Production of hydroxyectoine with an engineered strain of Methylomicrobium alcaliphilum

Title: Production of hydroxyectoine with an engineered strain of Methylomicrobium alcaliphilum

Abstract:

Methylomicrobium alcaliphilum is a halotolerant methanotroph, which produces ectoine under high salinity conditions. Ectoine is an osmoprotector and protein stabilizer that allows microorganisms to survive at high salt concentrations (up to 9% in the case of M. alcaliphilum) and has a high market price (> 1000 €/kg). Ectoine synthesis is coded in the Ect operon, which also contains a gene annotated as ectoine hydroxylase. However, the protein coded by this gene has been shown to be catalytically inactive. Hydroxyectoine, a derivate of ectoine, is more common among gram-positive halotolerant bacteria and shows additional protective properties including resistance to heat stress. The market prize of hydroxyectoine is 40% higher than that of ectoine, which makes it an interesting product with high added value. Here we integrated a catalytically active ectoine hydroxylase from Pseudomonas stutzeri into the chromosome of M. alcalyphilum. The gene was inserted under the control of the Ect promoter, but separately from the natural Ect operon.

The potential of the modified strain to be used as an industrial producer of hydroxyectoine, using methane as substrate, was tested at pilot scale. One major challenge for the efficient utilization of methane as an industrial feedstock, is its low water solubility, which limits the gas-liquid mass transport. A promising bioreactor configuration are Taylor flow reactors, in which elongated gas bubbles circulate in capillary tubes. Using Taylor flow systems, we were able to obtain hydroxyectoine concentrations over 100 mg per gram of dry cellular weight. These results open the way to the utilization of methane as a feedstock for the production of high value chemicals.

Audience Take Away Notes:

• Researchers will get familiar with the potential of methane as a feedstock for industrial biotechnology
• Our research will be of interest for microbiologists interested in methanotrophs and halotolerant microorganisms
• Researchers working in the field of gas fermentation will be introduced to the use of Taylor

Biography:

Dr. Bordel studied Chemical Engineering at the University of Valladolid (Spain) and graduated as MS in 2003. He received his PhD degree in 2007 at the same institution. He was a Postdoc (for two years) and an assistant professor (for four years) at the Chalmers University of Technology (Sweden), where he worked at the Systems Biology group, led by Professor Jens Nielsen. where he specialized in Genome Scale Metabolic Models. After three years working in industry (ThermoFisher scientific), he came back to the University of Valladolid in 2017, with a Marie Curie individual fellowship. From the mentioned date he focused his research on the metabolism of methanotrophs. Sergio Bordel has currently published 62 peer reviewed articles: 62 and has an h-factor of 25.