The bacteria that can be grown in the laboratory are only a small fraction of the total diversity that exists in nature. At all levels of bacterial phylogeny, uncultured clades that do not grow on standard media are playing critical roles in cycling carbon, nitrogen, and other elements, synthesizing novel natural products, and impacting the surrounding organisms and environment. While molecular techniques, such as metagenomic sequencing, can provide some information independent of our ability to culture these organisms, it is essentially impossible to learn new gene and pathway functions from pure sequence data. A true understanding of the physiology of these bacteria and their roles in ecology, host health, and natural product production requires their cultivation in the laboratory. Recent advances in growing these species include coculture with other bacteria, recreating the environment in the laboratory, and combining these approaches with microcultivation technology to increase throughput and access rare species. These studies are unraveling the molecular mechanisms of unculturability and are identifying growth factors that promote the growth of previously unculturable organisms. This minireview summarizes the recent discoveries in this area and discusses the potential future of the field.

/pdf/growing-unculturable-bacteria-2sigs455wj.pdf

Growing Unculturable Bacteria

The purpose of this announcement is to effect the valid publication of the following effectively published new names and new combinations under the procedure described in the Bacteriological Code (1990 Revision). Authors and other individuals wishing to have new names and/or combinations included in future lists should send three copies of the pertinent reprint or photocopies thereof, or an electronic copy of the published paper to the IJSEM Editorial Office for confirmation that all of the other requirements for valid publication have been met. It is also a requirement of IJSEM and the ICSP that authors of new species, new subspecies and new combinations provide evidence that types are deposited in two recognized culture collections in two different countries. It should be noted that the date of valid publication of these new names and combinations is the date of publication of this list, not the date of the original publication of the names and combinations. The authors of the new names and combinations are as given below. Inclusion of a name on these lists validates the publication of the name and thereby makes it available in the nomenclature of prokaryotes. The inclusion of a name on this list is not to be construed as taxonomic acceptance of the taxon to which the name is applied. Indeed, some of these names may, in time, be shown to be synonyms, or the organisms may be transferred to another genus, thus necessitating the creation of a new combination.

List of new names and new combinations previously effectively, but not validly, published.

Oxygen minimum zones (OMZs), also known as oceanic dead zones , are widespread oceanographic features currently expanding due to global warming and coastal eutrophication. Although inhospitable to metazoan life, OMZs support a thriving but cryptic microbiota whose combined metabolic activity is intimately connected to nutrient and trace gas cycling within the global ocean. Here we report time-resolved metagenomic analyses of a ubiquitous and abundant but uncultivated OMZ microbe (SUP05) closely related to chemoautotrophic gill symbionts of deep-sea clams and mussels. The SUP05 metagenome harbors a versatile repertoire of genes mediating autotrophic carbon assimilation, sulfur-oxidation and nitrate respiration responsive to a wide range of water column redox states. Thus, SUP05 plays integral roles in shaping nutrient and energy flow within oxygen-deficient oceanic waters via carbon sequestration, sulfide detoxification and biological nitrogen loss with important implications for marine productivity and atmospheric greenhouse control.

Metagenome of a Versatile Chemolithoautotroph from Expanding Oceanic Dead Zones

Bacteriophages from the Inoviridae family (inoviruses) are characterized by their unique morphology, genome content and infection cycle. One of the most striking features of inoviruses is their ability to establish a chronic infection whereby the viral genome resides within the cell in either an exclusively episomal state or integrated into the host chromosome and virions are continuously released without killing the host. To date, a relatively small number of inovirus isolates have been extensively studied, either for biotechnological applications, such as phage display, or because of their effect on the toxicity of known bacterial pathogens including Vibrio cholerae and Neisseria meningitidis. Here, we show that the current 56 members of the Inoviridae family represent a minute fraction of a highly diverse group of inoviruses. Using a machine learning approach leveraging a combination of marker gene and genome features, we identified 10,295 inovirus-like sequences from microbial genomes and metagenomes. Collectively, our results call for reclassification of the current Inoviridae family into a viral order including six distinct proposed families associated with nearly all bacterial phyla across virtually every ecosystem. Putative inoviruses were also detected in several archaeal genomes, suggesting that, collectively, members of this supergroup infect hosts across the domains Bacteria and Archaea. Finally, we identified an expansive diversity of inovirus-encoded toxin-antitoxin and gene expression modulation systems, alongside evidence of both synergistic (CRISPR evasion) and antagonistic (superinfection exclusion) interactions with co-infecting viruses, which we experimentally validated in a Pseudomonas model. Capturing this previously obscured component of the global virosphere may spark new avenues for microbial manipulation approaches and innovative biotechnological applications.

