High hydrostatic pressure harnesses the biosynthesis of secondary metabolites via the regulation of polyketide synthesis genes of hadal sediment-derived fungi

Deep-sea fungi have evolved extreme environmental adaptation and possess huge biosynthetic potential of bioactive compounds. However, not much is known about the biosynthesis and regulation of secondary metabolites of deep-sea fungi under extreme environments. Here, we presented the isolation of 15 individual fungal strains from the sediments of the Mariana Trench, which were identified by internal transcribed spacer (ITS) sequence analysis as belonging to 8 different fungal species. High hydrostatic pressure (HHP) assays were performed to identify the piezo-tolerance of the hadal fungi. Among these fungi, Aspergillus sydowii SYX6 was selected as the representative due to the excellent tolerance of HHP and biosynthetic potential of antimicrobial compounds. Vegetative growth and sporulation of A. sydowii SYX6 were affected by HHP. Natural product analysis with different pressure conditions was also performed. Based on bioactivity-guided fractionation, diorcinol was purified and characterized as the bioactive compound, showing significant antimicrobial and antitumor activity. The core functional gene associated with the biosynthetic gene cluster (BGC) of diorcinol was identified in A. sydowii SYX6, named as AspksD. The expression of AspksD was apparently regulated by the HHP treatment, correlated with the regulation of diorcinol production. Based on the effect of the HHP tested here, high pressure affected the fungal development and metabolite production, as well as the expression level of biosynthetic genes which revealed the adaptive relationship between the metabolic pathway and the high-pressure environment at the molecular level

Oxidation of trimethylamine to trimethylamine N-oxide facilitates high hydrostatic pressure tolerance in a generalist bacterial lineage

High hydrostatic pressure (HHP) is a characteristic environmental factor of the deep ocean. However, it remains unclear how piezotolerant bacteria adapt to HHP. Here, we identify a two-step metabolic pathway to cope with HHP stress in a piezotolerant bacterium. Myroides profundi D25T, obtained from a deep-sea sediment, can take up trimethylamine (TMA) through a previously unidentified TMA transporter, TmaT, and oxidize intracellular TMA into trimethylamine N-oxide (TMAO) by a TMA monooxygenase, MpTmm. The produced TMAO is accumulated in the cell, functioning as a piezolyte, improving both growth and survival at HHP. The function of the TmaT-MpTmm pathway was further confirmed by introducing it into Escherichia coli and Bacillus subtilis. Encoded TmaT-like and MpTmm-like sequences extensively exist in marine metagenomes, and other marine Bacteroidetes bacteria containing genes encoding TmaT-like and MpTmm-like proteins also have improved HHP tolerance in the presence of TMA, implying the universality of this HHP tolerance strategy in marine Bacteroidetes

Improve Requirement Prioritization By End-user Demands : Model Building and Evaluation

Background: The selection and prioritizing of requirements is the most difficult challenge insoftware development. Prioritizing requirements is a difficult task. Due to the importance of thepriority of requirements, many methods have been developed on how to prioritize requirements.However, with the increase of software modules and the expansion of software platforms, thesingle requirement prioritization method can no longer match the increase in the number ofrequirements. Little is know in how to find and develop integrated requirement prioritizationmethod. Objectives: The main purpose of this research is to explore the main challenges and successcriteria that practitioners consider when determining the priority of product requirements. Builda good requirement prioritization model to tackle these challenges. And evaluate the strengthsand limitations of this model. Method: We conducted a questionnaire survey to learn more about the major problems andsuccess criteria for prioritizing product requirements. After that, we presented a model thatcombined the KANO model and Analytic Hierarchy Process (AHP), and we examined its practicality. Finally, using Focus Group Research, we analyzed the benefits and limitations of theintegrated model and improved solutions. Result: The results show that practitioners face many challenges in product requirement prioritization. The model we developed is suitable for a variety of scenarios. It helps practitionersmanage priorities and improve end-user satisfaction, which can solve these challenges to a certain extent. Conclusion: Our research collected many major challenges encountered by requirement analysts and product managers in the process of requirement prioritization. And developed a newrequirement prioritization model, got a better understanding of requirement prioritization whichcan inspire practitioners to build more better requirement prioritization models.

