Pricia antarctica gen. nov., sp. nov., a member of the family Flavobacteriaceae, isolated from Antarctic intertidal sediment

Identification and expression of MarCE, a marine carboxylesterase with synthetic ester-degrading activity

Carboxylic ester hydrolases with the capacity to degrade polyesters are currently highly sought after for their potential use in the biological degradation of PET and other chemically synthesized polymers. Here, we describe MarCE, a carboxylesterase family protein identified via genome mining of a Maribacter sp. isolate from the marine sponge Stelligera stuposa. Based on phylogenetic analysis, MarCE and its closest relatives belong to marine-associated genera from the Cytophaga-Flavobacterium-Bacteroides taxonomic group and appear evolutionarily distinct to any homologous carboxylesterases that have been studied to date in terms of structure or function. Molecular docking revealed putative binding of BHET, a short-chain PET derivative, onto the predicted MarCE three-dimensional structure. The synthetic ester-degrading activity of MarCE was subsequently confirmed by MarCE-mediated hydrolysis of 2 mM BHET substrate, indicated by the release of its breakdown products MHET and TPA, which were measured, respectively, as 1.28 and 0.12 mM following 2-h incubation at 30°C. The findings of this study provide further insight into marine carboxylic ester hydrolases, which have the potential to display unique functional plasticity resulting from their adaptation to complex and fluctuating marine environmentsw.

Genomic and phenotypic characterization of 26 novel marine bacterial strains with relevant biogeochemical roles and widespread presence across the global ocean

Prokaryotes dominate global oceans and shape biogeochemical cycles, yet most taxa remain uncultured and uncharacterized as of today. Here we present the characterization of 26 novel marine bacterial strains from a large isolate collection obtained from Blanes Bay (NW Mediterranean) microcosm experiments made in the four seasons. Morphological, cultural, biochemical, physiological, nutritional, genomic, and phylogenomic analyses were used to characterize and phylogenetically place the novel isolates. The strains represent 23 novel bacterial species and six novel genera: three novel species pertaining to class Alphaproteobacteria (families Rhodobacteraceae and Sphingomonadaceae), six novel species and three new genera from class Gammaproteobacteria (families Algiphilaceae, Salinispheraceae, and Alteromonadaceae), 13 novel species and three novel genera from class Bacteroidia (family Flavobacteriaceae), and one new species from class Rhodothermia (family Rubricoccaceae). The bacteria described here have potentially relevant roles in the cycles of carbon (e.g., carbon fixation or energy production via proteorhodopsin), nitrogen (e.g., denitrification or use of urea), sulfur (oxidation of sulfur compounds), phosphorus (acquisition and use of different forms of phosphorus and remodeling of membrane phospholipids), and hydrogen (oxidation of hydrogen to obtain energy). We mapped the genomes of the presented strains to the Tara Oceans metagenomes to reveal that these strains were globally distributed, with those of the family Flavobacteriaceae being the most widespread and abundant, while Rhodothermia being the rarest and most localized. While molecular-only approaches are also important, our study stresses the importance of culturing as a powerful tool to further understand the functioning of marine bacterial communities.

Metagenomic analysis of carbohydrate-active enzymes and their contribution to marine sediment biodiversity

