Methylocystis suflitae sp. nov., a novel type II methanotrophic bacterium isolated from landfill cover soil.

A bacterial strain, designated NLS-7T, was isolated through enrichment of landfill cover soil in methane-oxidizing conditions. Strain NLS-7T is a Gram-stain negative, non-motile rod, approximately 0.8 µm wide by 1.3 µm long. Phylogenetic analysis based on 16S rRNA gene sequencing places it within the genus Methylocystis, with its closest relatives being M. hirsuta, M. silviterrae and M. rosea, with 99.9, 99.7 and 99.6 % sequence similarity respectively. However, average nucleotide identity and average amino acid identity values below the 95 % threshold compared to all the close relatives and digital DNA-DNA hybridization values between 20.9 and 54.1 % demonstrate that strain NLS-7T represents a novel species. Genome sequencing generated 4.31 million reads and genome assembly resulted in the generation of 244 contigs with a total assembly length of 3 820 957 bp (N50, 37 735 bp; L50, 34). Genome completeness is 99.5 % with 3.98 % contamination. It is capable of growth on methane and methanol. It grows optimally at 30 °C between pH 6.5 and 7.0. Strain NLS-7T is capable of atmospheric dinitrogen fixation and can use ammonium (as NH4Cl), l-aspartate, l-arginine, yeast extract, nitrate, l-leucine, l-proline, l-methionine, l-lysine and l-alanine as nitrogen sources. The major fatty acids are C18:1 ω8c and C18:1 ω7c. Based upon this polyphasic taxonomic study, strain NLS-7T represents a novel species of the genus Methylocystis, for which the name Methylocystis suflitae sp. nov. is proposed. The type strain is NLS-7T (=ATCC TSD-256T=DSM 112294T). The 16S rRNA gene and genome sequences of strain NLS-7T have been deposited in GenBank under accession numbers ON715489 and GCA_024448135.1, respectively.

The global Microcystis interactome.

Bacteria play key roles in the function and diversity of aquatic systems, but aside from study of specific bloom systems, little is known about the diversity or biogeography of bacteria associated with harmful cyanobacterial blooms (cyanoHABs). CyanoHAB species are known to shape bacterial community composition and to rely on functions provided by the associated bacteria, leading to the hypothesized cyanoHAB interactome, a coevolved community of synergistic and interacting bacteria species, each necessary for the success of the others. Here, we surveyed the microbiome associated with Microcystis aeruginosa during blooms in 12 lakes spanning four continents as an initial test of the hypothesized Microcystis interactome. We predicted that microbiome composition and functional potential would be similar across blooms globally. Our results, as revealed by 16S rRNA sequence similarity, indicate that M. aeruginosa is cosmopolitan in lakes across a 280° longitudinal and 90° latitudinal gradient. The microbiome communities were represented by a wide range of operational taxonomic units and relative abundances. Highly abundant taxa were more related and shared across most sites and did not vary with geographic distance, thus, like Microcystis, revealing no evidence for dispersal limitation. High phylogenetic relatedness, both within and across lakes, indicates that microbiome bacteria with similar functional potential were associated with all blooms. While Microcystis and the microbiome bacteria shared many genes, whole-community metagenomic analysis revealed a suite of biochemical pathways that could be considered complementary. Our results demonstrate a high degree of similarity across global Microcystis blooms, thereby providing initial support for the hypothesized Microcystis interactome.

Sphingobacterium puteale sp. nov., isolated from a deep subsurface aquifer.

