A novel soluble di-iron monooxygenase from the soil bacterium Solimonas soli.

Soluble di-iron monooxygenase (SDIMO) enzymes enable insertion of oxygen into diverse substrates and play significant roles in biogeochemistry, bioremediation and biocatalysis. An unusual SDIMO was detected in an earlier study in the genome of the soil organism Solimonas soli, but was not characterized. Here, we show that the S. soli SDIMO is part of a new clade, which we define as 'Group 7'; these share a conserved gene organization with alkene monooxygenases but have only low amino acid identity. The S. soli genes (named zmoABCD) could be functionally expressed in Pseudomonas putida KT2440 but not in Escherichia coli TOP10. The recombinants made epoxides from C2 C8 alkenes, preferring small linear alkenes (e.g. propene), but also epoxidating branched, carboxylated and chlorinated substrates. Enzymatic epoxidation of acrylic acid was observed for the first time. ZmoABCD oxidised the organochlorine pollutants vinyl chloride (VC) and cis-1,2-dichloroethene (cDCE), with the release of inorganic chloride from VC but not cDCE. The original host bacterium S. soli could not grow on any alkenes tested but grew well on phenol and n-octane. Further work is needed to link ZmoABCD and the other Group 7 SDIMOs to specific physiological and ecological roles.

Acetylcysteine increases sensitivity of ceftazidime-avibactam-resistant enterobacterales with different enzymatic resistance to ceftazidime-avibactam in vitro and in vivo.

BACKGROUND: Ceftazidime-avibactam (CZA) improves treatment outcomes for infections caused by carbapenem-resistant organisms, but has led to serious bacterial resistance. Acetylcysteine (NAC) is an approved medication that protects the respiratory tract through antioxidant and anti-inflammatory effects. RESULTS: This study found that NAC combined with CZA effectively inhibits the growth of CZA-resistant clinical Enterobacterales strains. The CZA/NAC combination inhibits biofilm formation in vitro and decreases bacterial burden in a mouse thigh infection model. The combination is biocompatible and primarily increases cell membrane permeability to cause bacterial death. CONCLUSIONS: These findings prove that the CZA/NAC combination has potential as a treatment for CZA-resistant Enterobacterales infections.

Dynamic changes in the microbial community in the surface seawater of Jiaozhou Bay after crude oil spills: An in situ microcosm study.

The changes in the composition and structure of microbial communities in Jiaozhou Bay are strongly affected by marine oil pollution, but the outcomes of the microbial responses and effects of dispersant application remain unclear. Herein, we performed an in situ microcosm study to investigate the response of the indigenous microbial community under crude oil alone and combined oil and dispersant treatment in the surface seawater of a semi-enclosed marine area of Jiaozhou Bay. The dynamics of the bacterial classification based on 16s rDNA sequencing were used to assess the changes with the crude oil concentration, dispersant use, and time. The crude oil resulted in a high abundance of the genera Pseudohongiella, Cycloclasticus, Marivita, and C1-B045 from the Gammaproteobacteria and Alphaproteobacteria classes, suggesting for hydrocarbon degradation. However, the dispersant treatment was more advantageous for Pacificibacter, Marivita, and Loktanella. Besides accelerating the rate of bacterial community succession, the dispersants had significantly stronger effects on the structure of the bacterial community and the degradation functions than the oil. A higher dose of oil exposure corresponded to fewer dominant species with a high relative abundance. Our study provides information for screening potential degradation bacteria and assessing the risks that oil spills pose to marine ecosystems.

Enhanced Large-Scale Production of Hahella chejuensis-Derived Prodigiosin and Evaluation of Its Bioactivity.

