Low Supply Rates Research Articles

Activity of novel virus families infecting soil nitrifiers is concomitant with host niche differentiation.

Chemolithoautotrophic nitrifiers are model groups for linking phylogeny, evolution, and ecophysiology. Ammonia-oxidising bacteria (AOB) typically dominate the first step of ammonia oxidation at high ammonium supply rates, ammonia-oxidising archaea (AOA) and complete ammonia-oxidising Nitrospira (comammox) are often active at lower supply rates or during AOB inactivity, and nitrite-oxidising bacteria (NOB) complete canonical nitrification. Soil virus communities are dynamic but contributions to functional processes are largely undetermined. In addition, characterising viruses infecting hosts with low relative abundance, such as nitrifiers, may be constrained by vast viral diversity, partial genome recovery, and difficulties in host linkage. Here, we describe a targeted incubation study that aimed to determine whether growth of different nitrifier groups in soil is associated with active virus populations and if process-focussed analyses facilitate characterisation of high-quality virus genomes. dsDNA viruses infecting different nitrifier groups were enriched in situ via differential host inhibition. Growth of each nitrifier group was consistent with predicted inhibition profiles and concomitant with the abundance of their viruses. These included 61 high-quality/complete virus genomes 35-173kb in length with minimal similarity to validated families. AOA viruses lacked ammonia monooxygenase sub-unit C (amoC) genes found in marine AOA viruses but some encoded AOA-specific multicopper oxidase type 1 (MCO1), previously implicated in copper acquisition, and suggesting a role in supporting energy metabolism of soil AOA. Findings demonstrate focussed incubation studies facilitate characterisation of active host-virus interactions associated with specific processes and viruses of soil AOA, AOB and NOB are dynamic and potentially influence nitrogen cycling processes.

Achieving Long-Term Stability of Partial Nitrification and Autotrophic Denitrification in an MABR via Sulfide Dosing.

While partial nitrification (PN) has the potential to reduce energy for aeration, it has proven to be unstable when treating low-strength wastewater. This study introduces an innovative combined strategy incorporating a low rate of oxygen supply, pH control, and sulfide addition to selectively inhibit nitrite-oxidizing bacteria (NOB). This strategy led to a stable PN in a laboratory-scale membrane aerated biofilm reactor (MABR). Over a period of 260 days, the nitrite accumulation ratio exceeded 60% when treating synthetic sewage containing 50 mg NH4+-N/L. Through in situ activity testing and high-throughput sequencing, the combined strategy led to low levels of nitrite-oxidation activity (<5.5 mg N/m2 h), Nitrospira species (relative abundance <1%), and transcription of nitrite-oxidation genes (undetectable). The addition of sulfide led to simultaneous PN and autotrophic denitrification in the single-stage MABR, resulting in over 60% total inorganic nitrogen removal. Sulfur-based autotrophic denitrification consumed nitrite and inhibited NOB conversion of nitrite to nitrate. The combined strategy has potential to be applied in large-scale sewage treatment and deserves further exploration.

Application of the authigenic 10Be/9Be dating to constrain the age of a long-lived lake and its regression in an isolated intermontane basin: The case of Late Miocene Lake Turiec, Western Carpathians

