scholarly journals Benzene Degradation by a Variovorax Species within a Coal Tar-Contaminated Groundwater Microbial Community

2016 ◽  
Vol 83 (4) ◽  
Author(s):  
Kevin M. Posman ◽  
Christopher M. DeRito ◽  
Eugene L. Madsen
Keyword(s):  
Microbial Community ◽  
Stable Isotope ◽  
16S Rrna ◽  
Microbial Communities ◽  
Coal Tar ◽  
Stable Isotope Probing ◽  
Contaminated Groundwater ◽  
Content Type ◽  
Benzene Degradation ◽  
Naturally Occurring

ABSTRACT Investigations of environmental microbial communities are crucial for the discovery of populations capable of degrading hazardous compounds and may lead to improved bioremediation strategies. The goal of this study was to identify microorganisms responsible for aerobic benzene degradation in coal tar-contaminated groundwater. Benzene degradation was monitored in laboratory incubations of well waters using gas chromatography mass spectrometry (GC-MS). Stable isotope probing (SIP) experiments using [13C]benzene enabled us to obtain 13C-labled community DNA. From this, 16S rRNA clone libraries identified Gammaproteobacteria and Betaproteobacteria as the active benzene-metabolizing microbial populations. Subsequent cultivation experiments yielded nine bacterial isolates that grew in the presence of benzene; five were confirmed in laboratory cultures to grow on benzene. The isolated benzene-degrading organisms were genotypically similar (>97% 16S rRNA gene nucleotide identities) to the organisms identified in SIP experiments. One isolate, Variovorax MAK3, was further investigated for the expression of a putative aromatic ring-hydroxylating dioxygenase (RHD) hypothesized to be involved in benzene degradation. Microcosm experiments using Variovorax MAK3 revealed a 10-fold increase in RHD (Vapar_5383) expression, establishing a link between this gene and benzene degradation. Furthermore, the addition of Variovorax MAK3 to microcosms prepared from site waters accelerated community benzene degradation and correspondingly increased RHD gene expression. In microcosms using uninoculated groundwater, quantitative (q)PCR assays (with 16S rRNA and RDH genes) showed that Variovorax was present and responsive to added benzene. These data demonstrate how the convergence of cultivation-dependent and -independent techniques can boost understandings of active populations and functional genes in complex benzene-degrading microbial communities. IMPORTANCE Benzene is a human carcinogen whose presence in contaminated groundwater drives environmental cleanup efforts. Although the aerobic biodegradation of benzene has long been established, knowledge of the identity of the microorganisms in complex naturally occurring microbial communities responsible for benzene biodegradation has evaded scientific inquiry for many decades. Here, we applied a molecular biology technique known as stable isotope probing (SIP) to the microbial communities residing in contaminated groundwater samples to identify the community members active in benzene biodegradation. We complemented this approach by isolating and growing in the laboratory a bacterium representative of the bacteria found using SIP. Further characterization of the isolated bacterium enabled us to track the expression of a key gene that attacks benzene both in pure cultures of the bacterium and in the naturally occurring groundwater microbial community. This work advances information regarding the documentation of microbial processes, especially the populations and genes that contribute to bioremediation.

scholarly journals RNA-Based Stable Isotope Probing and Isolation of Anaerobic Benzene-Degrading Bacteria from Gasoline-Contaminated Groundwater

2006 ◽  
Vol 72 (5) ◽  
pp. 3586-3592 ◽  
Author(s):  
Yuki Kasai ◽  
Yoh Takahata ◽  
Mike Manefield ◽  
Kazuya Watanabe
Keyword(s):  
Stable Isotope ◽  
16S Rrna ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Stable Isotope Probing ◽  
Contaminated Groundwater ◽  
Rrna Gene ◽  
Major Band ◽  
Benzene Degradation ◽  
Dgge Analysis ◽  
Degrading Bacteria