/pdf/cryptic-inoviruses-revealed-as-pervasive-in-bacteria-and-ddttfm3yz7.pdf

Cryptic inoviruses revealed as pervasive in bacteria and archaea across Earth's biomes.

The recognition of a new family of rhodopsins in marine planktonic bacteria, proton-pumping proteorhodopsin, expanded the known phylogenetic range, environmental distribution, and sequence diversit ...

Marine Bacterial and Archaeal Ion-Pumping Rhodopsins: Genetic Diversity, Physiology, and Ecology

A bacterial strain named IMCC1877T was obtained from surface seawater collected near the coast of Deokjeok island (Yellow Sea), using a standard dilution-plating method. The strain was Gram-negative, chemoheterotrophic and facultatively anaerobic, requiring NaCl, and cells were motile rods with a single polar flagellum. Colonies on marine agar were very small (average diameter 0.1 mm). Based on 16S rRNA gene sequences, the most closely related species to strain IMCC1877T was Marinobacterium stanieri (93.7 % sequence similarity to the type strain). Phylogenetic analyses based on 16S rRNA gene sequences showed that this marine isolate belonged to the order Oceanospirillales and formed an independent phyletic line within the clade forming the genus Marinobacterium. The DNA G+C content of the strain was 60.7 mol% and the predominant constituents of the cellular fatty acids were C18 : 1
ω7c (36.6 %), C16 : 1
ω7c and/or iso-C15 : 0 2-OH (26.7 %) and C16 : 0 (24.3 %). Based on the taxonomic data, only a distant relationship could be established between strain IMCC1877T and other Marinobacterium species; the strain therefore represents a novel species of the genus Marinobacterium, for which the name Marinobacterium litorale sp. nov. is proposed. The type strain is IMCC1877T (=KCTC 12756T=LMG 23872T).

Marinobacterium litorale sp. nov. in the order Oceanospirillales.

A Gram-negative, non-motile, chemoheterotrophic, facultatively aerobic, short-rod-shaped bacterium, designated IMCC1097(T), was isolated from coastal seawater (10 m depth) of the East Sea, Korea. The temperature, pH and NaCl ranges for growth were 15-30 degrees C, pH 5.0-10.0 and 1.5-10 % NaCl. The colonies of the strain were very small, having a mean diameter of 0.05 mm. 16S rRNA gene sequence data indicated that the strain was most closely related to genera within the class Gammaproteobacteria. Members of the most closely related genera showed less than 90 % sequence similarity and included Saccharospirillum (89.3 %), Oleiphilus (88.7 %), Reinekea (88.2 %), Alcanivorax (86.4-87.6 %) and Zooshikella (87.6 %), which represent five different families of the order Oceanospirillales. Phylogenetic analyses showed that this marine strain represented a distinct phylogenetic lineage in the order Oceanospirillales and could not be assigned to any of the defined families in the order. The predominant fatty acids were C(16 : 1) omega 7c and/or iso-C(15 : 0) 2-OH, C(18 : 1) omega 7c and C(10 : 0) 3-OH, and the DNA G+C content was 57.9 mol%. These chemotaxonomic properties, together with phenotypic characteristics, served to differentiate the strain from phylogenetically closely related genera. The very low sequence similarities (<90 %) and distant relationships between IMCC1097(T) and members of the order Oceanospirillales suggested that the strain merited classification within a novel genus within a novel family in the order. On the basis of taxonomic evidence collected in this study, a novel genus and species are proposed, Litoricola lipolytica gen. nov., sp. nov., within a new family Litoricolaceae fam. nov. Strain IMCC1097(T) (=KCCM 42360(T) =NBRC 102074(T)) is the type strain of Litoricola lipolytica.

