Enhanced Biomass Production Research Articles

Green light as supplementary light for enhancing biomass production of Ettlia sp. and preventing population invasion from other microalgae

The biomass and carotenoid productivities of a freshwater microalga, Ettlia sp. YC001 (Chlorophyta, Chlamydomonadales), were investigated in continuous culture systems irradiated with various LEDs. Green light was effectively used by Ettlia sp. for its biomass growth compared to blue and red LED light. This effective use of green light was assumed to be beneficial for Ettlia sp., especially in competition with other microalgae. Thus, in a competition between Ettlia sp. and Chlorella vulgaris, Ettlia sp. out-competed C. vulgaris without losing any overall biomass productivity when green and white LEDs were used simultaneously. However, since Ettlia sp. also showed relatively low oxygen production under green light, further studies are needed on its photosynthesis and biomass production mechanisms. Notwithstanding, LEDs are potentially useful for identifying strain-specific photosynthetic characteristics of microalgae, thereby increasing their biomass productivity and controlling contamination from other microalgae in open culture systems.

Manipulating Nutritional Conditions and Salinity-Gradient Stress for Enhanced Lutein Production in Marine Microalga Chlamydomonas sp.

Marine microalgae has great potential for lutein production with the advantage of saving fresh water resource. Thus, marine microalga Chlamydomonas sp. JSC4 is investigated as a potential lutein producer in this study. The medium types, nitrate-N and sea salt concentration are individually investigated to promote the cell growth rate and lutein production of JSC4. In Modified Bold Basal 3N medium, cell growth and lutein content are optimal at the nitrate-N concentration of 1000 mg L-1 and sea salt concentration of 2%. In addition, an innovative salinity-gradient strategy is operated to dramatically enhance biomass productivity (560 mg/L/d) and lutein content (3.42 mg g-1 ), resulting in the optimal lutein productivity (1.92 mg/L/d). Overall, this study clearly demonstrates that salinity is a significant inducer of lutein accumulation by strain JSC4 and that lutein production can be successfully optimized using the salinity-gradient strategy, which is beneficial for the outdoor large-scale lutein production in the future.

Arbuscular mycorrhizal fungi alleviate Cd phytotoxicity by altering Cd subcellular distribution and chemical forms in Zea mays

Arbuscular mycorrhizal fungus (AMF) can relieve Cd phytotoxicity and improve plant growth, but the mechanisms involved in this process have still been not completely known. In the present work, a pot experiment was conducted to examine productions of glutathione (GSH) and phytochelatins (PCs), and absorption, chemical forms and subcellular distribution of Cd in maize (Zea mays) inoculated with or without AMF (Rhizophagus intraradices (Ri) and Glomus versiforme (Gv)) in Cd-amended soils (0, 1 and 5 mg Cd kg−1 soil). In general, both Ri and Gv inoculation dramatically enhanced biomass production and reduced Cd concentrations in shoots and roots of maize when compared to the non-mycorrhizal treatment. Moreover, both Ri and Gv symbiosis obviously increased contents of GSH and PCs, both in shoots and roots. Subcellular distribution of Cd in maize indicated that most of Cd (more than 90%) was accumulated in cell wall and soluble fraction. In addition, Cd proportions in soluble fractions in shoots of maize inoculated with Gv or Ri were considerably increased, but reduced in cell wall fractions compared to non-mycorrhizal maize, indicating that mycorrhizal symbiosis promoted Cd transfer to vacuoles. Furthermore, proportions of Cd in inorganic and water-soluble forms were declined, but elevated in pectates and proteins-integrated forms in mycorrhizal maize, which suggested that Gv and Ri could convert Cd into inactive forms. These observations could provide a further understanding of potential Cd detoxification mechanism in maize inoculated with AMF.

Biodiesel Potentiality of Microalgae Species: evaluation Using Various Nitrogen Sources

