The need to stabilize the bacterial community present in the cultures of the marine diatom Haslea ostrearia

Abstract

Objectives: Haslea ostrearia is a microalgae associated with the marrenine, a blue pigment known for its economic interest when it attaches to oyster gills. Complex to grow under axenic conditions, H. ostrearia probably needs its own bacterial procession to survive. Consequently, this important bacterial presence greatly complicates any study of its ecological, physiological and genomic content. Results: We therefore tested a first approach of a protocol to control the bacterial concentration without killing the microalgae, by growing four H. ostrearia NCC 532 cultures under two culture conditions: two with and two without antibiotic treatment. We also performed a first bacterial identification method by 16S sequencing adapted to the bacterial community of H. ostrearia. The V3V4 16S region allowed precise identification of bacteria present in H. ostrearia culture. An antibiotic treatment was found as necessary to stabilize the bacterial population of the cultures before the DNA extraction.