ABSTRACT Stable isotope probing (SIP) of benzene-degrading bacteria in gasoline-contaminated groundwater was coupled to denaturing gradient gel electrophoresis (DGGE) of DNA fragments amplified by reverse transcription-PCR from community 16S rRNA molecules. Supplementation of the groundwater with [13C6]benzene together with an electron acceptor (nitrate, sulfate, or oxygen) showed that a phylotype affiliated with the genus Azoarcus specifically appeared in the 13C-RNA fraction only when nitrate was supplemented. This phylotype was also observed as the major band in DGGE analysis of bacterial 16S rRNA gene fragments amplified by PCR from the gasoline-contaminated groundwater. In order to isolate the Azoarcus strains, the groundwater sample was streaked on agar plates containing nonselective diluted CGY medium, and the DGGE analysis was used to screen colonies formed on the plates. This procedure identified five bacterial isolates (from 60 colonies) that corresponded to the SIP-identified Azoarcus phylotype, among which two strains (designated DN11 and AN9) degraded benzene under denitrifying conditions. Incubation of these strains with [14C]benzene showed that the labeled carbon was mostly incorporated into 14CO2 within 14 days. These results indicate that the Azoarcus population was involved in benzene degradation in the gasoline-contaminated groundwater under denitrifying conditions. We suggest that RNA-based SIP identification coupled to phylogenetic screening of nonselective isolates facilitates the isolation of enrichment/isolation-resistant microorganisms with a specific function.

scholarly journals Refining the Application of Microbial Lipids as Tracers of Staphylococcus aureus Growth Rates in Cystic Fibrosis Sputum

2018 ◽  
Vol 200 (24) ◽  
Author(s):  
Cajetan Neubauer ◽  
Ajay S. Kasi ◽  
Nora Grahl ◽  
Alex L. Sessions ◽  
Sebastian H. Kopf ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Fatty Acids ◽  
Microbial Community ◽  
Stable Isotope ◽  
Community Composition ◽  
Growth Rates ◽  
Microbial Community Composition ◽  
Stable Isotope Probing ◽  
Content Type ◽  
Lung Infections

ABSTRACT Chronic lung infections in cystic fibrosis (CF) could be treated more effectively if the effects of antimicrobials on pathogens in situ were known. Here, we compared changes in the microbial community composition and pathogen growth rates in longitudinal studies of seven pediatric CF patients undergoing intravenous antibiotic administration during pulmonary exacerbations. The microbial community composition was determined by counting rRNA with NanoString DNA analysis, and growth rates were obtained by incubating CF sputum with heavy water and tracing incorporation of deuterium into two branched-chain (“anteiso”) fatty acids (a-C15:0 and a-C17:0) using gas chromatography-mass spectrometry (GC/MS). Prior to this study, both lipids were thought to be specific for Staphylococcaceae; hence, their isotopic enrichment was interpreted as a growth proxy for Staphylococcus aureus. Our experiments revealed, however, that Prevotella is also a relevant microbial producer of a-C17:0 fatty acid in some CF patients; thus, deuterium incorporation into these lipids is better interpreted as a more general pathogen growth rate proxy. Even accounting for a small nonmicrobial background source detected in some patient samples, a-C15:0 fatty acid still appears to be a relatively robust proxy for CF pathogens, revealing a median generation time of ∼1.5 days, similar to prior observations. Contrary to our expectation, pathogen growth rates remained relatively stable throughout exacerbation treatment. We suggest two straightforward “best practices” for application of stable-isotope probing to CF sputum metabolites: (i) parallel determination of microbial community composition in CF sputum using culture-independent tools and (ii) assessing background levels of the diagnostic metabolite. IMPORTANCE In chronic lung infections, populations of microbial pathogens change and mature in ways that are often unknown, which makes it challenging to identify appropriate treatment options. A promising tool to better understand the physiology of microorganisms in a patient is stable-isotope probing, which we previously developed to estimate the growth rates of S. aureus in cystic fibrosis (CF) sputum. Here, we tracked microbial communities in a cohort of CF patients and found that anteiso fatty acids can also originate from other sources in CF sputum. This awareness led us to develop a new workflow for the application of stable-isotope probing in this context, improving our ability to estimate pathogen generation times in clinical samples.

scholarly journals Novel Biphenyl-Oxidizing Bacteria and Dioxygenase Genes from a Korean Tidal Mudflat

