Gram-negative Aerobic Bacterium Research Articles

Complete genome sequence of Delftia tsuruhatensis strain HA60 isolated from a commercial hydroxyapatite nano-particle product (nano-hydroxyapatite).

Delftia tsuruhatensis is a Gram-negative rod-shaped aerobic bacterium with environmental remediation functions. D. tsuruhatensis strain HA60 was isolated from a commercial nano-particle product, nano-hydroxyapatite. We report that the genome of D. tsuruhatensis strain HA60 has a circular genome of 6,922,195 base pairs with a G+C content of 66.45%.

Stenotrophomonas maltophilia Outbreak in an ICU: Investigation of Possible Routes of Transmission and Implementation of Infection Control Measures.

Stenotrophomonas maltophilia, a non-fermentative, ubiquitous, gram-negative aerobic bacterium, is associated with high mortality rates, particularly in immunocompromised or debilitated patients. The prevalence rate of ICU-acquired pneumonia episodes caused by this microorganism has been found to be 2%. S. maltophilia has been identified as one of the top 10 microorganisms responsible for such infections in EU/EEA countries. This study describes an outbreak of S. maltophilia in an intensive care unit of a hospital in northern Italy. This includes an epidemiological investigation of the cases, the environmental microbiological controls carried out, a comparison of the strains by multilocus sequence typing (MLST), and the measures taken to prevent and control the outbreak. Among the seven clinical isolates of S. maltophilia analyzed herein, six demonstrated susceptibilities to trimethoprim-sulfamethoxazole. Conversely, one isolate of S. maltophilia exhibited resistance to first-line antibiotics. ST was found to be identical for six patients (ST 4), as well as in the environmental feedback on the trolley of Box 2. The analysis of the temporal and spatial progression of the outbreak has suggested that the transmission of S. maltophilia may have occurred through cross-transmission during care practices.

Tuning bio-derived solvents for the rapid solubilization of astaxanthin-rich extracts from non-conventional bacterium Paracoccus carotinifaciens

Astaxanthin (AXT) is a ketocarotenoid widely used in food, feed, and pharmaceutical industries. Its biological sourcing is preferred over chemical methods due to higher physiological and commercial value. Paracoccus carotinifaciens, an aerobic marine Gram-negative bacterium, is known for producing a carotenoid mixture with AXT as the main component. This study explores the use of bio-based solvents, both pure and mixed, for extracting AXT-rich extracts (ARE). Using COSMO-SAC, a quantum chemistry-based thermodynamic model, we assessed the AXT-solvent affinity. The ethyl acetate: acetic acid mixture (EtOAc:AA) gave the best results, with 1.41 mg/mL of ARE. The solvent selection process was evaluated through the Eco Scale to compare with conventional methods. Next, optimization of extraction conditions resulted in 3.28 mg/mL of ARE at 78 °C, 10 min, and a solid-to-liquid ratio of 0.5 g/mL. Ultrasound-assisted extraction (UAE) was employed to tuning the mass-transfer process, leading to an increase of ARE (18.9 %) in reduced processing time. Concerning the stability of ARE in the EtOAc:AA mixture, the half-life (t1/2) reached 18 and 26 days under the light and dark conditions, respectively at 25 °C. In both light and dark conditions, positive enthalpy (ΔH) values revealed an endothermic process and both entropy (ΔS) and Gibbs free energy (ΔG) values suggest that the degradation of ARE is less disordered and non-spontaneous process. The solvent mixture was effectively reused for three cycles under optimally tuned conditions without a significant decline of ARE extraction efficiency.

Parendozoicomonas callyspongiae sp. nov. Isolated from a Marine Sponge, Callyspongia elongate, and Reclassification of Sansalvadorimonas verongulae as Parendozoicomonas verongulae comb. nov.