Prodigiosin as a high-valued compound, which is a microbial secondary metabolite, has the potential for antioxidant and anticancer effects. However, the large-scale production of functionally active Hahella chejuensis-derived prodigiosin by fermentation in a cost-effective manner has yet to be achieved. In the present study, we established carbon source-optimized medium conditions, as well as a procedure for producing prodigiosin by fermentation by culturing H. chejuensis using 10 L and 200 L bioreactors. Our results showed that prodigiosin productivity using 250 ml flasks was higher in the presence of glucose than other carbon sources, including mannose, sucrose, galactose, and fructose, and could be scaled up to 10 L and 200 L batches. Productivity in the glucose (2.5 g/l) culture while maintaining the medium at pH 6.89 during 10 days of cultivation in the 200 L bioreactor was measured and increased more than productivity in the basal culture medium in the absence of glucose. Prodigiosin production from 10 L and 200 L fermentation cultures of H. chejuensis was confirmed by high-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS) analyses for more accurate identification. Finally, the anticancer activity of crude extracted prodigiosin against human cancerous leukemia THP-1 cells was evaluated and confirmed at various concentrations. Conclusively, we demonstrate that culture conditions for H. chejuensis using a bioreactor with various parameters and ethanol-based extraction procedures were optimized to mass-produce the marine bacterium-derived high purity prodigiosin associated with anti-cancer activity.

Single-component near-infrared optogenetic systems for gene transcription regulation.

Near-infrared (NIR) optogenetic systems for transcription regulation are in high demand because NIR light exhibits low phototoxicity, low scattering, and allows combining with probes of visible range. However, available NIR optogenetic systems consist of several protein components of large size and multidomain structure. Here, we engineer single-component NIR systems consisting of evolved photosensory core module of Idiomarina sp. bacterial phytochrome, named iLight, which are smaller and packable in adeno-associated virus. We characterize iLight in vitro and in gene transcription repression in bacterial and gene transcription activation in mammalian cells. Bacterial iLight system shows 115-fold repression of protein production. Comparing to multi-component NIR systems, mammalian iLight system exhibits higher activation of 65-fold in cells and faster 6-fold activation in deep tissues of mice. Neurons transduced with viral-encoded iLight system exhibit 50-fold induction of fluorescent reporter. NIR light-induced neuronal expression of green-light-activatable CheRiff channelrhodopsin causes 20-fold increase of photocurrent and demonstrates efficient spectral multiplexing.

Innovative, ecofriendly biosorbent-biodegrading biofilms for bioremediation of oil- contaminated water.

Immobilization of microorganisms capable of degrading specific contaminants significantly promotes bioremediation processes. In this study, innovative and ecofriendly biosorbent-biodegrading biofilms have been developed in order to remediate oil-contaminated water. This was achieved by immobilizing hydrocarbon-degrading gammaproteobacteria and actinobacteria on biodegradable oil-adsorbing carriers, based on polylactic acid and polycaprolactone electrospun membranes. High capacities for adhesion and proliferation of bacterial cells were observed by scanning electron microscopy. The bioremediation efficiency of the systems, tested on crude oil and quantified by gas chromatography, showed that immobilization increased hydrocarbon biodegradation by up to 23 % compared with free living bacteria. The resulting biosorbent biodegrading biofilms simultaneously adsorbed 100 % of spilled oil and biodegraded more than 66 % over 10 days, with limited environmental dispersion of cells. Biofilm-mediated bioremediation, using eco-friendly supports, is a low-cost, low-impact, versatile tool for bioremediation of aquatic systems.

Bulbimidazoles A-C, Antimicrobial and Cytotoxic Alkanoyl Imidazoles from a Marine Gammaproteobacterium Microbulbifer Species.

Three new alkanoyl imidazoles, designated bulbimidazoles A-C (1-3), were found from the culture extract of the gammaproteobacterium Microbulbifer sp. DC3-6 isolated from a stony coral of the genus Tubastraea. The absolute configuration of the anteiso-methyl substitution in 1 was established to be a mixture of (R)- and (S)-configurations in a ratio of 9:91 by applying the Ohrui-Akasaka method. Compounds 1-3 displayed unique broad-spectrum antimicrobial activity against Gram-positive and -negative bacteria and fungi with MICs ranging from 0.78 to 12.5 µg/mL. They also exhibited cytotoxicity toward P388 murine leukemia cells with IC50 in the micromolar range.

