Metabolic Profiling of Geobacter sulfurreducens during Industrial Bioprocess Scale-Up.
During the industrial scale-up of bioprocesses it is important to establish that the biological system has not changed significantly when moving from small laboratory-scale shake flasks or culturing bottles to an industrially relevant production level. Therefore, during upscaling of biomass production for a range of metal transformations, including the production of biogenic magnetite nanoparticles by Geobacter sulfurreducens, from 100-ml bench-scale to 5-liter fermentors, we applied Fourier transform infrared (FTIR) spectroscopy as a metabolic fingerprinting approach followed by the analysis of bacterial cell extracts by gas chromatography-mass spectrometry (GC-MS) for metabolic profiling. FTIR results clearly differentiated between the phenotypic changes associated with different growth phases as well as the two culturing conditions. Furthermore, the clustering patterns displayed by multivariate analysis were in agreement with the turbidimetric measurements, which displayed an extended lag phase for cells grown in a 5-liter bioreactor (24 h) compared to those grown in 100-ml serum bottles (6 h). GC-MS analysis of the cell extracts demonstrated an overall accumulation of fumarate during the lag phase under both culturing conditions, coinciding with the detected concentrations of oxaloacetate, pyruvate, nicotinamide, and glycerol-3-phosphate being at their lowest levels compared to other growth phases. These metabolites were overlaid onto a metabolic network of G. sulfurreducens, and taking into account the levels of these metabolites throughout the fermentation process, the limited availability of oxaloacetate and nicotinamide would seem to be the main metabolic bottleneck resulting from this scale-up process. Additional metabolite-feeding experiments were carried out to validate the above hypothesis. Nicotinamide supplementation (1 mM) did not display any significant effects on the lag phase of G. sulfurreducens cells grown in the 100-ml serum bottles. However, it significantly improved the growth behavior of cells grown in the 5-liter bioreactor by reducing the lag phase from 24 h to 6 h, while providing higher yield than in the 100-ml serum bottles.
School of Chemistry, Manchester Institute of Biotechnology, University of Manchester, Manchester, United Kingdom.
Howbeer
H
Muhamadali
School of Chemistry, Manchester Institute of Biotechnology, University of Manchester, Manchester, United Kingdom.
Yun
Y
Xu
School of Chemistry, Manchester Institute of Biotechnology, University of Manchester, Manchester, United Kingdom.
David I
DI
Ellis
School of Chemistry, Manchester Institute of Biotechnology, University of Manchester, Manchester, United Kingdom.
J William
JW
Allwood
School of Chemistry, Manchester Institute of Biotechnology, University of Manchester, Manchester, United Kingdom.
Nicholas J W
NJ
Rattray
School of Chemistry, Manchester Institute of Biotechnology, University of Manchester, Manchester, United Kingdom.
Elon
E
Correa
School of Chemistry, Manchester Institute of Biotechnology, University of Manchester, Manchester, United Kingdom.
Haitham
H
Alrabiah
Williamson Research Centre for Molecular Environmental Science, School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Manchester, United Kingdom jon.lloyd@manchester.ac.uk roy.goodacre@manchester.ac.uk.
Jonathan R
JR
Lloyd
School of Chemistry, Manchester Institute of Biotechnology, University of Manchester, Manchester, United Kingdom jon.lloyd@manchester.ac.uk roy.goodacre@manchester.ac.uk.
Royston
R
Goodacre
D019149:Bioreactors / Q000382:microbiology; D005650:Fumarates / Q000378:metabolism; D008401:Gas Chromatography-Mass Spectrometry; D045302:Geobacter / Q000737:chemistry / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D007218:Industrial Microbiology; D055432:Metabolomics; D009536:Niacinamide / Q000378:metabolism; D062907:Oxaloacetic Acid / Q000378:metabolism; D019289:Pyruvic Acid / Q000378:metabolism
D005650:Fumarates; D009536:Niacinamide; D062907:Oxaloacetic Acid; D019289:Pyruvic Acid