Project description:Polyhydroxyalkanoates (PHAs) are bio-based, biodegradable polyesters that can be produced from organic-rich waste streams using mixed microbial cultures. To maximize PHA production, mixed microbial cultures may be enriched for PHA-producing bacteria with a high storage capacity through the imposition of cyclic, aerobic feast-famine conditions in a sequencing batch reactor (SBR). Though enrichment SBRs have been extensively investigated a bulk solutions-level, little evidence at the proteome level is available to describe the observed SBR behavior to guide future SBR optimization strategies. As such, the purpose of this investigation was to characterize proteome dynamics of a mixed microbial culture in an SBR operated under aerobic feast-famine conditions using fermented dairy manure as the feedstock for PHA production. At the beginning of the SBR cycle, excess PHA precursors were provided to the mixed microbial culture (i.e., feast), after which followed a long duration devoid of exogenous substrate (i.e., famine). Two-dimensional electrophoresis was used to separate protein mixtures during a complete SBR cycle, and proteins of interest were identified.
Project description:Human umbilical cord mesenchymal stem cells (hUC-MSCs) are widely used in cell therapy due to their powerful immunomodulatory and tissue regenerative capabilities. In order to meet the number and quality of cells for clinical applications, we developed a hUC-MSCs culture process based on homemade microcarriers and stirred bioreactors. In this study, the biological properties of hUC-MSCs amplified by planar culture and microcarrier bioreactor systems are systematically compared. It was found that microcarrier-expanded hUC-MSCs had a relatively lower degree of aging, relatively stronger proliferation capacity, and fewer cells stayed in the cell cycle retardation period. At the same time, RNA-seq was used to compare the differences in gene expression between the two cultures, and the pathways and genes related to cell aging were identified. Comparing the transcription levels of these aging-related gene sets can also confirm that cells cultured by microcarrier reactors are more youthful. Results show that our reactor culture method greatly improved the cell proliferation efficiency, while maintaining the basic properties and younger state of stem cells.