A bacterial strain M05W1-28T was isolated from a well that collected water for irrigation from a deep aquifer at a depth of 400 m. Cells were observed to be rod-shaped, non-motile, aerobic, stained Gram-negative. Optimal growth was obtained at pH 7.0 (range: 6.0-9.0), 28 °C (range: 15-37 °C) and 0 % NaCl (range: 0-1.5 %, w/v) in modified tryptic soy broth (mTSB) without added NaCl and R2A. The cells were found to be positive for catalase and oxidase activities. The major fatty acids (>10 %) were identified as summed feature 3 (C16 : 1 ω7c / C16 : 1 ω6c) and iso-C15 : 0. The major polar lipids were phosphatidylethanolamine, glycolipid, phosphoglycolipids, phospholipids, and unidentified lipids. The major respiratory quinone was menaquinone-7 (MK-7). The genomic G+C content of strain M05W1-28T was 40.7 %. Based on similarities of 16S rRNA gene sequences, strain M05W1-28T was affiliated with the genus Sphingobacterium, exhibiting the highest sequence similarities with S. multivorum LMG 8342T (97.5 %), S. ginsenosidimutans THG07T (97.1 %) and less than 97.0 % to other members of the genus. The average nucleotide identity (ANI) and digital DNA-DNA hybridisation values (dDDH) between M05W1-28T and S. multivorum LMG 8342T were 78.1 and 22.5 %, respectively. Phenotypic characteristics including enzyme activities and carbon source utilisation differentiated the strain from other Sphingobacterium species. The phenotypic, chemotaxonomic and phylogenetic properties suggested that strain M05W1-28T represented a novel species within the genus Sphingobacterium, for which the name Sphingobacterium puteale sp. nov. is proposed. The type strain is M05W1-28T (=CGMCC 1.13711T=KCTC 72027T).

Flavobacterium cyanobacteriorum sp. nov., isolated from cyanobacterial aggregates in a eutrophic lake.

A Gram-reaction-negative, aerobic, non-flagellated, non-gliding, rod-shaped and yellow-pigmented bacterium, designated strain TH021T, was isolated from cyanobacterial aggregates in a eutrophic lake, Taihu Lake, China. Optimal growth occurred at pH 7.0 (range: 5.0-10.0), 28 °C (range, 4-32 °C) and 0 % (w/v) NaCl (range, 0-1.0 %) in Reasoner's 2A broth. No growth was observed at 37 °C. The cells were found to be positive for oxidase and catalase activities. The major respiratory quinone was menaquinone-6. The major fatty acids (>10 %) were identified as iso-C15 : 0 and C16 : 1ω7c/C16 : 1ω6c. The major polar lipid was phosphatidylethanolamine. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the isolate was affiliated with the genus Flavobacterium, with the highest sequence similarity found to Flavobacterium hauense BX12T (94.92 %), followed by Flavobacterium suzhouense XIN-1T (94.85 %), Flavobacterium arcticum SM1502T (94.79 %) and Flavobacterium beibuense F44-8T (94.30 %). The genomic G+C content of strain TH021T was 41.9 mol% based on total genome calculations. Average nucleotide identities and digital DNA-DNA hybridizations values for complete genomes ranged from 69.4 to 72.8 and 18.0 to 23.8 % between strain TH021T and strains within the genus Flavobacterium. The phenotypic, chemotaxonomic and phylogenetic properties, and genome analysis suggested that strain TH021T represents a novel species within the genus Flavobacterium, for which the name Flavobacterium cyanobacteriorum sp. nov. is proposed. The type strain is TH021T (=LMG 29720T=CGMCC 1.16325T).

Niveispirillum lacus sp. nov., isolated from cyanobacterial aggregates in a eutrophic lake.

A bacterial strain, 1-14T, was isolated from cyanobacterial aggregates in a eutrophic lake, Taihu Lake, China. Cells were observed to be slightly curved, rod-shaped, aerobic and Gram-stain-negative. Optimal growth occurred at pH 7.0 (range: 5.0-9.0), 28 °C (range: 20-32 °C) and 0 % (w/v) NaCl (range: 0-1.0 %) in R2A broth. No growth is observed at 37 °C. The cells were found to be positive for oxidase and catalase activities. The major respiratory quinone was ubiquinone Q-10. The major fatty acids (>10 %) were identified as C18 : 1ω6c/C18 : 1ω7c, C16 : 0 3-OH and C18 : 1 2-OH. The major polar lipids were found to consist of phosphatidylethanolamine, phosphatidylmonomethylethanolamine, phosphatidylglycerol and phosphatidylcholine. Within the genus Niveispirillum, strain 1-14T was most closely related to Niveispirillum cyanobacteriorum TH16T (98.3 % 16S rRNA gene sequence similarity), followed by Niveispirillum irakense DSM 11586T (97.8 %) and Niveispirillum fermenti CC-LY736T (97.0 %). The genomic G+C content of strain 1-14T was 62.2 mol% based on total genome calculations. Genes coding for light-harvesting complexes LHI and LHII, and a photosynthetic reaction centre were detected in the genome. Average nucleotide identities and digital DNA-DNA hybridizations for complete genomes ranged from 76.4 to 83.5 and from 21.5 to 27.4 % between strain 1-14T and strains within the genus Niveispirillum. The phenotypic, chemotaxonomic and phylogenetic properties, and genome analysis suggested that strain 1-14T represents a novel species within the genus Niveispirillum, for which the name Niveispirillum lacus sp. nov. is proposed. The type strain is 1-14T (=CGMCC 1.12980T=LMG 28363T).