Marine sediments constitute the world's most substantial long-term carbon repository. The microorganisms dwelling in these sediments mediate the transformation of fixed oceanic carbon, but their contribution to the carbon cycle is not fully understood. Previous culture-independent investigations into sedimentary microorganisms have underscored the significance of carbohydrates in the carbon cycle. In this study, we employ a metagenomic methodology to investigate the distribution and abundance of carbohydrate-active enzymes (CAZymes) in 37 marine sediments sites. These sediments exhibit varying oxygen availability and were isolated in diverse regions worldwide. Our comparative analysis is based on the metabolic potential for oxygen utilisation, derived from genes present in both oxic and anoxic environments. We found that extracellular CAZyme modules targeting the degradation of plant and algal detritus, necromass, and host glycans were abundant across all metagenomic samples. The analysis of these results indicates that the oxic/anoxic conditions not only influence the taxonomic composition of the microbial communities, but also affect the occurrence of CAZyme modules involved in the transformation of necromass, algae and plant detritus. To gain insight into the sediment microbial taxa, we reconstructed metagenome assembled genomes (MAG) and examined the presence of primary extracellular carbohydrate active enzyme (CAZyme) modules. Our findings reveal that the primary CAZyme modules and the CAZyme gene clusters discovered in our metagenomes were prevalent in the Bacteroidia, Gammaproteobacteria, and Alphaproteobacteria classes. We compared those MAGs to organisms from the same taxonomic classes found in soil, and we found that they were similar in its CAZyme repertoire, but the soil MAG contained a more abundant and diverse CAZyme content. Furthermore, the data indicate that abundant classes in our metagenomic samples, namely Alphaproteobacteria, Bacteroidia and Gammaproteobacteria, play a pivotal role in carbohydrate transformation within the initial few metres of the sediments.

Aggregatimonas sangjinii gen. nov., sp. nov., a novel silver nanoparticle synthesizing bacterium belonging to the family Flavobacteriaceae

Microbially synthesized nanoparticles has received increasing attentions owing to the broad applications in biology and medicine. In this study, we report a novel bacterium that biologically generates silver nanoparticles (AgNPs). This bacterium, designated strain F202Z8^T, was isolated from a rusty iron plate found in the intertidal region of Taean, South Korea. The morphological, biochemical and molecular characteristics predicted that strain F202Z8^T belongs to the family Flavobacteriaceae. Phylogenetic analysis based on 16S rRNA gene sequence revealed that strain F202Z8^T forms a distinct lineage with closely related genera Maribacter, Pelagihabitans, Pseudozobellia, Zobellia, Pricia, and Costertonia and showed the highest similarity to Maribacter aestuarii GY20^T (94.5%). The digital DNA-DNA hybridization and average nucleotide identity values calculated from the whole genome-sequence comparison between strain F202Z8^T and other members of the family Flavobacteriaceae were in the ranges of 12.7%-16.9% and 70.3%-74.4%, respectively, suggesting that strain F202Z8^T represented a novel genus. The complete genome sequence of strain F202Z8^T is 4,723,614 bp, with 43.26% G + C content. Based on the COG, GO, KEGG, NR, and Swiss-Prot databases, the genomic analysis of F202Z8^T revealed the presence of 17 putative genes responsible for the synthesis of AgNPs. Our polyphasic taxonomic results suggested that this strain represents a novel species of a novel genus in the family Flavobacteriaceae, for which the name Aggregatimonas sangjinii gen. nov., sp. nov. is proposed. The type strain of Aggregatimonas sangjinii is F202Z8^T (= KCCM 43411^T = LMG 31494^T). Overall, our data provide fundamental information to potentially utilize this novel bacterium for synthesis of nanoparticles.

Description of Aureibaculum luteum sp. nov. and Aureibaculum flavum sp. nov. isolated from Antarctic intertidal sediments

