The Pseudomonas Quinolone Signal (PQS): Not Just for Quorum Sensing Anymore

The Pseudomonas quinolone signal (PQS) has been studied primarily in the context of its role as a quorum-sensing signaling molecule. Recent data suggest, however, that this molecule may also function to mediate iron acquisition, cytotoxicity, outer-membrane vesicle biogenesis, or to exert host immune modulatory activities

Izdvajanje dihidromiricetina iz lišća biljke Ampelopsis grossedentata mikrovalnom i višefaznom protustrujnom ekstrakcijom

Microwave-assisted extraction (MAE) technique in combination with multi-stage countercurrent extraction (MCE), namely microwave multi-stage countercurrent extraction (MMCE), was evaluated for the extraction of dihydromyricetin (DMY) from Ampelopsis grossedentata. Ethanol, methanol and water were used as extract solvents in the MMCE method. Of the three solvents used, water was found to be the best in extracting DMY from Ampelopsis grossedentata because it had a good extraction yield and is inexpensive, non-toxic and environmentally friendly. The optimal conditions of MMCE for the extraction of DMY can be determined to be the ratio of the extraction solvent to plant material of 30:1, the extraction time of 5 min, the extraction temperature of 110 °C and the microwave power of 600 W. In addition, the extraction efficiency of the MMCE method was compared with that of the microwave static batch extraction (MSBE) under the optimum extraction conditions. It was found that the MMCE method offered higher extraction efficiency than the MSBE method. Thus, the study suggests that the MMCE method provides an alternative technique in terms of both cost and efficiency.Ekstrakcija dihidromiricetina iz lišća biljke Ampelopsis grossedentata pokusno je provedena metodom mikrovalne ekstrakcije u kombinaciji s višefaznom protustrujnom ekstrakcijom. Kao otapalo upotrijebljeni su etanol, metanol i voda. Voda je najbolja za ekstrakciju dihidromiricetina iz Ampelopsis grossedentata jer daje dobro iskorištenje, jeftina je, nije toksična i ekološki je prihvatljiva. Kao optimalni uvjeti ovako kombinirane metode za ekstrakciju dihidromiricetina određeni su: omjer otapala i biljnog materijala 30:1, vrijeme ekstrakcije od 5 min, temperatura od 110 °C i snaga mikrovalova od 600 W. Uspoređujući učinkovitost ove metode s metodom diskontinuirane mikrovalne ekstrakcije u optimalnim uvjetima, vidi se da se veća učinkovitost ekstrakcije postiže višefaznom nego diskontinuiranom mikrovalnom ekstrakcijom. Stoga se, s obzirom na troškove i njezinu učinkovitost, može preporučiti kao alternativna metoda

Functions of the Clostridium acetobutylicium FabF and FabZ proteins in unsaturated fatty acid biosynthesis

<p>Abstract</p> <p>Background</p> <p>The original anaerobic unsaturated fatty acid biosynthesis pathway proposed by Goldfine and Bloch was based on in <it>vivo </it>labeling studies in <it>Clostridium butyricum </it>ATCC 6015 (now <it>C. beijerinckii</it>) but to date no dedicated unsaturated fatty acid biosynthetic enzyme has been identified in Clostridia. <it>C. acetobutylicium </it>synthesizes the same species of unsaturated fatty acids as <it>E. coli</it>, but lacks all of the known unsaturated fatty acid synthetic genes identified in <it>E. coli </it>and other bacteria. A possible explanation was that two enzymes of saturated fatty acid synthesis of <it>C. acetobutylicium</it>, FabZ and FabF might also function in the unsaturated arm of the pathway (a FabZ homologue is known to be an unsaturated fatty acid synthetic enzyme in enterococci).</p> <p>Results</p> <p>We report that the FabF homologue located within the fatty acid biosynthetic gene cluster of <it>C. acetobutylicium </it>functions in synthesis of both unsaturated fatty acids and saturated fatty acids. Expression of this protein in <it>E. coli </it>functionally replaced both the FabB and FabF proteins of the host in <it>vivo </it>and replaced <it>E. coli </it>FabB in a defined in <it>vitro </it>fatty acid synthesis system. In contrast the single <it>C. acetobutylicium </it>FabZ homologue, although able to functionally replace <it>E. coli </it>FabZ in <it>vivo </it>and in <it>vitro</it>, was unable to replace FabA, the key dehydratase-isomerase of <it>E. coli </it>unsaturated fatty acid biosynthesis in <it>vivo </it>and lacked isomerase activity in <it>vitro</it>.</p> <p>Conclusion</p> <p>Thus, <it>C. acetobutylicium </it>introduces the double of unsaturated fatty acids by use of a novel and unknown enzyme.</p

Limosilactobacillus balticus sp. nov., Limosilactobacillus agrestis sp. nov., Limosilactobacillus albertensis sp. nov., Limosilactobacillus rudii sp. nov. and Limosilactobacillus fastidiosus sp. nov., five novel Limosilactobacillus species isolated from the vertebrate gastrointestinal tract, and proposal of six subspecies of Limosilactobacillus reuteri adapted to the gastrointestinal tract of specific vertebrate hosts