A strictly aerobic Gram-negative bacterium, designated 2012CJ34-2T, was isolated from marine sponge to Chuja-do in Jeju-island, Republic of Korea and taxonomically characterized. Cells were catalase- and oxidase-positive, and non-motile rods (without flagella). Growth was observed at 15-42°C (optimum, 30°C), pH 6-9 (optimum, pH 7), and in the presence of 0.5-10% (w/v) NaCl (optimum, 2-3%). The major cellular fatty acid and respiratory quinones were identified summed feature 3 (C16:1 ω7c/C16:1 ω6c), and Q-8 and Q-9, respectively. The polar lipids comprised diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, an unidentified aminophospholipid, two unidentified phospholipids, and three unidentified lipids. The DNA G+C content was 48.0mol%. Phylogenetic analyses based on 16S rRNA gene and whole genome sequences showed that strain 2012CJ34-2T formed a clade with Parendozoicomonas haliclonae S-B4-1UT and Sansalvadorimonas verongulae LMG 29871T within the family Endozoicomodaceae. Genome relatedness values, including dDDH, ANI and AF, and AAI and POCP, among strain 2012CJ34-2T, P. haliclonae S-B4-1UT, and S. verongulae LMG 29871T were within the range of the bacterial genus cut-off values. Based on the phylogenetic, chemotaxonomic, and genomic analyses, strain 2012CJ34-2T represents a novel bacterial species of the family Endozoicomodaceae, for which the name Parendozoicomonas callyspongiae sp. nov. is proposed. The type strain is 2012CJ34-2T (= KACC 22641T = LMG 32581T). Additionally, we proposed the reclassification of Sansalvadorimonas verongulae of the family Hahellaceae as Parendozoicomonas verongulae of the family Endozoicomonadaceae.

Antibiotic resistance in Neisseria gonorrhoeae: broad-spectrum drug target identification using subtractive genomics.

Neisseria gonorrhoeae is a Gram-negative aerobic diplococcus bacterium that primarily causes sexually transmitted infections through direct human sexual contact. It is a major public health threat due to its impact on reproductive health, the widespread presence of antimicrobial resistance, and the lack of a vaccine. In this study, we used a bioinformatics approach and performed subtractive genomic methods to identify potential drug targets against the core proteome of N. gonorrhoeae (12 strains). In total, 12,300 protein sequences were retrieved, and paralogous proteins were removed using CD-HIT. The remaining sequences were analyzed for non-homology against the human proteome and gut microbiota, and screened for broad-spectrum analysis, druggability, and anti-target analysis. The proteins were also characterized for unique interactions between the host and pathogen through metabolic pathway analysis. Based on the subtractive genomic approach and subcellular localization, we identified one cytoplasmic protein, 2Fe-2S iron-sulfur cluster binding domain-containing protein (NGFG RS03485), as a potential drug target. This protein could be further exploited for drug development to create new medications and therapeutic agents for the treatment of N. gonorrhoeae infections.

Chitinophaga horti sp. nov., Isolated from Garden Soil

A strictly aerobic Gram-negative bacterium, designated R8T, isolated from garden soil in South Korea was subjected to a taxonomic study. The cells were non-spore-forming, oxidase-positive and catalase-negative, and non-motile rods (without flagella). Growth was observed between 10°C and 40°C (optimum, 30°C) and between pH 6.0 and 9.0 (optimum, pH 7.0) and in the presence of 0%-1.5% (w/v) NaCl (optimum, 0%). The G + C content of the genomic DNA was 49.9% and the major isoprenoid quinone was found to be menaquinone-7. The major fatty acids of strain R8T were iso-C15:0, C16:1 ω5c, and summed feature 3 (comprising iso-C15:0 2-OH and/or C16:1 ω7c/ω6c). Phosphatidylethanolamine was identified as a major polar lipid. Comparative 16S rRNA gene sequence analysis showed that strain R8T had the highest 16S rRNA gene sequence similarity of 98.3% with Chitinophaga sedimenti TFL-3T. Phylogenetic analyses using 16S rRNA gene sequences and concatenated 92 marker protein sequences revealed that strain R8T formed a robust phylogenetic lineage with C. sedimenti within the genus Chitinophaga. Average nucleotide identity and digital DNA-DNA hybridization values of strain R8T to Chitinophaga species were less than 77.9% and 21.1%, respectively. The phenotypic, phylogenetic, and chemotaxonomic properties support that strain R8T represents a novel species of the genus Chitinophaga, for which the name Chitinophaga horti sp. nov. is proposed. The type strain is R8T (= KACC 19895T = JCM 33215T).

