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Klebsiella pneumoniae (K. pneumoniae) exhibits the ability to form biofilms as a means of adapting to its adverse surroundings. K. pneumoniae in this biofilm state demonstrates remarkable resistance, evades immune system attacks, and poses challenges for complete eradication, thereby complicating clinical anti-infection efforts. Moreover, the precise mechanisms governing biofilm formation and disruption remain elusive. Recent studies have discovered that fingolimod (FLD) exhibits biofilm properties against Gram-positive bacteria. Therefore, the antibiofilm properties of FLD were evaluated against multidrug-resistant (MDR) K. pneumoniae in this study. The antibiofilm activity of FLD against K. pneumoniae was assessed utilizing the Alamar Blue assay along with confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM), and crystal violet (CV) staining. The results showed that FLD effectively reduced biofilm formation, exopolysaccharide (EPS), motility, and bacterial abundance within K. pneumoniae biofilms without impeding its growth and metabolic activity. Furthermore, the inhibitory impact of FLD on the production of autoinducer-2 (AI-2) signaling molecules was identified, thereby demonstrating its notable anti-quorum sensing (QS) properties. The results of qRT-PCR analysis demonstrated that FLD significantly decreased the expression of genes associated with the efflux pump gene (AcrB, kexD, ketM, kdeA, and kpnE), outer membrane (OM) porin proteins (OmpK35, OmpK36), the quorum-sensing (QS) system (luxS), lipopolysaccharide (LPS) production (wzm), and EPS production (pgaA). Simultaneously, FLD exhibited evident antibacterial synergism, leading to an increased survival rate of G. mellonella infected with MDR K. pneumoniae. These findings suggested that FLD has substantial antibiofilm properties and synergistic antibacterial potential for colistin in treating K. pneumoniae infections. [ABSTRACT FROM AUTHOR]

was initially described as Amylax diacantha from Belgian coastal waters a century ago but its detailed morphology needed restudy. Here, we established nine strains of G. verior by germinating cysts or isolating cells from localities from the European Atlantic to the Caspian Sea and the Pacific Ocean. Both cyst and thecal morphology were examined by light and scanning electron microscopy. SSU, LSU and/or ITS-5.8S rRNA gene sequences were obtained from all strains. Cells of G. verior have a plate formula of Po, 4′, 2a, 6-7′′, 6C, 6S, 6′′′, 1p, 1′′′′ with an L-type ventral organisation, characterised by two either straight or curved antapical horns of variable length. Cysts of G. verior are oval, smooth and contain one or two yellow accumulation bodies. The maximum-likelihood and Bayesian inference analyses based on SSU and LSU rRNA gene sequences revealed two clades of G. verior, referred to as ribotypes A and B. Genetic distances based on ITS-5.8S rRNA gene sequences within the same ribotype were less than 0.06, but greater than 0.32 between ribotypes. G. verior is reclassified as Sourniaea diacantha gen. et comb. nov., which is attributed to Lingulodiniaceae together with Pyxidinopsis, Lingulodinium and Amylax. Our results suggest that Lingulodiniaceae can be separated from Protoceratiaceae and Gonyaulacaceae based on ventral organisation, apical complex, ventral pore and number of anterior intercalary plates. One strain of S. diacantha was examined for yessotoxin production by LC-MS/MS but did not produce toxin. [ABSTRACT FROM AUTHOR]

A Cochlodinium-like species was isolated from the Korean coast and examined by light microscopy and scanning electron microscopy (SEM). The species was characterised by cellular torsion, cingulum with 1.25 turns and sulcus with 0.25 turn, and a hemispherical hypocone. The nucleus was curved, and sausage-shaped, and there were small, dark grains distributed at the cell periphery, which were also reported in the original description of Gyrodinium flavescens by Kofoid & Swezy (1921). SEM observations revealed that the apical structure complex of the species formed a complete circle surrounding the cell apex, consisting of three parallel rows of vesicles; and that the outer rows, composed of small vesicles, were visible along the sides of cingulum. These morphological features were identical to those of Torquentidium convolutum. Phylogeny-based on small subunit and large subunit rDNA sequences, confirmed that the species was closely related to T. convolutum within the family Ceratoperidiniaceae. However, the species was distinct from T. convolutum by differences in cingulum and sulcus turn numbers, shape of hypocone in dorsal view and size. Based on morphological and phylogenetic analyses, we propose Torquentidium flavescens comb. nov. nested within the family Ceratoperidiniaceae. [ABSTRACT FROM AUTHOR]

