Project description:We worked with microarrys analysis in presence of 3-oxo-C12-HSL molecule to analyze the profile of the genes implicated in the Quorum Quenching network in A.baumannii clinical strains. Interestingly, only 13 genes were overexpressed under 3-oxo-C12-HSL molecule being the most level a gene which encodes an Alpha/beta hydrolase enzyme (5.01). The 46.15% of the genes overexpressed were implicated in the synthesis of the acyl-homoserine lactones (AHLs).
Project description:Quorum sensing (QS) is a widespread process in bacteria used to coordinate gene expression with cell density, diffusion dynamics, and spatial distribution through the production of diffusible chemical signals. To date, most studies on QS have focused on model bacteria that are amenable to genetic manipulation and capable of high growth rates, but many environmentally important bacteria have been overlooked. For example, representatives of proteobacteria that participate in nitrification, the aerobic oxidation of ammonia to nitrate via nitrite, produce QS signals called acyl-homoserine lactones (AHLs). Nitrification emits nitrogen oxide gases (NO, NO2, and N2O), which are potentially hazardous compounds that contribute to global warming. Despite considerable interest in nitrification, the purpose of QS in the physiology/ecology of nitrifying bacteria is poorly understood. Through a quorum quenching approach, we investigated the role of QS in a well-studied AHL-producing nitrite oxidizer, Nitrobacter winogradskyi.We added a recombinant AiiA lactonase to N. winogradskyi cultures to degrade AHLs to prevent their accumulation and to induce a QS-negative phenotype and then used mRNA sequencing (mRNA-Seq) to identify putative QS-controlled genes. Our transcriptome analysis showed that expression of nirK and nirK cluster genes (ncgABC) increased up to 19.9-fold under QS-proficient conditions (minus active lactonase). These data led to us to query if QS influenced nitrogen oxide gas fluxes in N. winogradskyi. Production and consumption of NOx increased and production of N2O decreased under QS-proficient conditions. Quorum quenching transcriptome approaches have broad potential to identify QS-controlled genes and phenotypes in organisms that are not genetically tractable.
Project description:Purpose: Deconstructing the soil microbiome into reduced-complexity functional modules represents a novel method of microbiome analysis. The goals of this study are to confirm differences in transcriptomic patterns among five functional module consortia. Methods: mRNA profiles of 3 replicates each of functional module enrichments of soil inoculum in M9 media with either 1) xylose, 2) n-acetylglucosamine, 3) glucose and gentamycin, 4) xylan, or 5) pectin were generated by sequencing using an Illumina platform (GENEWIZ performed sequencing). Sequence reads that passed quality filters were aligned to a soil metagenome using Burrows Wheeler Aligner. Resulting SAM files were converted to raw reads using HTSeq, and annotated using Uniref90 or EGGNOG databases. Results: To reduce the size of the RNA-Seq counts table and increase its computational tractability, transcripts containing a minimum of 75 total counts, but no more than 3 zero counts, across the 15 samples were removed. The subsequent dataset was normalized using DESeq2, resulting in a dataset consisting of 6947 unique transcripts across the 15 samples, and 185,920,068 reads. We identified gene categories that were enriched in a sample type relative to the overall dataset using Fisher’s exact test. Conclusions: our dataset confirms that the functional module consortia generated from targeted enrichments of a starting soil inoculum had distinct functional trends by enrichment type.
Project description:Synthetic microbial consortia represent a new frontier for synthetic biology given that they can solve more complex problems than monocultures. However, most attempts to co-cultivate these artificial communities fail because of the ‘‘winner-takes-all’’ in nutrients competition. In soil, multiple species can coexist with a spatial organization. Inspired by nature, here we show that an engineered spatial segregation method can assemble stable consortia with both flexibility and precision. We create microbial swarmbot consortia (MSBC) by encapsulating subpopulations with polymeric microcapsules. The crosslinked structure of microcapsules fences microbes, but allows the transport of small molecules and proteins. MSBC method enables the assembly of various synthetic communities and the precise control over the subpopulations. These capabilities can readily modulate the division of labor and communication. Our work integrates the synthetic biology and material science to offer new insights into consortia assembly and server as foundation to diverse applications from biomanufacturing to engineered photosynthesis.
Project description:The human opportunistic pathogen Pseudomonas aeruginosa orchestrates the expression of many genes in a cell density-dependent manner by using a molecular communication system referred to as quorum sensing (QS). This bacterium uses an intricate network of regulators and QS molecules known as autoinducers. Among these autoinducers are two acyl-homoserine lactones (AHL) involved in QS circuits which modulate virulence factors production, biofilm formation, and antimicrobial sensitivity. Disrupting QS, a strategy referred to as quorum quenching (QQ), is a promising approach to modulate virulence while not directly challenging bacterial survival. For P. aeruginosa, QQ can be achieved using exogenous AHL-degrading lactonases. However, the importance of enzyme specificity on quenching efficacy has never been investigated. Here, we used two lactonases both targeting the signal molecules N-(3-oxododecanoyl)-L-Homoserine lactone (3-oxo-C12 HSL) and butyryl-homoserine lactone (C4 HSL) albeit with different efficacy on C4 HSL. Interestingly, both lactonases similarly decreased the concentrations of AHL and comparably impacted the expression of AHL-based circuits. Conversely, strong variations were observed in Pseudomonas Quinolone Signal (PQS) regulation. Both lactonases were then found to decrease virulence factors production and biofilm formation in vitro, albeit with different efficiencies. Unexpectedly, only the lactonase with substrate preference for 3-oxo-C12 HSL was able to inhibit P. aeruginosa pathogenicity in vivo in an amoeba infection model. Similarly, large variations between lactonases were observed in proteins involved in antibiotic resistance, biofilm formation, virulence and diverse cellular mechanisms. This global analysis provides the first evidence that QQ enzyme specificity is crucial to modulate QS-associated behavior in P. aeruginosa PA14.