Enhanced biodegradation of thiamethoxam with a novel polyvinyl alcohol (PVA)/sodium alginate (SA)/biochar immobilized Chryseobacterium sp H5.

Long-term and extensive usage of thiamethoxam, the second-generation neonicotinoid insecticide, has caused a serious threat to non-target organisms and ecological security. Efficient immobilized microorganism techniques are a sustainable solution for bioremediation of thiamethoxam contamination. A Gram-negative aerobic bacterium Chryseobacterium sp H5 with high thiamethoxam-degrading efficiencies was isolated from activated sludge. Then we developed a novel polyvinyl alcohol (PVA)/sodium alginate (SA)/biochar bead with this functional microbe immobilization to enhance the biodegradation and removal of thiamethoxam. Results indicated that the total removal and biodegradation rate of thiamethoxam with PVA/SA/biochar (0.7 %) beads with Chryseobacterium sp H5 immobilization at 30°C and pH of 7.0 within 7 d reached about 90.47 % and 68.03 %, respectively, much higher than that using PVA/SA immobilized microbes (75.06 %, 56.05 %) and free microbes (61.72 %). Moreover, the PVA/SA/biochar (0.7 %) immobilized microbes showed increased tolerance to extreme conditions. Biodegradation metabolites of thiamethoxam were identified and two intermediates were first reported. Based on the identified biodegradation intermediates, cleavage of C-N between the 2-chlorothiazole ring and oxadiazine, dichlorination, nitrate reduction and condensation reaction would be the major biodegradation routes of thiamethoxam. Results of this work suggested the novel PVA/SA/biochar beads with Chryseobacterium sp H5 immobilization would be helpful for the effective bioremediation of thiamethoxam contamination.

Ochratoxin A degrading enzymes of Stenotrophomonassp. 043-1a.

Ochratoxin A is a secondary metabolite that acts as a mycotoxin and is produced by Aspergillus, Penicillium, and other fungal species. It is a threat to animal and human health due to nephrotoxic, carcinogenic, and genotoxic properties and its widespread incidence in agricultural products. To reduce this threat, biological remediation processes are of growing interest. The aerobic gram-negative bacterium Stenotrophomonassp. 043-1a, isolated from soil, was previously shown to degrade ochratoxin A into the non-toxic ochratoxin α and l-phenylalanine (Schatzmayr et al. 2002). However, the enzyme or enzymes catalyzing this reaction in this strain remained elusive. Here, we report the targeted purification of Stenotrophomonassp. 043-1a lysate via ammonium sulfate precipitation, size-exclusion chromatography, and hydrophobic interaction chromatography to identify the ochratoxin A degrading enzymes by subsequent peptide fragment fingerprinting. The metallo-dependent hydrolase Chr1_3858681_3267 and a member of the peptidase S9 family, Chr1_3858681_771, were shown to degrade ochratoxin A. This was, to our knowledge, the first report of an ochratoxin A degrading enzyme from the peptidase S9 family.

Successful Treatment of Aortic Endocarditis by Achromobacter xylosoxidans with Cefiderocol Combination Therapy in a Non-Hodgkin Lymphoma Patient: Case Report and Literature Review.

Achromobacter xylosoxidans is a Gram-negative aerobic opportunistic bacterium, belonging to the order of Burkholderiales, that can cause infections of virtually all body districts in patients with underlying diseases. However, A. xylosoxidans has rarely been associated with infective endocarditis. The treatment of A. xylosoxidans infections is complicated by both intrinsic and acquired resistance. Here we report on a case of aortic endocarditis by A. xylosoxidans in a Non-Hodgkin lymphoma patient treated with a combination of cefiderocol and other antibiotics, and summarize the available literature.

