Identification and classification of the principal microflora of the sea pineapple Halocynthia roretzi using MALDI biotyping and 16S rRNA analysis

Abstract

Halocynthia roretzi (phylum Cordata), also called ‘sea pineapples’, live in shallow coastal waters and typically feed on plankton and detritus that they filter from seawater. It has been reported that symbiotic microflora associated with H. roretzi act as protective agents that strengthen its immune system or control energy metabolism. This study analyzed the culturable microflora from the coelomic fluid of the sea pineapple using MALDI-biotyping and 16S rRNA sequencing, combining a recent technology with the conventional method of bacteria identification. The MALDI-biotyper enabled the classification of the symbiotic microflora into 5 groups based on the specific patterns of their mass spectrum. The 16S rRNA sequencing was then used to establish the identity of the dominant bacteria in 4 groups, later revealed as 2 groups of Vibrio spp., Shwanella spp. and Bacillus spp. MALDI-biotyping was applied for the identification of microorganisms directly from cultured agar, and, coupled with numerical taxonomic analyses, we determined the major microflora associated with H. roretzi.