Paper accepted: Customized chitooligosaccharide production – controlling their length via engineering of Rhizobial chitin synthases and the choice of expression system

Today, the first paper of Rita Weyer’s doctoral thesis was accepted for publication in the journal “Frontiers in Bioengineering and Biotechnology”. The study builds on previous work done during the doctoral project of Dr. Stefanie Hamer-Timmermann who is now working at the company altona Diagnostics in Hamburg. The bioinformatic part of the work described was performed in collaboration with our doctoral candidate Margareta Hellmann and supported by our post-doctoral researcher Dr. Ratna Singh. The initial work was part of the European research project ChitoBioEngineering, continued in the framework of the NRW graduate school on sustainable batteries, GrEEn. This work was driven by our (and our colleagues’) need for the availability of significant amounts of pure, partially acetylated chitosan oligomers. While these can be produced on small scale by chemical synthesis or enzymatic in vitro modification of chitin or glucosamine oligomers, these methods cannot provide larger amounts, e.g. in gram-scale. This could be achieved using an in vivo cell factory approach in which a chitin oligomer synthase along with a chitin deacetylase gene is expressed in a micro-organism. Such an approach is scalable and can even provide kg amounts, but so far only of a very limited set of chitosan oligomers. In the current paper, we describe the first step in this direction, namely the heterologous expression of different bacterial chitin oligomer synthases in different bacterial hosts. We found that both the gene used and the production organism influence the chain length of the chitin oligomers produced, even allowing us to biotechnologically produce rather pure chitin hexamer. The next step now will be the incorporation of different chitin deacetylase genes to convert the chitin oligomers into defined chitosan oligomers.