Parahaliea maris sp. nov., isolated from surface seawater and emended description of the genus Parahaliea.

A Gram-stain-negative strictly aerobic, short-rod-shaped, and non-motile bacterial strain designated HSLHS9T was isolated from surface seawater collected from the South China Sea. Strain HSLHS9T could grow at 15-41°C (optimum 28°C), at pH 5.0-9.0 (optimum 6.0-7.0), and in 0-7% (w/v) NaCl (optimum 2-3%). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain HSLHS9T shared high identities with the closely related Parahaliea aestuarii S2-26T (98.6%) and Parahaliea mediterranea 7SM29T (97.8%) and formed a distinct lineage within the genus Parahaliea. Wholegenome sequencing of strain HSLHS9T revealed the size of 4.8 Mbp and DNA G + C content of 61.8 mol%. Strain HSLHS9T shared the digital DNA-DNA hybridization values of 22.4% and 23.0%, and the average nucleotide identities of 79.7% and 79.9%, respectively, with the two type strains above. The predominant cellular fatty acids of the strain were summed feature 8 (C18:1ω6c and/or C18:1ω7c), summed feature 3 (C16:1ω7c and/or C16:1ω6c), C17:1ω8c, and C16:0. The sole isoprenoid quinone was identified as Q-8. The polar lipids were phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, aminolipid, and two glycolipids. Based on taxonomic data obtained in this study, it is suggested that strain HSLHS9T represents a novel species of the genus Parahaliea, for which the name Parahaliea maris sp. nov. is proposed. The type strain is HSLHS9T (= MCCC 1A06717T = KCTC 52307T). An emended description of the genus Parahaliea is also provided.

Volatile Organic Compound Profiling from Postmortem Microbes using Gas Chromatography-Mass Spectrometry.

Volatile organic compounds (VOCs) are by-products of cadaveric decomposition and are responsible for the odor associated with decomposing remains. The direct link between VOC production and individual postmortem microbes has not been well characterized experimentally. The purpose of this study was to profile VOCs released from three postmortem bacterial isolates (Bacillus subtilis, Ignatzschineria indica, I. ureiclastica) using solid-phase microextraction arrow (SPME Arrow) and gas chromatography-mass spectrometry (GC-MS). Species were inoculated in headspace vials on Standard Nutrient Agar and monitored over 5 days at 24°C. Each species exhibited a different VOC profile that included common decomposition VOCs. VOCs exhibited upward or downward temporal trends over time. Ignatzschineria indica produced a large amount of dimethyldisulfide. Other compounds of interest included alcohols, aldehydes, aromatics, and ketones. This provides foundational data to link decomposition odor with specific postmortem microbes to improve understanding of underlying mechanisms for decomposition VOC production.

Corallincola spongiicola sp. nov., isolated from sponge.

A gram-negative, motile, strictly aerobic, and rod-shaped bacterium designated 176GS2-150T was isolated from the sponge Hymeniacidon sinapium. The taxonomic position of the novel isolate was confirmed using the polyphasic approach. Strain 176GS2-150T grew well at 25 °C on marine agar. Based on its 16S rRNA gene sequence, we showed that strain 176GS2-150T belongs to the family Psychromonadaceae and class Gammaproteobacteria and is related to Corallincola platygyrae JLT2006T (96.84% sequence similarity). The G + C content of the genomic DNA was 49.0 mol%. The assembled draft genome of strain 176GS2-150T was 4.2 Mbp and consisted of 14 contigs. The major respiratory quinone was Q-8, and the major fatty acids were summed feature 3 (comprising C16 :1ω6c and/or C16:1ω7c), summed feature 8 (comprising C18 :1ω7c and/or C18:1ω6c), C17:0 iso, C16:0, and C15:0 iso. The polar lipids were phosphatidylglycerol, phosphatidylethanolamine, 3 unidentified phospholipids, and 1 unidentified polar lipid. On the basis of the genotypic and phenotypic characteristics, strain 176GS2-150T can be placed as a new species within the genus Corallincola; the name Corallincola spongiicola sp. nov. has been proposed, with type strain 176GS2-150T (= KACC 19890T = LMG 31317T).

