Cohaesibacter intestini sp. nov., isolated from the intestine of abalone, Haliotis discus hannai.

A Gram-stain-negative, rod-shaped and facultative anaerobic strain named YE-B6T was isolated from the intestine of abalone, Haliotis discus hannai. The reactions of oxidase and catalase were both positive. Strain YE-B6T could grow at 10-37 °C (optimum, 28-33 °C), at pH 7-9 (optimum, pH 7) and in salinity of 0-8 % NaCl (w/v; optimum, 2 %). The 16S rRNA gene sequence of strain YE-B6T had maximum sequence similarities to Cohaesibacter celericrescens H1304T (98.0 %), Cohaesibacter marisflavi DQHS21T (97.4 %), Cohaesibacter haloalkalitolerans JC131T (97.4 %) and Cohaesibacter gelatinilyticus CL-GR15T (97.3 %). Results of phylogenetic analysis showed that it was affiliated to the genus Cohaesibacter within the order Rhizobiales in the Alphaproteobacteria. The respiratory quinone of strain YE-B6T was Q-10. The cellular fatty acids mainly comprised C18 : 1 ω7c and summed feature 3 (C16 : 1ω6c and/or C16 : 1ω7c). The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylmonomethylethanolamine, two unidentified aminolipids, two unidentified polar lipids and one unidentified phospholipid. The G+C content of strain YE-B6T was 55.6 mol%. Based on its genotypic, physiological and biochemical characteristics, strain YE-B6T represented a novel species within the genus Cohaesibacter, for which the name Cohaesibacterintestini sp. nov. is proposed. The type strain of the new species is YE-B6T (=MCCC 1A13131T=KCTC 62716T).

Chengkuizengella marina sp. nov., isolated from deep-sea sediment of the Pacific Ocean.

A taxonomic study was carried out on strain YPA3-1-1T, which was isolated from deep-sea sediment of the Pacific Ocean. The bacterium was Gram-stain-positive, oxidase-positive, catalase-negative, rod-shaped and spore-forming. Growth was observed at salinities of 1.0-6.0 % and at temperatures of 10-40 °C. The isolate could degrade gelatin and aesculin. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain YPA3-1-1T belonged to the genus Chengkuizengella, with the highest sequence similarity to the only typespecies, Chengkuizengella sediminis J15A17T (98.5 %). The estimated average nucleotide identity and DNA-DNA hybridization values between strain YPA3-1-1T and C. sediminis J15A17T were 88.1 and 35.0 %, respectively. The cell wall of strain YPA3-1-1T contained meso-diaminopimelic acid. The principal fatty acids (>10 %) were iso-C16 : 0 (35.5 %) and anteiso-C15 : 0 (17.5 %). The G+C content of the chromosomal DNA was 33.1 mol%. The respiratory quinone was determined to be MK-7 (100 %). The polar lipids were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, glycolipid and three unidentified phospholipids. The combined genotypic and phenotypic data show that strain YPA3-1-1T represents a novel species within the genus Chengkuizengella, for which the name Chengkuizengella marina sp. nov. is proposed, with the type strain YPA3-1-1T (=MCCC 1A14042T=KCTC 43019T).

Bacterial biogeography in the coastal waters of northern Zhejiang, East China Sea is highly controlled by spatially structured environmental gradients.

The underlying mechanisms of microbial community assembly in connective coastal environments are unclear. The coastal water area of northern Zhejiang, East China Sea, is a complex marine ecosystem with multiple environmental gradients, where the distributions and determinants of bacterioplankton communities remain unclear. We collected surface water samples from 95 sites across eight zones in this area for investigating bacterial community with 16S rRNA gene high-throughput sequencing. Bacterial alpha-diversity exhibits strong associations with water chemical parameters and latitude, with 75.5% of variation explained by suspended particle. The composition of dominant phyla can group the sampling sites into four bacterial provinces, and most key discriminant phyla and families/genera of each province strongly associate with specific environmental features, suggesting that local environmental conditions shape the biogeographic provincialism of bacterial taxa. At a broader and finer phylogenetic scale, bacterial beta-diversity is dominantly explained by the shared variation of environmental and spatial factors (63.3%); meanwhile, the environmental determinants of bacterial ß-diversity generally exhibit spatially structured patterns, suggesting that bacterial assembly in surface water is highly controlled by spatially structured environmental gradients in this area. This study provides evidence for the unique biogeographic pattern of bacterioplankton communities at an entire scale of this marine ecosystem.

The temporal scaling of bacterioplankton composition: high turnover and predictability during shrimp cultivation.

