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Separation of the bacterial species, Escherichia coli, from mixed-species microbial communities for transcriptome analysis.

ABSTRACT: BACKGROUND: The study of bacterial species interactions in a mixed-species community can be facilitated by transcriptome analysis of one species in the community using cDNA microarray technology. However, current applications of microarrays are mostly limited to single species studies. The purpose of this study is to develop a method to separate one species, Escherichia coli as an example, from mixed-species communities for transcriptome analysis. RESULTS: E. coli cells were separated from a dual-species (E. coli and Stenotrophomonas maltophilia) community using immuno-magnetic separation (IMS). High recovery rates of E. coli were achieved. The purity of E. coli cells was as high as 95.0% separated from suspended mixtures consisting of 1.1 - 71.3% E. coli, and as high as 96.0% separated from biofilms with 8.1% E. coli cells. Biofilms were pre-dispersed into single-cell suspensions. The reagent RNAlater (Ambion, Austin, TX) was used during biofilm dispersion and IMS to preserve the transcriptome of E. coli. A microarray study and quantitative PCR confirmed that very few E. coli genes (only about eight out of 4,289 ORFs) exhibited a significant change in expression during dispersion and separation, indicating that transcriptional profiles of E. coli were well preserved. CONCLUSIONS: A method based on immuno-magnetic separation (IMS) and application of RNAlater was developed to separate a bacterial species, E. coli as an example, from mixed-species communities while preserving its transcriptome. The method combined with cDNA microarray analysis should be very useful to study species interactions in mixed-species communities.

SUBMITTER: Dai D

PROVIDER: S-EPMC3076228 | biostudies-literature | 2011

REPOSITORIES: biostudies-literature

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Separation of the bacterial species, Escherichia coli, from mixed-species microbial communities for transcriptome analysis.

Dai Dongjuan D Holder Diane D Raskin Lutgarde L Xi Chuanwu C

BMC microbiology 20110322

<h4>Background</h4>The study of bacterial species interactions in a mixed-species community can be facilitated by transcriptome analysis of one species in the community using cDNA microarray technology. However, current applications of microarrays are mostly limited to single species studies. The purpose of this study is to develop a method to separate one species, Escherichia coli as an example, from mixed-species communities for transcriptome analysis.<h4>Results</h4>E. coli cells were separat ...[more]

PMID: 21418656

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Project description:UnlabelledOur laboratory recently discovered that Escherichia coli cells starved for the DNA precursor dGTP are killed efficiently (dGTP starvation) in a manner similar to that described for thymineless death (TLD). Conditions for specific dGTP starvation can be achieved by depriving an E. coli optA1 gpt strain of the purine nucleotide precursor hypoxanthine (Hx). To gain insight into the mechanisms underlying dGTP starvation, we conducted genome-wide gene expression analyses of actively growing optA1 gpt cells subjected to hypoxanthine deprivation for increasing periods. The data show that upon Hx withdrawal, the optA1 gpt strain displays a diminished ability to derepress the de novo purine biosynthesis genes, likely due to internal guanine accumulation. The impairment in fully inducing the purR regulon may be a contributing factor to the lethality of dGTP starvation. At later time points, and coinciding with cell lethality, strong induction of the SOS response was observed, supporting the concept of replication stress as a final cause of death. No evidence was observed in the starved cells for the participation of other stress responses, including the rpoS-mediated global stress response, reinforcing the lack of feedback of replication stress to the global metabolism of the cell. The genome-wide expression data also provide direct evidence for increased genome complexity during dGTP starvation, as a markedly increased gradient was observed for expression of genes located near the replication origin relative to those located toward the replication terminus.ImportanceControl of the supply of the building blocks (deoxynucleoside triphosphates [dNTPs]) for DNA replication is important for ensuring genome integrity and cell viability. When cells are starved specifically for one of the four dNTPs, dGTP, the process of DNA replication is disturbed in a manner that can lead to eventual death. In the present study, we investigated the transcriptional changes in the bacterium E. coli during dGTP starvation. The results show increasing DNA replication stress with an increased time of starvation, as evidenced by induction of the bacterial SOS system, as well as a notable lack of induction of other stress responses that could have saved the cells from cell death by slowing down cell growth.

Dataset Information

Separation of the bacterial species, Escherichia coli, from mixed-species microbial communities for transcriptome analysis.

Publications

Separation of the bacterial species, Escherichia coli, from mixed-species microbial communities for transcriptome analysis.

Similar Datasets

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