Succession of microbial populations and nitrogen-fixation associated with the biodegradation of sediment-oil-agglomerates buried in a Florida sandy beach.

The Deepwater Horizon (DWH) oil spill contaminated coastlines from Louisiana to Florida, burying oil up to 70 cm depth in sandy beaches, posing a potential threat to environmental and human health. The dry and nutrient-poor beach sand presents a taxing environment for microbial growth, raising the question how the biodegradation of the buried oil would proceed. Here we report the results of an in-situ experiment that (i) characterized the dominant microbial communities contained in sediment oil agglomerates (SOAs) of DWH oil buried in a North Florida sandy beach, (ii) elucidated the long-term succession of the microbial populations that developed in the SOAs, and (iii) revealed the coupling of SOA degradation to nitrogen fixation. Orders of magnitude higher bacterial abundances in SOAs compared to surrounding sands distinguished SOAs as hotspots of microbial growth. Blooms of bacterial taxa with a demonstrated potential for hydrocarbon degradation (Gammaproteobacteria, Alphaproteobacteria, Actinobacteria) developed in the SOAs, initiating a succession of microbial populations that mirrored the evolution of the petroleum hydrocarbons. Growth of nitrogen-fixing prokaryotes or diazotrophs (Rhizobiales and Frankiales), reflected in increased abundances of nitrogenase genes (nifH), catalyzed biodegradation of the nitrogen-poor petroleum hydrocarbons, emphasizing nitrogen fixation as a central mechanism facilitating the recovery of sandy beaches after oil contamination.

Colistin Resistance in Enterobacterales Strains - A Current View.

Colistin is a member of cationic polypeptide antibiotics known as polymyxins. It is widely used in animal husbandry, plant cultivation, animal and human medicine and is increasingly used as one of the last available treatment options for patients with severe infections with carbapenem-resistant Gram-negative bacilli. Due to the increased use of colistin in treating infections caused by multidrug-resistant (MDR) bacteria, the resistance to this antibiotic ought to be monitored. Bacterial resistance to colistin may be encoded on transposable genetic elements (e.g. plasmids with the mcr genes). Thus far, nine variants of the mcr gene, mcr-1 - mcr-9, have been identified. Chromosomal resistance to colistin is associated with the modification of lipopolysaccharide (LPS). Various methods, from classical microbiology to molecular biology methods, are used to detect the colistin-resistant bacterial strains and to identify resistance mechanisms. The broth dilution method is recommended for susceptibility testing of bacteria to colistin.Colistin is a member of cationic polypeptide antibiotics known as polymyxins. It is widely used in animal husbandry, plant cultivation, animal and human medicine and is increasingly used as one of the last available treatment options for patients with severe infections with carbapenem-resistant Gram-negative bacilli. Due to the increased use of colistin in treating infections caused by multidrug-resistant (MDR) bacteria, the resistance to this antibiotic ought to be monitored. Bacterial resistance to colistin may be encoded on transposable genetic elements (e.g. plasmids with the mcr genes). Thus far, nine variants of the mcr gene, mcr-1 ­ mcr-9, have been identified. Chromosomal resistance to colistin is associated with the modification of lipopolysaccharide (LPS). Various methods, from classical microbiology to molecular biology methods, are used to detect the colistin-resistant bacterial strains and to identify resistance mechanisms. The broth dilution method is recommended for susceptibility testing of bacteria to colistin.

Thiocyanate Degradation by a Highly Enriched Culture of the Neutrophilic Halophile Thiohalobacter sp. Strain FOKN1 from Activated Sludge and Genomic Insights into Thiocyanate Metabolism.