Ten strains, BG-AF3-A(T), pH52_RY, WF-MT5-A(T), BG-MG3-A, Lr3000(T), RRLNB_1_1, STM3_1(T), STM2_1, WF-MO7-1(T) and WF-MA3-C, were isolated from intestinal or faecal samples of rodents, pheasant and primate. 16S rRNA gene analysis identified them as Limosilactobacillus reuteri. However, average nucleotide identity and digital DNA-DNA hybridization values based on whole genomes were below 95 and 70%, respectively, and thus below the threshold levels for bacterial species delineation. Based on genomic, chemotaxonomic and morphological analyses, we propose five novel species with the names Limosilactobacillus balticus sp. nov. (type strain BG-AF3-A(T)=DSM 110574(T)=LMG 31633(T)), Limosilactobacillus agrestis sp. nov. (type strain WF-MT5-A(T)=DSM 110569(T)=LMG 31629(T)), Limosilactobacillus albertensis sp. nov. (type strain Lr3000(T)=DSM 110573(T)=LMG 31632(T)), Limosilactobacillus rudii sp. nov. (type strain STM3_1(T)=DSM 110572(T)=LMG 31631(T)) and Limosilactobacillus fastidiosus sp. nov. (type strain WF-MO7-1(T)=DSM 110576(T)=LMG 31630(T)). Core genome phylogeny and experimental evidence of host adaptation of strains of L. reuteri further provide a strong rationale to consider a number of distinct lineages within this species as subspecies. Here we propose six subspecies of L. reuteri: L. reuteri subsp. kinnaridis subsp. nov. (type strain AP3(T)=DSM 110703(T)=LMG 31724(T)), L. reuteri subsp. porcinus subsp. nov. (type strain 3c6(T)=DSM 110571(T)=LMG 31635(T)), L. reuteri subsp. murium subsp. nov. (type strain lpuph1(T)=DSM 110570(T)=LMG 31634(T)), L. reuteri subsp. reuteri subsp. nov. (type strain F 275(T)=DSM 20016(T)=ATCC 23272(T)), L. reuteri subsp. suis subsp. nov. (type strain 1063(T)=ATCC 53608(T)=LMG 31752(T)) and L. reuteri subsp. rodentium subsp. nov. (type strain 100-23(T)=DSM 17509(T)=CIP 109821(T))

The role of the type VI secretion system in the stress resistance of plant-associated bacteria

Abstract The type VI secretion system (T6SS) is a powerful bacterial molecular weapon that can inject effector proteins into prokaryotic or eukaryotic cells, thereby participating in the competition between bacteria and improving bacterial environmental adaptability. Although most current studies of the T6SS have focused on animal bacteria, this system is also significant for the adaptation of plant-associated bacteria. This paper briefly introduces the structure and biological functions of the T6SS. We summarize the role of plant-associated bacterial T6SS in adaptability to host plants and the external environment, including resistance to biotic stresses such as host defenses and competition from other bacteria. We review the role of the T6SS in response to abiotic factors such as acid stress, oxidation stress, and osmotic stress. This review provides an important reference for exploring the functions of the T6SS in plant-associated bacteria. In addition, characterizing these anti-stress functions of the T6SS may provide new pathways toward eliminating plant pathogens and controlling agricultural losses

Geochemical Characterization of the Eocene Coal-Bearing Source Rocks, Xihu Sag, East China Sea Shelf Basin, China: Implications for Origin and Depositional Environment of Organic Matter and Hydrocarbon Potential

Eocene coal-bearing source rocks of the Pinghu Formation from the W-3 well in the western margin of the Xihu Sag, East China Sea Shelf Basin were analyzed using Rock-Eval pyrolysis and gas chromatography–mass spectrometry to investigate the samples’ source of organic matter, depositional environment, thermal maturity, and hydrocarbon generative potential. The distribution patterns of n-alkanes, isoprenoids and steranes, high Pr/Ph ratios, abundant diterpanes, and the presence of non-hopanoid triterpanes indicate predominant source input from higher land plants. The contribution of aquatic organic matter was occasionally slightly elevated probably due to a raised water table. High hopane/sterane ratios and the occurrence of bicyclic sesquiterpanes and A-ring degraded triterpanes suggest microbial activity and the input of microbial organisms. Overwhelming predominance of gymnosperm-derived diterpanes over angiosperm-derived triterpanes suggest a domination of gymnosperms over angiosperms in local palaeovegetation during the period of deposition. The high Pr/Ph ratios, the plot of Pr/n-C17 versus Ph/n-C18, the almost complete absence of gammacerane, and the distribution pattern of hopanes suggest that the samples were deposited in a relatively oxic environment. Generally, fluctuation of redox potential is coupled with source input, i.e., less oxic conditions were associated with more aquatic organic matter, suggesting an occasionally raised water table. Comprehensive maturity evaluation based on Ro, Tmax, and biomarker parameters shows that the samples constitute a natural maturation profile ranging from marginally mature to a near peak oil window. Hydrogen index and atomic H/C and O/C ratios of kerogens suggest that the samples mainly contain type II/III organic matter and could generate mixed oil and gas