2011 ◽  
Vol 77 (11) ◽  
pp. 3888-3891 ◽  
Author(s):  
Tae Kwon Lee ◽  
Jaejin Lee ◽  
Woo Jun Sul ◽  
Shoko Iwai ◽  
Benli Chai ◽  
...  
Keyword(s):  
Amino Acid ◽  
Stable Isotope ◽  
16S Rrna ◽  
Amino Acid Identity ◽  
Stable Isotope Probing ◽  
Content Type ◽  
Acid Identity ◽  
Rrna Sequences ◽  
Mudflat Sediments ◽  
16S Rrna Sequences

ABSTRACTGene-targeted FLX titanium pyrosequencing integrated with stable isotope probing (SIP) using [13C]biphenyl substrate revealed that tidal mudflat sediments harbor novel aromatic ring hydroxylating dioxygenases (ARHD). More than 80% of the detected ARHD genes comprise four clades (0.5 distance) with 49 to 70% amino acid identity to sequences in public databases. The 16S rRNA sequences enriched in the13C fraction were from theBetaproteobacteria, bacilli (primarilyPaenibacillus-like), and unclassified phyla.

scholarly journals Stable-Isotope Probing Identifies Uncultured Planctomycetes as Primary Degraders of a Complex Heteropolysaccharide in Soil

2015 ◽  
Vol 81 (14) ◽  
pp. 4607-4615 ◽  
Author(s):  
Xiaoqing Wang ◽  
Christine E. Sharp ◽  
Gareth M. Jones ◽  
Stephen E. Grasby ◽  
Allyson L. Brady ◽  
...  
Keyword(s):  
Stable Isotope ◽  
16S Rrna ◽  
Soil Bacteria ◽  
Stable Isotope Probing ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Rrna Gene ◽  
Content Type ◽  
Degrading Bacteria ◽  
Aerobic Soil

ABSTRACTThe exopolysaccharides (EPSs) produced by some bacteria are potential growth substrates for other bacteria in soil. We used stable-isotope probing (SIP) to identify aerobic soil bacteria that assimilated the cellulose produced byGluconacetobacter xylinusor the EPS produced byBeijerinckia indica. The latter is a heteropolysaccharide comprised primarily ofl-guluronic acid,d-glucose, andd-glycero-d-mannoheptose.13C-labeled EPS and13C-labeled cellulose were purified from bacterial cultures grown on [13C]glucose. Two soils were incubated with these substrates, and bacteria actively assimilating them were identified via pyrosequencing of 16S rRNA genes recovered from13C-labeled DNA. Cellulose C was assimilated primarily by soil bacteria closely related (93 to 100% 16S rRNA gene sequence identities) to known cellulose-degrading bacteria. However,B. indicaEPS was assimilated primarily by bacteria with low identities (80 to 95%) to known species, particularly by different members of the phylumPlanctomycetes. In one incubation, members of thePlanctomycetesmade up >60% of all reads in the labeled DNA and were only distantly related (<85% identity) to any described species. Although it is impossible with SIP to completely distinguish primary polysaccharide hydrolyzers from bacteria growing on produced oligo- or monosaccharides, the predominance ofPlanctomycetessuggested that they were primary degraders of EPS. Other bacteria assimilatingB. indicaEPS included members of theVerrucomicrobia, candidate division OD1, and theArmatimonadetes. The results indicate that some uncultured bacteria in soils may be adapted to using complex heteropolysaccharides for growth and suggest that the use of these substrates may provide a means for culturing new species.

scholarly journals Stable Isotope Probing for Microbial Iron Reduction in Chocolate Pots Hot Spring, Yellowstone National Park

2018 ◽  
Vol 84 (11) ◽  
Author(s):  
Nathaniel W. Fortney ◽  
Shaomei He ◽  
Ajinkya Kulkarni ◽  
Michael W. Friedrich ◽  
Charlotte Holz ◽  
...  
Keyword(s):  
Microbial Community ◽  
Stable Isotope ◽  
Yellowstone National Park ◽  
National Park ◽  
Hot Spring ◽  
Redox Cycling ◽  
Stable Isotope Probing ◽  
Content Type ◽  
Insight Into