Two Gram-stain-negative, aerobic, non-motile, and rod-shaped bacterial strains, designated SM1352^T and A20^T, were isolated from intertidal sediments collected from King George Island, Antarctic. They shared 99.8% 16S rRNA gene sequence similarity with each other and had the highest sequence similarity of 98.1% to type strain of Aureibaculum marinum but < 93.4% sequence similarity to those of other known bacterial species. The genomes of strains SM1352^T and A20^T consisted of 5,108,092 bp and 4,772,071 bp, respectively, with the G + C contents both being 32.0%. They respectively encoded 4360 (including 37 tRNAs and 6 rRNAs) and 4032 (including 36 tRNAs and 5 rRNAs) genes. In the phylogenetic trees based on 16S rRNA gene and single-copy orthologous clusters (OCs), both strains clustered with Aureibaculum marinum and together formed a separate branch within the family Flavobacteriaceae. The ANI and DDH values between the two strains and Aureibaculum marinum BH-SD17^T were all below the thresholds for species delineation. The major cellular fatty acids (> 10%) of the two strains included iso-C_15:0, iso-C_15:1 G, iso-C_17:0 3-OH. Their polar lipids predominantly included phosphatidylethanolamine, one unidentified aminophospholipid, one unidentified aminolipid, and two unidentified lipids. Genomic comparison revealed that both strains possessed much more glycoside hydrolases and sulfatase-rich polysaccharide utilization loci (PULs) than Aureibaculum marinum BH-SD17^T. Based on the above polyphasic evidences, strains SM1352^T and A20^T represent two novel species within the genus Aureibaculum, for which the names Aureibaculum luteum sp. nov. and Aureibaculum flavum sp. nov. are proposed. The type strains are SM1352^T (= CCTCC AB 2014243 ^T = JCM 30335 ^T) and A20^T (= CCTCC AB 2020370 ^T = KCTC 82503 ^T), respectively.

Extremophiles in Soil Communities of Former Copper Mining Sites of the East Harz Region (Germany) Reflected by Re-Analyzed 16S rRNA Data

The east and southeast rim of Harz mountains (Germany) are marked by a high density of former copper mining places dating back from the late 20th century to the middle age. A set of 18 soil samples from pre- and early industrial mining places and one sample from an industrial mine dump have been selected for investigation by 16S rRNA and compared with six samples from non-mining areas. Although most of the soil samples from the old mines show pH values around 7, RNA profiling reflects many operational taxonomical units (OTUs) belonging to acidophilic genera. For some of these OTUs, similarities were found with their abundances in the comparative samples, while others show significant differences. In addition to pH-dependent bacteria, thermophilic, psychrophilic, and halophilic types were observed. Among these OTUs, several DNA sequences are related to bacteria which are reported to show the ability to metabolize special substrates. Some OTUs absent in comparative samples from limestone substrates, among them Thaumarchaeota were present in the soil group from ancient mines with pH > 7. In contrast, acidophilic types have been found in a sample from a copper slag deposit, e.g., the polymer degrading bacterium Granulicella and Acidicaldus, which is thermophilic, too. Soil samples of the group of pre-industrial mines supplied some less abundant, interesting OTUs as the polymer-degrading Povalibacter and the halophilic Lewinella and Halobacteriovorax. A particularly high number of bacteria (OTUs) which had not been detected in other samples were found at an industrial copper mine dump, among them many halophilic and psychrophilic types. In summary, the results show that soil samples from the ancient copper mining places contain soil bacterial communities that could be a promising source in the search for microorganisms with valuable metabolic capabilities.

Bioprospecting potential of microbial communities in solid waste landfills for novel enzymes through metagenomic approach

Landfills are repository for complex microbial diversity responsible for bio-degradation of solid waste. To elucidate this complexity, samples from three different landfill sites of North India (sample V: Bhalswa near Karnal byepass road, New Delhi, India; sample T: Chandigarh, India and sample S3: Una, H.P., India) were analyzed using metagenomic approach. Selected landfill sites had different geographical location, varied in waste composition, size of landfill and climate zone. For comparison, one sample from high altitude (sample J) having less human interference was taken in this study. The aim of this study was to explore microbial diversity of communities responsible for degradation of landfill. Samples were characterized by 16S rRNA gene sequencing. Data from three landfill sites showed abundance of phylum Proteobacteria while less contaminated sample from high altitude showed abundance of phylum Cholroflexi followed by phylum Proteobacteria. The most abundant genus was unknown suggesting that these landfills could be repository for various novel bacterial communities. Sample T was relatively more active in terms of microbial activity. It was relatively abundant in enzymes responsible for dioxin degradation, styrene degradation, steroid degradation, streptomycin biosynthesis, carbapenem biosynthesis, monobactam biosynthesis, furfural degradation pathways while sample J was predicted to be enriched in plant cell wall degrading enzymes. Co-occurrence analysis revealed presence of complex interaction networks between microbial assemblages responsible for bio-degradation of hydrocarbons. The data provides insights about synergetic interactions and functional interplay between bacterial communities in different landfill sites which could be further exploited to develop an effective bioremediation process.