Thiocyanate (SCN-) is harmful to a wide range of organisms, and its removal is essential for environmental protection. A neutrophilic halophile capable of thiocyanate degradation, Thiohalobacter sp. strain FOKN1, was highly enriched (relative abundance; 98.4%) from activated sludge collected from a bioreactor receiving thiocyanate-rich wastewater. The enrichment culture degraded 3.38 mM thiocyanate within 140 h, with maximum activity at pH 8.8, 37°C, and 0.18 M sodium chloride. Thiocyanate degradation was inhibited by 30 mg L-1 phenol, but not by thiosulfate. Microbial thiocyanate degradation is catalyzed by thiocyanate dehydrogenase, while limited information is currently available on the molecular mechanisms underlying thiocyanate degradation by the thiocyanate dehydrogenase of neutrophilic halophiles. Therefore, (meta)genomic and proteomic analyses of enrichment cultures were performed to elucidate the whole genome sequence and proteome of Thiohalobacter sp. strain FOKN1. The 3.23-Mb circular Thiohalobacter sp. strain FOKN1 genome was elucidated using a PacBio RSII sequencer, and the expression of 914 proteins was identified by tandem mass spectrometry. The Thiohalobacter sp. strain FOKN1 genome had a gene encoding thiocyanate dehydrogenase, which was abundant in the proteome, suggesting that thiocyanate is degraded by thiocyanate dehydrogenase to sulfur and cyanate. The sulfur formed may be oxidized to sulfate by the sequential oxidation reactions of dissimilatory sulfite reductase, adenosine-5'-phosphosulfate reductase, and dissimilatory ATP sulfurylase. Although the Thiohalobacter sp. strain FOKN1 genome carried a gene encoding cyanate lyase, its protein expression was not detectable. The present study advances the understanding of the molecular mechanisms underlying thiocyanate degradation by the thiocyanate dehydrogenase of neutrophilic halophiles.

The Challenge of the Sponge Suberites domuncula (Olivi, 1792) in the Presence of a Symbiotic Bacterium and a Pathogen Bacterium.

Sponges, which are in close contact with numerous bacteria in prey/predator, symbiotic and pathogenic relationships, must provide an appropriate response in such situations. This starts with a discriminating recognition of the partner either by a physical contact or through secreted molecules or both. We investigated the expression of the Toll-like receptor, Caspase 3/7, Tumor Necrosis Factor receptor-associated factor 6, Bcl-2 homology protein-2 and macrophage expressed genes of axenic sponge cells in the presence of a symbiotic bacterium (Endozoicomonas sp. Hex311), a pathogen bacterium (Pseudoalteromonas sp. 1A1), their exoproducts and lipopolysaccharides. The vast majority of answers are in line with what could be observed with the symbiotic bacterium. The pathogenic bacterium seems to profit from the eukaryotic cell: suppression of the production of the antibacterial compound, inhibition of the apoptosis caspase-dependent pathway, deregulation of bacterial recognition. This work contributes new scientific knowledge in the field of immunology and apoptosis in early branching metazoan harboring within its tissue and cells a large number of symbiotic bacteria.

Diversity and Dynamics of "Candidatus Endobugula" and Other Symbiotic Bacteria in Chinese Populations of the Bryozoan, Bugula neritina.

Bugula neritina is a common invasive cosmopolitan bryozoan that harbors (like many sessile marine invertebrates) a symbiotic bacterial (SB) community. Among the SB of B. neritina, "Candidatus Endobugula sertula" continues to receive the greatest attention, because it is the source of bryostatins. The bryostatins are potent bioactive polyketides, which have been investigated for their therapeutic potential to treat various cancers, Alzheimer's disease, and AIDS. In this study, we compare the metagenomics sequences for the 16S ribosomal RNA gene of the SB communities from different geographic and life cycle samples of Chinese B. neritina. Using a variety of approaches for estimating alpha/beta diversity and taxonomic abundance, we find that the SB communities vary geographically with invertebrate and fish mariculture and with latitude and environmental temperature. During the B. neritina life cycle, we find that the diversity and taxonomic abundances of the SB communities change with the onset of host metamorphosis, filter feeding, colony formation, reproduction, and increased bryostatin production. "Ca. Endobugula sertula" is confirmed as the symbiont of the Chinese "Ca. Endobugula"/B. neritina symbiosis. Our study extends our knowledge about B. neritina symbiosis from the New to the Old World and offers new insights into the environmental and life cycle factors that can influence its SB communities, "Ca. Endobugula," and bryostatins more globally.

