Alkalicaulis satelles gen. nov., sp. nov., a novel haloalkaliphile isolated from a laboratory culture cyanobacterium Geitlerinema species and proposals of Maricaulaceae fam. nov., Robiginitomaculaceae fam. nov., Maricaulales ord. nov. and Hyphomonadales ord. nov.

Abstract

A prosthecate bacterial strain, designated G-192T, was isolated from decaying biomass of a haloalkaliphilic cyanobacterium Geitlerinema sp. Z-T0701. The cells were aerobic, Gram-negative, non-endospore-forming and dimorphic, occurring either as sessile bacteria with a characteristic stalk or as motile flagellated cells. The strain utilized a limited range of substrates, mostly peptonaceous, but was able to degrade whole proteins. Growth occurred at 5–46 °C (optimum, 35–40 °C), pH 7.3–10.3 (optimum, pH 8.0–9.0), 0–14 % NaCl (v/w; optimum, 2.0–6.0 %, v/w). The G+C content of the genomic DNA of strain G-192T was 66.8%. Phylogenetic analysis of the 16S rRNA gene sequence revealed that strain G-192T formed a distinct evolutionary lineage within the family Hyphomonadaceae . Strain G-192T showed the highest 16S rRNA sequence similarity to Glycocaulis profundi ZYF765T (95.2%), Oceanicaulis stylophorae GISW-4T (94.2%) and Marinicauda salina WD6-1T (95.5%). The major cellular fatty acids (>5% of the total) were C18:1 ω9c, C18:0 and 11-methyl-C18:1 ω7c. The major polar lipids were glycolipids and phospholipids. The only respiratory quinone was ubiquinone-10 (Q-10). Based on polyphasic results including phylogenomic data, the novel strain could be distinguished from other genera, which suggests that strain G-192T represents a novel species of a new genus, for which the name Alkalicaulis satelles gen. nov., sp. nov. is proposed. The type strain is G-192T (=VKM B-3306T=KCTC 72746T). The strain is the first representative of the stalked bacteria associated with a haloalkaliphilic cyanobacterium. Based on phylogenomic indices and phenotypic data, it is proposed to evolve two novel families Maricaulaceae fam. nov. and Robiginitomaculaceae fam. nov. out of the current family Hyphomonadaceae . In addition, it is proposed to place the first two families in the novel order Maricaulales ord. nov. and novel order Hyphomonadales ord. nov. is proposed to accommodate the family Hyphomonadaceae .

New Alphaproteobacteria Thrive in the Depths of the Ocean with Oxygen Gradient

“…To reduce the problem of limited resolution in the branches of clade c, the alignment used in Figure 5 was extended to NuoD proteins of late branching lineages, such as Hyphomonadaceae and Robiginitomaculum, which are now considered to be sisters rather than part of the related orders of Rhodobacterales and Caulobacterales [13,49]. The MAGs classified in the TMED25 division of Rhizobiales [14], which are abundant in marine metagenomes (Table 2 and [15]), cluster together with Hyphomonadaceae and Robiginitomaculaceae (Figure 5), as expected from the highly derived genomes of these taxa.…”

Diverse aerobic anoxygenic phototrophs synthesize bacteriochlorophyll in oligotrophic rather than copiotrophic conditions, suggesting ecological niche

“…Taken together, Erythrobacteraceae , Sphingomonadaceae , and Sphingosinicellaceae members had typical ovoid to rod‐shaped cells that were motile, whereas a few elongated forms were not. Likely, this differentiated free pelagic species from those that benefited from larger sizes, potentially weaving into mat‐like matrices of cyanobacteria (Kevbrin et al, 2021), or forming associations with filter‐feeding predators such as zebra mussels (Kuzyk et al, 2021). While Erythrobacteraceae had a predominantly orange carotenoid composition, Sphingomonadaceae and Sphingosinicellaceae had similar major yellow presence, where certain additional carotenoids among some members provided a deep brown hue, especially when stimulated with excess organics.…”

Maricaulis alexandrii sp. nov., a novel dimorphic prosthecate and active bioflocculants-bearing bacterium isolated from phycosphere microbiota of laboratory cultured highly-toxic Alexandrium catenella LZT09

“…The genus of Maricaulis was originally derived from the genus Caulobacter within the family Hyphomonadaceae of the order Rhodobacterales, and composed of dimorphic and prosthecate bacteria (Abraham et al 1999;2002). Recently, the genus Maricaulis has been transferred to the newly-proposed family Maricaulaceae in the order Maricaulales by Kevbrin et al (2021). At the time of writing, the genus of Maricaulis contains ve validly named species all isolated from seawater (https://lpsn.dsmz.de/genus/ maricaulis) (Abraham et al 2002).…”