Multifunctional Enzyme with Endoglucanase and Alginase/Glucuronan Lyase Activities from Bacterium Cellulophaga lytica.

Cellulophaga lytica is a Gram-negative aerobic bacterium in the genome of which there are many genes encoding polysaccharide degrading enzymes. One of the enzymes named ClGP contains a glycoside hydrolase domain from the GH5 family and a polysaccharide lyase domain from the PL31 family. The enzyme also contains the TAT signaling peptide and the TIGR04183 domain that indicates extracellular nature of the enzyme. Phylogenetic analysis has shown that the enzymes most closely related to ClGP and containing all four domains (TAT, GH5, PL31, TIGR04183) are widespread among bacterial species belonging to the Flavobacteriaceae family. ClGP produced by the recombinant strain of E. coli was purified and characterized. ClGP exhibited activity of endoglucanase (EC 3.2.1.4) and catalyzed hydrolysis of β-D-glucan, carboxymethyl cellulose sodium salt (CMC-Na), and amorphous cellulose, but failed to hydrolyze microcrystalline cellulose and xylan. Products of CMC hydrolysis were cellobiose and cellotriose, whereas β-D-glucan was hydrolyzed to glucose, cellobiose, cellotetraose, and cellopentaose. ClGP was more active against the poly-β-D-mannuronate blocks than against the poly-α-L-glucuronate blocks of alginic acid. This indicates that the enzyme is a polyM lyase (EC 4.2.2.3). ClGP was active against polyglucuronic acid, so it displayed a glucuronan lyase (EC 4.2.2.14) activity. The enzyme had a neutral pH-optimum, was stable in the pH range 6.0-8.0, and displayed moderate thermal stability. ClGP effectively saccharified two species of brown algae, Saccharina latissima and Laminaria digitata, that suggests its potential for use in the production of biofuel from macroalgae.

Detection of the aadA1 and aac (3)-1V resistance genes in Acinetobacter baumannii.

Acinetobacter baumannii is a gram-negative aerobic bacterium that can be found in different environments, such as food, containing vegetables, meat, and fish; moreover, it can be present in soil and freshwater. A. baumannii has globally considered an opportunistic nosocomial bacterium in the healthcare setting contributing to increased morbidity and mortality. The current study aimed to detect the aminoglycoside genes in A. baumannii isolated from different clinical causes. In total, 20 isolates of A. baumannii were obtained from different clinical cases. Bacterial isolate DNA was extracted using a DNA extraction kit. Quantus Fluorometer was used to detect the concentration of the extracted DNA in order to detect the goodness of samples. 1 μl of DNA and 199 μl of diluted QuantiFlour Dye were mixed. After 5 min incubation at room temperature, DNA concentration values were evaluated, and following the initial amplification of the A. baumannii aadA1 gene, 20 μl of PCR product with F and R primers were sent to Sanger sequencing. The results of the antimicrobial susceptibility revealed that A. baumannii isolates were resistant to Gentamicin (95%), Amikacin (90%), and Tobramycin (60%). Molecular investigation of the aadA1 and aac (3)-IV genes exhibited that the aadA1 gene was detected in 15% of the isolates. However, the aac (3)-IV gene was not detected in any of the isolates. The gel electrophoresis revealed that the molecular weight of the aadA1 gene was 490bp. The DNA sequence of the aadA1 gene was conducted in this study, and the results exhibited no mutations in all isolates.

In silico functional and structural characterization revealed virulent proteins of Francisella tularensis strain SCHU4.

