Quantum-Confined-Superfluidics-Enabled Multiresponsive MXene-Based Actuators.

MXene, renowned for its natural "quantum-confined-superfluidic" (QSF) channels, demonstrates superior electrical/thermal conductivity, favorable hydrophilicity, and remarkable mechanical strength, rendering it an ideal candidate for multiresponsive actuators, which are promising for soft electronics and robots. Currently, most MXene-based actuators are mainly prepared by combining an active layer and an inner layer, with only a few utilizing regulated QSF channels. However, tailoring QSF channels for multiresponsive actuators is extremely challenging. Herein, we introduce a multiresponsive graphene oxide (GO)&Fe3O4/MXene actuator that can respond to humidity, light, heat, electricity, and magnetic fields by constructing asymmetric QSF channels. The asymmetric water adsorption, transportation, and desorption behaviors, controlled by the different QSF channels between the GO&Fe3O4 layer and the MXene layer, enable the multiresponsiveness of the actuator. As proof-of-concept demonstrations, several smart devices, such as a bionic crab-like crawler, a transporting flower robot, and a smart gripper, are prepared, holding great potential for advancing future soft robotics.

Gracilimonas amylolytica sp. nov., isolated from deep-sea sediment.

A Gram-stain-negative, aerobic, non-motile and rod-shaped bacterium, designated LA399T, was isolated from deep-sea sediment collected from the Pacific Ocean. Cells of strain LA399T grew in the medium containing 0-10.0 % of NaCl (w/v; optimum 3.0-5.0 %), pH 6.5-8.0 (optimum 7.0) and 20-40 °C (optimum 37 °C). Aesculin, gelatin, starch and Tween 80 were hydrolysed. Strain LA399T was closely related to Gracilimonas halophila WDS2C40T (97.0 % sequence similarity), Gracilimonas mengyeensis YIM J14T (96.4 %), Gracilimonas rosea CL-KR2T (96.4 %) and Gracilimonas tropica DSM 19535T (96.0 %), and exhibited equal or less than 96.0 % sequence similarity to other type strains of species with validly published names. Phylogenetic analyses revealed that strain LA399T clustered with the clade comprising the Gracilimonas species and formed an independent lineage. Strain LA399T contained menaquinone 7 as the sole isoprenoid quinone and iso-C15 : 0, anteiso-C15 : 0, summed feature 3 (C16 : 1ω7c/C16 : 1ω6c) and summed feature 9 (iso-C17 : 1ω9c/10-methyl C16 : 0) as the predominant cellular fatty acids. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, one unidentified phospholipid and three unidentified glycolipids. The DNA G+C content was 45.3 mol%. According to the phylogenetic, chemotaxonomic and phenotypic data, it represents a novel species of the genus Gracilimonas, for which the name Gracilimonas amylolytica is proposed. The type strain is LA399T (=CGMCC 1.16248T=KCTC 52885T).

[Intestinal bacterial community is indicative for the healthy status of Litopenaeus vannamei].

High density and intensive Litopenaeus vannamei aquaculture has increased the frequency of shrimp disease, however, it remains uncertain whether change in intestinal bacteria could be indicative of shrimp health state (healthy or diseased). Therefore, we collected water and shrimp intestine samples from ponds with or without diseased shrimps. Using bacterial 16S rRNA gene as a biomarker, the bacterial community structure and diversity were evaluated with the Illumina MiSeq sequencing technique. The results showed that the variations of bacterioplankton community were primarily shaped by the levels of NO2(-)-N, chlorophyll a and PO4(3-)-P. Bacterial diversity was signif-7 icantly lower in diseased shrimps than in healthy ones. Using a response ratio analysis, we screened 28 operational taxonomic units (OTUs), and their abundances significantly changed in the intestines between healthy and diseased shrimps. In general, the abundances of OTUs belonged to Actinobacteria, Flavobacteria and Bacilli significantly decreased in diseased shrimps compared with those in healthy shrimps., while the OTUs affiliated to Clostridia showed an opposite pattern. In addition, we obtained 61 indicator species that primarily affiliated to Bacteroidetes, Proteobacteria, Firmicutes, Planctomycetes and Actinobacteria. Notably, the identified indicator taxa exhibited clearly discriminative patterns among habitats (water or intestine) and health status. Collectively, this study provided scientific information for development of new probiotics and disease prevention.

Pseudoalteromonas gelatinilytica sp. nov., isolated from surface seawater.

