Interplay between the microalgae and its symbiont sp. HH091.

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 MZCH 672 and the bacterial isolate 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 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 sp. HH091. Omics analysis exposed T9SS genes: , , , , , , , , and . Besides, genes not considered as the T9SS components but required for gliding motility and protein secretion (, , , , , , , , were also identified at this analysis. A first model of T9SS apparatus of was proposed in a course of this research. Using the combination of fluorescence labeling of sp. HH091, we examined the bacterial colonisation and penetration into the cell wall of the algal host MZCH 672.