Francisella tularensis is a pathogenic, aerobic gram-negative coccobacillus bacterium. It is the causative agent of tularemia, a rare infectious disease that can attack skin, lungs, eyes, and lymph nodes. The genome of F. tularensis has been sequenced, and ~16% of the proteome is still uncharacterized. Characterizations of these proteins are essential to find new drug targets for better therapeutics. In silico characterization of proteins has become an extremely important approach to determine the functionality of proteins as experimental functional elucidation is unable to keep pace with the current growth of the sequence database. Initially, we have annotated 577 Hypothetical Proteins (HPs) of F. tularensis strain SCHU4 with seven bioinformatics tools which characterized them based on the family, domain and motif. Out of 577 HPs, 119 HPs were annotated by five or more tools and are further screened to predict their virulence properties, subcellular localization, transmembrane helices as well as physicochemical parameters. VirulentPred predicted 66 HPs out of 119 as virulent. These virulent proteins were annotated to find the interacting partner using STRING, and proteins with high confidence interaction scores were used to predict their 3D structures using Phyre2. The three virulent proteins Q5NH99 (phosphoserine phosphatase), Q5NG42 (Cystathionine beta-synthase) and Q5NG83 (Rrf2-type helix turn helix domain) were predicted to involve in modulation of cytoskeletal and innate immunity of host, H2S (hydrogen sulfide) based antibiotic tolerance and nitrite and iron metabolism of bacteria. The above predicted virulent proteins can serve as novel drug targets in the era of antibiotic resistance.

Effect of Ferredoxin Receptor FusA on the Virulence Mechanism of Pseudomonas plecoglossicida.

Pseudomonas plecoglossicida is an aerobic Gram-negative bacterium, which is the pathogen of “Visceral white spot disease” in large yellow croaker. P. plecoglossicida is a temperature-dependent bacterial pathogen in fish, which not only reduces the yield of large yellow croaker but also causes continuous transmission of the disease, seriously endangering the healthy development of fisheries. In this study, a mutant strain of fusA was constructed using homologous recombination technology. The results showed that knockout of P. plecoglossicida fusA significantly affected the ability of growth, adhesion, and biofilm formation. Temperature, pH, H2O2, heavy metals, and the iron-chelating agent were used to treat the wild type of P. plecoglossicida; the results showed that the expression of fusA was significantly reduced at 4°C, 12°C, and 37°C. The expression of fusA was significantly increased at pH 4 and 5. Cu2+ has a significant inducing effect on the expression of fusA, but Pb2+ has no obvious effect; the expression of fusA was significantly upregulated under different concentrations of H2O2. The expression of the fusA gene was significantly upregulated in the 0.5~4-μmol/l iron-chelating agent. The expression level of the fusA gene was significantly upregulated after the logarithmic phase. It was suggested that fusA included in the TBDR family not only was involved in the transport of ferredoxin but also played important roles in the pathogenicity and environment adaptation of P. plecoglossicida.

The contributions of fliG gene to the pathogenicity of Pseudomonas plecoglossicida and pathogen-host interactions with Epinephelus coioides

Pseudomonas plecoglossicida is a Gram-negative aerobic rod-shaped bacterium with polar flagella. It is the causative agent of visceral white spot disease in cultured fish, resulting in serious economic losses. In our previous study, RNA sequencing showed that the expression of the fliG gene in P. plecoglossicida is significantly up-regulated during infection of orange-spotted grouper (Epinephelus coioides). In this study, four P. plecoglossicida RNA interference (RNAi) mutants were successfully constructed by linking four short hairpin RNAs (shRNAs), which target different sites of the fliG gene, to pCM130/tac, respectively. The mRNA expression levels of the fliG gene in P. plecoglossicida were significantly decreased in four mutants. The shRNA-335 mutant (fliG-RNAi strain) showed the best silencing efficiency (88.2%) and was thus chosen for further analysis. Electron microscopy indicated that the flagella of the fliG-RNAi strain of P. plecoglossicida were shorter and finer than those of the wild type strain. The fliG-RNAi strain also showed significantly decreased mobility, chemotaxis, adhesion, and biofilm formation. Furthermore, compared with wild type strain infection, E. coioides infected with the fliG-RNAi strain exhibited a 0.5-d delay in the time of first death and 55% reduction in accumulated mortality, as well as milder splenic symptoms. RNAi of the fliG gene significantly affected the transcriptomes of both pathogen and host in the infected spleens of E. coioides. KEGG analysis revealed that the flagellar assembly pathway, bacterial chemotaxis pathway, and starch and sucrose metabolism pathway were significantly enriched in the pathogen at 3 days post infection (dpi). In contrast, the complement and coagulation cascade pathway and antigen processing and presentation pathway were significantly enriched in the host at 3 dpi. More immune-related pathways were enriched at 5 dpi and more differentially expressed genes were found in the complement and coagulation cascade and antigen processing and presentation pathways. Cytokine-cytokine receptor interaction, hematopoietic cell lineage, and IgA-producing intestinal immune network pathways were significantly enriched in the host at 5 dpi. These results indicate that fliG is an important virulence gene of P. plecoglossicida and contributes to the pathogenicity of P. plecoglossicida as well as pathogen-host interactions with E. coioides.