Three Gram-stain-negative, rod-shaped bacteria, designated strains NH153T, F-2-11 and M-1-78, were isolated from surface seawater of the South China Sea and the East China Sea. The three isolates were able to grow at 15-45 °C (optimum 28-37 °C), but no growth occurred at 4 or 50 °C. The pH range for growth was pH 5.5-9.5 (optimum pH 7.5-8.5). The isolates required sea salts for growth and growth occurred in the presence of 0-10 % (w/v) NaCl (optimum 3-5 %); no growth occurred in the presence of 12.0, 15.0 or 20.0 % (w/v) NaCl. They were positive for hydrolysis of gelatin and Tween 80. The sole respiratory quinone was ubiquinone-8 (Q-8). The major cellular fatty acids (>10 %) were C16 : 0, C18 : 1ω7c and summed feature 3 (C16 : 1ω7c and/or iso-C15 : 0 2-OH). The major polar lipid components were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, one unidentified glycolipid, one unidentified phospholipid and one unidentified lipid. The genomic DNA G+C content of strain NH153T was 41.4 mol%. Based on 16S rRNA gene sequence analysis, the isolates were closely related to the type strain of Pseudoalteromonas shioyasakiensis (98.0-98.6 % sequence similarity). The 16S rRNA gene sequence similarities between the three isolates were 98.8-99.7 %. Phylogenetic analysis indicated that they formed a distinct lineage and clustered with P. shioyasakiensis and Pseudoalteromonas arabiensis. The level of DNA-DNA relatedness among the three isolates was 78.0-85.5 %. Strain NH153T exhibited average nucleotide identity values of 93.4 and 84.2 % with respect to P. shioyasakiensisJCM 18891T and P. arabiensisJCM 17292T, respectively. The genome-to-genome distance analysis revealed that strain NH153T shared 52.4 % DNA relatedness with P. shioyasakiensisJCM 18891T and 28.1 % with P. arabiensisJCM 17292T. On the basis of the phenotypic, genotypic and chemotaxonomic characterizations, as well as phylogenetic inference obtained in this study, strains NH153T, F-2-11 and M-1-78 represent a novel species within the genus Pseudoalteromonas, for which the name Pseudoalteromonasgelatinilytica sp. nov. is proposed. The type strain is NH153T (=CGMCC 1.15370T=DSM 100951T), and F-2-11 (=CGMCC 1.15364=DSM 100953) and M-1-78 (=CGMCC 1.15365=DSM 100952), are additional strains of the species.

Development and evaluation of a real-time fluorogenic loop-mediated isothermal amplification assay integrated on a microfluidic disc chip (on-chip LAMP) for rapid and simultaneous detection of ten pathogenic bacteria in aquatic animals.

Rapid, low-cost, and user-friendly strategies are urgently needed for early disease diagnosis and timely treatment, particularly for on-site screening of pathogens in aquaculture. In this study, we successfully developed a real-time fluorogenic loop-mediated isothermal amplification assay integrated on a microfluidic disc chip (on-chip LAMP), which was capable of simultaneously detecting 10 pathogenic bacteria in aquatic animals, i.e., Nocardia seriolae, Pseudomonas putida, Streptococcus iniae, Vibrio alginolyticus, Vibrio anguillarum, Vibrio fluvialis, Vibrio harveyi, Vibrio parahaemolyticus, Vibrio rotiferianus, and Vibrio vulnificus. The assay provided a nearly-automated approach, with only a single pipetting step per chip for sample dispensing. This technique could achieve limits of detection (LOD) ranging from 0.40 to 6.42pg per 1.414µL reaction in less than 30 min. The robust reproducibility was demonstrated by a little variation among duplications for each bacterium with the coefficient of variation (CV) for time to positive (Tp) value less than 0.10. The clinical sensitivity and specificity of this on-chip LAMP assay in detecting field samples were 96.2% and 93.8% by comparison with conventional microbiological methods. Compared with other well-known techniques, on-chip LAMP assay provides low sample and reagent consumption, ease-of-use, accelerated analysis, multiple bacteria and on-site detection, and high reproducibility, indicating that such a technique would be applicable for on-site detection and routine monitoring of multiple pathogens in aquaculture.

Community analysis of ammonia oxidizer in the oxygen-limited nitritation stage of OLAND system by DGGE of PCR amplified 16S rDNA fragments and FISH.

OLAND (oxygen limited autotrophic nitrification and denitrification) nitrogen removal system was constructed by coupling with oxygen limited nitritation stage and anaerobic ammonium oxidation stage. Ammonia oxidizer, as a kind of key bacteria in N cycle, plays an important role at the oxygen limited nitritation stage of OLAND nitrogen removal system. In this study, specific amplification of 16S rDNA fragment of ammonia oxidizer by nested PCR, separation of mixed PCR samples by denaturing gradient gel electrophoresis (DGGE), and the quantification of ammonia oxidizer by fluorescence in situ hybridization (FISH) were combined to investigate the shifts of community composition and quantity of ammonia oxidizer of the oxygen limited nitritation stage in OLAND system. It showed that the community composition of ammonia oxidizer changed drastically when dissolved oxygen was decreased gradually, and the dominant ammonia oxidizer of the steady nitrite accumulation stage were completely different from that of the early stage of oxygen limited nitritation identified by DGGE. It was concluded that the Nitrosomonas may be the dominant genus of ammonia oxidizer at the oxygen limited nitritation stage of OLAND system characterized by nested PCR-DGGE and FISH, and the percentage of Nitrosomonas was 72.5% +/- 0.8% of ammonia oxidizer at the steady nitrite accumulation stage detected by FISH.