Sandarakinorhabdus cyanobacteriorum sp. nov., a novel bacterium isolated from cyanobacterial aggregates in a eutrophic lake.

A bacterial strain, designated TH057T, was isolated from cyanobacterial aggregates in a eutrophic lake in China. Cells were observed to be slightly curved, rod-shaped, capsule-forming and stained Gram-negative. Optimal growth was obtained at pH 7.0 (range: pH 5-9) and 30 °C (range: 20-37 °C) in R2A broth. According to the absorption spectrum, carotenoids (455 and 490 nm) and light-harvesting complex LHI (857 nm) were present in the cells. The cells were found to be positive for oxidase and catalase activities. The major respiratory quinone was ubiquinone Q-10. The major fatty acids were identified as C17 : 1ω6c, C16 : 1ω7c/C16 : 1ω6c, C18 : 1ω6c/C18 : 1ω7c and C16 : 0. The major polar lipids were found to consist of phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol, unidentified glycolipid and two sphingoglycolipids. Strain TH057T shared highest 16S rRNA gene sequence similarity to Sandarakinorhabdus limnophila so42T (96.8 %), followed by Polymorphobacter fuscus D40PT (95.8 %). The genomic G+C content of strain TH057T was 66.1 mol% based on total genome calculations. The average nucleotide identity and the digital DNA-DNA hybridization value for the complete genomes were 81.0 and 23.0 % between strain TH057T and Sandarakinorhabdus limnophila so42T. The phenotypic, chemotaxonomic and phylogenetic properties, and genome analysis suggested that strain TH057T represents a novel species within the genus Sandarakinorhabdus, for which the name Sandarakinorhabduscyanobacteriorum sp. nov. is proposed. The type strain is TH057T (=CGMCC 1.15803T=LMG 30294T).

Flavobacterium aurantiibacter sp. nov., an orange-pigmented bacterium isolated from cyanobacterial aggregates in a eutrophic lake.

A bacterial strain, designated TH167T, was isolated from cyanobacterial aggregates in eutrophic Lake Taihu in China. Cells were observed to be slightly curved rod-shaped, motile by gliding, aerobic, Gram-stain-negative, proteorhodopsin-containing. Optimal growth was obtained at pH 7.0 (range: 6.0-9.0), 28 °C (range: 4-32 °C) and 0 % (w/v) NaCl (range: 0-2.0 %) in Reasoner's 2A broth. No growth was observed at 37 °C. The cells were found to be positive for catalase and oxidase activities. The major fatty acids (>10 %) were identified as iso-C15 : 0, iso-C15 : 1 G and anteiso-C15 : 0. The major polar lipids of the isolate comprised phosphatidylethanolamine, one unidentified phospholipid and two unidentified aminolipids. The major respiratory quinone was menaquinone-6. The genomic G+C content of strain TH167T was 40.4 mol% based on total genome calculations. Based on similarities of 16S rRNA gene sequences, strain TH167T was affiliated with the genus Flavobacterium, exhibiting the highest sequence similarities to Flavobacterium eburneum SA31T (94.16 %), Flavobacterium yanchengensehgT (94.09 %) and Flavobacterium lacus NP180T (93.95 %). The phenotypic, chemotaxonomic and phylogenetic properties, and genome analysis suggested that strain TH167T represented a novel species within the genus Flavobacterium, for which the name Flavobacterium aurantiibacter sp. nov. is proposed. The type strain is TH167T (=CGMCC 1.15805T=LMG 29719T).