Although the genus Pseliodinium within the family Ceratoperidiniaceae includes Ceratoperidinium falcatum, Cochlodinium cf. convolutum, C. cf. helix and unidentified Cochlodinium species, it is in need of reclassification because of the morphological differences and lack of morphological details of the species within the genus. A Cochlodinium-like species was isolated from a Korean coastal area and examined by light and scanning electron microscopy, as well as by the analysis of nuclear-encoded small subunit (SSU) and large subunit (LSU) rDNA. The Korean isolate was morphologically characterized by cellular torsion, and outer rows consisting of small rectangular and polygonal vesicles were visible along the sides of the cingulum. The apical structure complex (ASC) formed a complete circle surrounding the cell apex, consisting of three parallel rows of vesicles. In the ASC, the upper row was sometimes hidden and very small knobs were present on the central row. Morphological characteristics separated the Korean isolate from Ce. margalefii, Pseliodinium fusus(=Ce. falcatum), Kirithra asteri and Gymnodinium species (Gymnodinium sp. 1 and sp. 2) within the family Ceratoperidiniaceae. However, the morphological characteristics coincided with those of the previously recorded C. convolutum, C. cf. helix and other Cochlodinium species within the same family. Phylogeny based on SSU and LSU rDNA sequences revealed that the Korean isolate forms a clade independent from P. fusus, although they have high sequence similarity. Based on the morphological and phylogenetic analyses, we propose the new genus Torquentidium gen. nov. and a new combination for C. cf. helix and the Korean isolate Torquentidium convolutum erected within the family Ceratoperidiniaceae. [ABSTRACT FROM AUTHOR]

SUMMARY An unarmored dinoflagellate, Karlodinium jejuense sp. nov., was isolated from the northern East China Sea. The species was characterized by light, fluorescence, and scanning electron microscopy of laboratory cultures, as well as SSU rDNA, ITS region (ITS1‐5.8S‐ITS2) and LSU rDNA gene sequences. Cells were ellipsoid to oval, small‐sized, 9.9–16.0 μm in length and 6.2–12.7 μm in width. The chloroplasts were 7–10 in number and yellow‐green in color. The central nucleus was large, located in the center of the cell. The linear apical groove with outward thick rolled margins was very short, and there was no ventral pore. Small pores were irregularly distributed on the cell surface. The amphiesmal vesicles were hexagonal and pentagonal. Karlodinium jejuense was morphologically similar to K. ballantinum but differed in cell surface characteristics and swimming pattern. The partial LSU sequence of K. jejuense differed by 3.7–4.1% from that of K. ballantinum. Molecular phylogenetic analyses of multi‐gene sequences revealed that K. jejuense was an independent species nested within the Karlodinium clade. Phylogenetic analysis based on partial LSU rDNA gene sequences indicated that K. jejuense was most closely related to K. gentienii and K. ballantinum. [ABSTRACT FROM AUTHOR]

ABSTRACT Anion-exchange resins (AERs) were regenerated with Mg/Al double-metal hydroxides as the regenerant. Electrical conductivity breakthrough curves were adopted to estimate the relatively rapid regenerative effect of the AERs. The results show that the optimal regenerative effect of AER was obtained when the Mg/Al molar ratio was 3 and the dosages of Mg and Al hydroxides were 0.045 and 0.015 mol, respectively. The highest effluent water yield was obtained at an AER/cation-exchange resin volume ratio of 2:1. Characterization through scanning electron microscopy, X-ray diffraction, and thermogravimetry-differential thermal analysis showed that the regenerant was transformed and exhibited the distinguishing features of Mg/Al layered double hydrotalcites. Cycle experimentation showed that all calcined products effectively regenerated the fouled resins, and the regenerative mechanism was then established. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42928. [ABSTRACT FROM AUTHOR]

Dense patches were observed in the tidal pools of the southern area of Korea. To clarify the causative organisms, the cells were collected and their morphological features were examined using light and scanning electron microscopy (SEM). In addition, after establishing strains for the cells the molecular phylogeny was inferred with concatenated small subunit (SSU) and large subunit (LSU) rRNA sequences. The cells were characterized by a nucleus in the hypotheca, strong reticulations in thecal plates, the separation of plates 2a and 3a, the tear-shaped apical pore complex, an elongated rectangular 1a plate and the absence of the right sulcal list. The thecal plate formula was Po, X, 4′, 3a, 7″, 6c, 4S, 5′′′, 2′′′′. Based on these morphological features, the cells were identified as Bysmatrum subsalsum. In the culture, the spherical cysts of B. subsalsum without thecal plates were observed. Molecular phylogeny revealed two ribotypes of B. subsalsum are identified; The Korean isolates were nested within the ribotype B consisting of the isolates from China, Malaysia and the French Atlantic, whereas the ribotype A includes only the isolates from the Mediterranean Sea. In the phylogeny, B. subsalsum and B. austrafrum were grouped. This can be supported by the morphological similarity between the two species, indicating that the two species may be conspecific, however B. subsalsum may distinguish from B. austrafrum, because of differences in the types of eyespots reported in previous studies. These findings support the idea that there is cryptic diversity within B. subsalsum. [ABSTRACT FROM AUTHOR]

Two new benthic freshwater species belonging to the genus Achnanthidium were found in Korea. Achnanthidium ovale sp. nov. and A. cavitatum sp. nov. are described as new species based on light and scanning electron microscopy observations and molecular analyses. Both species are compared with the type material of morphologically similar taxa. Achnanthidiumovale differs from other species belonging to the A.pyrenaicum complex in outline, striation pattern, raphe central endings, and freestanding areolae at the apices. Achnanthidiumcavitatum differs from other species in the A.minutissimum complex in outline, broad axial central area in the raphel ess valve, and slit-like areolae near the axial central area. We assessed their molecular characteristics by analyzing nuclear small subunit (SSU) rRNA and chloroplast-encoded rbcL gene sequences. Both the morphological comparison and the SSU and rbcL sequence analyses provide strong evidence to support the recognition of A. ovale and A. cavitatum as new species. [ABSTRACT FROM AUTHOR]