Assessment of biodegradation of the anionic surfactant sodium lauryl ether sulphate used in two foaming agents for mechanized tunnelling excavation.

The anionic surfactant sodium lauryl ether sulphate (SLES) is the main component in most foaming agents used for mechanized tunneling excavation. The process produces huge amounts of soil debris that can have a potential impact on ecosystems. The lack of accurate information about SLES persistence in excavated soil has aroused increasing concern about how it is recycled. The objective of this study was to assess SLES biodegradability in two commercial foaming agents (P1 and P2). Microcosm experiments were performed with two different soils collected from a tunnel construction site and conditioned with P1 or P2 (85.0 or 83.0 mg kg -1 of SLES, respectively). At selected times soil samples were collected for assessing the SLES residual concentration using Pressured Liquid Extraction followed by methylene blue active substance analysis (MBAS). Simultaneously, soil microbial abundance (DAPI counts), viability (Live/Dead method), activity (dehydrogenase analysis) and phylogenetic structure (Fluorescent In Situ Hybridization) were evaluated. SLES halved faster in the silty-clay soil (6 d) than in the gravel in a clay-silty-sand matrix (8-9 days). At day 28 it was degraded in both soils. Its biodegradation was ascribed to the significant increase in Gamma-Proteobacteria. At this time, the spoil material can be considered as a by-product.

Description of Wenzhouxiangella salilacus sp. nov., a moderate halophilic bacterium isolated from a salt lake in Xinjiang Province, China.

A Gram-stain negative, non-motile, strictly aerobic and rod-shaped bacterium, designated as 15181T, was isolated from a salt lake in Xinjiang Province, China. Strain 15181T was able to grow at 10-40 °C (optimum 37 °C), pH 6.0-8.5 (optimum 7.0) and with 1-14% NaCl (optimum 4%, w/v). According to phylogenetic analysis based on 16S rRNA gene sequences, strain 15181T was assigned to the genus Wenzhouxiangella with high 16S rRNA gene sequence similarity of 97.4% to Wenzhouxiangella sediminis XDB06T, followed by Wenzhouxiangella marina KCTC 42284T (95.9%). Strain 15181T exhibited ANI values of 80.0% and 72.0% to W. sediminis XDB06T and W. marina KCTC 42284T, respectively. The in silico DDH analysis revealed that strain 15181T shared 19.1% and 18.7% DNA relatedness with W. sediminis XDB06T and W. marina KCTC 42284T, respectively. Chemotaxonomic analysis showed that the sole respiratory quinone was ubiquinone-8, the major fatty acids included iso-C15:0, iso-C16:0 and summed feature 9 (C16:0 10-methyl and/or iso-C17:1ω9c). The major polar lipids included diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, two unidentified glycolipids, two unidentified phospholipids, two unidentified aminophospholipids and an unidentified lipid. On the basis of phenotypic, genotypic and chemotaxonomic characteristics presented in this study, strain 15181T is concluded to represent a novel species in the genus Wenzhouxiangella, for which the name Wenzhouxiangella salilacus sp. nov. is proposed. The type strain is 15181T (=KCTC 62172T=MCCC 1K03442T).

Comparative analyses of cellular physiological responses of non-target species to cypermethrin and its formulated product: Contribution to mode of action research.