ABSTRACTChocolate Pots hot springs (CP) is a circumneutral-pH Fe-rich geothermal feature located in Yellowstone National Park. Previous Fe(III)-reducing enrichment culture studies with CP sediments identified close relatives of known dissimilatory Fe(III)-reducing bacterial (FeRB) taxa, includingGeobacterandMelioribacter. However, the abundances and activities of such organisms in the native microbial community are unknown. Here, we used stable isotope probing experiments combined with 16S rRNA gene amplicon and shotgun metagenomic sequencing to gain an understanding of thein situFe(III)-reducing microbial community at CP. Fe-Si oxide precipitates collected near the hot spring vent were incubated with unlabeled and13C-labeled acetate to target active FeRB. We searched reconstructed genomes for homologs of genes involved in known extracellular electron transfer (EET) systems to identify the taxa involved in Fe redox transformations. Known FeRB taxa containing putative EET systems (Geobacter,Ignavibacteria) increased in abundance under acetate-amended conditions, whereas genomes related toIgnavibacteriumandThermodesulfovibriothat contained putative EET systems were recovered from incubations without electron donor. Our results suggest that FeRB play an active role in Fe redox cycling within Fe-Si oxide-rich deposits located at the hot spring vent.IMPORTANCEThe identification of past near-surface hydrothermal environments on Mars emphasizes the importance of using modern Earth environments, such as CP, to gain insight into potential Fe-based microbial life on other rocky worlds, as well as ancient Fe-rich Earth ecosystems. By combining stable carbon isotope probing techniques and DNA sequencing technology, we gained insight into the pathways of microbial Fe redox cycling at CP. The results suggest that microbial Fe(III) oxide reduction is prominentin situ, with important implications for the generation of geochemical and stable Fe isotopic signatures of microbial Fe redox metabolism within Fe-rich circumneutral-pH thermal spring environments on Earth and Mars.

scholarly journals Linking Microbial Community Function to Phylogeny of Sulfate-Reducing Deltaproteobacteria in Marine Sediments by Combining Stable Isotope Probing with Magnetic-Bead Capture Hybridization of 16S rRNA

2009 ◽  
Vol 75 (15) ◽  
pp. 4927-4935 ◽  
Author(s):  
Tetsuro Miyatake ◽  
Barbara J. MacGregor ◽  
Henricus T. S. Boschker
Keyword(s):  
Microbial Community ◽  
Stable Isotope ◽  
16S Rrna ◽  
Marine Sediments ◽  
Magnetic Bead ◽  
Stable Isotope Probing ◽  
Target Range ◽  
Microbial Community Function ◽  
Sulfate Reducing ◽  
Community Function

ABSTRACT We further developed the stable isotope probing, magnetic-bead capture method to make it applicable for linking microbial community function to phylogeny at the class and family levels. The main improvements were a substantial decrease in the protocol blank and an approximately 10-fold increase in the detection limit by using a micro-elemental analyzer coupled to isotope ratio mass spectrometry to determine 13C labeling of isolated 16S rRNA. We demonstrated the method by studying substrate utilization by Desulfobacteraceae, a dominant group of complete oxidizing sulfate-reducing Deltaproteobacteria in marine sediments. Stable-isotope-labeled [13C]glucose, [13C]propionate, or [13C]acetate was fed into an anoxic intertidal sediment. We applied a nested set of three biotin-labeled oligonucleotide probes to capture Bacteria, Deltaproteobacteria, and finally Desulfobacteraceae rRNA by using hydrophobic streptavidin-coated paramagnetic beads. The target specificities of the probes were examined with pure cultures of target and nontarget species and by determining the phylogenetic composition of the captured sediment rRNA. The specificity of the final protocol was generally very good, as more than 90% of the captured 16S rRNA belonged to the target range of the probes. Our results indicated that Desulfobacteraceae were important consumers of propionate but not of glucose. However, the results for acetate utilization were less conclusive due to lower and more variable labeling levels in captured rRNA. The main advantage of the method in this study over other nucleic acid-based stable isotope probing methods is that 13C labeling can be much lower, to the extent that δ13C ratios can be studied even at their natural abundances.

scholarly journals Characterization ofpara-Nitrophenol-Degrading Bacterial Communities in River Water by Using Functional Markers and Stable Isotope Probing