Ulvibacterium marinum gen. nov., sp. nov., a novel marine bacterium of the family Flavobacteriaceae, isolated from a culture of the green alga Ulva prolifera

A Gram-stain negative, aerobic, rod-shaped, and non-motile bacterium, designated strain CCMM003^T, was isolated from a culture of the green alga Ulva prolifera. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain CCMM003^T belongs to the family Flavobacteriaceae and exhibits a close relationship to Pseudozobellia thermophila DSM 19858^T (92.5%). Optimal growth occurred in the presence of 4% (w/v) NaCl, at pH 7.0 and 30 °C. The polar lipids of strain CCMM003^T consisted of phosphatidylethanolamine and six unidentified lipids. The predominant isoprenoid quinone was MK-6. The major fatty acids were iso-C_15:0, iso-C_15:1 G, iso-C_17:0 3-OH and summed feature 3 (C_16:1ω7c and/or iso-C_15:0 2-OH). The DNA G + C content of strain CCMM003^T calculated on the basis of the genome sequence was 41.2 mol% and the genome size was 5.9 Mbp. On the basis of data from this polyphasic study, strain CCMM003^T is considered to represent a novel genus and species of the family Flavobacteriaceae, for which the name Ulvibacterium marinum gen. nov., sp. nov. is proposed. The type strain is CCMM003^T (= MCCC 1K03244^T =KCTC 52639^T).

Coraliitalea coralii gen. nov., sp. nov., a Marine Bacterium of the Family Flavobacteriaceae Isolated from the Hard Coral Galaxea fascicularis

A polyphasic taxonomic study was performed on a novel strain designated as 04OKA-3-121^T, which was isolated from the hard coral Galaxea fascicularis L. collected at Akajima, Okinawa, Japan. These bacterial cells were observed to be pale-yellow, Gram-stain-negative, strictly aerobic, chemoheterotrophic, non-spore forming, non-motile, and rod-shaped. Phylogenetic analysis based on the 16S rRNA gene sequence revealed that the novel marine isolate is affiliated with the family Flavobacteriaceae of the phylum Bacteroidetes and that it shared the highest (93.6%) sequence similarity with Pseudozobellia thermophila KMM 3531^T. The strain could be phenotypically differentiated from related members of the family Flavobacteriaceae. Major fatty acids of strain 04OKA-3-121^T were iso-C15:0, iso-C15:1 G, and C16:1 ω7c and/or C16:1 ω6c. The DNA G + C content of the strain was determined to be 38.8 mol% and the major respiratory quinone was identified as menaquinone 6 (MK-6). Strain 04OKA-3-121^T had phosphatidylethanolamine, two unidentified aminolipids, and eight unidentified lipids as polar lipids. From the distinct phylogenetic position and combination of genotypic and phenotypic characteristics, the strain is considered to represent a novel genus in the family Flavobacteriaceae, for which the name Coraliitalea coralii gen. nov., sp. nov. is proposed. The type strain of C. coralii gen. nov., sp. nov. is 04OKA-3-121^T (= KCTC 52378^T = NBRC 112329^T).

Changchengzhania lutea gen. nov., sp. nov., a new member of the family Flavobacteriaceae isolated from Antarctic intertidal sediment