Taxonomic description of Pseudomonas rhizovicinus sp. nov., isolated from the rhizosphere of a desert shrub Haloxylon ammodendron.

A Gram-negative aerobic bacterium, strain M30-35T, was isolated from the rhizosphere of Haloxylon ammodendron in Tengger desert, Gansu province, northwest China. Our previous research indicated that strain M30-35T can promote the growth of ryegrass (Lolium perenne L.). In this study, strain M30-35T was subjected to a polyphasic taxonomic study. Phylogenetic analysis of the 16S rRNA gene and two other housekeeping genes (gyrB, rpoD) showed that strain M30-35T is a member of Pseudomonas anguilliseptica group. The average nucleotide identity (ANI) scores for strains KMM 3042T and FR1439T were 76.5% and 83.7%, respectively, and DNA-DNA hybridization (DDH) were 21.6% and 26.6%, respectively, and the rates were less than the threshold range for species determination. The dominant cellular fatty acids of strain M30-35T were C16:0 (22.7%), summed feature 3 (C16:1ω7c and/or C16:1ω6c; 18.5%), summed feature 8 (C18:1ω7c and/or C18:1ω6c; 23.1%). The major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phospholipid and aminophospholipid and the predominant respiratory quinone was ubiquinone (Q9). On the basis of above data, it can be concluded that strain M30-35T represents a novel species in the genus Pseudomonas, for which the name Pseudomonas rhizovicinus sp. nov. is proposed. The type strain is M30-35T (= MCCC 1K03247T = KCTC 52664T).

Case Report: Pseudomonas can take a toll on a patient

Pseudomonas aeruginosa( P. aeruginosa) is an aerobic Gram-negativebacterium that is implicated in the development of severe systemic infections among pediatric patients. It is identified in hospitalized chronically ill pediatric patients in association with genitourinary, respiratory tract, and skin or soft tissue infections as well as severe and life-threating infection including sepsis. A variety of immunologic mechanisms play a vital role in the host defense mechanisms against invasive infections with P. aeruginosa. Rarely, specific inborn errors of immune function are implicated in deficiencies that predispose to invasive infections with P. aeruginosa. Innate immune function including germ-line encoded pattern recognition receptors such as toll-like receptors (TLRs) and their downstream signaling is vital in the host defense against P. aeruginosa through the generation of antimicrobial peptides, cytokines/chemokines, and shaping of adaptive immune responses. Herein, we describe a previously healthy two-year-old female with an invasive skin, soft tissue, and central nervous system infection secondary to P. aeruginosa. The invasive nature of this infection prompted a careful evaluation for an inborn error of immunity. Decreased cytokine response to agonists of TLRs was documented. Targeted sequencing of interleukin-1 receptor-associated kinase (IRAK)-4 documented a homozygous deletion of exons 8-13 consistent with IRAK-4 deficiency. This report provides a vital educative message in the existing scientific literature by underscoring the importance of considering inborn errors of immunity in all patients with severe P. aeruginosa infections. Functional assessments of immune function often in combination with sequencing can accurately assign a diagnosis in a timely fashion allowing for definitive treatment and the use of necessary supportive care.