The depositional record of intermontane basins provides a valuable archive of the temporal evolution of orogenic belts; their common isolated nature may, however, hinder the efficient usage of standard approaches to constrain the age of a basin fill. In this paper the authigenic 10Be/9Be dating method is employed and tested to construct an age model of the existence and regression of Lake Turiec, which appeared during the Late Miocene in the intermontane Turiec Basin, Central Western Carpathians (Central Europe). The initial authigenic 10Be/9Be ratio, essential for the dating method, was analyzed on five sites of the Pleistocene-Holocene age, and back-calculation of the paleo-initial ratio was performed using lacustrine succession dated by magnetostratigraphy. Noteworthy, the initial ratio appears to be affected mainly by (post)depositional settings, and not by different provenance of the analyzed sediment. The sedimentological analysis of the Upper Miocene outcrops allowed the definition of the facies associations of an alluvial fan, a braided river, a fan delta and an open lake. The distribution of facies associations in the basin fill implies an increase in sediment supply to accommodation rate ratio due to the replacement of the open lake environment by the interconnected alluvial fan-braided river-fan delta system. Authigenic 10Be/9Be dating yielded ages of the lacustrine succession reaching ∼10.7–7.8 Ma, while the age of the fan delta succession, considered as the timing of the regression, was established to ∼6.7 Ma. The deposition of alluvial fans dominated the basin after the regression of the lake, possibly up to ∼4.0 Ma. The abrupt increase in sediment supply to the accommodation ratio at ∼6.7 Ma was caused by the uplift of the Malá Fatra Mts. at the western margin of the Turiec Basin, which had previously formed a moderate topography. The timing of this process generally coincides with the overall decrease in accommodation rates in the region due to the inversion of the Pannonian Basin System. The endorheic character of the basin before ∼6.7 Ma prevented the transport of the sediment denudated from the recently most uplifted parts of the Western Carpathians and carried towards the Pannonian Basin System, while the present-day source-to-sink system could only be formed later. This implies a low sediment supply and restricted denudation rate not only from the morphostructures surrounding the basin, but also from the Tatra Mts. and Nízke Tatry Mts. during the period ∼10.7–6.7 Ma. The research supports the suitability of intermontane basins for authigenic 10Be/9Be dating in a setting of high accommodation rates and limited redeposition of older muddy sediment. However, a special attention has to be paid to the depositional settings during determination of initial 10Be/9Be ratios.

Enhanced nutrient removal of agricultural waste-pyrite bioretention system for stormwater pollution treatment

Pyrite as filler applied to bioretention cells has the potential for simultaneous nitrogen and phosphorus removal, but its low electron supply rate cannot adapt to the demand for nitrogen and phosphorus removal under high rainfall intensity and continuous rainfall conditions. In this study, novel pyrite-based bioretention cells with agricultural waste amendment (corn cobs, rice husks, wood chips) were developed, and the pollution removal of each cell was evaluated under simulated complex rainfall conditions. The bioretention cell amended with woodchips achieved significantly higher efficiency and stability for dissolved nutrient removal compared with the pyrite bioretention cell. Its average removal efficiency of nitrate nitrogen, total nitrogen, and phosphate phosphorus was 69.39%, 45.60%, and 60.01% higher than that of the control group. The average chemical oxygen demand (COD) and total iron (TFe) concentrations in the effluent were slightly higher than those from the pyrite bioretention cell but were significantly lower than those from the corn cob and the rice husk-pyrite bioretention cell. Microbiological analysis revealed that the addition of woodchips significantly increased the relative abundance of Thiobacillus (the main functional genus of autotrophic denitrification) and Thauera (the main functional genus of heterotrophic denitrification) in the bioretention cell to 25.17% and 3.06%. The results indicated that woodchips promoted the proliferation of both heterotrophic and autotrophic microorganisms, therefore enhancing the nitrogen removal efficiency of mixotrophic denitrification.

Experimental study and CFD modelling of four-bed hospital ward with all-air wall induction unit for air-conditioning

This study focuses on a prototype all-air wall induction unit. While maintaining the non-reheating and power saving conveying characteristics of the induction systems, this unit is water pipe free and has a low air supply velocity, and is therefore suitable for application in hospital wards. However, its ventilation and thermal performance have not been sufficiently investigated for further improvement. Thus, this study performs a full-scale experiment in which induction units are vertically installed in the ward's four corners. CO2 is generated to represent pollutants from a sample patient, and the steady-state temperature and CO2 concentration distribution are measured and analyzed under different supply conditions. Moreover, computational fluid dynamics (CFD) modeling methods are proposed and validated for this unit. The results show that the wall induction system can maintain a normalized concentration near the hospital beds that are away from the pollution source of less than 0.7 by producing displacement ventilation (DV). Supplying the air from the bottom half of the wall corner with a low supply rate while the bed is surrounded by a curtain can halve the CO2 concentration in the occupied zone by improving the efficiency of the DV. The vertical distribution of room temperature ranges from Δ3 °C to Δ4 °C depending on the supply volume, which is considered acceptable in the ward usage. Furthermore, in the ward CFD simulation, the accuracy of the Standard k-ϵ (SKE) model with specific heat transfer boundaries has been proved to be nearly identical to the low-Reynolds calculation results.

