Coastal phytoplankton blooms are frequently followed by successive blooms of heterotrophic bacterial clades. The class Flavobacteriia within the Bacteroidetes has been shown to play an important role in the degradation of high molecular weight substrates that become available in the later stages of such blooms. One of the flavobacterial clades repeatedly observed over the course of several years during phytoplankton blooms off the coast of Helgoland, North Sea, is Vis6. This genus-level clade belongs to the family Cryomorphaceae and has been resistant to cultivation to date. Based on metagenome assembled genomes, comparative 16S rRNA gene sequence analyses and fluorescence in situ hybridization, we here propose a novel candidate genus Abditibacter, comprising three novel species Candidatus Abditibacter vernus, Candidatus Abditibacter forsetii and Candidatus Abditibacter autumni. While the small genomes of the three novel photoheterotrophic species encode highly similar gene repertoires, including genes for degradation of proteins and algal storage polysaccharides such as laminarin, two of them – Ca. A. vernus and Ca. A. forsetii – seem to have a preference for spring blooms, while Ca. A. autumni almost exclusively occurs in late summer and autumn.

沿海浮游植物的开花通常是异养细菌进化枝的连续开花。类Flavobacteriia的内拟杆菌已被证明在成为这样绽放的晚期阶段可利用高分子基质的降解中发挥了重要的作用。Vis6是在数年间反复浮游的黄细菌分支之一，是在北海Helgoland海岸附近的浮游植物开花期间。这种属水平的进化枝属于低温形态科（Cryomorphaceae），迄今对栽培具有抗性。基于元基因组组装的基因组，比较性16S rRNA基因序列分析和原位荧光杂交，我们在这里提出了一个新颖的候选人属Abditibacter，包括三个新种暂定Abditibacter vernus，暂定Abditibacter forsetii和暂定Abditibacter autumni。虽然这三种新的光异养物种的小型基因组编码的基因库非常相似，包括蛋白质降解的基因和藻类贮藏多糖（如层板蛋白），但其中两个是Ca。A. vernus和Ca. A. forsetii –似乎更喜欢春季开花，而Ca. 秋季土壤曲霉几乎只发生在夏末和秋季。