Litoricolaceae fam. nov., to include Litoricola lipolytica gen. nov., sp. nov., a marine bacterium belonging to the order Oceanospirillales.

A marine bacterium, designated IMCC2115T, was isolated from
coastal seawater (Yellow Sea, Korea) using a high throughput cultivation
method based on dilution-to-extinction, and taxonomically investigated. Cells
of the strain formed tiny, beige to off-white colonies and were Gram-stain-negative,
obligately aerobic, chemoheterotrophic, non-motile cocci. Based on 16S rRNA
gene sequence comparisons, the strain was most closely related to the genera Marinimicrobium (92.0–92.4 %) and Microbulbifer (91.6–92.8 %), but phylogenetic
trees showed that the strain formed a distinct phyletic line in the class Gammaproteobacteria adjacent to the OM60 and SAR92 clades. The DNA G+C
content of the strain was 47.8 mol% and the predominant cellular
fatty acids were anteiso-C15 : 0 (67.6 %),
anteiso-C17 : 0 (14.4 %)
and C16 : 0 (6.9 %). The
16S rRNA gene sequence analyses and phenotypic and chemotaxonomic tests allowed
the differentiation of IMCC2115T from other related genera in the
class Gammaproteobacteria. Therefore, strain IMCC2115T (=KCCM
42369T =NBRC 102686T) is proposed as the
representative of a new genus and species, for which the name Porticoccus
litoralis gen. nov., sp. nov. is proposed.

Porticoccus litoralis gen. nov., sp. nov., a gammaproteobacterium isolated from the Yellow Sea.

A marine bacterium designated strain IMCC4074(T) was isolated from surface seawater collected off Incheon Port, the Yellow Sea, and subjected to a polyphasic taxonomy. The strain was Gram-negative, chemoheterotrophic, slightly halophilic, strictly aerobic, and motile rods. Based on 16S rRNA gene sequence comparisons, the strain was most closely related to Marinobacterium litorale KCTC 12756(T) (93.9%) and shared low 16S rRNA gene sequence similarities with members of the genus Marinobacterium (91.8-93.9%) and the genus Neptunomonas (93.4%) in the order Oceanospirillales. Phylogenetic analyses showed that this marine isolate formed an independent phyletic line within the genus Marinobacterium clade. The DNA G+C composition of the strain was 56.0 mol% and the predominant constituents of the cellular fatty acids were C(16:0) (28.0%), C(16:1 )omega7c and/or iso-C(15:0) 2-OH (19.3%), C(18:1 )omega7c (17.8%), and C(17:1) cyclo (12.5%), which differentiated the strain from other Marinobacterium species. Based on the taxonomic data collected in this study, only a distant relationship could be found between strain IMCC4074(T) and other members of the genus Marinobacterium, thus the strain represents a novel species of the genus Marinobacterium, for which the name Marinobacterium marisflavi sp. nov. is proposed. The type strain of Marinobacterium marisflavi is IMCC4074(T) (= KCTC 12757(T) = LMG 23873(T)).

Marinobacterium marisflavi sp. nov., Isolated from a Costal Seawater

Strain IMCC2047 was isolated from the Yellow Sea using dilution-to-extinction culturing. The strain was shown to occupy a distinct phylogenetic position within the Gammaproteobacteria. Here we present the genome sequence of strain IMCC2047, which harbors genes for various metabolic pathways, including proteorhodopsin and ribulose bisphosphate carboxylase.

Hana Kim

Papers

Marinobacterium litorale sp. nov. in the order Oceanospirillales.

Litoricolaceae fam. nov., to include Litoricola lipolytica gen. nov., sp. nov., a marine bacterium belonging to the order Oceanospirillales.

Porticoccus litoralis gen. nov., sp. nov., a gammaproteobacterium isolated from the Yellow Sea.

Marinobacterium marisflavi sp. nov., Isolated from a Costal Seawater

Genome Sequence of Strain IMCC2047, a Novel Marine Member of the Gammaproteobacteria