Study on the Oxygen Consumption Rule of Hydroponic Cotton in Different Periods.

In this paper, the decay law of dissolved oxygen in the culture solution of cotton in the seedling stage, bud stage, and blossoming and boll-forming stage was studied via hydroponic cotton experiments, and then, the oxygen consumption and its rule of cotton were explored. The results showed that with the increase of the cultivation time, the dissolved oxygen concentration of the cotton at seedling stage, bud stage, and blossoming and boll-forming stage showed an exponential function decrease. The dissolved oxygen concentration of the culture medium decreased from about 7.5 mg·L−1 to a relatively stable dissolved oxygen concentration, which was 4.92 mg·L−1, 1.64 mg·L−1, and 1.82 mg·L−1, respectively. When CK is about 7.1 mg·L−1, a relative equilibrium point between low oxygen absorption rate of cotton and oxygen supply is reached. The sudden drop points of the instant oxygen consumption rate of cotton seedling stage and bud stage are at about 5.15 mg·L−1 and 5.89 mg·L−1, respectively, while the sudden drop point was not obvious at the blossoming and boll-forming stage. The budding cotton can absorb oxygen when the dissolved oxygen in the culture solution is at a higher level. The blossoming and boll-forming stage cotton is more resistant to hypoxia stress.

Importance of vaccine action and availability and epidemic severity for delaying the second vaccine dose

Following initial optimism regarding potentially rapid vaccination, delays and shortages in vaccine supplies occurred in many countries during spring 2021. Various strategies to counter this gloomy reality and speed up vaccination have been set forth, of which the most popular has been to delay the second vaccine dose for a longer period than originally recommended by the manufacturers. Controversy has surrounded this strategy, and overly simplistic models have been developed to shed light on this issue. Here we use three different epidemic models, all accounting for then actual COVID-19 epidemic in the Czech Republic, including the real vaccination rollout, to explore when delaying the second vaccine dose by another 3 weeks from 21 to 42 days is advantageous. Using COVID-19-related deaths as a quantity to compare various model scenarios, we find that the way of vaccine action at the beginning of the infection course (preventing infection and symptoms appearance), mild epidemic and sufficient vaccine supply rate call for the original inter-dose period of 21 days regardless of vaccine efficacy. On the contrary, for the vaccine action at the end of infection course (preventing severe symptoms and death), severe epidemic and low vaccine supply rate, the 42-day inter-dose period is preferable, at any plausible vaccine efficacy.

Translithospheric magma plumbing system of intraplate volcanoes as revealed by electrical resistivity imaging

AbstractThe magma plumbing systems of volcanoes in subduction and divergent tectonic settings are relatively well known, whereas those of intraplate volcanoes remain elusive; robust geophysical information on the magma pathways and storage zones is lacking. We inverted magnetotelluric data to image the magma plumbing system of an intraplate monogenetic volcanic field located above the stagnant Pacific slab in northeast China. We identified a complex, vertically aligned, low-resistivity anomaly system extending from the asthenosphere to the surface consisting of reservoirs with finger- to lens-like geometries. We show that magma forms as CO2-rich melts in a 150-km-deep asthenospheric plume crossing the whole lithosphere as hydrated melt, inducing underplating at 50 km depth, evolving in crustal reservoirs, and erupting along dikes. Intraplate volcanoes are characterized by low degrees of melting and low magma supply rates. Their plumbing systems have a geometry not so different from that of volcanoes in subduction settings.