2015 ◽  
Vol 81 (19) ◽  
pp. 6890-6900 ◽  
Author(s):  
Agnieszka Kowalczyk ◽  
Özge Eyice ◽  
Hendrik Schäfer ◽  
Oliver R. Price ◽  
Christopher J. Finnegan ◽  
...  
Keyword(s):  
Stable Isotope ◽  
16S Rrna ◽  
River Water ◽  
Stable Isotope Probing ◽  
Functional Markers ◽  
Polymorphism Analysis ◽  
Specific Marker ◽  
Environmental Distribution ◽  
Gram Negative ◽  
Content Type

ABSTRACTMicrobial degradation is a major determinant of the fate of pollutants in the environment.para-Nitrophenol (PNP) is an EPA-listed priority pollutant with a wide environmental distribution, but little is known about the microorganisms that degrade it in the environment. We studied the diversity of active PNP-degrading bacterial populations in river water using a novel functional marker approach coupled with [13C6]PNP stable isotope probing (SIP). Culturing together with culture-independent terminal restriction fragment length polymorphism analysis of 16S rRNA gene amplicons identifiedPseudomonas syringaeto be the major driver of PNP degradation in river water microcosms. This was confirmed by SIP-pyrosequencing of amplified 16S rRNA. Similarly, functional gene analysis showed that degradation followed the Gram-negative bacterial pathway and involvedpnpAfromPseudomonasspp. However, analysis of maleylacetate reductase (encoded bymar), an enzyme common to late stages of both Gram-negative and Gram-positive bacterial PNP degradation pathways, identified a diverse assemblage of bacteria associated with PNP degradation, suggesting thatmarhas limited use as a specific marker of PNP biodegradation. Both thepnpAandmargenes were detected in a PNP-degrading isolate,P. syringaeAKHD2, which was isolated from river water. Our results suggest that PNP-degrading cultures ofPseudomonasspp. are representative of environmental PNP-degrading populations.

scholarly journals Diversity of Five Anaerobic Toluene-Degrading Microbial Communities Investigated Using Stable Isotope Probing

2011 ◽  
Vol 78 (4) ◽  
pp. 972-980 ◽  
Author(s):  
Weimin Sun ◽  
Alison M. Cupples
Keyword(s):  
Stable Isotope ◽  
Microbial Communities ◽  
Contaminated Soil ◽  
Agricultural Soil ◽  
Stable Isotope Probing ◽  
Functional Gene ◽  
Toluene Degradation ◽  
Content Type ◽  
The Family ◽  
Benzylsuccinate Synthase

ABSTRACTTime-series DNA-stable isotope probing (SIP) was used to identify the microbes assimilating carbon from [13C]toluene under nitrate- or sulfate-amended conditions in a range of inoculum sources, including uncontaminated and contaminated soil and wastewater treatment samples. In all, five different phylotypes were found to be responsible for toluene degradation, and these included previously identified toluene degraders as well as novel toluene-degrading microorganisms. In microcosms constructed from granular sludge and amended with nitrate, the putative toluene degraders were classified in the genusThauera, whereas in nitrate-amended microcosms constructed from a different source (agricultural soil), microorganisms in the familyComamonadaceae(genus unclassified) were the key putative degraders. In one set of sulfate-amended microcosms (agricultural soil), the putative toluene degraders were identified as belonging to the classClostridia(genusDesulfosporosinus), while in other sulfate-amended microcosms, the putative degraders were in the classDeltaproteobacteria, within the familySyntrophobacteraceae(digester sludge) orDesulfobulbaceae(contaminated soil) (genus unclassified for both). Partial benzylsuccinate synthase gene (bssA, the functional gene for anaerobic toluene degradation) sequences were obtained for some samples, and quantitative PCR targeting this gene, along with SIP, was further used to confirm anaerobic toluene degradation by the identified species. The study illustrates the diversity of toluene degraders across different environments and highlights the utility of ribosomal and functional gene-based SIP for linking function with identity in microbial communities.

scholarly journals Identification of a Toluene-Degrading Bacterium from a Soil Sample through H218O DNA Stable Isotope Probing