A Gram-negative, aerobic, yellow pigmented, non-flagellated, non-gliding, rod-shaped bacterial strain, designated SM1355^T, was isolated from Antarctic intertidal sediment collected near the Chinese Antarctic Great Wall Station. The strain grew at 4-35 °C and with 0.5-7.0 % (w/v) NaCl. It hydrolysed aesculin but didn't reduce nitrate to nitrite. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain SM1355^T formed a distinct phylogenetic lineage within the family Flavobacteriaceae, sharing the highest 16S rRNA gene sequence similarity with Flaviramulus ichthyoenteri (96.3 %) and fairly high sequence similarities (95.0-96.0 %) with over 20 recognized species in eight genera of the family Flavobacteriaceae. The predominant fatty acids were anteiso-C15 : 0, iso-C15 : 0 and iso-C15 : 1 G. The major polar lipids were phosphatidylethanolamine and one unidentified lipid. The genomic DNA G+C content of strain SM1355^T was 36.2 mol%. Based on the results of the polyphasic characterization for strain SM1355^T, it is identified as the representative of a novel species in a new genus of the family Flavobacteriaceae, for which the name Changchengzhania lutea gen. nov., sp. nov. is proposed. The type strain of Changchengzhania lutea is SM1355^T (=JCM 30336^T=CCTCC AB 2014246^T).

Arcticiflavibacter luteus gen. nov., sp. nov., a member of the family Flavobacteriaceae isolated from intertidal sand

A yellow-pigmented, rod-shaped, non-flagellated, aerobic and Gram-reaction-negative bacterium, designated strain SM1212T, was isolated from intertidal sand of Kongsfjorden, Svalbard. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain SM1212T constituted a distinct lineage within the family Flavobacteriaceae. It shared highest 16S rRNA gene sequence similarities with the type strains of Bizionia echini (96.0 %), Lacinutrix jangbogonensis (95.8 %) and Psychroserpens damuponensis (95.7 %) and < 95.6 % sequence similarity with other recognized species in the family Flavobacteriaceae. The strain grew at 4-35 °C and with 0-6.0 % (w/v) NaCl. It hydrolysed gelatin, DNA, starch and Tween 80 but did not reduce nitrate to nitrite. The major cellular fatty acids were anteiso-C15 : 0, iso-C15 : 0, iso-C15 : 1 G, anteiso-C15 : 1 A, iso-C15 : 0 3-OH, C17 : 0 2-OH and iso-C17 : 0 3-OH and the major respiratory quinone was menaquinone MK-6. Polar lipids included phosphatidylethanolamine, one unidentified phospholipid, one unidentified aminophospholipid, three unidentified aminolipids and nine unidentified lipids. The genomic DNA G+C content of strain SM1212T was 36.6 mol%. On the basis of data from this polyphasic study, strain SM1212T represents a novel species in a new genus in the family Flavobacteriaceae, for which the name Arcticiflavibacter luteus gen. nov., sp. nov. is proposed. The type strain of Arcticiflavibacter luteus is SM1212T ( = MCCC 1K00234T = KCTC 32514T).

Aureicoccus marinus gen. nov., sp. nov., a member of the family Flavobacteriaceae , isolated from seawater

A coccoid and amorphous-shaped, non-gliding, proteorhodopsin-containing, yellow bacterium, designated strain SG-18T, was isolated from seawater in the western North Pacific Ocean near Japan. The strain was Gram-stain-negative, obligately aerobic, heterotrophic and oxidase-positive. It hydrolysed aesculin but not DNA, urea, gelatin or agar. Growth occurred in the presence of 1–5 % NaCl, with optimum growth at 2 % NaCl. The strain grew at 15–37 °C with an optimum temperature of 25–30 °C. The DNA G+C content of the genomic DNA of strain SG-18T was 47.0 mol% (HPLC). The predominant isoprenoid quinone was MK-6, and major cellular fatty acids were iso-C15 : 1 G, iso-C15 : 0, iso-C15 : 0 3-OH. Phylogenetic trees generated by using 16S rRNA gene sequences revealed that strain SG-18T belonged to the family Flavobacteriaceae and showed 92.7 % sequence similarity to the most closely related species, Croceitalea eckloniae DOKDO 025T. On the basis of phenotypic and phylogenetic features, strain SG-18T is classified as representing a novel species of a new genus within the family Flavobacteriaceae , for which the name Aureicoccus marinus gen. nov., sp. nov. is proposed. The type strain of the type species is SG-18T ( = NBRC 108814T = KCTC 23967T).