Project description:mRNA sequencing in bacteria is challenging due to the abundance of ribosomal rRNA that cannot be easily removed prior to sequencing. While commercially available kits target specific rRNA sequences found in defined lists of common bacterial species, they are frequently inefficient when applied to other divergent species, including those from environmental isolates. Similar to the commercial kits, other common techniques for rRNA depletion typically employ large probe sets that tile full-length rRNA sequences; however, such approaches are both time consuming and expensive when applied to multiple species or complex consortia of non-model microbes. To overcome these limitations, we present EMBR-seq+, which employs less than twenty target oligonucleotides per rRNA molecule, and builds upon our previous rRNA depletion approach, EMBR-seq, through the addition of an RNase H depletion step, to achieve rRNA removal efficiencies of up to 99%. First, we applied EMBR-seq+ to monocultures of Escherichia coli, Geobacter metallireducens, and Fibrobacter succinogenes strain UWB7 to deplete rRNA to approximately 1-7% of the sequencing reads, demonstrating that the new method can be easily extended to diverse bacterial species. Further, in more complex co-cultures between F. succinogenes strain UWB7 and anerobic fungal species, we applied EMBR-seq+ to deplete both bacterial and fungal rRNA, with an approximately 4-fold improved bacterial rRNA depletion efficiency compared to a previous report using a commercial kit, thereby showing that the method can be effectively translated to non-model microbial mixtures. Notably, we also demonstrate that for microbial species with poorly annotated genomes and unknown rRNA sequences, the RNase H depletion component of EMBR-seq+ enables rapid iterations in probe design without requiring to start experiments from total RNA each time, and was key for depleting fungal rRNA to enrich the bacterial mRNA readout in co-cultures. Finally, efficient depletion of rRNA enabled systematic quantification of the reprogramming of the bacterial transcriptome when cultured in the presence of the anerobic fungi, Anaeromyces robustus and Caecomyces churrovis. We observed that F. succinogenes strain UWB7 transcribes nearly 200 carbohydrate-active enzyme (CAZyme) genes in both monoculture and co-culture conditions, with several lignocellulose-degrading CAZymes downregulated in the presence of an anerobic gut fungus. This finding is consistent with the premise that bacteria and fungi specialize in different aspects of biomass breakdown, such that the presence of one regulates the CAZyme production of the other. This also supports previous findings that the fungi release excess reducing sugars in the supernatant, which benefits other members of the microbial community. Thus EMBR-seq+ provides a new and detailed perspective of a rumen microbiome model system by dramatically improving the efficiency of mRNA sequencing, and more generally also enables high-throughput, cost-effective and rapid quantification of the transcriptome to gain functional insights into less-studied and non-model microbial systems.
Project description:The use of microbiological cultures for diagnosing bacterial infections in young febrile infants have substantial limitations, including false positive and false negative cultures, and non-ideal turn-around times. Analysis of host genomic expression patterns (“RNA biosignatures”) in response to the presence of specific pathogens, however, may provide an alternate and potentially improved diagnostic approach. This study was designed to define bacterial and non-bacterial RNA biosignatures to distinguish these infections in young febrile infants.
Project description:Network analysis of large metagenomic datasets generated by current sequencing technologies can reveal significant co-occurrence patterns between microbial species of a biological community. These patterns can be analyzed in terms of pairwise combinations between all species comprising a community. Here, we construct a co-occurrence network for abundant microbial species encompassing the three dominant phyla found in human gut. This was followed by an in vitro evaluation of the predicted microbe-microbe co-occurrences, where we chose species pairs Bifidobacterium adolescentis and Bacteroides thetaiotaomicron, as well as Faecalibacterium prausnitzii and Roseburia inulinivorans as model organisms for our study. We then delineate the outcome of the co-cultures when equal distributions of resources were provided. The growth behavior of the co-culture was found to be dependent on the types of microbial species present, their specific metabolic activities, and resulting changes in the culture environment. Through this reductionist approach and using novel in vitro combinations of microbial species under anaerobic conditions, the results of this work will aid in the understanding and design of synthetic community formulations.