Physiological responses of bacterial, fish, rat and human hepatoma cells to the technical cypermethrin (AS), cypermethrin-based plant protection product (PPP), and the major co-formulant (solvent) were compared. The endpoints included: bioluminescence, total protein content, activity of mitochondrial dehydrogenase and cytochrome P450 (CYP) enzymes CYP1A and CYP1B, and expression of several genes encoding different CYP enzyme isoforms. Toxicity of PPP was compared with the toxicity predicted using concentration addition model. Cypermethrin disturbs the activity of mitochondrial dehydrogenase. Induction of CYP1A1-, CYP1A2- and CYP1B1-associated activity was more pronounced in PPP than in cypermethrin treatment. The predominant biotransformation pathway of cypermethrin is related to Cyp3a1 induction. Deviations between observed and predicted toxicity of PPP indicate synergistic effects of cypermethrin and a solvent. In vitro cellular assays may serve as rapid pre-screening tool and provide for a good indication of mixture effects and prompt further in vivo testing of PPPs when really needed.

Polycyclic Aromatic Hydrocarbon (PAH) Degradation Pathways of the Obligate Marine PAH Degrader Cycloclasticus sp. Strain P1.

Bacteria play an important role in the removal of polycyclic aromatic hydrocarbons (PAHs) from polluted environments. In marine environments, Cycloclasticus is one of the most prevalent PAH-degrading bacterial genera. However, little is known regarding the degradation mechanisms for multiple PAHs by CycloclasticusCycloclasticus sp. strain P1 was isolated from deep-sea sediments and is known to degrade naphthalene, phenanthrene, pyrene, and other aromatic hydrocarbons. Here, six ring-hydroxylating dioxygenases (RHDs) were identified in the complete genome of Cycloclasticus sp. P1 and were confirmed to be involved in PAH degradation by enzymatic assays. Further, five gene clusters in its genome were identified to be responsible for PAH degradation. Degradation pathways for naphthalene, phenanthrene, and pyrene were elucidated in Cycloclasticus sp. P1 based on genomic and transcriptomic analysis and characterization of an interconnected metabolic network. The metabolic pathway overlaps in many steps in the degradation of pyrene, phenanthrene, and naphthalene, which were validated by the detection of metabolic intermediates in cultures. This study describes a pyrene degradation pathway for Cycloclasticus. Moreover, the study represents the integration of a PAH metabolic network that comprises pyrene, phenanthrene, and naphthalene degradation pathways. Taken together, these results provide a comprehensive investigation of PAH metabolism in CycloclasticusIMPORTANCE PAHs are ubiquitous in the environment and are carcinogenic compounds and tend to accumulate in food chains due to their low bioavailability and poor biodegradability. Cycloclasticus is an obligate marine PAH degrader and is widespread in marine environments, while the PAH degradation pathways remain unclear. In this report, the degradation pathways for naphthalene, phenanthrene, and pyrene were revealed, and an integrated PAH metabolic network covering pyrene, phenanthrene, and naphthalene was constructed in Cycloclasticus This overlapping network provides streamlined processing of PAHs to intermediates and ultimately to complete mineralization. Furthermore, these results provide an additional context for the prevalence of Cycloclasticus in oil-polluted marine environments and pelagic settings. In conclusion, these analyses provide a useful framework for understanding the cellular processes involved in PAH metabolism in an ecologically important marine bacterium.

Natural products and morphogenic activity of γ-Proteobacteria associated with the marine hydroid polyp Hydractinia echinata.

Illumina 16S rRNA gene sequencing was used to profile the associated bacterial community of the marine hydroid Hydractinia echinata, a long-standing model system in developmental biology. 56 associated bacteria were isolated and evaluated for their antimicrobial activity. Three strains were selected for further in-depth chemical analysis leading to the identification of 17 natural products. Several γ-Proteobacteria were found to induce settlement of the motile larvae, but only six isolates induced the metamorphosis to the primary polyp stage within 24h. Our study paves the way to better understand how bacterial partners contribute to protection, homeostasis and propagation of the hydroid polyp.