Investigating the marine biotin cycle - from microbial interactions to microbial community

• Applicant: Dr. Gerrit Wienhausen
• Subject Area: Microbial Ecology and Applied Microbiology
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 550295176

Biotin is an indispensable coenzyme that is involved in essential metabolic reactions and is therefore vital for all living organisms. Since many organisms cannot synthesize biotin de novo, its occurrence in the marine ecosystem is critical. We therefore hypothesize that individual biotin-prototrophic and desthiobiotin-utilizing bacteria actively share biotin with surrounding microbes and therefore constitute an integral feature of the marine biotin cycle. Desthiobiotin concentrations in various marine ecosystems have been shown to be higher than those of biotin. At the same time, the fraction of desthiobiotin-utilizing cultivated bacteria accounts for up to 20 %. To date, there is no clear explanation to why the precursor of biotin occurs in such high concentrations in the marine environment and why so many marine bacteria encode solely bioB, while the remaining biotin pathway is absent. However, several lines of evidence suggest that iron is critical for the biosynthesis of biotin and that it is directly linked to the release of desthiobiotin. Therefore, we hypothesize that the availability of iron has a direct influence on the conversion of desthiobiotin to biotin and that iron deficiency can lead to a high release of desthiobiotin. By means of cultivation experiments using chemical and molecular biological methods, we would like to investigate this question. Varying bacterial taxonomic groups exhibit variable biotin biosynthesis capabilities. Thus, over time, successions within the bacterioplankton community are likely to lead to a simultaneous shift in bacterial biotin producers and consumers. Consequently, we hypothesize that successions of marine bacterioplankton populations lead to a change in biotin and desthiobiotin concentrations. Therefore, we would like to investigate this pattern by setting up a mesocosm experiment and applying a novel B-vitamin detection method and simultaneous metagenome analysis of the prokaryotic community.

• DFG Programme: Research Grants