PhD position offer: Understanding redox homeostasis in gasfed purple non-sulfur bacteria for enhanced performance

Job description and scientific context

Securing sustainable food production is imperative, and microbial protein (MP) offers a promising alternative to plant- or animal-derived proteins. The PURPROTEX project, funded by the French ANR, aims to develop and optimize a purple non-sulfur bacteria (PNSB)-based MP production process for the valorization of gaseous streams (H2, CO2, N2, and gaseous organic acids).

PNSB possess unique metabolic flexibility, including anoxygenic photosynthesis, photoheterotrophy, CO2 fixation, and biological nitrogen fixation. While PNSB have been studied as model organisms for bacterial photosynthesis, most research has focused on their photoheterotrophic capabilities and their autotrophic and diazotrophic metabolisms remain poorly understood, particularly regarding how electron allocation and energy distribution affect redox homeostasis, growth rates, and biomass composition.

As part of PhD 1 in PURPROTEX, you will experimentally characterize the metabolic pathways governing redox homeostasis in various specialized PNSB strains, focusing on diazotrophic and autotrophic growth.
You will also evaluate process performance in both batch tests (for screening of operational conditions) and continuous gas-fed photobioreactors.

Key objectives

• Strain benchmarking: Screen and rank specialized PNSB strains for growth rates and biomass yields under autotrophic and diazotrophic conditions under varying light, pH, temperature, and gas compositions.
• Metabolic pathway identification: use of advanced molecular tools to identify essential gene sets governing autotrophy, BNF, CO2 fixation, and redox regulation.
• Continuous estimation of performance indicators: operate state-of-the-art continuous gas-fed photobioreactors to generate dynamic and steady-state KPI datasets.

Specific tasks

• Execute batch strain screening experiments to assess performance across various gas ratios, wavelengths, and light intensities.
• Perform DNA/RNA extraction, mutant library generation, and analysis of sequencing data.
• Set up, operate, and monitor 5-30 L continuous gas-fed photobioreactors under different operational strategies.
• Collect operational data and biomass samples, transferring datasets to project partners for biomass characterization and hybrid model development.

Training and skills

Master's degree/Engineering degree

• Academic background: Master’s degree (or equivalent) in Microbiology, Bioprocess Engineering, Biotechnology, or a related discipline.
• Skills: Hands-on experience with microbial cultivation, bioreactor operation, or molecular biology techniques (e.g., DNA/RNA extraction, sequencing workflows).
• Attributes: self-motivated, rigorous, enthusiastic about experimental problem-solving, and comfortable working both independently and as part of an interdisciplinary team.
• Language: fluent use of English; knowledge of French is an advantage but not required.
• Motivation: the candidate should be enthusiastic and outgoing when searching for solutions to challenges that will arise during the experimental work. The candidate should aim for scientific output in top conferences and scientific journals.

INRAE's life quality

• Cutting-edge research environment: work in a state-of-the-art laboratory equipped with the latest technologies in environmental biotechnology, gas-fed photobioreactor platforms, ATEXcertified gas handling systems, and molecular biology facilities. The equipment is fully shared, so you will have access to all the facilities.
• Mentorship and training: receive guidance from leading experts in the field and access to a comprehensive training program.
• Collaborative network: engage with a dynamic interdisciplinary team spanning microbiology,bioinformatics, bioprocess engineering, and food science across INRAE and international partners.
• Funding and resources: full doctoral contract funding, research support, and dedicated travel budget for international conferences and stays.
• Career development: opportunities for professional growth, including workshops, seminars, and networking events.
• Work atmosphere: Join a supportive, friendly, and dynamic team passionate about driving
  innovative solutions for environmental sustainability.
• Great working conditions: 30 days of annual leave (+ 15 days of time recovery); support for parenting; inexpensive collective catering; flexible schedule; on-site sports facilities; Sunny Mediterranean weather.

Specifically, the PhD student will learn advanced bioprocess engineering, gas-fed photobioreactor operation, omics data analysis, functional genomics, and data-driven bioprocess evaluation. The student will have the continuous support of experienced researchers and engineering technicians.

How to apply

Interested candidates should submit the following documents to gabriel.capson-tojo_at_inrae.fr and laura.alvarez-fraga_at_inrae.fr by September 15th, 2026:

• A detailed CV, including academic achievements and relevant research experience.
• A cover letter outlining your motivation and suitability for the PhD project.

We look forward to receiving your application and welcoming you to our team at INRAE-LBE!