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An executive master's programme thesis from Aalborg University
Book cover


Optimized production and prebiotic uses of sulfonolipids

Author

Term

4. term

Publication year

2026

Submitted on

Pages

129

Abstract

Inflammatory bowel disease (IBD) affects 2.5–3 million people in Europe and involves chronic inflammation of the gastrointestinal tract. Its causes are not fully understood, but both genetic factors and shifts in the gut microbiome (the community of microbes in the gut)—including changes in diversity, sulfur metabolism, and specific bacterial groups—appear important. Modifying the microbiome through diet or prebiotics is therefore a promising approach. Sulfonolipids (Sols) are lipids made by certain bacteria and have been proposed as potential anti-inflammatory compounds, but their production and effects on the microbiome remain unclear. In this study, we optimized Sol production in the bacterium Flavobacterium johnsoniae. A CYE growth medium supplemented with 0.5 g/L cysteate increased biomass and Sol output, and the Sol profile resembled that of the gut-associated genus Alistipes. To test effects on gut microbes, we incubated pooled human stool samples with the extracted lipids. Adding Sols markedly increased hydrogen sulfide (H2S, a sulfur-containing gas produced by some gut microbes), but did not consistently change levels of short-chain fatty acids (SCFAs, beneficial acids formed when microbes break down dietary fiber), as measured by capillary electrophoresis and quantitative NMR. 16S rRNA gene sequencing (a standard way to profile bacterial communities) showed no significant changes in diversity, and quantitative PCR (to count specific bacteria) indicated no effect on the absolute abundance of Alistipes. Overall, Sols can shift microbial metabolism by increasing H2S, but they do not substantially alter microbiome composition or SCFA production under the conditions tested.

Inflammatorisk tarmsygdom (IBD) rammer 2,5–3 millioner mennesker i Europa og er kendetegnet ved kronisk betændelse i mave-tarm-kanalen. Årsagen er ikke fuldt klarlagt, men både genetiske faktorer og ændringer i tarmmikrobiomet (de mange bakterier i tarmen) ser ud til at spille en rolle, herunder ændringer i mangfoldighed, svovlstofskifte og bestemte bakteriegrupper. At påvirke mikrobiomet gennem kost eller præbiotika er derfor en lovende strategi. Sulfonolipider (Sols) er fedtstoffer fra visse bakterier, som er blevet foreslået som potentielle antiinflammatoriske stoffer, men vi ved stadig lidt om, hvordan de dannes, og hvordan de påvirker mikrobiomet. I dette studie optimerede vi dannelsen af Sols i bakterien Flavobacterium johnsoniae. Et CYE-vækstmedie tilsat 0,5 g/L cysteat gav mere biomasse og højere Sol-produktion, og bakterien dannede en Sol-profil, der ligner den hos tarmrelaterede Alistipes. For at teste effekterne på tarmmikrober inkuberede vi samlede (poolede) menneskelige afføringsprøver med de udtrukne lipider. Tilsætning af Sols øgede tydeligt produktionen af hydrogensulfid (H2S, en svovlholdig gas som nogle tarmbakterier danner), men påvirkede ikke konsekvent niveauerne af kortkædede fedtsyrer (SCFA’er, gavnlige syrer som dannes, når bakterier nedbryder kostfibre), målt med kapillærelektroforese og kvantitativ NMR. 16S rRNA-gen sekventering (en standard metode til at kortlægge bakteriesammensætning) viste ingen betydende ændringer i diversiteten, og kvantitativ PCR (en tællemetode for specifikke bakterier) viste ingen effekt på den absolutte mængde af Alistipes. Samlet set kan Sols påvirke mikrobers stofskifte ved at øge H2S, men de ændrer ikke væsentligt mikrobiomets sammensætning eller produktionen af kortkædede fedtsyrer under de testede betingelser.

[This apstract has been rewritten with the help of AI based on the project's original abstract]