Experimental Investigation of Nozzle Clogging Using Vibration Signal-Based Condition Monitoring for Fused Deposition Modeling

Fused deposition modeling (FDM) or 3D printing is one of the promising techniques widely preferred to fabricate complex and customized 3D objects or prototypes for various engineering and non-engineering applications. With the growing demands of customized prototypes, researchers are facing a major challenge for maintaining effective part quality with adequate surface finish and strength; and minimizing the cost, defects, and waste in 3D printing. Condition monitoring is one of the strategies to achieve the aforementioned. It has a huge potential to minimize defects and print failures in 3D printing. The main objective of this research work is to perform online condition monitoring of the nozzle status with the help of vibration signals in fused deposition modelling process. The effect of nozzle clogging on the consistency of material deposition and its effect on surface finish has experimentally investigated in this work. The set of experiments were performed by artificially creating the condition of nozzle clogging to investigate the effect of nozzle clogging on print quality (surface finish). Nozzle clogging condition was created by increasing the feed rate of polylactic acid (PLA) filament at a low heat supply rate to the nozzle by modifying the commands of 3D printer. The layer thickness was varied throughout the experiments to observe the nozzle clogging. The vibrations signals were acquired by using an accelerometer that was mounted near the nozzle. The data acquisition frequency of the accelerometer was 12500Hz. Further, the acquired vibration signals were analyzed using the Fast Fourier transformation (FFT) signal processing technique. Results revealed that nozzle clogging severely affects surface quality and geometrical accuracy of the fabricated 3D part due to nozzle vibration and non-uniform material deposition. Moreover, nozzle clogging and its relevant consequences like non uniform material deposition can be monitored using vibration signal-based condition monitoring during part fabrication and based upon that appropriate measures can be taken for defects and waste elimination.

Three‐dimensional submerged wall jets and their transition to density flows: Morphodynamics and implications for the depositional record

AbstractJets that expand from an orifice into an ambient water body represent a basic flow model for depositional environments related to expanding flows. Momentum‐dominated jets evolve into gravity‐dominated density flows. To understand this transition and its sedimentological relevance, three‐dimensional tank experiments with submerged wall jets were conducted, systematically varying parameters such as the initial density difference, bed slope, grain size and sediment supply. Bedform successions could be subdivided into those related to the jet and those related to the density flow. Jet deposits included early‐stage bedforms, scours and mouth bars. Early‐stage bedforms are asymmetrical dunes that spread concentrically from the orifice. Sediment entrainment by eddies from the expanding jets led to the formation of scours and mouth bars. Flows with lesser initial density difference produced more elongate scours. Conversely, scours became deeper for denser incoming flows. Coarser‐grained sediment caused the formation of higher and steeper mouth bars and vice versa. The transition from momentum‐dominated jets to gravity‐dominated density flows occurred approximately at the mouth‐bar crest. Hydraulic jumps were absent in the expanding jet regions and at the transitions to density flows. Instead, complex flow patterns and circulations were inferred from the velocity measurements within the scour and at the mouth‐bar crests. Bedform trains related to the density flow were controlled by the grain size and sediment supply. Coarse‐grained sediment and high supply rates caused strong mouth‐bar aggradation and flow splitting, leading to the formation of bedform trains laterally adjacent to the mouth bar. Fine‐grained sediment and low supply rates caused the formation of bedform trains downflow of the mouth bar. The symmetrical bedforms deposited by the density flows always displayed an in‐phase relationship with the flow, indicating that they were antidunes. The experimental jet deposits resemble successions known from subaqueous ice‐contact fans and deep water channel‐lobe transition zones.

Development of activity collecting system for grazing cattle in vast land

AbstractDairy farming in Japan has low milk supply and reproductive rate per cattle, which is considered to be due to lack of proper breeding management. In order to solve this problem, there is a demand for a breeding management system that does not require human intervention, utilizing the ICT and robot technology. Studies on cow health and breeding management using various sensors have been reported; in this paper, we develop the system to collect the amount of activity and position of the grazing cattle in vast land. The developed system is (i) the “cattle sensor” composed of a GPS module and an acceleration sensor and (ii) the data transfer system composed of a wireless module and solar cells. The cow sensor can be used continuously for 2 months without battery replacement and is a system that can be used in vast land and mountain areas. And the data obtained from the sensor suggest the possibility of estrus detection.

