The planctomycete Stieleria maiorica Mal15T employs stieleriacines to alter the species composition in marine biofilms

Nicolai Kallscheuer,Jörn Petersen,Frank Surup,Birthe Sandargo,Manfred Rohde,Christian Boedeker,Christian Jogler,Pascal Bartling,Marnix H Medema,Sandra Wiegand,Mareike Jogler,Olga Jeske

doi:10.1038/s42003-020-0993-2

Abstract

Bacterial strains of the phylum Planctomycetes occur ubiquitously, but are often found on surfaces of aquatic phototrophs, e.g. alga. Despite slower growth, planctomycetes are not outcompeted by faster-growing bacteria in biofilms on such surfaces; however, strategies allowing them to compensate for slower growth have not yet been investigated. Here, we identified stieleriacines, a class of N-acylated tyrosines produced by the novel planctomycete Stieleria maiorica Mal15T, and analysed their effects on growth of the producing strain and bacterial species likely co-occurring with strain Mal15T. Stieleriacines reduced the lag phase of Mal15T and either stimulated or inhibited biofilm formation of two bacterial competitors, indicating that Mal15T employs stieleriacines to specifically alter microbial biofilm composition. The genetic organisation of the putative stieleriacine biosynthetic cluster in strain Mal15T points towards a functional link of stieleriacine biosynthesis to exopolysaccharide-associated protein sorting and biofilm formation.

Highlights

Bacterial strains of the phylum Planctomycetes occur ubiquitously, but are often found on surfaces of aquatic phototrophs, e.g. alga
Planctomycetes grow rather slowly compared to competing microorganisms occupying the same ecological niche, they are not outcompeted by their natural competitors
The genus belongs to the phylum Planctomycetes, class Planctomycetia, order Pirellulales, family Pirellulaceae

Summary

Introduction

Bacterial strains of the phylum Planctomycetes occur ubiquitously, but are often found on surfaces of aquatic phototrophs, e.g. alga. Surfaces of marine macroscopic phototrophs are nutrientrich ‘oases’, densely packed with all sorts of alluring organic compounds, which can serve as nutrient sources In aquatic environments, such biotic surfaces represent desirable ecological niches and are rapidly occupied by bacterial biofilms[1,2]. Species belonging to the family Pirellulaceae, including the marine model planctomycete Rhodopirellula baltica, switch between different lifestyles, in which they either live as motile free-swimming cells or attach to surfaces[8]. Such a complex lifecycle requires control at additional stages beyond canonical transcription factor-based regulation of gene expression. We inferred a putative biosynthetic pathway based on the genome sequence of strain Mal15T obtained during a detailed characterisation of the novel strain

Methods

Results

Conclusion