Ecological memory of recurrent drought modifies soil processes via changes in soil microbial community.

Climate change is altering the frequency and severity of drought events. Recent evidence indicates that drought may produce legacy effects on soil microbial communities. However, it is unclear whether precedent drought events lead to ecological memory formation, i.e., the capacity of past events to influence current ecosystem response trajectories. Here, we utilize a long-term field experiment in a mountain grassland in central Austria with an experimental layout comparing 10 years of recurrent drought events to a single drought event and ambient conditions. We show that recurrent droughts increase the dissimilarity of microbial communities compared to control and single drought events, and enhance soil multifunctionality during drought (calculated via measurements of potential enzymatic activities, soil nutrients, microbial biomass stoichiometry and belowground net primary productivity). Our results indicate that soil microbial community composition changes in concert with its functioning, with consequences for soil processes. The formation of ecological memory in soil under recurrent drought may enhance the resilience of ecosystem functioning against future drought events.

Phylo-taxogenomics of the genus Tautonia with descriptions of Tautonia marina sp. nov., Tautonia rosea sp. nov., and emended description of the genus.

Four strains of Planctomycetes, (JC636, JC649, JC650T, JC657T) which are all salt and alkali tolerant, pink coloured, with spherical to oval shaped, Gram-stain-negative, non-motile cells were isolated from different regions of Chilika lagoon, India. All strains have obligate requirement for N-acetylglucosamine (NAG) and share highest 16S rRNA gene sequence identity with members of the genus Tautonia (<95%) of the family Isosphaeraceae. The 16S rRNA gene sequence identity between strains was >99.5%. Respiratory quinone for all the strains was MK6. Major fatty acids of all the strains were C18:1ω9c, C16:0 and C18:0. Major polar lipid of the strain JC650T was phosphatidylethanolamine, while, phosphatidylcholine and phosphatidylglycerol for strain JC657T. Spermidine was the only common polyamine for all the four strains. Strains JC657T, JC636 and JC649 shared highest phenotypic similarity along with 100% 16S rRNA gene sequence identity. Strains JC657T, JC636 and JC649 differed from strain JC650T phenotypically, chemotaxonomically and genotypically, thus belong to a different species. The genomic size of strain JC650T and JC657T are 7.06 Mb and 6.96 Mb with DNA G + C content of 63.9 and 62.7 mol%, respectively. Based on phylogenetic, genomic (ANI, AAI, POCP, dDDH), chemotaxonomic, physiological and biochemical characteristics, we conclude that strains JC650T and JC657T (together with strains JC636, JC649) belong to the genus Tautonia and constitute two novel species for which we propose the names Tautonia marina sp. nov., and Tautonia rosea sp. nov., respectively. These two novel species are represented by the type strains JC650T (=KCTC 72177T = NBRC 113885T) and JC657T (=KCTC 72597T = NBRC 113883T) respectively.

"Candidatus Laterigemmans baculatus" gen. nov. sp. nov., the first representative of rod shaped planctomycetes with lateral budding in the family Pirellulaceae.

Two axenic cultures of Planctomycetes were isolated from distinct geographical regions of the east coast of India. The two closely related strains (JC640 and CH01) showed <93.3% 16S rRNA gene sequence identity with members of the genus Roseimaritima followed by Rhodopirellula (<91%). Both strains displayed non-canonical cell morphology of Planctomycetes, such as rod shaped cells with division by lateral budding. Both strains showed crateriform structures on their surfaces and cells lack fimbriae. The genomes have a size of about 5.76 Mb and DNA G+C content of 63.6mol%. Phylogenetic analysis based on 16S rRNA gene sequence and 92 core genes based RAxML phylogenetic tree place both the strains in the family Pirellulaceae and indicated Roseimaritima sediminicola as their closest relative. The AAI and POCP values differentiate both strains from rest of the members of the family Pirellulaceae. The axenic cultures of both strains were able to grow up to 8-10 passages and subsequently the cells became non-viable with pleomorphic shapes. Supported by genomic, phylogenetic and morphological differences, we conclude that both strains belong to a novel genus. However, since the new isolates lost their viability on passaging, we propose the novel genus as "Candidatus Laterigemmans" gen. nov. and the novel species as "Candidatus Laterigemmans baculatus" sp. nov.