Development of High Pressure and Constant Low Flow Test System for Hydraulic Support Safety Valve

The existing test equipment for safety valve with low-flow start and overflow closure characteristics of hydraulic support cannot provide the test conditions stipulated in relevant standards, which affects the accuracy of test results. Aiming at the shortage of the existing test equipment, a test system of high pressure and low flow rate of safety valve with hydraulic support is designed, and a technical solution of using straight line driver to push the plunger cylinder to realize high pressure and low flow rate of liquid supply is put forward. The simulation software AMESim was used to construct the virtual prototype of the test system, and the simulation analysis was carried out to determine the main parameters and the influencing rules of the rigidity of the liquid supply velocity. Based on the simulation study, prototype trial production, flow calibration and field experiment were completed. The experimental results showed that the instantaneous output flow fluctuation of the test system was within the range of ±10% of the rated value of 40ml/min, and the output flow fluctuation range was reduced by 25% compared with the existing way.

Capping dewatered oil sands fluid fine tailings with salvaged reclamation soils at varying depths to grow woody plants

Managing fluid fine tailings (FFT) present a major cause of industrial and environmental concerns in oil sands surface mining production. A potential management solution is to dewater and cap the FFT solids for use in land reclamation. A 16 wk greenhouse study was conducted to assess whether FFT centrifuge cake with caps of various reclamation soil mixes (forest floor mineral mix, peat mineral mix, and a mixture of both) and depths (0, 5, 10, and 20 cm) would support growth of trembling aspen (Populus tremuloides — native broadleaf tree) and beaked willow (Salix bebbiana — native broadleaf shrub). Beaked willow had a much greater survival rate (100%) when grown directly in FFT cake compared with trembling aspen (16.7%). Plants grown directly in FFT cake were negatively impacted by high water content, low nitrate supply rates, and high metal concentrations with beaked willow seedlings having 10 times higher foliar concentrations of Al, Cr, and Ti compared with any other treatments. Adding soil caps substantially increased aboveground biomass for both species, but differences among soil cap types and depths did not have as significant of an effect on plant growth. Results from this study show that capping FFT substantially improves woody plant growth, and S. bebbiana and P. tremuloides are potentially suitable species for tailings reclamation.

Million-year lag times in a post-orogenic sediment conveyor.

Understanding how sediment transport and storage will delay, attenuate, and even erase the erosional signal of tectonic and climatic forcings has bearing on our ability to read and interpret the geologic record effectively. Here, we estimate sediment transit times in Australia's largest river system, the Murray-Darling basin, by measuring downstream changes in cosmogenic 26Al/10Be/14C ratios in modern river sediment. Results show that the sediments have experienced multiple episodes of burial and reexposure, with cumulative lag times exceeding 1 Ma in the downstream reaches of the Murray and Darling rivers. Combined with low sediment supply rates and old sediment blanketing the landscape, we posit that sediment recycling in the Murray-Darling is an important and ongoing process that will substantially delay and alter signals of external environmental forcing transmitted from the sediment's hinterland.

Controlling dietary cation-anion differences in forages by chloride fertilisation

Rations with low to negative dietary cation-anion difference (DCAD) given to dairy cows before calving reduce the risk of hypocalcaemia (milk fever). Different strategies for increasing forage DCAD were investigated in field trials in Central and Western Norway. Fertilisation with 70, 140 or 210 kg Cl per hectare as calcium chloride and low supply rates of K reduced DCAD in forage harvested at late developmental stages in spring growth of timothy and meadow fescue. The ideal negative DCAD was only attained on soils very low in plant available K. Timing (spring versus late spring) and source of Cl (CaCl2 versus MgCl2) were of no importance for the result. When pure stands of seven grasses were fertilised in spring either without chloride or with 140 kg chloride per hectare, the lowest values of DCAD after chloride fertilisation were found in perennial ryegrass and reed canary grass. By comparison, cocksfoot had equally high or higher Cl concentrations in its tissues, but accumulated more K, and seemed to be poorly suited for low DCAD forage production. It was concluded that Cl fertilisation is a more efficient means of controlling DCAD than sward species composition.