Complete Genome Sequence of Kaistia sp. Strain 32K, Isolated from Soil as a Mixed Single Colony with Methylobacterium sp. Strain ME121.

Kaistia sp. strain 32K, an aerobic Gram-negative bacterium, was isolated from soil in Japan. Here, we report the complete genome sequence of this bacterium, which has a 5.4-Mbp genome sequence, containing 4,919 protein-coding sequences.

Complete Genome Sequence of Citrobacter koseri Strain MPUCK001.

Citrobacter koseri, an aerobic Gram-negative bacterium, is isolated from the human skin and intestinal tract. Here, we report the complete genome sequence of Citrobacter koseri strain MPUCK001, which has a 4.9-Mbp genome, containing 4,536 protein-coding sequences.

Mechanisms of Acinetobacter baumannii Capsular Polysaccharide Cleavage by Phage Depolymerases

Aerobic gram-negative bacterium Acinetobacter baumannii has recently become one of the most relevant pathogens associated with hospital-acquired infections worldwide. A. baumannii produces a capsule around the cell, which represents a thick viscous layer of structurally variable capsular polysaccharide (CPS). The capsule protects the bacteria against unfavorable environmental factors and biological systems, including bacteriophages and host immune system. Many A. baumannii phages have structural depolymerases (tailspikes) that specifically recognize and digest bacterial CPS. In this work, we studied the interaction of tailspike proteins of four lytic depolymerase-carrying phages with A. baumannii CPS. Depolymerases of three bacteriophages (Fri1, AS12, and BS46) were identified as specific glycosidases that cleave the CPS of A. baumannii strains 28, 1432, and B05, respectively, by the hydrolytic mechanism. The gp54 depolymerase from bacteriophage AP22 was characterized as a polysaccharide lyase that cleaves the CPS of A. baumannii strain 1053 by β-elimination at hexuronic acid (ManNAcA) residues.

Pukyongia salina gen. nov., sp. nov., a novel genus in the family Flavobacteriaceae.

A Gram-negative aerobic bacterium, designated RR4-38T, was isolated from a biofilter in a seawater recirculating aqua-culture system (RAS) in Busan, South Korea. The bacteria were irregular, short, rod-shaped, non-motile, oxidase-positive, and catalase-negative. Growth of the strain RR4-38T was observed at 15-35·C (optimum, 25-30·C), pH 5.5-9.5 (optimum, pH 8.0), and in the presence of 0-5% (w/v) NaCl (optimum, 3%). Phylogenetic analysis based on the 16S rRNA gene sequences showed that the strain RR4-38T formed a distinct lineage with close genera Ulvibacter (≤ 95.01% 16S rRNA gene sequence similarity), Aureitalea (94.74%), Aureisphaera (≤ 93.27%), and Jejudonia (93.07%) that all belong to the family Flavobacteriaceae. Whole-genome sequence comparison revealed that the ANI (average nucleotide identity) and digital DDH (DNA-DNA hybridization) values between strain RR4-38T and the two closest strains, Ulvibacter antarcticus DSM 23424T and Aureitalea marina S1-66T, were 68.96-69.88% and 17.4-19%, respectively. The genome analysis revealed that the strain might be involved in biodegradation of organic debris produced by farmed fish in aquaculture systems. The predominant respiratory quinone was menaquinone MK-6 and the major cellular fatty acids were iso-C15:0 (26.5%), iso-C17:0 3-OH (16.4%), iso-C15:1 G (15%), and iso-C16:0 3-OH (9.6%). The major cellular polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, unidentified aminolipids, and glycolipids. Based on phenotypic, chemotaxonomic, and phylogenetic features, strain RR4-38t represents a novel genus and species in the family Flavobacteriaceae, for which the name Pukyongia salina gen. nov., sp. nov. is proposed. The type strain is RR4-38T (= KCTC 52651T = DSM 108068T).