Elstera cyanobacteriorum sp. nov., a novel bacterium isolated from cyanobacterial aggregates in a eutrophic lake.

A bacterial strain, TH019T, was isolated from cyanobacterial aggregates in a eutrophic lake, Taihu Lake, China. Cells were observed to be slightly curved rod-shaped and stained Gram-negative. Optimal growth was obtained at pH 7.0 (range, 5.0-9.0) and 28 °C (range, 20-37 °C) in R2A broth. The cells were found to be positive for oxidase and catalase activities, nitrate reduction and denitrification. The major respiratory quinone was ubiquinone Q-10. The major fatty acids were identified as C18 : 1 ω6c/C18 : 1 ω7c and C18 : 1 2OH. The 16S rRNA gene sequence of strain TH019T was phylogenetically related to Elstera litoralis Dia-1T (97.9 % similarity). The genomic G+C content of strain TH019T was 62.4 mol% based on total genome calculations. Average nucleotide identity and digital DNA-DNA hybridization values for complete genomes were 78.8 and 19.8 %, respectively, between strain TH019T and Elstera litoralis Dia-1T. The phenotypic, chemotaxonomic and phylogenetic properties, and genome analysis suggested that strain TH019T represented a novel species within the genus Elstera, for which the name Elstera cyanobacteriorum sp. nov. is proposed. The type strain is TH019T (=CGMCC 1.15802T=LMG 29721T).

Interconnection of Key Microbial Functional Genes for Enhanced Benzo[a]pyrene Biodegradation in Sediments by Microbial Electrochemistry.

Sediment microbial fuel cells (SMFCs) can stimulate the degradation of polycyclic aromatic hydrocarbons in sediments, but the mechanism of this process is poorly understood at the microbial functional gene level. Here, the use of SMFC resulted in 92% benzo[a]pyrene (BaP) removal over 970 days relative to 54% in the controls. Sediment functions, microbial community structure, and network interactions were dramatically altered by the SMFC employment. Functional gene analysis showed that c-type cytochrome genes for electron transfer, aromatic degradation genes, and extracellular ligninolytic enzymes involved in lignin degradation were significantly enriched in bulk sediments during SMFC operation. Correspondingly, chemical analysis of the system showed that these genetic changes resulted in increases in the levels of easily oxidizable organic carbon and humic acids which may have resulted in increased BaP bioavailability and increased degradation rates. Tracking microbial functional genes and corresponding organic matter responses should aid mechanistic understanding of BaP enhanced biodegradation by microbial electrochemistry and development of sustainable bioremediation strategies.

Aquidulcibacter paucihalophilus gen. nov., sp. nov., a novel member of family Caulobacteraceae isolated from cyanobacterial aggregates in a eutrophic lake.

A bacterial strain, TH1-2T, was isolated from cyanobacterial aggregates in the eutrophic Lake Taihu, Jiangsu Province, China. Cells were observed to be Gram-negative, slightly curved and rod-shaped. Optimal growth was obtained at pH 7.0 (range 5.5-8.5) and 30 °C (range 20-37 °C) in trypticase soy broth (TSB) without NaCl. Growth was not observed in TSB with 1.0% (w/v) NaCl added. The cells were found to be positive for oxidase and catalase activities. The major fatty acids were identified as 3-hydroxy hexadecanoic acid (C16:0 3-OH), C16:1 ω5c and summed feature 8 (consisting of C18:1 ω6c and cis-11-Octadecenoic acid (C18:1 ω7c). The major polar lipids were identified as diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol. The 16S rRNA gene sequence of strain TH1-2T was found to be phylogenetically related to those of Glycocaulis abyssi MCS 33T and Brevundimonas naejangsanensis BIO-TAS2-2T (90.5 and 90.0% similarity, respectively). The genomic G+C content of strain TH1-2T was 55.6 mol% based on whole genome calculations. Average nucleotide identities (ANI) and the digital DNA-DNA hybridizations (DDH) for complete genomes ranged from 66.84 to 67.32 and 21.3 to 31.8% between strain TH1-2T and type strains within the family Caulobacteraceae, higher than those between strain TH1-2T and the strains within the family Hyphomonadaceae. The phenotypic, chemotaxonomic and phylogenetic properties, and genome analysis, indicate that strain TH1-2T (=CGMCC 1.12979T = LMG 28362T) represents a novel species in a new genus within the family Caulobacteraceae; thus, the name Aquidulcibacter paucihalophilus gen. nov., sp. nov., is proposed.