Feedstock Dependence of Emissions from a Reverse-Downdraft Gasifier Cookstove

The present study investigates the combustion process of the producer gas from a gasifier cookstove, for four solid biomass fuels: wood pellets (WP), wheat straw (WS), sheep manure (SM) and cow manure (CM). It was found that more primary air and/or a deeper fuel bed reduces tars in the producer gas and increases the combustion efficiency, especially from low-ash-containing WP. At higher air supply rates, indications of a strong influence from the fuel ash content on the emissions were found. Although more combustible gases and fewer tars are produced in the conversion process, a substantial increase in particulate matter (PM) emissions is noted. At low air supply rates, the emissions of particulates with an aerodynamic diameter ≤2.5 μm (PM2.5) released from the combustion process are in the range of 6–30 mg⋅MJreleased−1 (WP<WS<SM<CM), low when compared with similar devices. However, when the air supply is increased by a factor of three, the PM2.5 emissions almost double for WP and increase more than ten fold for CM. At lower air supply rates, low emissions of both PM and CO are achieved. This is likely due to lower peak temperatures (reducing ash devolatilisation) and larger char yields (to retain ash particulates) from the thermochemical solid biomass conversion process. This shows that low air supply rates and the combined production of heat, for cooking, and char, for subsequent applications, may achieve substantial benefits for the emissions of pollutants from gasifer cookstoves.

Holocene delta progradation into an epeiric sea in northeastern Australia

Progradation of the Quaternary Gilbert River megafan and Holocene delta, located in the low gradient intracratonic basin and epeiric sea of the Gulf of Carpentaria, Australia, has been enhanced by the slight fall in sea level during the late Holocene. The monsoonal floods and channel avulsions on the megafan have controlled the rate of progradation and supply of sediment to the delta front. The mixed-influence delta can be classified as a tide dominated, fluvially influenced and wave affected (Tfw) delta. Palaeogeographic reconstruction of the Gilbert River megafan, delta and palaeoshorelines was created through GIS analysis of beach and chenier ridges combined with field observations, previous cross-section data, and radiocarbon and thermoluminescence dating. Progradation rates on the Gilbert River delta are about 0.85 to 0.9 m/yr in the northern and central parts of the delta and increase to 1.8 m/yr in the southern part of the delta. Sedimentation rates vary from 0.2 to 1.0 mm/yr with a total Holocene delta volume of about 9.4 × 109 m3 and a sediment supply rate of ~1 Mm3/yr. The low sediment supply rate is characteristic of most Australian river systems but is about two orders of magnitude less than on many of the larger Southeast Asian deltas. The low onshore and offshore accommodation space on the Gilbert and Mitchell River deltas is a function of the epeiric sea setting of these deltas, and hence the thin succession of Holocene sediments on these deltas also represent a significant difference from most Southeast Asian deltas.

Oversight or New Insight? Comments on Several Recent Papers Studying High-Temperature Oxidation of Si-Containing Steels

Recently, a group of researchers conducted experimental studies on the high-temperature oxidation behaviour of Si-containing steels and published a series of papers in several international journals. Many of the research “findings” in these papers were inconsistent and contradictory with previous results. Based on the different findings, it was claimed that they arrived at “new insights” to the oxidation behaviour of Si-containing steels and discovered a “new method” to reduce the oxide scale amount generated during reheating of Si-containing steels. After examining the experimental methods used, it was revealed that most of the “new findings” were likely the direct consequence of the use of a very low gas flow rate (30 mL/min) in their experiments. This resulted in an extremely low oxygen supply rate when the oxygen concentration in the experimental gas was low, which in turn limited the reaction rate that could be possibly achieved by gas–steel reaction if abundant gas had been made available. The kinetics results and scale thickness/structures thus produced were therefore misleading, which also led to the erroneous interpretation of the results. This paper comments on the main results presented in these papers and briefly discuss several fundamental issues related to the design of steel oxidation experiments.