2011 ◽  
Vol 77 (17) ◽  
pp. 5995-5999 ◽  
Author(s):  
Angela Woods ◽  
Maribeth Watwood ◽  
Egbert Schwartz
Keyword(s):  
Stable Isotope ◽  
16S Rrna ◽  
16S Rrna Gene ◽  
Stable Isotope Probing ◽  
Rrna Gene ◽  
Soil Dna ◽  
Content Type ◽  
Degrading Bacterium ◽  
Rhodococcus Jostii ◽  
Oxygen Atoms

ABSTRACTDNA stable isotope probing (DNA-SIP) with H218O was used to identify a toluene-degrading bacterium in soil amended with 48 ppm toluene. After quantification of toluene degradation rates in soil, DNA was extracted from soil incubated with H218O, H216O, H216O and 48 ppm toluene, or H218O and 48 ppm toluene. A single DNA band formed along a cesium chloride gradient after isopycnic centrifugation of extracts from soils incubated with H216O. With extracts from soils to which only H218O was added, two distinct DNA bands formed, while three bands formed when DNA extracted from soil incubated with both H218O and toluene was analyzed. We suggest that this third band formed because toluene does not contain any oxygen atoms and toluene-degrading organisms had to transfer oxygen atoms from H218O into metabolic intermediates to form nucleic acidsde novo. We extracted the third DNA band and amplified a large fraction of the bacterial 16S rRNA gene. Direct sequencing of the PCR product obtained from the labeled DNA, as well as cloned 16S rRNA amplicons, identified a known toluene degrader,Rhodococcus jostiiRHA1. A toluene-degrading bacterial strain was subsequently isolated from soil and shown to beRhodococcus jostiiRHA1. Finally, quantitative real-time PCR analysis showed that the abundance of the 16S rRNA gene ofRhodococcus jostiiRHA1 increased in soil after toluene exposure but not in soils from which toluene was withheld. This study indicates that H218O DNA-SIP can be a useful method for identifying pollutant-degrading bacteria in soil.

scholarly journals Stable Isotope Probing Analysis of Interactions between Ammonia Oxidizers

2010 ◽  
Vol 76 (8) ◽  
pp. 2468-2477 ◽  
Author(s):  
Maria Tourna ◽  
Thomas E. Freitag ◽  
James I. Prosser
Keyword(s):  
Stable Isotope ◽  
16S Rrna ◽  
Microbial Communities ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Ammonia Concentration ◽  
Stable Isotope Probing ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Rrna Gene ◽  
High Ammonia

ABSTRACT The response of natural microbial communities to environmental change can be assessed by determining DNA- or RNA-targeted changes in relative abundance of 16S rRNA gene sequences by using fingerprinting techniques such as denaturing gradient gel electrophoresis (DNA-DGGE and RNA-DGGE, respectively) or by stable isotope probing (SIP) of 16S rRNA genes following incubation with a 13C-labeled substrate (DNA-SIP-DGGE). The sensitivities of these three approaches were compared during batch growth of communities containing two or three Nitrosospira pure or enriched cultures with different tolerances to a high ammonia concentration. Cultures were supplied with low, intermediate, or high initial ammonia concentrations and with 13C-labeled carbon dioxide. DNA-SIP-DGGE provided the most direct evidence for growth and was the most sensitive, with changes in DGGE profiles evident before changes in DNA- and RNA-DGGE profiles and before detectable increases in nitrite and nitrate production. RNA-DGGE provided intermediate sensitivity. In addition, the three molecular methods were used to follow growth of individual strains within communities. In general, changes in relative activities of individual strains within communities could be predicted from monoculture growth characteristics. Ammonia-tolerant Nitrosospira cluster 3b strains dominated mixed communities at all ammonia concentrations, and ammonia-sensitive strains were outcompeted at an intermediate ammonia concentration. However, coexistence of ammonia-tolerant and ammonia-sensitive strains occurred at the lowest ammonia concentration, and, under some conditions, strains inhibited at high ammonia in monoculture were active at high ammonia in mixed cultures, where they coexisted with ammonia-tolerant strains. The results therefore demonstrate the sensitivity of SIP for detection of activity of organisms with relatively low yield and low activity and its ability to follow changes in the structure of interacting microbial communities.

Sign in / Sign up

Export Citation Format

Share Document