Niveispirillum cyanobacteriorum sp. nov., a nitrogen-fixing bacterium isolated from cyanobacterial aggregates in a eutrophic lake.

A Gram-stain-negative, slightly curved rod-shaped, non-spore-forming diazotrophic bacterium, designated strain TH16T, was isolated from cyanobacterial aggregates taken from eutrophic Lake Taihu, Jiangsu Province, China. The pH range for growth was 5-9 (optimum at pH 7.0), salinity range was 0-2% (w/v) NaCl (optimum 0%) and temperature range was 20-37 °C (optimum 30 °C) in nutrient broth. Phylogenetic analysis indicated that strain TH16T clusters near and is closely related to the genus Niveispirillum within the family Rhodospirillaceae of the class Alphaproteobacteria. Within the genus Niveispirillum, strain TH16T was related most closely to Niveispirillum irakense KBC1T (98.1% 16S rRNA gene sequence similarity) and Niveispirillum fermenti CC-LY736T (97.0 %). The DNA G+C content of strain TH16T was 64 mol%. DNA-DNA relatedness between strain TH16T and the type strains of N. irakense and N. fermenti was 39.6 and 30.1%, respectively. The major respiratory quinone was ubiquinone Q-10.The major fatty acids (>10%) were C18  :  1ω6c/C18  :  1ω7c, C18  :  1 2-OH and C16  :  0 3-OH. Genes in the puf operon, encoding proteins of the photosynthetic reaction centre and core light-harvesting complexes, were also present. Based on morphological, chemotaxonomic and phylogenetic data, strain TH16T represents a novel species within the genus Niveispirillum, for which the name Niveispirillum cyanobacteriorum sp. nov. is proposed. The type strain is TH16T ( = CGMCC 1.12958T = LMG 28334T).

Aerobic anoxygenic phototrophs play important roles in nutrient cycling within cyanobacterial Microcystis bloom microbiomes.

BACKGROUND: During the bloom season, the colonial cyanobacterium Microcystis forms complex aggregates which include a diverse microbiome within an exopolymer matrix. Early research postulated a simple mutualism existing with bacteria benefitting from the rich source of fixed carbon and Microcystis receiving recycled nutrients. Researchers have since hypothesized that Microcystis aggregates represent a community of synergistic and interacting species, an interactome, each with unique metabolic capabilities that are critical to the growth, maintenance, and demise of Microcystis blooms. Research has also shown that aggregate-associated bacteria are taxonomically different from free-living bacteria in the surrounding water. Moreover, research has identified little overlap in functional potential between Microcystis and members of its microbiome, further supporting the interactome concept. However, we still lack verification of general interaction and know little about the taxa and metabolic pathways supporting nutrient and metabolite cycling within Microcystis aggregates. RESULTS: During a 7-month study of bacterial communities comparing free-living and aggregate-associated bacteria in Lake Taihu, China, we found that aerobic anoxygenic phototrophic (AAP) bacteria were significantly more abundant within Microcystis aggregates than in free-living samples, suggesting a possible functional role for AAP bacteria in overall aggregate community function. We then analyzed gene composition in 102 high-quality metagenome-assembled genomes (MAGs) of bloom-microbiome bacteria from 10 lakes spanning four continents, compared with 12 complete Microcystis genomes which revealed that microbiome bacteria and Microcystis possessed complementary biochemical pathways that could serve in C, N, S, and P cycling. Mapping published transcripts from Microcystis blooms onto a comprehensive AAP and non-AAP bacteria MAG database (226 MAGs) indicated that observed high levels of expression of genes involved in nutrient cycling pathways were in AAP bacteria. CONCLUSIONS: Our results provide strong corroboration of the hypothesized Microcystis interactome and the first evidence that AAP bacteria may play an important role in nutrient cycling within Microcystis aggregate microbiomes. Video Abstract.