The spatial distribution of microbial communities has recently been reliably documented in the form of a distance-similarity decay relationship. In contrast, temporal scaling, the pattern defined by the microbial similarity-time relationships (STRs), has received far less attention. As a result, it is unclear whether the spatial and temporal variations of microbial communities share a similar power law. In this study, we applied the 454 pyrosequencing technique to investigate temporal scaling in patterns of bacterioplankton community dynamics during the process of shrimp culture. Our results showed that the similarities decreased significantly (P = 0.002) with time during the period over which the bacterioplankton community was monitored, with a scaling exponent of w = 0.400. However, the diversities did not change dramatically. The community dynamics followed a gradual process of succession relative to the parent communities, with greater similarities between samples from consecutive sampling points. In particular, the variations of the bacterial communities from different ponds shared similar successional trajectories, suggesting that bacterial temporal dynamics are predictable to a certain extent. Changes in bacterial community structure were significantly correlated with the combination of Chl a, TN, PO4 (3-), and the C/N ratio. In this study, we identified predictable patterns in the temporal dynamics of bacterioplankton community structure, demonstrating that the STR of the bacterial community mirrors the spatial distance-similarity decay model.

Size-dependent cytotoxicity of nanocarbon blacks.

In this study, we investigated the toxic effects of nanocarbon blacks (NCBs) with different sizes to mouse macrophage RAW264.7 cells. MTT and fluorescence-based LIVE assays demonstrated that NCBs uptake caused a size and dose-dependent growth inhibition to the cells. Optical microscopy observations and (99m)Tc radionuclide labeling techniques were used to investigate the cellular uptake of NCBs with different sizes qualitatively and quantitatively, respectively. Results showed that the cellular uptake amounts of NCBs increased with their increasing size. Large quantities of internal NCBs induced oxidative stress and nuclear damage in cells; these effects may be the critical factors involved in the cytotoxicity of NCBs. The implications associated with these findings are discussed.

Combination of non-sterilized wastewater purification and high-level CO2 bio-capture with substantial biomass yield of an indigenous Chlorella strain.

The indigenous microalga Chlorella sorokiniana NBU-3 grown under air, 5 %, 15 %, and 25 % CO2 supply was evaluated to determine its potential for flue gas bio-capture, nutrient removal capacity and biomass yield using non-sterilized wastewater as growth medium. The results indicated that C. sorokiniana NBU-3 exhibited high nutrient removal efficiency (>95 % for NH4+-N, TN and TP) with either air or CO2 aeration. 5 %-15 % CO2 supplies promote biomass yield, nutrient utilization and CO2 biofixation of C. sorokiniana NBU-3. In particular, 15 % CO2 promotes C. sorokiniana NBU-3 growth in non-sterilized MW, but inhibits its growth in BG11 medium, indicating the importance of non-sterilized MW and high CO2 aeration concurrence for C. sorokiniana NBU-3 economically practical cultivation. Moreover, the highest values of lipid (27.84 ± 2.12 %) and protein (32.65 ± 4.11 %) contents were obtained in MW with 15 % CO2 aeration. Conceivably, microalgal-bacterial symbiosis may help C. sorokiniana NBU-3 tolerate high concentration of CO2 and promote microalga growth. The succession of the community diversity toward the specific functional bacterial species such as Methylobacillus and Methylophilus (Proteobacteria) which were predicted to possess the function of methylotroph, methanol oxidation and ureolysis would help facilitate the microalgal-bacterial symbiosis and promote the microalgae biomass accumulation with high dosage of CO2 aeration. Overall, these findings clearly highlight the potential of this indigenous microalga C. sorokiniana NBU-3 for industrial-emission level CO2 mitigation and commercial microalga biomass production in MW.

Cytotoxicity of phenol red in toxicity assays for carbon nanoparticles.

To explore the novel properties of carbon nanoparticles (CNPs) in nanotoxicity assays, the adsorption of phenol red (a pH indicator for culture medium) by multi-walled carbon nanotubes (MWNTs) and three kinds of carbon blacks (CBs) with nanosize, and its effects on cytotoxicity were studied. Results indicated that the phenol red adsorbed and delivered into cells by CBs was responsible for the toxicity to Hela cells in the medium without serum. The cellular uptake of phenol red was verified using 125I-labeling techniques. The size-dependent cytotoxicity of CBs was found to closely correlate to adsorption of phenol red, cellular uptake of phenol red-CB complexes and the amount of phenol red delivered into the cells by CBs. Although the CBs were either nontoxic or slightly toxic, as vehicles of phenol red, they played an essential role in the cytotoxicity induced by phenol red. However, MWNTs showed an intrinsic cytotoxicity independent of phenol red. The implications associated with these findings are discussed.

Response of microbial community to the lysis of Phaeocystis globosa induced by a biological algicide, prodigiosin.