Short-Term Exposure to High-Temperature Water Causes a Shift in the Microbiome of the Common Aquarium Sponge Lendenfeldia chondrodes.

Marine sponges harbor diverse microbiomes that contribute to their energetic and metabolic needs. Although numerous studies on sponge microbial diversity exist, relatively few focused on sponge microbial community changes under different sources of environmental stress. In this study, we assess the impact of elevated seawater temperature on the microbiome of cultured Lendenfeldia chondrodes, a coral reef sponge commonly found in marine aquaria. Lendenfeldia chondrodes exhibits high thermal tolerance showing no evidence of tissue damage or bleaching at 5 °C above control water temperature (26 °C). High-throughput sequencing of the bacterial 16S rRNA V4 region revealed a response of the microbiome of L. chondrodes to short-term exposure to elevated seawater temperature. Shifts in abundance and richness of the dominant bacterial phyla found in the microbiome of this species, namely Proteobacteria, Cyanobacteria, Planctomycetes, and Bacteroidetes, characterized this response. The observed resilience of L. chondrodes and the responsiveness of its microbiome to short-term increases in seawater temperature suggest that this holobiont may be capable of acclimating to anthropogenic-driven sublethal environmental stress via a re-accommodation of its associated bacterial community. This sheds a new light on the potential for resilience of some sponges to increasing surface seawater temperatures and associated projected regime shifts in coral reefs.

Additions to the genus Gimesia: description of Gimesia alba sp. nov., Gimesia algae sp. nov., Gimesia aquarii sp. nov., Gimesia aquatilis sp. nov., Gimesia fumaroli sp. nov. and Gimesia panareensis sp. nov., isolated from aquatic habitats of the Northern Hemisphere.

Thirteen novel planctomycetal strains were isolated from five different aquatic sampling locations. These comprise the hydrothermal vent system close to Panarea Island (Italy), a biofilm on the surface of kelp at Monterey Bay (CA, USA), sediment and algae on Mallorca Island (Spain) and Helgoland Island (Germany), as well as a seawater aquarium in Braunschweig, Germany. All strains were shown to belong to the genus Gimesia. Their genomes cover a size range from 7.22 to 8.29 Mb and have a G+C content between 45.1 and 53.7%. All strains are mesophilic (Topt 26-33 °C) with generation times between 12 and 32 h. Analysis of fatty acids yielded palmitic acid (16:0) and a fatty acid with the equivalent chain length of 15.817 as major compounds. While five of the novel strains belong to the already described species Gimesia maris and Gimesia chilikensis, the other strains belong to novel species, for which we propose the names Gimesia alba (type strain Pan241wT = DSM 100744T = LMG 31345T = CECT 9841T = VKM B-3430T), Gimesia algae (type strain Pan161T = CECT 30192T = STH00943T = LMG 29130T), Gimesia aquarii (type strain V144T = DSM 101710T = VKM B-3433T), Gimesia fumaroli (type strain Enr17T = DSM 100710T = VKM B-3429T) and Gimesia panareensis (type strain Enr10T = DSM 100416T = LMG 29082T). STH numbers refer to the Jena Microbial Resource Collection (JMRC).

Paludisphaera soli sp. nov., a new member of the family Isosphaeraceae isolated from high altitude soil in the Western Himalaya.

A novel strain of Planctomycetes, designated JC670T, was isolated from a high altitude (~ 2900 m above sea level) soil sample collected from Garhwal region in the Western Himalaya. Colonies of this strain were observed to be light pink coloured with spherical to oval shaped cells having crateriform structures distributed all over the cell surface. The cells divide by budding. Strain JC670T was found to grow well at pH 7.0 and pH 8.0 and to tolerate up to 2% NaCl (w/v). MK6 was the only respiratory quinone identified. The major fatty acids of strain JC670T were identified as C18:1ω9c, C18:0 and C16:0, and phosphatidylcholine, two unidentified phospholipids and six unidentified lipids are present as the polar lipids. The polyamines putrescine and sym-homospermidine were detected. Strain JC670T shows high 16S rRNA gene sequence identity (95.4%) with Paludisphaera borealis PX4T. The draft genome size of strain JC670T is 7.97 Mb, with G + C content of 70.4 mol%. Based on phylogenetic analyses with the sequences of ninety-two core genes, low dDDH value (20.6%), low gANI (76.8%) and low AAI (69.1%) results, differential chemotaxonomic and physiological properties, strain JC670T (= KCTC 72850T = NBRC 114339T) is recognised as the type strain of a new species of the genus Paludisphaera, for which we propose the name Paludisphaera soli sp. nov.

