Project description:Bio-augmentation could be a promising strategy to improve processes for treatment and resource recovery from wastewater. In this study, the Gram-positive bacterium Bacillus subtilis was co-cultured with the microbial communities present in wastewater samples with high concentrations of nitrate or ammonium. Glucose supplementation (1%) was used to boost biomass growth in all wastewater samples. In anaerobic conditions, the indigenous microbial community bio-augmented with B. subtilis was able to rapidly remove nitrate from wastewater. In these conditions, B. subtilis overexpressed nitrogen assimilatory and respiratory genes including NasD, NasE, NarG, NarH, and NarI, which arguably accounted for the observed boost in denitrification. Next, we attempted to use the the ammonium- and nitrate-enriched wastewater samples bio-augmented with B. subtilis in the cathodic compartment of bioelectrochemical systems (BES) operated in anaerobic condition. B. subtilis only had low relative abundance in the microbial community, but bio-augmentation promoted the growth of Clostridium butyricum and C. beijerinckii, which became the dominant species. Both bio-augmentation with B. subtilis and electrical current from the cathode in the BES promoted butyrate production during fermentation of glucose. A concentration of 3.4 g/L butyrate was reached with a combination of cathodic current and bio-augmentation in ammonium-enriched wastewater. With nitrate-enriched wastewater, the BES effectively removed nitrate reaching 3.2 mg/L after 48 h. In addition, 3.9 g/L butyrate was produced. We propose that bio-augmentation of wastewater with B. subtilis in combination with bioelectrochemical processes could both boost denitrification in nitrate-containing wastewater and enable commercial production of butyrate from carbohydrate- containing wastewater, e.g. dairy industry discharges. These results suggest that B. subtilis bio-augmentation in our BES promotes simultaneous wastewater treatment and butyrate production.
Project description:Wastewater has been extensively studied along the years. However, these studies have been focused on the analysis of small molecules. There are no studies about the proteins present in wastewater and let alone an established method to study them. We propose a method for the study of the proteins in wastewater overcoming their low concentration and the interference of other molecules. Moreover, we differentiate between the proteins that are soluble and the ones in the particulate. This method is based on concentration, lysis and clean-up steps. The samples were analyzed afterward using liquid chromatography coupled to high-resolution mass spectrometry (HR-LC/MS) and the data searched with Proteome Discoverer. Thus, this complete method has allowed us to characterize the proteomic composition of different wastewater samples with a low volume.
Project description:Anaerobic digestion is a popular and effective microbial process for waste treatment. The performance of anaerobic digestion processes is contingent on the balance of the microbial food web in utilizing various substrates. Recently, co-digestion, i.e., supplementing the primary substrate with an organic-rich co-substrate has been exploited to improve waste treatment efficiency. Yet the potential effects of elevated organic loading on microbial functional gene community remains elusive. In this study, functional gene array (GeoChip 5.0) was used to assess the response of microbial community to the addition of poultry waste in anaerobic digesters treating dairy manure. Consistent with 16S rRNA gene sequences data, GeoChip data showed that microbial community compositions were significantly shifted in favor of copiotrophic populations by co-digestion, as taxa with higher rRNA gene copy number such as Bacilli were enriched. The acetoclastic methanogen Methanosarcina was also enriched, while Methanosaeta was unaltered but more abundant than Methanosarcina throughout the study period. The microbial functional diversity involved in anaerobic digestion were also increased under co-digestion.
Project description:Nitrogen (N) emissions became a huge topic under environmental and nutrient concerns in dairy farming. Nitrogen is metabolized in cows as a consequence of feed crude protein digestion which is either recycled or excreted via urine, faeces and/or milk. In dairy cows differences between cows in N-recycling and N-emissions have been postulated. This study investigated 24 Holstein dairy cows in late lactation. The experimental design comprises two dietary groups (low (LP) vs normal (NP) crude protein) and two groups of milk urea content, high (HMU) vs low (LMU). Transcriptomic profiles of the liver, rumen, mammalian gland and kidney tissues were comparatively assessed by mRNA sequencing.
Project description:Laboratory tests with marine flatfish were conducted to investigate associations among gene expression, higher biological responses and wastewater effluent exposure. Previous studies showed molecular responses such as elevated concentrations of plasma estradiol and vitellogenin in wild male hornyhead turbot (Pleuronichthys verticalis). In the present study, male hornyhead turbot were exposed to environmentally realistic (0.5%) and higher (5%) concentrations of chemically enhanced advanced-primary (PL) and full-secondary treated (HTP) effluents from two southern California wastewater treatment plants (WWTP). Hepatic gene expression was examined using a custom low-density microarray. <br><br>