Depth-Resolved Variations of Cultivable Bacteria and Their Extracellular Enzymes in the Water Column of the New Britain Trench

Marine microorganisms and their extracellular enzymes (ECEs) play an important role in the remineralization of organic material by hydrolyzing high-molecular-weight substrates to sizes sufficiently small to be transported through cell membrane, yet the diversity of the enzyme-producing bacteria and the types of ECEs involved in the degradation process are largely unknown. In this work, we investigated the diversity of cultivable bacteria and their ECEs and the potential activities of aminopeptidase in the water column at eight different depths of the New Britain Trench. There was a great diversity of cultivable bacteria and ECEs, and depth appears an important driver of the diversity. The 16S rRNA sequence analysis revealed that the cultivable bacteria were affiliated mostly with the phyla Proteobacteria and Actinobacteria, and the predominant genera were Pseudoalteromonas (62.7%) and Halomonas (17.3%). Moreover, 70.7% of the isolates were found to produce hydrolytic zone on casein and gelatin plates, in which Pseudoalteromonas was the predominant group, exhibiting relatively high protease production. Inhibitor analysis showed that the extracellular proteases from the isolated bacteria were serine proteases in the surface water and metalloproteases in the deep water. Meanwhile, the Vmax and Km of aminopeptidase exhibited a maximum in the surface water and low values in the deep bathy- and abyssopelagic water, indicating lower rates of hydrolysis and higher substrate affinity in the deeper waters. These results shed new insights into the diversity of the cultivable bacteria and bacterial ECEs and their likely biogeochemical functions in the trench environment

Insight into the adaptation mechanisms of high hydrostatic pressure in physiology and metabolism of hadal fungi from the deepest ocean sediment

ABSTRACTHigh hydrostatic pressure (HHP) influences the life processes of organisms living at depth in the oceans. While filamentous fungi are one of the essential members of deep-sea microorganisms, few works have explored their piezotolerance to HHP. Here, we obtained three homogeneous Aspergillus sydowii from terrestrial, shallow, and hadal areas, respectively, to compare their pressure resistance. A set of all-around evaluation methods including determination of growth rate, metabolic activity, and microscopic staining observation was established and indicated that A. sydowii DM1 from the hadal area displayed significant piezotolerance. Global analysis of transcriptome data under elevated HHP revealed that A. sydowii DM1 proactively modulated cell membrane permeability, hyphae morphology, and septal quantities for seeking a better livelihood under mild pressure. Besides, differentially expressed genes were mainly enriched in the biosynthesis of amino acids, carbohydrate metabolism, cell process, etc., implying how the filamentous fungi respond to elevated pressure at the molecular level. We speculated that A. sydowii DM1 could acclimatize itself to HHP by adopting several strategies, including environmental response pathway HOG-MAPK, stress proteins, and cellular metabolisms.IMPORTANCEFungi play an ecological and biological function in marine environments, while the physiology of filamentous fungi under high hydrostatic pressure (HHP) is an unknown territory due to current technologies. As filamentous fungi are found in various niches, Aspergillus sp. from deep-sea inspire us to the physiological trait of eukaryotes under HHP, which can be considered as a prospective research model. Here, the evaluation methods we constructed would be universal for most filamentous fungi to assess their pressure resistance, and we found that Aspergillus sydowii DM1 from the hadal area owned better piezotolerance and the active metabolisms under HHP indicated the existence of undiscovered metabolic strategies for hadal fungi. Since pressure-related research of marine fungi has been unexpectedly neglected, our study provided an enlightening strategy for them under HHP; we believed that understanding their adaptation and ecological function in original niches will be accelerated in the perceivable future

Red-emitting CaLa4(SiO4)(3)O:Eu3+ phosphor with superior thermal stability and high quantum efficiency for warm w-LEDs

To accelerate the next generation of high power white light-emitting diodes, the development of efficient and stable red-emitting phosphors is urgent. In this regard, a series of CaLa4(SiO4)(3)O: Eu3+ phosphors with red-emitting band centered at 612 nm are prepared by a high temperature solid state reaction. Xray diffraction patterns and Rietveld refinement confirm that all the samples are oxyapatite structure with space group of P63/m. Impressively, the quantum efficiency of the prepared red phosphor reaches as high as 97.5% under blue light excitation, and its emission intensity at 423 K remains 82.4% of that at room temperature, which are comparable to those of the commercial Y2O3: Eu3+ red phosphor. As a consequence, a warm white light-emitting diode with a luminous efficiency of 84.9 lm/W, a correlated color temperature of 4012 K and a color rendering index of 84.4 is realized by blending red-emitting CaLa4(SiO4)(3)O: Eu3+ phosphors and yellow-emitting Y3Al5O12: Ce3+ ones with a blue LED chip. It is expected that the explored CaLa4(SiO4)3O: Eu3+ red phosphor can be a good candidate for application in solid-state lighting. (C) 2016 Elsevier B.V. All rights reserved