Project description:The use of microbiological cultures for diagnosing bacterial infections in young febrile infants have substantial limitations, including false positive and false negative cultures, and non-ideal turn-around times. Analysis of host genomic expression patterns (âRNA biosignaturesâ) in response to the presence of specific pathogens, however, may provide an alternate and potentially improved diagnostic approach. This study was designed to define bacterial and non-bacterial RNA biosignatures to distinguish these infections in young febrile infants. A total of 279 febrile infants and 19 healthy afebrile control infants aged 0-6 months (for a total of 298 samples) for microarray analysis. For analytic purposes, we classified patients into two groups, those with bacterial infections (n=89) and those with non-bacterial infections (n=190). 144 of the samples were run on Illumina HT12 V4 R1 chips. Of these, there were 34 bacterial infections, 105 non-bacterial infections, and 5 healthy afebrile controls. 154 of the samples were run on Illumina HT12 V4 R2 chips. Of these, there were 55 bacterial infections, 85 non-bacterial infections, and 14 healthy afebrile controls.
Project description:ImportanceMicrobes present one of the most diverse sources of biochemistry in nature, and mRNA sequencing provides a comprehensive view of this biological activity by quantitatively measuring microbial transcriptomes. However, efficient mRNA capture for sequencing presents significant challenges in prokaryotes as mRNAs are not poly-adenylated and typically make up less than 5% of total RNA compared with rRNAs that exceed 80%. Recently developed methods for sequencing bacterial mRNA typically rely on depleting rRNA by tiling large probe sets against rRNAs; however, such approaches are expensive, time-consuming, and challenging to scale to varied bacterial species and complex microbial communities. Therefore, we developed EMBR-seq+, a method that requires fewer than 10 short oligonucleotides per rRNA to achieve up to 99% rRNA depletion in diverse bacterial species. Finally, EMBR-seq+ resulted in a deeper view of the transcriptome, enabling systematic quantification of how microbial interactions result in altering the transcriptional state of bacteria within co-cultures.
Project description:Fungal co-cultivation has emerged as a promising way for activating cryptic biosynthetic pathways and discovering novel antimicrobial metabolites. For the success of such studies, a key element remains the development of standardized co-cultivation methods compatible with high-throughput analytical procedures. To efficiently highlight induction processes, it is crucial to acquire a holistic view of intermicrobial communication at the molecular level. To tackle this issue, a strategy was developed based on the miniaturization of fungal cultures that allows for a concomitant survey of induction phenomena in volatile and non-volatile metabolomes. Fungi were directly grown in vials, and each sample was profiled by head space solid phase microextraction gas chromatography mass spectrometry (HS-SPME-GC-MS), while the corresponding solid culture medium was analyzed by liquid chromatography high resolution mass spectrometry (LC-HRMS) after solvent extraction. This strategy was implemented for the screening of volatile and non-volatile metabolite inductions in an ecologically relevant fungal co-culture of Eutypa lata (Pers.) Tul. & C. Tul. (Diatrypaceae) and Botryosphaeria obtusa (Schwein.) Shoemaker (Botryosphaeriaceae), two wood-decaying fungi interacting in the context of esca disease of grapevine. For a comprehensive evaluation of the results, a multivariate data analysis combining Analysis of Variance and Partial Least Squares approaches, namely AMOPLS, was used to explore the complex LC-HRMS and GC-MS datasets and highlight dynamically induced compounds. A time-series study was carried out over 9 days, showing characteristic metabolite induction patterns in both volatile and non-volatile dimensions. Relevant links between the dynamics of expression of specific metabolite production were observed. In addition, the antifungal activity of 2-nonanone, a metabolite incrementally produced over time in the volatile fraction, was assessed against Eutypa lata and Botryosphaeria obtusa in an adapted bioassay set for volatile compounds. This compound has shown antifungal activity on both fungi and was found to be co-expressed with a known antifungal compound, O-methylmellein, induced in solid media. This strategy could help elucidate microbial inter- and intra-species cross-talk at various levels. Moreover, it supports the study of concerted defense/communication mechanisms for efficiently identifying original antimicrobials.