The planctomycete Stieleria maiorica Mal15T employs stieleriacines to alter the species composition in marine biofilms.

Bacterial strains of the phylum Planctomycetes occur ubiquitously, but are often found on surfaces of aquatic phototrophs, e.g. alga. Despite slower growth, planctomycetes are not outcompeted by faster-growing bacteria in biofilms on such surfaces; however, strategies allowing them to compensate for slower growth have not yet been investigated. Here, we identified stieleriacines, a class of N-acylated tyrosines produced by the novel planctomycete Stieleria maiorica Mal15T, and analysed their effects on growth of the producing strain and bacterial species likely co-occurring with strain Mal15T. Stieleriacines reduced the lag phase of Mal15T and either stimulated or inhibited biofilm formation of two bacterial competitors, indicating that Mal15T employs stieleriacines to specifically alter microbial biofilm composition. The genetic organisation of the putative stieleriacine biosynthetic cluster in strain Mal15T points towards a functional link of stieleriacine biosynthesis to exopolysaccharide-associated protein sorting and biofilm formation.

Gimesia benthica sp. nov., a planctomycete isolated from a deep-sea water sample of the Northwest Indian Ocean.

A Gram-stain-negative, stalked, oval-shaped and budding bacterial strain, designated E7T, was isolated from a deep-sea water sample collected from the Northwest Indian Ocean. The novel strain was strictly aerobic, and catalase- and oxidase-positive. It grew at 6-40 °C (optimum 30 °C) and pH 5.5-8.0 (optimum pH 7.0-7.5). The strain required 0.5-9.0 % (w/v) NaCl (optimum 3.0-5.0 %) for growth. Aesculin, starch, pectin and Tween 20 were hydrolysed. Based on 16S rRNA gene sequence analysis, strain E7T showed the highest similarity with Gimesia maris DSM 8797T (97.5 %). The average nucleotide identity and in silico DNA-DNA hybridization values between strain E7T and G. maris DSM 8797T were 78.0 and 19.3 %, respectively. The predominant cellular fatty acids of strain E7T were C16 : 0 and summed feature 3 (comprising C16 : 1ω7c and/or C16 : 1ω6c). The major respiratory quinone was menaquinone-6 (MK-6) and the major polar lipids were phosphatidylethanolamine (PE), phosphatidylmonomethylethanolamine (PMME), phosphatidyldimethylethanolamine (PDME), phosphatidylcholine (PC) and diphosphatidylglycerol (DPG). The genomic DNA G+C content of strain E7T was 52.8 mol%. On the basis of phylogenetic inference and phenotypic characteristics, it is proposed that strain E7T represents a novel species of the genus Gimesia, for which the name Gimesia benthica sp. nov. is proposed. The type strain is E7T (=CGMCC 1.16119T=KCTC 72737T).

Alienimonas chondri sp. nov., a novel planctomycete isolated from the biofilm of the red alga Chondrus crispus.

The phylum Planctomycetes comprises bacteria with peculiar and very unique characteristics among prokaryotes. In marine environments, macroalgae biofilms are well known for harboring planctomycetal diversity. Here, we describe a novel isolate obtained from the biofilm of the red alga Chondrus crispus collected at a rocky beach in Porto, Portugal. The novel strain LzC2T is motile, rosette-forming with spherical- to ovoid-shaped cells. LzC2T forms magenta- to pinkish-colored colonies in M13 and M14 media. Transmission and scanning electron microscopy observations showed a division by polar and lateral budding. Mother cells are connected to the daughter cells by a tubular neck-like structure. The strain requires salt for growth. Vitamins are not required for growth. Optimal growth occurs from 15 to 30°C and within a pH range from 5.5 to 10.0. Major fatty acids are anteiso-C15:0 (54.2%) and iso-C15:0 (19.5%). Phosphatidylglycerol, diphosphatidylglycerol and an unidentified glycolipid represent the main lipids and menaquinone 6 (MK-6) is the only quinone present. 16S rRNA gene-based phylogenetic analysis supports the affiliation to the phylum Planctomycetes and family Planctomycetaceae, with Alienimonas as the closest relative. Strain LzC2T shares 97% 16S rRNA gene sequence similarity with Alienimonas californiensis. LzC2T has a genome size of 5.3 Mb and a G+C content of 68.3%. Genotypic and phenotypic comparison with the closest relatives strongly suggest that LzC2T (=CECT 30038T=LMG XXXT) is a new species of the genus Alienimonas, for which we propose the name Alienimonas chondri sp. nov., represented by LzC2T as type strain. 16S rRNA gene accession number: GenBank=MN757873.1. Genome accession number: GenBank=WTPX00000000.

