Project description:Microarrays have become established tools for describing microbial systems, however the assessment of expression profiles for environmental microbial communities still presents unique challenges. Notably, the concentration of particular transcripts are likely very dilute relative to the pool of total RNA, and PCR-based amplification strategies are vulnerable to amplification biases and the appropriate primer selection. Thus, we apply a signal amplification approach, rather than template amplification, to analyze the expression of selected lignin-degrading enzymes in soil. Controls in the form of known amplicons and cDNA from Phanerochaete chrysosporium were included and mixed with the soil cDNA both before and after the signal amplification in order to assess the dynamic range of the microarray. We demonstrate that restored prairie soil expresses a diverse range of lignin-degrading enzymes following incubation with lignin substrate, while farmed agricultural soil does not. The mixed additions of control cDNA with soil cDNA indicate that the mixed biomass in the soil does interfere with low abundance transcript changes, nevertheless our microarray approach consistently reports the most robust signals. Keywords: comparative analysis, microbial ecology, soil microbial communities We used lignin degradation as a model process to demonstrate the use of an oligonucleotide microarray for directly detecting gene expression in soil communities using signal amplification instead of template amplification to avoid the introduction of PCR bias. In the current study, we analyzed mRNA isolated from two distinct soil microbial communities and demonstrate our ability to detect the expression of a small subset of lignin degrading genes following exposure to a lignitic substrate. We also included purified control amplicons and mixed target experiments with pure P. chrysosporium genomic cDNA to determine the level of interference from soil biomass on target hybridization.

Project description:Characterization of microbial communities at the genomic, transcriptomic, proteomic and metabolomic levels, with a special interest on lipid accumulating bacterial populations, which are naturally enriched in biological wastewater treatment systems and may be harnessed for the conversion of mixed lipid substrates (wastewater) into biodiesel. The project aims to elucidate the genetic blueprints and the functional relevance of specific populations within the community. It focuses on within-population genetic and functional heterogeneity, trying to understand how fine-scale variations contribute to differing lipid accumulating phenotypes. Insights from this project will contribute to the understanding the functioning of microbial ecosystems, and improve optimization and modeling strategies for current and future biological wastewater treatment processes. This project contains datasets derived from the same biological wastewater treatment plant. The data includes metagenomes, metatranscriptomes, metaproteomes and organisms isolated in pure cultures. Characterization of microbial communities at the genomic, transcriptomic, proteomic and metabolomic levels, with a special interest on lipid accumulating bacterial populations, which are naturally enriched in biological wastewater treatment systems and may be harnessed for the conversion of mixed lipid substrates (wastewater) into biodiesel. The project aims to elucidate the genetic blueprints and the functional relevance of specific populations within the community. It focuses on within-population genetic and functional heterogeneity, trying to understand how fine-scale variations contribute to differing lipid accumulating phenotypes. Insights from this project will contribute to the understanding the functioning of microbial ecosystems, and improve optimization and modeling strategies for current and future biological wastewater treatment processes. This project contains datasets derived from the same biological wastewater treatment plant. The data includes metagenomes, metatranscriptomes, metaproteomes and organisms isolated in pure cultures.

Project description:This study investigates the role of carbon-to-phosphorus (C/P) ratios in shaping microbial community dynamics and polyhydroxyalkanoates (PHA) production in sequencing batch reactors (SBR) fed with volatile fatty acids. Three conditions, characterized by fixed organic loading rates but varying C/P ratios (Run 1 = 170 Cmol Pmol-1; Run 2 = 235 Cmol Pmol-1; Run 3 = 400 Cmol Pmol-1), were tested to explore their impact on PHA accumulation, biomass growth, and reactor stability. Results indicate that the moderate phosphorus limitation of Run 2 achieves the best overall performance, with a PHA volumetric productivity of 2.02 g PHA L-1 d-1 and process stability. Conversely, higher C/P ratio increased the storage yield but lowered the productivity (1.55 gPHA L-1 d-1), compromising sludge settleability and reactor stability, indicating impaired microbial functionality. Full-length 16S/18S rRNA gene sequencing using PacBio technology enabled high-resolution profiling of microbial communities, revealing ecological shifts across conditions. Run 2 exhibited the highest bacterial and eukaryotic diversity, featuring multiple PHA-accumulating bacteria (mainly Sphaerotilus, Leadbetterella, and uncultured Rhodobacteraceae) and a well-structured eukaryotic community dominated by K-strategist bacterivorous protists, e.g. Rhogostoma (Rhizaria) and Vorticella (Ciliophora, Oligohymenophorea) and predatory protozoa, e.g. Tokophrya (Ciliophora, Suctoria). In contrast, Sphaerotilus dominated under suboptimal conditions and may be linked to bulking. These results suggest that eukaryotic diversity may support system stability through selective predation. Transmission electron microscopy (TEM) further confirmed the presence of intracellular PHA granules and polyphosphate reserves, reinforcing the connection between nutrient limitation and adaptive microbial strategies. Overall, these findings highlight the critical role of the C/P ratio in shaping the performance of mixed microbial cultures, demonstrating that a well-balanced nutrient supply can enhance PHA production while maintaining microbial community stability. The results contribute to optimizing the selection process for mixed microbial cultures, offering valuable insights into the impact of carbon-to-nutrient ratios in the feeding strategy.

			Action	DRS
	SRR30909169.fastq.gz	Fastqsanger.gz
	SRR30909170.fastq.gz	Fastqsanger.gz
	SRR30909171.fastq.gz	Fastqsanger.gz
	SRR30909172.fastq.gz	Fastqsanger.gz
	SRR30909173.fastq.gz	Fastqsanger.gz

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