Analysis of the attached microbial community on mucilaginous cyanobacterial aggregates in the eutrophic Lake Taihu reveals the importance of Planctomycetes.

The phylogenetic diversity of the microbial community assemblage of the carpet-like mucilaginous cyanobacterial blooms in the eutrophic Lake Taihu was investigated. 16S ribosomal DNA clone libraries produced from the DNA of cyanobacterial assemblages that had been washed to remove unattached bacteria contained only cyanobacteria. However, a further treatment which included grinding the freeze-dried material to physically detach cells followed by the removal of larger cells by filtration allowed us to detect a large variety of bacteria within the cyanobacterial bloom community. Interestingly, the dominant members of the microbial community were Planctomycetes followed by Cytophaga-Flavobacterium-Bacteroides (CFB), Betaproteobacteria, and Gammaproteobacteria. The analysis of the 16S ribosomal DNA clone libraries made from enrichment culture revealed much higher phylogenetic diversity of bacteria. Dominant bacterial groups in the enrichment system were identified as members of the Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, and Deltaproteobacteria subdivisions, CFB group, and Planctomycetes. In addition, the clone libraries constructed from Planctomycetes-specific 16S ribosomal RNA primers also verified that the enrichment allowed a diversity of Planctomycetes to proliferate, although the community composition was altered after enrichment.

Heterogeneity in metal binding by individual fluorescent components in a eutrophic algae-rich lake.

Dissolved organic matter (DOM) affects the toxicity, mobility and bioavailability of metals in aquatic environment. In this study, the interactions between two metals of environmental concern [Cu(II) and Fe(III)] with DOM in a euthrophic algae-rich lake (Lake Taihu, China), including dissolved natural organic matter (NOM) and algal extracellular polymeric substance (EPS), were studied using fluorescence excitation-emission matrix (EEM) quenching titration combined with parallel factor (PARAFAC) analysis. Obvious protein-like peaks were detected in algal EPS matrix, while both protein- and humic-like peaks can be found in NOM. PARAFAC analysis identified four fluorescent components, including one humic-, one tryptophan- and two tyrosine-like components, from 114 EEM samples. It was shown that fluorescent tyrosine- (log K(M) > 5.21) and humic-like substances (log K(M) > 4.84) in NOM fraction exhibited higher metal binding capacities than those in EPS matrix, while algal EPS was characterized with a high metal-tryptophan-like substances affinity (log K(M) > 5.08). Moreover, for the eutrophic algae-rich lakes, fluorescent tryptophan- and humic-like substances were responsible for Cu transportation, whereas the mobility of Fe would be related with the tyrosine-like substances. The results facilitate a further insight into the biogeochemical behaviors of metals in eutrophic algae-rich ecosystems as well as other related aquatic environments.

Microcystis pangenome reveals cryptic diversity within and across morphospecies.

Microcystis, a common harmful algal bloom (HAB) taxon, threatens water supplies and human health, yet species delimitation is contentious in this taxon, leading to challenges in research and management of this threat. Historical and common morphology-based classifications recognize multiple morphospecies, most with variable and diverse ecologies, while DNA sequence-based classifications indicate a single species with multiple ecotypes. To better delimit Microcystis species, we conducted a pangenome analysis of 122 genomes. Core- and non-core gene phylogenetic analyses placed 113 genomes into 23 monophyletic clusters containing at least two genomes. Overall, genome-related indices revealed that Microcystis contains at least 16 putative genospecies. Fifteen genospecies included at least one Microcystis aeruginosa morphospecies, and 10 genospecies included two or more morphospecies. This classification system will enable consistent taxonomic identification of Microcystis and thereby aid in resolving some of the complexities and controversies that have long characterized eco-evolutionary research and management of this important HAB taxon.

[Gene transfer agent--a novel and widespread occurrence mechanism of gene exchange in ocean-a review].