Alleviation of Drought Stress and Plant Growth Promotion by Pseudomonas libanensis EU-LWNA-33, a Drought-Adaptive Phosphorus-Solubilizing Bacterium

Drought is a very common abiotic stress worldwide in arid and semiarid areas. It decreases the growth and yield of the crops. Due to drought stress, there is insufficient intake of the nutrients, the low rate of photosynthesis and limited supply of water in plants. Inoculating crops with plant growth-promoting rhizobacteria (PGPR) mitigates the deleterious effects of stress by promoting beneficial effects such as helping them in the acquisition of less available nutrients, increasing the levels of plant growth regulators, improving the physiological health of the plants. In the present study, drought-tolerant phosphorus-solubilizing rhizobacteria with multifunctional plant growth-promoting attributes were isolated from different cereal crops grown in the Divine Valley of Baru Sahib, Himachal Pradesh, using a different nutrient combination. A total of 86 bacteria were isolated from different growth media. All 86 could tolerate 5% PEG, and 19, 6 and 6 isolates could tolerate 6%, 7% and 8% PEG-8000, respectively. Among 86, 48 drought-adapted and P-solubilizing strains were selected and screened for diverse PGP attributes such as solubilization of potassium and zinc, production of siderophores, hydrogen cyanide, ammonia and 1-aminocyclopropane-1-carboxylate deaminase. The efficient drought-adaptive P-solubilizing strain was used for seed germination and plant growth-promoting ability in different pot assays under laboratory and greenhouse conditions at different water regimes. The strain EU-LWNA-33 positively influencing the growth parameters and physiological parameters was identified using 16 S rRNA gene sequencing as Pseudomonas libanensis. To our knowledge, this is the first report for P. libanensis EU-LWNA-33 to solubilize a considerable amount of P under the water-deficient conditions. The use of stress-adaptive and P-solubilizing PGPR provides significant promise to overcome the challenges of sustainable agriculture in stressed environmental conditions.

Microbial Methane Conversion to Short-Chain Fatty Acids Using Various Electron Acceptors in Membrane Biofilm Reactors.

Given our vast methane reserves and the forecasted shortage of crude oil in the not too distant future, the conversion of methane into value-added liquid chemicals or fuels would be beneficial. The generated chemicals or fuels could augment the petroleum-dominated chemical market, and also satisfy the increasing demand for transportation fuels. While methane bioconversion to liquid chemicals has just been reported recently, there is limited understanding of the process. This study aims to clarify the potential electron acceptors that could support the process. Here we operated four membrane biofilm reactors (MBfRs) fed with nitrate, nitrite, oxygen at a relatively low rate, and oxygen at a relatively high rate, respectively, to study if they can support methane bioconversion to short-chain fatty acids (SCFAs) and the associated microbiological features. All tested electron acceptors facilitated methane bioconversion to SCFAs (ranging from 1.1 to 36.7 mg acetate L-1 d-1, or 3.4 to 114.6 mg acetate d-1 m-2 of biofilm). The carbon efficiency was estimated to be 7.9 ± 1.4% to 148.5 ± 1.3%, with an efficiency higher than 100%, suggesting the assimilation of other carbon, very likely CO2, into the products. A low oxygen supply rate of 46.4 ± 2.3 mg O2 d-1 m-2 was found to be the most favorable among all the electron conditions provided according to the SCFAs production rate and also the carbon utilization efficiency. Microbial characterization revealed that completely different communities evolved in the respective reactors, suggesting diverse microbial pathways exist for methane bioconversion into value-added chemicals.