  
Carlos Pedr�s-Ali� ◽  
Terence L. Marsh ◽  
Ramon Massana

ABSTRACT We used denaturing gradient gel electrophoresis (DGGE) to study the diversity of picoeukaryotes in natural marine assemblages. Two eukaryote-specific primer sets targeting different regions of the 18S rRNA gene were tested. Both primer sets gave a single band when used with algal cultures and complex fingerprints when used with natural assemblages. The reproducibility of the fingerprints was estimated by quantifying the intensities of the same bands obtained in independent PCR and DGGE analyses, and the standard error of these estimates was less than 2% on average. DGGE fingerprints were then used to compare the picoeukaryotic diversity in samples obtained at different depths and on different dates from a station in the southwest Mediterranean Sea. Both primer sets revealed significant differences along the vertical profile, whereas temporal differences at the same depths were less marked. The phylogenetic composition of picoeukaryotes from one surface sample was investigated by excising and sequencing DGGE bands. The results were compared with an analysis of a clone library and a terminal restriction fragment length polymorphism fingerprint obtained from the same sample. The three PCR-based methods, performed with three different primer sets, revealed very similar assemblage compositions; the same main phylogenetic groups were present at similar relative levels. Thus, the prasinophyte group appeared to be the most abundant group in the surface Mediterranean samples as determined by our molecular analyses. DGGE bands corresponding to prasinophytes were always found in surface samples but were not present in deep samples. Other groups detected were prymnesiophytes, novel stramenopiles (distantly related to hyphochytrids or labyrinthulids), cryptophytes, dinophytes, and pelagophytes. In conclusion, the DGGE method described here provided a reasonably detailed view of marine picoeukaryotic assemblages and allowed tentative phylogenetic identification of the dominant members.


2003 ◽  
Vol 69 (11) ◽  
pp. 6380-6385 ◽  
Author(s):  
R. Temmerman ◽  
L. Masco ◽  
T. Vanhoutte ◽  
G. Huys ◽  
J. Swings

ABSTRACT The taxonomic characterization of a bacterial community is difficult to combine with the monitoring of its temporal changes. None of the currently available identification techniques are able to visualize a “complete” community, whereas techniques designed for analyzing bacterial ecosystems generally display limited or labor-intensive identification potential. This paper describes the optimization and validation of a nested-PCR-denaturing gradient gel electrophoresis (DGGE) approach for the species-specific analysis of bifidobacterial communities from any ecosystem. The method comprises a Bifidobacterium-specific PCR step, followed by purification of the amplicons that serve as template DNA in a second PCR step that amplifies the V3 and V6-V8 regions of the 16S rRNA gene. A mix of both amplicons is analyzed on a DGGE gel, after which the band positions are compared with a previously constructed database of reference strains. The method was validated through the analysis of four artificial mixtures, mimicking the possible bifidobacterial microbiota of the human and chicken intestine, a rumen, and the environment, and of two fecal samples. Except for the species Bifidobacterium coryneforme and B. indicum, all currently known bifidobacteria originating from various ecosystems can be identified in a highly reproducible manner. Because no further cloning and sequencing of the DGGE bands is necessary, this nested-PCR-DGGE technique can be completed within a 24-h span, allowing the species-specific monitoring of temporal changes in the bifidobacterial community.


Author(s):  
Marcial-Quino J. ◽  
Garcia-Ocón B. ◽  
Mendoza-Espinoza J.A. ◽  
Gómez-Manzo S. ◽  
Sierra-Palacios E

Currently it is well known that yeasts play an essential role in the production of different beverages. In this paper, were identified some of the yeasts involved in the fermentation process of the pulque, a Mexican traditional beverage. Samples were collected from different regions of Mexico and yeasts were detected directly from samples without cultivation. Identifying the yeasts was obtained using amplification the D1/D2 domain of the 26S rRNA gene and Denaturing Gradient Gel Electrophoresis (DGGE). The results of DGGE showed different profiles of bands in each of the analyzed samples, indicating the presence of several species of yeast, which was also confirmed by sequencing of the bands corresponding to the domain D1/D2, succeeded in identifying five species of yeasts. The results obtained in this work demonstrated that the technique used for identification of yeasts of pulque was efficient. Besides, the optimization of this method could also allow rapid identification of yeasts and help understand the role of these in the fermentation process of this beverage, as well as the isolation of strains of interest for biotechnological purposes such as production of ethanol or metabolites with nutraceutical activity.


2001 ◽  
Vol 67 (11) ◽  
pp. 5113-5121 ◽  
Author(s):  
Luca Cocolin ◽  
Marisa Manzano ◽  
Carlo Cantoni ◽  
Giuseppe Comi

ABSTRACT In this study, a PCR-denaturing gradient gel electrophoresis (DGGE) protocol was used to monitor the dynamic changes in the microbial population during ripening of natural fermented sausages. The method was first optimized by using control strains from international collections, and a natural sausage fermentation was studied by PCR-DGGE and traditional methods. Total microbial DNA and RNA were extracted directly from the sausages and subjected to PCR and reverse transcription-PCR, and the amplicons obtained were analyzed by DGGE. Lactic acid bacteria (LAB) were present together with other organisms, mainly members of the family Micrococcaceae and meat contaminants, such as Brochothrix thermosphacta andEnterococcus sp., during the first 3 days of fermentation. After 3 days, LAB represented the main population, which was responsible for the acidification and proteolysis that determined the characteristic organoleptic profile of the Friuli Venezia Giulia fermented sausages. The PCR-DGGE protocol for studying sausage fermentation proved to be a good tool for monitoring the process in real time, and it makes technological adjustments possible when they are required.


