Project description:Population dynamics of methanogenic genera was investigated in pilot anaerobic digesters. Cattle manure and two-phase olive mill wastes were codigested at a 3:1 ratio in two reactors operated at 37 ï¾°C and 55 ï¾°C. Other two reactors were run with either residue at 37 ï¾°C. Sludge DNA extracted from samples taken from all four reactors on days 4, 14 and 28 of digestion was used for hybridisation with the AnaeroChip, an oligonucleotide microarray targeting those groups of methanogenic archaea that are commonly found under mesophilic and thermophilic conditions (Franke-Whittle et al. 2009, in press, doi:10.1016/j.mimet.2009.09.017).
Project description:Caldicellulosiruptor bescii is an anaerobic hyper thermophile that can utilize a wide range of substrates. However, inhibitors released from biomass can result in unfavorable growth conditions and limit bioconversion to products. Medium as well as intracellular pH are conditions critical for growth and prone to change in effect of fermentation end or by products such as, CO2, organic acids etc. Growth pH for C. bescii as currently reported is a narrow range of 6.8-7.3. In this study, we examined the physiological and systems level responses of C. bescii to growth at acidic pH. Samples collected from bottles, controlled batch, fed-batch and chemostat systems were subjected to growth, product and integrated omics profiling. It was discovered that in batch reactors, lowering pH from 7.2 to 6.0 at the mid-log phase, led to a significant increase in growth and product yields. Time course transcriptomics data collected from these batch reactors was analyzed to try and get a better understanding of the underlying mechanisms for improved growth.
Project description:Low concentrations of pharmaceutical compounds were shown to induce transcriptional responses in isolated microorganisms, which could have consequences on ecosystem dynamics. In order to test if these transcriptional responses could also be observed in complex river microbial communities, biofilm reactors were inoculated with water from two distinct rivers and supplemented with environmentally relevant doses of four pharmaceutical products (erythromycin-ER, gemfibrozil-GM, sulfamethazine-SN and sulfamethoxazole-SL). To follow the expression of functional genes, we constructed a 9,600 features anonymous DNA microarray platform onto which cDNA from the various biofilms was hybridized. The reactor design for biofilm development has been previously described (Lawrence et al., 2004; Lawrence et al., 2000). Two duplicate experiments were carried out, with reactors being inoculated with either water from the WC (nutrient rich) or the SSR (nutrient poor). Treatments consisted in the addition of various pharmaceutical compounds: 1 µg l-1 erythromycin (ER), 1 µg l-1 gemfibrozil (GM), 0.5 µg l-1 sulfamethazine (SN), 0.5 µg l-1 sulfamethoxazole (SL). Nothing was added to control reactors (CO). All treatments were replicated independently three times. A reference sample (composite sample from Wascana Creek reactors used to construct the microarray) was hybridized (Cy5) on each slide.
Project description:Enterococcus faecalis is a common commensal organism and a prolific nosocomial pathogen that causes biofilm-associated infections. Numerous E. faecalis OG1RF genes required for biofilm formation have been identified, but few studies have compared genetic determinants of biofilm formation and biofilm morphology across multiple conditions. Here, we cultured transposon (Tn) libraries in CDC biofilm reactors in two different media and used Tn sequencing (TnSeq) to identify core and accessory biofilm determinants, including many genes that are poorly characterized or annotated as hypothetical. Multiple secondary assays (96-well plates, submerged Aclar, and MultiRep biofilm reactors) were used to validate phenotypes of new biofilm determinants.
Project description:Two parallel anaerobic digestion lines were designed to match a "bovid-like" digestive structure. Each of the lines consisted of two Continuous Stirred Tank Reactors placed in series and separated by an acidic treatment step. The first line was inoculated with industrial inocula whereas the second was seeded with cow digestive tract contents. After three month of continuous sewage sludge feeding, samples were recovered for shotgun metaproteomic and DNA-based analysis. Strikingly, protein inferred and 16S rDNA tags based taxonomic community profiles were not fully consistent. Principal Component analysis however revealed a similar clustering pattern of the samples, suggesting that reproducible methodological and/or biological factors underlie this observation. The performances of the two digestion lines did not differ significantly and the cow derived inocula did not establish in the reactors. A low throughput metagenomic dataset (3.4x106 reads, 1.1 Gb) was also generated for one of the samples. It allowed a substantial increase of the analysis depth (increase of the spectral identification rate). For the first time, a high level of proteins expressed by members of the "Candidatus Competibacter" group is reported in an anaerobic digester, a key microbial player in environmental bioprocess communities.