Gimesia chilikensis sp. nov., a haloalkali-tolerant planctomycete isolated from Chilika lagoon and emended description of the genus Gimesia.

A Gram-stain-negative, aerobic, non-motile, salt- and alkali-tolerant, pear to oval shaped, rosette-forming, white coloured, bacterium, designated as strain JC646T, was isolated from a sediment sample collected from Chilika lagoon, India. Strain JC646T reproduced through budding, grew well at up to pH 9.0 and tolerated up to 7 % NaCl. Strain JC 646T utilized α-d-glucose, fumarate, lactose, sucrose, fructose, d-galactose, mannose, maltose and d-xylose as carbon sources. Peptone, l-isoleucine, l-serine, l-lysine, l-glutamic acid, l-aspartic acid, dl-threonine and l-glycine were used by the strain as nitrogen sources for growth. The respiratory quinone was MK6. Major fatty acids were C16 : 1 ω7c/C16 : 1 ω6c and C16 : 0. The polar lipids of strain JC646T comprised phosphatidyl-dimethylethanolamine, phosphatidylcholine, diphosphatidylglycerol, an unidentified amino lipid and two unidentified lipids. Strain JC646T had highest (97.3 %) 16S rRNA gene sequence identity to the only species of the genus Gimesia, Gimesia maris DSM 8797T. The genome of strain JC646T was 7.64 Mbp with a DNA G+C content of 53.2 mol%. For the resolution of the phylogenetic congruence of the novel strain, the phylogeny was also reconstructed with the sequences of 92 housekeeping genes. Based on phylogenetic analyses, digital DNA-DNA hybridization (19.0 %), genome average nucleotide identity (74.5 %) and average amino acid identity/percentageof conserved proteins (77 %) results, chemotaxonomic characteristics, and differential physiological properties, strain JC646T is recognized as representing a new species of the genus Gimesia, for which we propose the name Gimesia chilikensis sp. nov. The type strain is JC646T (=KCTC 72175T=NBRC 113881T).

Metatranscriptomic identification of polyamine-transforming bacterioplankton in the Gulf of Mexico.

The importance of short-chained aliphatic polyamines (PAs) to bacterioplankton-mediated carbon and nitrogen cycles has been repeatedly proposed. However, bacterial taxa and genes involved in the transformations of different PA compounds and their potential spatial variations remain unclear. This study collected surface bacterioplankton from nearshore, offshore, and open ocean stations in the Gulf of Mexico and examined how metatranscriptomes responded to additions of three single PA model compounds (i.e. putrescine, spermidine, or spermine). Our data showed an overrepresentation of genes affiliated with γ-glutamylation and spermidine cleavage pathways in metatranscriptomes received PA amendments and the expression level of each pathway varied among different PA compounds and sampling locations. PA-transforming taxa were affiliated with Actinobacteria, Bacteroidetes, Cyanobacteria, Planctomycetes, and Proteobacteria and their relative importance was also compound and location specific. These findings suggest that PAs are transformed via multiple pathways and by a diversity of marine bacterioplankton in the Gulf of Mexico. The relative importance of different PA transforming pathways and composition of functional microbial communities may be regulated by nutrient status of local environments.

Roseimaritima sediminicola sp. nov., a new member of Planctomycetaceae isolated from Chilika lagoon.