2001 ◽  
Vol 43 (1) ◽  
pp. 77-82 ◽  
Author(s):  
O.-C. Chan ◽  
W.-T. Liu ◽  
H. H. Fang

The microbial community structure of granular sludge from an upflow anaerobic sludge blanket (UASB) reactor treating brewery effluent was studied by denaturing gradient gel electrophoresis (DGGE). Twelve major bands were observed in the DGGE fingerprint for the Bacteria domain and four bands for the Archaea domain. Of the bacterial bands observed, six were successfully purified and sequenced. Among them, three were related to the gram-positive low G+C group, one to the Delta subclass of the Proteobacteria, one to the Gamma subclass, and one to the Cytophaga group with no close related sequence. The 16S rRNA sequences of the four archaeal bands were closely associated with Methanosaeta concilii and Methanobacterium formicum.


2000 ◽  
Vol 66 (7) ◽  
pp. 2959-2964 ◽  
Author(s):  
Gregory M. Colores ◽  
Richard E. Macur ◽  
David M. Ward ◽  
William P. Inskeep

ABSTRACT We analyzed the impact of surfactant addition on hydrocarbon mineralization kinetics and the associated population shifts of hydrocarbon-degrading microorganisms in soil. A mixture of radiolabeled hexadecane and phenanthrene was added to batch soil vessels. Witconol SN70 (a nonionic, alcohol ethoxylate) was added in concentrations that bracketed the critical micelle concentration (CMC) in soil (CMC′) (determined to be 13 mg g−1). Addition of the surfactant at a concentration below the CMC′ (2 mg g−1) did not affect the mineralization rates of either hydrocarbon. However, when surfactant was added at a concentration approaching the CMC′ (10 mg g−1), hexadecane mineralization was delayed and phenanthrene mineralization was completely inhibited. Addition of surfactant at concentrations above the CMC′ (40 mg g−1) completely inhibited mineralization of both phenanthrene and hexadecane. Denaturing gradient gel electrophoresis of 16S rRNA gene segments showed that hydrocarbon amendment stimulatedRhodococcus and Nocardia populations that were displaced by Pseudomonas and Alcaligenespopulations at elevated surfactant levels. Parallel cultivation studies revealed that the Rhodococcus population can utilize hexadecane and that the Pseudomonas andAlcaligenes populations can utilize both Witconol SN70 and hexadecane for growth. The results suggest that surfactant applications necessary to achieve the CMC alter the microbial populations responsible for hydrocarbon mineralization.


2003 ◽  
Vol 49 (10) ◽  
pp. 602-612 ◽  
Author(s):  
Ingvild Wartiainen ◽  
Anne Grethe Hestnes ◽  
Mette M Svenning

The methanotrophic community in arctic soil from the islands of Svalbard, Norway (78°N) was analysed by combining group-specific PCR with PCR of the highly variable V3 region of the 16S rRNA gene and then by denaturing gradient gel electrophoresis (DGGE). Selected bands were sequenced for identification. The analyses were performed with DNA extracted directly from soil and from enrichment cultures at 10 and 20 °C. The two genera Methylobacter and Methylosinus were found in all localities studied. The DGGE band patterns were simple, and DNA fragments with single base differences were separated. The arctic tundra is a potential source of extensive methane emission due to climatic warming because of its large reservoirs of stored organic carbon. Higher temperatures due to climatic warming can cause increased methane production, and the abundance and activity of methane-oxidizing bacteria in the arctic soil may be important regulators for methane emission to the atmosphere.Key words: methanotrophic diversity, Svalbard, arctic wetland, denaturing gradient gel electrophoresis.


2011 ◽  
Vol 57 (2) ◽  
pp. 91-104 ◽  
Author(s):  
Julie Disnard ◽  
Carole Beaulieu ◽  
Richard Villemur

During the process of papermaking by pulp and paper plants, a thick and viscous deposits, termed slime, is quickly formed around the paper machines, which can affect the papermaking process. In this study, we explored the composition of the bacterial biota in slime that developed on shower pipes from 2 machines at a Canadian paper mill. Firstly, the composition was assessed for 12 months by DNA profiling with polymerase chain reaction coupled with denaturing gradient gel electrophoresis. Except for short periods (2–3 months), clustered analyses showed that the bacterial composition of the slime varied substantially over the year, with less than 50% similarity between the denaturing gradient gel electrophoresis profiles. Secondly, the screening of 16S rRNA gene libraries derived from 2 slime samples showed that the most abundant bacteria were related to 6 lineages, including Chloroflexi, candidate division OP10, Clostridiales, Bacillales, Burkholderiales, and the genus Deinococcus . Finally, the proportion of 8 bacterial lineages, such as Deinococcus sp., Meiothermus sp., and Chloroflexi, was determined by the Catalyzed Reporter Deposition – Fluorescence In Situ Hybridization in 2 slime samples. The results showed a high proportion of Chloroflexi, Tepidimonas spp., and Schlegelella spp. in the slime samples.


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