Algimonas arctica sp. nov., isolated from intertidal sand, and emended description of the genus Algimonas

Acidification decreases microbial community diversity in the Salish Sea, a region with naturally high pCO2

Most literature exploring the biological effects of ocean acidification (OA) has focused on macroscopic organisms and far less is known about how marine microbial communities will respond. Studies of OA and microbial community composition and diversity have examined communities from a limited number of ocean regions where the ambient pH is near or above the global average. At San Juan Island (Salish Sea), a region that experiences naturally low pH (average = 7.8), the picoplankton (cell diameter is 0.2–2μm) community was predicted to show no response to experimental acidification in a three-week mesocosm experiment. Filtered seawater mesocosms were maintained via semicontinuous culturing. Three control mesocosms were maintained at pH 8.05 and three acidified mesocosms were maintained at pH 7.60. Total bacteria was quantified daily with a flow cytometer. Microbial communities were sampled every two days via filtration followed by DNA extraction, 16S rRNA amplification, and MiSeq sequencing. There was no significant difference in total bacteria between pH treatments throughout the experiment. Acidification significantly reduced Shannon’s diversity over time. During the final week of the experiment, acidification resulted in a significant decrease in Shannon’s diversity, Faith’s phylogenetic distance, and Pielous’s Evenness. ANCOM results revealed four bacterial ASVs (amplicon sequence variants), in families Flavobaceriaceae and Hyphomonadaceae that significantly decreased in relative frequency under acidification and two bacterial ASVs, in families Flavobacteriaceae and Alteromonadaceae, that significantly increased under acidification. This is the first OA study on the microbial community of the Salish Sea, a nutrient rich, low pH region, and the first of its kind to report a decrease in both picoplankton richness and evenness with acidification. These findings demonstrate that marine microbial communities that naturally experience acidic conditions are still sensitive to acidification.

Proposal of Litorimonas haliclonae sp. nov., isolated from a marine sponge of the genus Haliclona

A bright-orange-pigmented, Gram-stain-negative, motile, and rod-shaped bacterium, strain MAA42^T, was isolated from a marine sponge of the genus Haliclona, which is in long-time culture in a marine aquarium system at the Justus Liebig University Giessen, Germany. The strain grew at 4-34 °C (optimum 28 °C), in the presence of 0.5-9.5 % (w/v) NaCl (optimum 3.5 %) and at pH 4.5-10.0 (optimum pH 7.5). Strain MAA42^T shared the highest 16S rRNA gene sequence similarity (98.1 %) with the type strain of Litorimonas taeanensis. Sequence similarities to all other closely related type strains were below 97 %. DNA-DNA hybridization of strain MAA42^T with L. taeanensis DSM 22008^T resulted in values of 4.7 % (reciprocal 17.7 %). Major cellular fatty acids of strain MAA42^T were C18 : 1ω7c (66.2 %), C18 : 1 2-OH (17.4 %), and C18 : 0 (14.1 %). Spermidine was predominant in the polyamine pattern, and ubiquinone Q-10 was the major respiratory quinone. The polar lipid profile contained the major compounds phosphatidylglycerol, monoglycosyldiglyceride, three unidentified phospholipids, and one unidentified glycolipid. Glucuronopyranosyldiglyceride was present as a minor compound. The diagnostic diamino acid of the peptidoglycan was meso-diaminopimelic acid. The genomic DNA G+C content was 52.8 mol%. Based on the genotypic, chemotaxonomic, and phenotypic analyses, strain MAA42^T represents a novel species of the genus Litorimonas, for which the name Litorimonas haliclonae is proposed. The type strain is MAA42^T (=CCM 8709^T=CIP 111178^T=LMG 29765^T).