Biology subjects

Gosset, G.

Publications and source records attributed to Gosset, G..

3 recordsLinked to original sources

bioRxiv2024

Sigma factors as potential targets to enhance recombinant protein expression

The transcriptional factors control the expression of many genes and represent an important layer of complexity in cell factories. However, the effect of individual sigma factor deletions from a biomanufacturing perspective has not been addressed. In this contribution, growth and oxygen consumption of E. coli BW25113 strains with individual inactivation of each sigma factor were characterized under various conditions. The deletion of rpoD has been reported to be lethal for E. coli. However, the evaluated rpoD mutant did not exhibit major growth defects in the mineral medium and is explained because the rpoD gene is duplicated in this strain. Recombinant protein was expressed at three different induction levels in a mineral and LB media. The fliA mutant was the best producer in the mineral medium, whereas the rpoD mutant overperformed the other strains in LB medium. This suggest that a lower rpoD gene dosage is positive for the performance of the cell factory in complex medium. In cultures at 20 {degrees}C, the rpoS mutant exhibited the greatest recombinant expression. To our knowledge, this is the first systematic study evaluating the potential of sigma factor deletion for improving recombinant protein production.

microbiology↗

bioRxiv2024

Automated adjustment of metabolic niches enables the control of natural and engineered microbial co-cultures

A lot of attention has been given to the understanding of microbial interactions leading to stable co-cultures, but the resulting technologies have been rarely challenged in dynamic cultivation conditions. In this work, substrate pulsing was performed to promote better control of the metabolic niches corresponding to each species, leading to the continuous co-cultivation of diverse microbial organisms. For this purpose, we used a cell-machine interface relying on automated flow cytometry, allowing to adjust the temporal profile of two metabolic niches according to a rhythm ensuring the successive growth of two species i.e., in our case a yeast and a bacterium. The resulting approach, called Automated Adjustment of Metabolic Niches (AAMN), was successfully employed for stabilizing both cooperative and competitive co-cultures. Additionally, AAMN can be considered as an enabling technology for the deployment of co-cultures in bioprocesses, demonstrated here based on the continuous bioproduction of p-coumaric acid. Taken altogether, the data accumulated suggest that AAMN could be used for a wider range of biological systems, but also to gain fundamental insights about microbial interaction mechanisms.

microbiology↗

bioRxiv2019

Segregostat: A novel concept to control phenotypic diversification dynamics on the example of Gram-negative bacteria

Controlling and managing the degree of phenotypic diversification of microbial populations is a challenging task. This task not only requires detailed knowledge regarding diversification mechanisms but also advances technical setups for the real-time analyses and control of population behavior on single-cell level. In this work, setup, design and operation of the so called segregostat is described which, in contrast to a traditional chemostats, allows the control of phenotypic diversification of microbial populations over time. Two exemplary case studies will be discussed, emphasizing the applicability and versatility of the proposed approach. In detail the phenotypic diversification of Eschericia coli or Pseudomonas putida based on monitoring membrane permeability will be controlled. We show that upon nutrient limitation, cell population tends to diversify into several subpopulations exhibiting distinct phenotypic (non-permeablized and permeablized cells). On-line analysis leads to the determination of the ratio between cells in these two states, which in turn trigger the addition of glucose pulses in order to maintain a pre-defined diversification ratio. These results prove that phenotypic diversification can be controlled by means of defined pulse-frequency modulation within continuously running bioreactor setups. This lays the foundation for systematic studies, not only of phenotypic diversification but also for all processes where dynamics single cell approaches are required, such as synthetic co-culture processes.

microbiology↗