Strain JC651T was isolated from a sediment sample collected from Chilika lagoon, which is one of the world's most important brackish water lakes with estuarine characteristics. Colonies of this strain are light pink and cells are Gram-stain negative, spherical to pear shaped and form rosettes. Strain JC651T grows well up to pH 9.0 and tolerates up to 5 % NaCl (w/v). The respiratory quinone is MK6. The detected major fatty acids are C18 : 1 ω9c and C16 : 0. Its polar lipids are diphosphatidylglycerol, an unidentified phospholipid, phosphatidylglycerol and phosphatidylcholine. Strain JC651T shows highest 16S rRNA gene sequence similarity (97.8%) to the type species of the genus Roseimaritima, Roseimaritima ulvae UC8T. The genome size of strain JC651T is 6.2 Mb with a G+C content of 62.4 mol%. For the resolution of the phylogenetic congruence of the novel strain, the phylogeny was also reconstructed with the sequences of 92 core genes. Based on the phylogenetic analyses, low digital DNA-DNA hybridization values (19.5%), low (74.9%) genome average nucleotide identity results, chemotaxonomic characteristics and differential physiological properties, strain JC651T is recognized as a new species of the genus Roseimaritima for which we propose the name Roseimaritima sediminicola sp. nov. The type strain is JC651T (=KCTC 72178T=NBRC 113926T).

Effects of Supplement of Marichromatium gracile YL28 on Water Quality and Microbial Structures in Shrimp Mariculture Ecosystems.

The elevated NH3-N and NO2-N pollution problems in mariculture have raised concerns because they pose threats to animal health and coastal and offshore environments. Supplement of Marichromatium gracile YL28 (YL28) into polluted shrimp rearing water and sediment significantly decreased ammonia and nitrite concentrations, showing that YL28 functioned as a novel safe marine probiotic in the shrimp culture industry. The diversity of aquatic bacteria in the shrimp mariculture ecosystems was studied by sequencing the V4 region of 16S rRNA genes, with respect to additions of YL28 at the low and high concentrations. It was revealed by 16S rRNA sequencing analysis that Proteobacteria, Planctomycete and Bacteroidetes dominated the community (>80% of operational taxonomic units (OTUs)). Up to 41.6% of the predominant bacterial members were placed in the classes Gammaproteobacteria (14%), Deltaproteobacteria (14%), Planctomycetacia (8%) and Alphaproteobacteria (5.6%) while 40% of OTUs belonged to unclassified ones or others, indicating that the considerable bacterial populations were novel in our shrimp mariculture. Bacterial communities were similar between YL28 supplements and control groups (without addition of YL28) revealed by the ß-diversity using PCoA, demonstrating that the additions of YL28 did not disturb the microbiota in shrimp mariculture ecosystems. Instead, the addition of YL28 increased the relative abundance of ammonia-oxidizing and denitrifying bacteria. The quantitative PCR analysis further showed that key genes including nifH and amoA involved in nitrification and nitrate or nitrite reduction significantly increased with YL28 supplementation (p < 0.05). The supplement of YL28 decreased the relative abundance of potential pathogen Vibrio. Together, our studies showed that supplement of YL28 improved the water quality by increasing the relative abundance of ammonia-oxidizing and denitrifying bacteria while the microbial community structure persisted in shrimp mariculture ecosystems.

Three novel Rubripirellula species isolated from plastic particles submerged in the Baltic Sea and the estuary of the river Warnow in northern Germany.

Planctomycetes are a unique and important phylum containing mostly aquatic bacteria, which are often associated with phototrophic surfaces. A complex lifestyle, their potential for the production of bioactive small molecules, their unusual cell biology and a large number of giant and hypothetical genes in their genomes make these microorganisms a fascinating topic for further research. Here, we characterise three novel planctomycetal strains isolated from polystyrene and polyethylene particles that were submerged in the German part of the Baltic Sea and the estuary of the river Warnow. All three strains showed typical planctomycetal traits such as division by polar budding and formation of rosettes. The isolated strains were mesophilic and neutrophilic chemoheterotrophs and reached generation times of 10-25 h during laboratory-scale cultivation. Taxonomically, the three strains belong to the genus Rubripirellula. Based on our analyses all three strains represent novel species, for which we propose the names Rubripirellula amarantea sp. nov., Rubripirellula tenax sp. nov. and Rubripirellula reticaptiva sp. nov. The here characterised strains Pla22T (DSM 102267T = LMG 29691T), Poly51T (DSM 103356T = VKM B-3438T) and Poly59T (DSM 103767T = LMG 29696T) are the respective type strains of these novel species. We also emend the description of the genus Rubripirellula.