Gene Transfer Agent (GTA) particles are released by bacteria and resemble small, tailed bacteriophages. GTA particles contain small, random pieces of host DNA rather than GTA structural genes or a phage genome. Gene transfer mediated by GTA is efficient and species specific based on knowledge of currently best studied GTAs produced by 4 anaerobes. Genome sequencing projects have revealed a remarkable distribution of GTA gene clusters in the genomes of marine bacterioplankton, implying GTA may be an important mechanism for horizontal gene transfer in ocean. On basis of characterization of the 4 best studied GTAs, this review described GTAs released by numerically dominant marine bacteria, discussed their properties that were important for horizontal gene transfer in ocean, and gave future perspectives to advance GTA research.

Distinct patterns of picocyanobacterial communities in winter and summer in the Chesapeake Bay.

In the Chesapeake Bay, picocyanobacteria were usually 100-fold less abundant in winter than in summer. However, little is known about how picocyanobacterial populations shift between winter and summer in the bay. This is due mainly to undetectable winter picocyanobacterial populations in bacterial 16S rRNA clone libraries. In this study, the winter and summer picocyanobacterial populations in the bay were detected using picocyanobacterium-specific primers and were compared based on the analysis of rRNA internal transcribed spacer sequences. Temperature was found to be the dominant environmental factor controlling picocyanobacterial populations in the Chesapeake Bay. In the summer, marine cluster B Synechococcus dominated the upper bay, while a unique cluster, CB1 (marine cluster A [MC-A] Synechococcus), made up the vast majority in the middle and lower bay. In the winter, the picocyanobacteria shifted to completely different populations. Subclades CB6 and CB7, which belong to MC-A Synechococcus and Cyanobium, respectively, made up the entire winter picocyanobacterial populations in the bay. Interestingly, the winter members in subclade CB6 clustered closely with Synechococcus CC9311, a coastal strain known to have a greater capacity to sense and respond to changing environments than oceanic strains.

Diverse and dynamic populations of cyanobacterial podoviruses in the Chesapeake Bay unveiled through DNA polymerase gene sequences.

Many podoviruses have been isolated which infect marine picocyanobacteria, and they may play a potentially important role in regulating the biomass and population composition of picocyanobacteria. However, little is known about the diversity and population dynamics of autochthonous cyanopodoviruses in marine environments. Using a set of newly designed PCR primers which specifically amplify the DNA pol from cyanopodoviruses, a total of 221 DNA pol sequences were retrieved from eight Chesapeake Bay virioplankton communities collected at different times and locations. All DNA pol sequences clustered with the eight known podoviruses that infect different marine picocyanobacteria, and could be divided into at least 10 different subclusters (I-X). The presence of these cyanopodovirus genotypes based on PCR-amplification of DNA pol gene sequences was supported by the existence of similar DNA pol genotypes with metagenome libraries of Chesapeake Bay virioplankton assemblages. The composition of cyanopodoviruses in the Bay also exhibited distinct winter and summer patterns which were likely related to corresponding seasonal changes in the composition of cyanobacterial populations. Our study suggests that diverse and dynamic populations of cyanopodoviruses are present in the estuarine environment. The PCR method developed in this study provides a specific and sensitive tool to explore the abundance, distribution and phylogenetic diversity of cyanopodoviruses in aquatic environments. Linking the dynamics of host and viral populations in the natural environment is critical to broader characterization of the ecological role of virioplankton within microbial communities.

Draft Genome Sequence of a Cold-Adapted Pseudomonas sp. Strain, BGI-2, Isolated from the Ice of Batura Glacier, Pakistan.

Pseudomonas sp. strain BGI-2 is a psychrotrophic bacterium isolated from the ice of Batura Glacier in the Karakoram mountain range. This strain produces a high yield of exopolysaccharide (EPS) at low temperatures and exhibits high freeze-thaw tolerance. The BGI-2 genome contains 11 EPS-producing genes, which are not found in the closely related Pseudomonas strains.

Genome Sequence of the Proteorhodopsin-Containing Bacterium Flavobacterium sp. Strain TH167, Isolated from Cyanobacterial Aggregates in a Eutrophic Lake.

Flavobacterium is the most abundant group of bacteria within the cyanobacterial aggregates in Lake Taihu, China. Here, we present the genome sequence and annotation of Flavobacterium sp. strain TH167. Genome analysis revealed the presence of a proteorhodopsin-encoding sequence, together with its retinal-producing pathway, indicating a putative photoheterotrophic lifestyle that generates energy from light.