Terminating harmful algal blooms by using algicidal agents is a strong disturbance event in marine environment, which has powerful structural influences on microbial ecosystems. But, the response of microbial ecosystem to algicidal agent is largely unknown. Here, we conducted Phaeocystis globosa microcosms to investigate the dynamics, assembly processes, and co-occurrence patterns of microbial communities in response to algicidal process induced by a highly efficient algicidal agent, prodigiosin, by using 16S rRNA gene amplicon sequencing. The α-diversity of microbial community showed no obvious changes during the algicidal process in P. globosa microcosm treated with prodigiosin (group PD). Rhodobacteraceae increased significantly (P < 0.05) during algicidal process in PD, and this was mainly due to the lysis of P. globosa cells. Compared to the control group, the temporal turnover rates of common and rare taxa in PD were significantly higher because of the lysis of P. globosa induced by prodigiosin. Neutral processes mainly drove the assembly of microbial communities in all microcosms, even though the algicidal process induced by prodigiosin had no effect on the assembly processes. In addition, the time-decay relationship and co-occurrence network analysis indicate that rare taxa play important roles in maintaining microbial community stability in response to the algicidal process, rather than prodigiosin. These findings suggest that prodigiosin cannot affect the dynamics of microbial communities directly; however, future investigations into the function of microbial communities in response to prodigiosin remain imperative.

The interaction and toxicity of multi-walled carbon nanotubes with Stylonychia mytilus.

The interaction of multi-walled carbon nanotubes (MWNTs) with living unicellular protozoan Stylonychia mytilus was studied. The results indicated that MWNTs were ingested largely by Stylonychia mytilus. Distribution of MWNTs in the cells, redistribution during dividing process of the cells, and excretion from the cells were observed successfully with optical microscope. The dependence of viability of Stylonychia mytilus was determined on the concentration of MWNTs, ranging from 0.1 microg/ml to 200 microg/ml. It was found that exposure of Stylonychia mytilus to the MWNTs with concentration higher than 1.0 microg/ml induced a dose-dependent growth inhibition to the cells and the damage occurred, by fluorescence microscopy, on the macronucleus and external membrane of the cells. The ultrastructure change by electron microscope revealed that the MWNTs exclusively localized to the mitochondria of the cells. It was proposed that the damage of macronucleus, micronucleus, and membrane of the cells, as well as growth inhibition of the cells might be a result of the damage of mitochondria, following this exclusive localization. Our finding provides important information on the bio-security of MWNTs and their migration in aqueous environment.

[Toxic Effect of Nano-ZnO in Liver of Zebrafish].

For acute toxicity test, zebrafish were respectively exposed to the different concentrations of nano-ZnO (0, 0.05, 0.1, 5, 10, 25, 50 mg x L(-1)) for 4, 24 and 96 h. The superoxide dismutase (SOD), malondialdehyde (MDA), and catalase (CAT) in the liver of zebrafish were studied, and the relative expression of Bcl-2, Bax, p53 and MDM2 in liver were also determined. Anatomical structure of the zebrafish liver was determined after exposure to nano-ZnO for 7, 15 and 30 d. Compared with the control group, the liver of the experimental groups showed obvious difference in following aspects: (1) oedema, cytoplastic vacuolation, and pyknotic nucleus were observed; (2) the number of hepatic macrophages deposited and the sinus clearance were increased; (3) the MDA contents and the activity of SOD were increased; (4) however, the activity of CAT was decreased; (5) the mRNA expression level of genes Bax/Bcl-2 ratio and p53 of stressed groups were up-regulated; the mRNA expression level of gene MDM2 down-regulation can be observed in the low concentration groups while the mRNA expression level of gene MDM2 was up-regulated in the high concentration groups. The results suggested that, the oxidative damage of nano-ZnO to the zebrafish liver was caused by the increase of oxidative stress, which made the change of antioxidant enzyme activity, induced the expression of cell apoptosis genetic and cell apoptosis, and caused the change of organizational structure of liver.

Comparative study of pathological lesions induced by multiwalled carbon nanotubes in lungs of mice by intratracheal instillation and inhalation.

The pathological lesions induced by multiwalled carbon nanotubes (MWCNTs) in bronchi and alveoli of mice were studied by intratracheal instillation and inhalation. In instillation groups, the dose was 0.05 mg MWCNTs/mouse. Similar size clumps of MWCNTs were distributed in bronchi and alveoli. The clumps led to inflammation to the lining wall of bronchi and severe destruction to alveolar netted structure around them. In the inhalation groups, the mice were exposed to aerosolized MWCNTs with mean concentration of 32.61 mg/m(3), the intralung deposition dose were roughly 0.07, 0.14, and 0.21 mg in the 8-day group, 16-day group, and 24-day group, respectively. Most of aggregations of MWCNTs in the alveoli were smaller than that in bronchi. The aggregations induced proliferation and thickening of alveolar walls. With the exception of these moderate pathological lesions, the general alveolar structure was still remained. The preliminary study demonstrated a difference in lung pathological lesions induced by instilled MWCNTs and inhaled ones, which may be due to the different size and distribution of aggregations of MWCNTs in lung.