A new chlorophyll d -containing cyanobacterium : evidence for niche adaptation in the genus Acaryochloris

TitleA new chlorophyll d -containing cyanobacterium : evidence for niche adaptation in the genus Acaryochloris
Publication TypeJournal Article
Year of Publication2010
AuthorsMohr R, Schliep M, Kurz T, Maldener I, Adams DG, Larkum ADW, Chen M, Hess WR
JournalThe ISME journal
Pagination1456–1469
Keywordsacaryochloris, chlorophyll d, coral reef, cyanobacteria, microbial diversity, overview, rcc, RCC1983
Abstract

Chlorophyll d is a photosynthetic pigment that, based on chemical analyses, has only recently been recognized to be widespread in oceanic and lacustrine environments. However, the diversity of organisms harbouring this pigment is not known. Until now, the unicellular cyanobacterium Acaryochloris marina is the only characterized organism that uses chlorophyll d as a major photopigment. In this study we describe a new cyanobacterium possessing a high amount of chlorophyll d, which was isolated from waters around Heron Island, Great Barrier Reef (231 260 31.200 S, 1511 540 50.400 E). The 16S ribosomal RNA is 2% divergent from the two previously described isolates of A. marina, which were isolated from waters around the Palau islands (Pacific Ocean) and the Salton Sea lake (California), suggesting that it belongs to a different clade within the genus Acaryochloris. An overview sequence analysis of its genome based on Illumina technology yielded 871 contigs with an accumulated length of 8 371965nt. Their analysis revealed typical features associated with Acaryochloris, such as an extended gene family for chlorophyll-binding proteins. However, compared with A. marina MBIC11017, distinct genetic, morphological and physiological differences were observed. Light saturation is reached at lower light intensities, Chl d/a ratios are less variable with light intensity and the phycobiliprotein phycocyanin is lacking, suggesting that cyanobacteria of the genus Acaryochloris occur in distinct ecotypes. These data characterize Acaryochloris as a niche-adapted cyanobacterium and show that more rigorous attempts are worthwhile to isolate, cultivate and analyse chlorophyll d-containing cyanobacteria for understanding the ecophysiology of these organisms. The

DOI10.1038/ismej.2010.67