Growth analysis in mixed microbial populations using microscopy coupled with computational approaches
EMSL Project ID
39706
Abstract
Microbial phototroph-heterotroph associations (PHA) are common in nature as they provide basis for many water- and terrestrial-based ecosystems. Metabolic interactions between partners are the foundation of most PHAs, however not much is known about the nature and extent of such interactions. These associations are highly relevant to the DOE mission areas of bioenergy, carbon cycling and sequestration, and contaminant fate and transport. Moreover, engineered PHAs have considerable potential for a wide range of biotechnological applications. To this end, our preliminary results demonstrated that mixed cultures may provide specific solutions to process engineering problems in biofuels production from light and CO2 as well as from light and waste organic carbon. The ultimate goals of studying biological systems interactions are to obtain predictive understanding of how phototroph-heterotroph interactions impart stability and resistance to stress, environmental fitness, and functional efficiency in microbial communities, and detailed understanding of phototroph-heterotroph metabolic interdependency underpinning the efficient harnessing of biofuels production by the means of microbial synthesis. These goals are well aligned with EMSL mission and the specific Focus Topics under Biological Interactions and Dynamics Science Theme. Specifically, our studies integrate: (i) the analysis and reconstruction of intercellular and intracellular networks, especially those networks involved in energy production and carbon sequestration, and (ii) fundamental studies on the source of heterogeneity in cell populations, including heterogeneity in cell composition, function and response to alterations in cell conditions.
To delineate metabolic interactions driving PHAs growth and stability we will use defined binary cultures of physiologically and genetically characterized species belonging to Shewanella, Synechococcus and Cyanothece groups. Metabolic modeling will be one of the important tools to characterize inter-species interactions, synergy, and interdependence in binary cultures. Accounting for and calculating numerically external fluxes of nutrients between cells of phototrophs and heterotrophs growing together will be an absolute necessity to build these models and computationally simulate metabolic processes. However, there are no available methods to quantitatively characterize growth of each member of a mixed culture with sufficient accuracy, especially in high-through-put mode. Our preliminary attempts to use cell-sorting technologies to assess biomass of different species in mixed populations were not successful because of cell aggregation and transformation of cyanobacterial single-cell status to filamentous growth under certain conditions. Furthermore, cell count alone cannot be translated into cell biomass unless total cell volume for each culture is calculated. Therefore, the proposed work is motivated and driven by the ultimate need for quantitative measurements of mixed microbial cultures growth to understand metabolic interaction between metabolically distant but interdependent species using common resources. We will use EMSL imaging and computational resources to develop and then use new high-through-put method for calculating total cell volume for each culture in mixed microbial populations and translation it into biomass dry weight. Additionally, (i) changes in thylakoid membranes architecture as the measure of photosynthesis state in response to changing growth conditions in PHAs and (ii) the nature of cell-cell interactions in unmixed PHAs will be studied by Cryo electron microscopy.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2010-10-01
End Date
2013-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Co-Investigator(s)
Team Members