100-year-old enigma solved: identification, genomic characterization and biogeography of the yet uncultured Planctomyces bekefii.

The first representative of the phylum Planctomycetes, Planctomyces bekefii, was described nearly one century ago. This morphologically conspicuous freshwater bacterium is a rare example of as-yet-uncultivated prokaryotes with validly published names and unknown identity. We report the results of molecular identification of this elusive bacterium, which was detected in a eutrophic boreal lake in Northern Russia. By using high-performance cell sorting, P. bekefii-like cell rosettes were selectively enriched from lake water. The retrieved 16S rRNA gene sequence was nearly identical to those in dozens of metagenomes assembled from freshwater lakes during cyanobacterial blooms and was phylogenetically placed within a large group of environmental sequences originating from various freshwater habitats worldwide. In contrast, 16S rRNA gene sequence similarity to all currently described members of the order Planctomycetales was only 83%-92%. The metagenome assembled for P. bekefii reached 43% genome coverage and showed the potential for degradation of peptides, pectins, and sulfated polysaccharides. Tracing the seasonal dynamics of P. bekefii by Illumina paired-end sequencing of 16S rRNA gene fragments and by fluorescence in situ hybridization revealed that these bacteria only transiently surpass the detection limit, with a characteristic population peak of up to 104 cells ml-1 following cyanobacterial blooms.

The intestinal microbiota of lake anchovy varies according to sex, body size, and local habitat in Taihu Lake, China.

Lake anchovy (Coilia ectenes taihuensis) is a sedentary, dominant fish species that forms an unmanaged fishery in Taihu Lake, eastern China. The environment and developmental stage of lake anchovy are likely important drivers of their gut microbiome, which is linked to host health and development. To investigate the relationship between the gut microbiome and three defined factors (fish sex, fish body size, and the local habitat), high-throughput sequencing of the 16S ribosomal RNA gene was used to study the microorganisms of 184 fish samples and four water samples collected in Taihu Lake. Four dominant bacterial phyla (Proteobacteria, Firmicutes, Planctomycetes, and Cyanobacteria) were present in all fish samples. We compared the microbial communities of males and females and found that the relative abundance of Corynebacteriaceae was significantly higher in males than in females, while the opposite trend was detected for Sphingomonadaceae. We also discovered that the relative abundance of Firmicutes was positively correlated with fish body size and that the proportions of Proteobacteria and Tenericutes were lower in larger fish than in fish of other sizes. Finally, we found that the difference in microbial richness between eastern and northern Taihu Lake was the most marked. Lake anchovy was rich in Lactobacillus and Clostridium in the eastern site, while those in the northern site had the highest abundance of Sphingomonas and Methylobacterium, suggesting that the local habitat may also influence the intestinal microbiome. These findings will not only help researchers understand the community composition of the intestinal microflora of lake anchovy but also contribute to the protection of fish resources in Lake Taihu and the sustainable use of lake anchovy.

Limnoglobus roseus gen. nov., sp. nov., a novel freshwater planctomycete with a giant genome from the family Gemmataceae.

The family Gemmataceae accommodates aerobic, chemoorganotrophic planctomycetes, which inhabit various freshwater ecosystems, wetlands and soils. Here, we describe a novel member of this family, strain PX52T, which was isolated from a boreal eutrophic lake in Northern Russia. This isolate formed pink-pigmented colonies and was represented by spherical cells that occurred singly, in pairs or aggregates and multiplied by budding. Daughter cells were highly motile. PX52T was an obligate aerobic chemoorganotroph, which utilized various sugars and some heteropolysaccharides. Growth occurred at pH 5.0-7.5 (optimum pH 6.5) and at temperatures between 10 and 30 °C (optimum 20-25 °C). The major fatty acids were C18 : 1É·7c, C18 : 0 and ßOH-C16:0; the major intact polar lipid was trimethylornithine, and the quinone was MK-6. The complete genome of PX52T was 9.38 Mb in size and contained nearly 8000 potential protein-coding genes. Among those were genes encoding a wide repertoire of carbohydrate-active enzymes (CAZymes) including 33 glycoside hydrolases (GH) and 87 glycosyltransferases (GT) affiliated with 17 and 12 CAZy families, respectively. DNA G+C content was 65.6 mol%. PX52T displayed only 86.0-89.8 % 16S rRNA gene sequence similarity to taxonomically described Gemmataceae planctomycetes and differed from them by a number of phenotypic characteristics and by fatty acid composition. We, therefore, propose to classify it as representing a novel genus and species, Limnoglobus roseus gen. nov., sp. nov. The type strain is strain PX52T (=KCTC 72397T=VKM B-3275T).

