AUTHOR=Astafyeva Yekaterina , Gurschke Marno , Streit Wolfgang R. , Krohn Ines 

TITLE=Interplay between the microalgae Micrasterias radians and its symbiont Dyadobacter sp. HH091

JOURNAL=Frontiers in Microbiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.1006609

DOI=10.3389/fmicb.2022.1006609

ISSN=1664-302X

ABSTRACT=<p>Based on previous research, related to detailed insight into mutualistic collaboration of microalga and its microbiome, we established an artificial plant-bacteria system of the microalga <italic>Micrasterias radians</italic> MZCH 672 and the bacterial isolate <italic>Dyadobacter</italic> sp. HH091. The bacteria, affiliated with the phylum Bacteroidota, strongly stimulated growth of the microalga when it was added to axenic algal cultures. For further advances, we studied the isolate HH091 and its interaction with the microalga <italic>M. radians</italic> using transcriptome and extensive genome analyses. The genome of HH091 contains predicted polysaccharide utilizing gene clusters co-working with the type IX secretion system (T9SS) and conceivably involved in the algae-bacteria liaison. Here, we focus on characterizing the mechanism of T9SS, implementing the attachment and invasion of microalga by <italic>Dyadobacter</italic> sp. HH091. Omics analysis exposed T9SS genes: <italic>gldK</italic>, <italic>gldL</italic>, <italic>gldM</italic>, <italic>gldN</italic>, <italic>sprA</italic>, <italic>sprE</italic>, <italic>sprF</italic>, <italic>sprT</italic>, <italic>porU</italic> and <italic>porV</italic>. Besides, <italic>gld</italic> genes not considered as the T9SS components but required for gliding motility and protein secretion (<italic>gldA</italic>, <italic>gldB</italic>, <italic>gldD</italic>, <italic>gldF</italic>, <italic>gldG</italic>, <italic>gldH</italic>, <italic>gldI</italic>, <italic>gldJ)</italic>, were also identified at this analysis. A first model of T9SS apparatus of <italic>Dyadobacter</italic> was proposed in a course of this research. Using the combination of fluorescence labeling of <italic>Dyadobacter</italic> sp. HH091, we examined the bacterial colonisation and penetration into the cell wall of the algal host <italic>M. radians</italic> MZCH 672.</p>