Serum Metabolic Characterization of Vitamin E Deficiency in <i>Holstein</i> Cows during the Transition Period Based on Proton Nuclear Magnetic Resonance Spectroscopy

Vitamin E, a potent antioxidant, is a necessary and complex micronutrient for cows. During the transition period, vitamin E deficiency (VED) is among the highest prevalent micronutrient deficits in dairy cows. It may eventually result in oxidative stress and immunological malfunction, and it increases the risk of peripartum disorders. At present, detailed data on blood metabolites in VED cows are limited. Consequently, the purpose of this research was to examine the alterations in the serum metabolic profile of VED cows throughout the early postpartum period. Using comprehensive 1H nuclear magnetic resonance (1H NMR), the alterations in serum metabolic activities of VED cows were analyzed. In total, 28 multiparous Holstein cows were assigned according to serum α-tocopherol (α-Toc) concentrations into normal (α-Toc ≥ 4 μg/mL, n = 14) and VED (α-Toc n = 14) groups at 21 days postpartum, and their blood samples were collected for biochemical and 1H NMR analyses. A t-test on independent samples as well as multivariate statistics were used to assess the findings. In comparison with normal cows, VED cows showed significantly worse body condition scores, milk yield, and dry matter intake (p p p > 0.05). Furthermore, 24 upregulated serum metabolites were identified under VED conditions. The metabolomics pathway analysis of these metabolites demonstrated that a global metabolic response to VED in cows was represented by changes in 11 metabolic pathways, comprising energy, carbohydrate, and amino acid metabolism. From these results, we conclude that VED cows were more likely to experience a negative energy balance characterized by alterations of common systemic metabolic processes and develop oxidative stress, inflammation, and ultimately liver injury. This study provides the first evidence of metabolic changes in cows with VED

Microwave Multi-Stage Countercurrent Extraction of Dihydromyricetin from Ampelopsis grossedentata

Microwave-assisted extraction (MAE) technique in combination with multi-stage countercurrent extraction (MCE), namely microwave multi-stage countercurrent extraction (MMCE), was evaluated for the extraction of dihydromyricetin (DMY) from Ampelopsis grossedentata. Ethanol, methanol and water were used as extract solvents in the MMCE method. Of the three solvents used, water was found to be the best in extracting DMY from Ampelopsis grossedentata because it had a good extraction yield and is inexpensive, non-toxic and environmentally friendly. The optimal conditions of MMCE for the extraction of DMY can be determined to be the ratio of the extraction solvent to plant material of 30:1, the extraction time of 5 min, the extraction temperature of 110 °C and the microwave power of 600 W. In addition, the extraction efficiency of the MMCE method was compared with that of the microwave static batch extraction (MSBE) under the optimum extraction conditions. It was found that the MMCE method offered higher extraction efficiency than the MSBE method. Thus, the study suggests that the MMCE method provides an alternative technique in terms of both cost and efficiency

Astronomical forcing of the Paleogene coal- bearing hydrocarbon source rocks of the East China Sea Shelf Basin

The Paleogene coal-bearing deposits (Pinghu Formation) of the Xihu Depression form the most productive hydrocarbon source in the East China Sea Shelf Basin. Due to the lack of reliable magnetostratigraphic, paleontologic and geochemical/isotope data, these source rocks are still poorly dated. The absence of a robust time frame results in many disputes on the age and duration of the Pinghu Formation and hampers a thorough understanding of its sedimentary evolution. Here, we study the cyclic changes in the depositional environment that can be retrieved from seismic interpretation and sequence stratigraphic analyses of well log data ( e. g., stacking patterns, logging, and lithofacies changes). We recognize one second-order sequence, three third-order sequences and 12 fourth-order parasequences. Next, we construct a floating astronomical time scale by using power spectra and evolutionary fast Fourier transformation analysis on the gamma-ray data. Wavelength variations in the gamma-ray spectra show similar ratios as the astronomically-forced Milankovitch cycles ( i. e., eccentricity, obliquity and precession). The filtered long and short orbital eccentricity cycles show a good match with the La2010d astronomical target curve, allowing to create an independent time frame based on cyclostratigraphy. Our floating astronomical time scale provides new numerical age constraints for the Pinghu Formation, resulting in a total duration of ~4.95 Myr. A re-analysis of the available age data indicates that the sequence stratigraphic framework of the Pinghu Formation is best constrained to the early Oligocene, instead of the previously assumed late Eocene. Our study highlights that astronomical interpretation of sequence stratigraphic analyses is an excellent method to estimate the duration of sedimentary successions in boreholes and adds to a better understanding of the temporal and spatial sediment distribution patterns in the East China Sea Shelf Basin