Planctopirus ephydatiae, a novel Planctomycete isolated from a freshwater sponge.

The microbiome of freshwater sponges is rarely studied, and not a single novel bacterial species has been isolated and subsequently characterized from a freshwater sponge to date. A previous study showed that 14.4% of the microbiome from Ephydatia fluviatilis belong to the phylum Planctomycetes. Therefore, we sampled an Ephydatia sponge from a freshwater lake and employed enrichment techniques targeting bacteria from the phylum Planctomycetes. The obtained strain spb1T was subject to genomic and phenomic characterization and found to represent a novel planctomycetal species proposed as Planctopirus ephydatiae sp. nov. (DSM 106606 = CECT 9866). In the process of differentiating spb1T from its next relative Planctopirus limnophila DSM 3776T, we identified and characterized the first phage - Planctopirus phage vB_PlimS_J1 - infecting planctomycetes that was only mentioned anecdotally before. Interestingly, classical chemotaxonomic methods would have failed to distinguish Planctopirus ephydatiae strain spb1T from Planctopirus limnophila DSM 3776T. Our findings demonstrate and underpin the need for whole genome-based taxonomy to detect and differentiate planctomycetal species.

Mangrove soil as a source for novel xylanase and amylase as determined by cultivation-dependent and cultivation-independent methods.

Xylanase and α-amylase enzymes participate in the degradation of organic matter, acting in hemicellulose and starch mineralization, respectively, and are in high demand for industrial use. Mangroves represent a promising source for bioprospecting enzymes due to their unique characteristics, such as fluctuations in oxic/anoxic conditions and salinity. In this context, the present work aimed to bioprospect xylanases from mangrove soil using cultivation-dependent and cultivation-independent methods. Through screening from a metagenomic library, three potentially xylanolytic clones were obtained and sequenced, and reads were assembled into contigs and annotated. The contig MgrBr135 was affiliated with the Planctomycetaceae family and was one of 30 ORFs selected for subcloning that demonstrated only amylase activity. Through the cultivation method, 38 bacterial isolates with xylanolytic activity were isolated. Isolate 11 showed an enzymatic index of 10.9 using the plate assay method. Isolate 39 achieved an enzyme activity of 0.43 U/mL using the colorimetric method with 3,5-dinitrosalicylic acid. Isolate 39 produced xylanase on culture medium with salinity ranging from 1.25 to 5%. Partial 16S rRNA gene sequencing identified isolates in the Bacillus and Paenibacillus genera. The results of this study highlight the importance of mangroves as an enzyme source and show that bacterial groups can be used for starch and hemicellulose degradation.

Tautonia sociabilis gen. nov., sp. nov., a novel thermotolerant planctomycete, isolated from a 4000 m deep subterranean habitat.

A novel aerobic bacterium, designated as strain GM2012T, was isolated from a microbial mat proliferating under the flow of thermal water dissipating from the wall of a 4000 m deep mine in South Africa. The cells were non-motile cocci, capable of budding, occurred in single or gathered in aggregates. The organism is a strictly aerobic chemoorganoheterotroph, preferring simple sugars and polysaccharides as growth substrates. The optimal growth occurred at 42 °C and pH 7.5-7.7. The predominant fatty acids were palmitate, stearate and oleate. The G+C content of the DNA was 70.1 mol%. The 16S rRNA gene sequence analysis placed strain GM2012T within the family Isosphaeraceae of the order Planctomycetales with 88-89 % sequence identity to Isosphaera pallida, Aquisphaeragiovannonii, Singulisphaera acidiphila, Paludisphaera borealis and Tundrisphaera lichenicola type strains. Based on the genotypic and phenotypic distinctive features of the new strain, we propose a novel genus and species Tautonia sociabilis gen. nov., sp. nov. with the type strain GM2012T (=VKM B-2860,=KCTC 72013).