The two fresh water microalgae species namely Scenedesmus dimorphus and Scenedesmus obliquus were selected as biomass feedstocks for biodiesel production due to high accumulation of their neutral lipid content which mainly composed of three significant biodiesel fatty acids profile viz saturated fatty acids (SFA: ≈ 53%), mono unsaturated fatty acids (MUFA: ≈ 24%) and poly unsaturated fatty acids (PUFA: ≈ 20%). Both algae strains were cultivated with five different nitrogen nutrients via (NH4)2SO4 (ammonium sulphate: AS), NH4NO3 (ammonium nitrate: AN), KNO3 (potassium nitrate: PN), (NH2)2CO (urea: UR) and NaNO3 (sodium nitrate: SN) of concentration ranging from 0.02 to 0.3 M in agricultural medium. The transesterification of micro algal lipids with absolute ethanol medium in the presence of Ni/H2 catalyst and Ni(II)–Schiff base chelate promoter was carried out to yield more algal oil. The extracted biodiesel components were analyzed cost–effectively using UV–Vis,1H NMR, 13C NMR and GC–MS spectral characterization to explore their biodiesel potentiality. The results revealed that the extracted microalgae biodiesels are quite suitable for biodiesel production with higher oxidation stability and cetane number. In this study, S. dimorphus and S. obliquus in the presence of five different nitrogen nutrients of concentration ranging from 0.02 to 0.3 M agar in cultural medium were observed to stimulate them to produce lipid for biodiesel generation. The transesterification of micro algal lipids with absolute ethanol medium in the presence of Ni/H2 catalyst and Ni(II)–Schiff base chelate promoter was carried out to yield more algal oil. The fatty acid composition of the extracted micro algal oils have been identified via UV–Vis, NMR and GC–MS spectral characterization techniques to investigate their biodiesel potentiality. It is noted that increased UR concentration (up to 0.3 M) can effectively enhances biomass production of S. dimorphus and S. obliquus as increased urea levels may enhances biomass production excluding cells may have a low lipid content, at times.

Identification, Optimization of Culture Conditions, and Bioactive Potential of Chinese Caterpillar Mushroom Ophiocordyceps sinensis (Ascomycetes) Mycelium Isolated from Fruiting Body.

The present study deals with the challenges acquainted with in vitro culture of Ophiocordyceps sinensis. We have optimized the culture conditions for the growth of O. sinensis mycelium in semi-synthetic liquid media and determined antibacterial potential of the cultured mycelia extracts. In this study, mycelia were isolated from fruiting bodies and the isolate was identified as O. sinensis anamorph based on sequencing of internal transcribed spacer region. We investigated different culture conditions to optimize the growth of mycelia. Through this investigation, the isolated strain was observed to have its optimum growth at temperature (20°C), which yielded biomass of 12.38 g/L and pH (6.0) yielded biomass of 11.24g/L. Further to augment the production of mycelia, different carbon and nitrogen sources were optimized for mycelium growth in liquid media, out of which sucrose and corn steep powder proved to be the best carbon and nitrogen sources yielding biomass 14.01 g/L and 14.14 g/L, respectively. The evaluation of aqueous and methanolic extracts for antibacterial activity depicted that these extracts are active against all bacterial strains tested here. Aqueous extract depicted minimum inhibitory concentration (MIC) of 0.312, 0.019, 0.078, 0.312, and 0.625 mg/mL and methanolic extract depicted 1.25, 0.078, 0.009, 1.25, and 0.156 mg/mL against Pseudomonas aeruginosa, Escherichia coli, Bacillus cereus, Staphylococcus aureus, and Listeria monocytogenes, respectively. These results led to optimization of enhanced biomass production of O. sinensis, which can be a better alternative approach for further physiological studies and large-scale cultivation of this mushroom for its utilization for therapeutics and nutraceutical values.

Activating de novo triacylglycerol synthesis in oleaginous yeast for improved bio-diesel quality

The economic production of yeast biofuels requires several strategies, such as multiomics techniques to gain insights into lipid biosynthesis pathway. Hence, metabolomic studies for amelioration of triacylglycerol (TAG) accumulation in oleaginous yeast strain to reveal potential targets in fatty acid synthesis pathway should be explored. The aim of this research experiment was to boost TAG agglomeration in novel isolated oleaginous yeast Cryptococcus psychrotolerans IITRFD using sodium bicarbonate as supplement for biodiesel production. Enhanced biomass productivity (83.5 ± 0.32 mg/L/h) and lipid productivity (56.8 ± 0.34 mg/L/h) have been estimated as compared to yeast nitrogen base media (YNB) used as control. Also, the bicarbonate supplementation (25 mM) leads to decrease in phospholipids (23.6 %) while increase in TAG amount (75.4 %) signifying that it redirects the phospholipids synthesis pathway in the direction of de novo TAG pathway. The fatty acid profile obtained revealed rise in monounsaturated fatty acid content and decrease in polyunsaturated fatty acid content demonstrating better oxidative stability (19 h) and cold flow behaviour (- 12 °C) of biodiesel produced. This novel strategy of utilizing bicarbonate as a triggering system may possibly revamp the commercial use of C. psychrotolerans IITRFD for high quality biodiesel production. This is the first study to augment TAG accumulation in this oleaginous yeast using sodium bicarbonate with improved fuel properties.

Rewiring metabolic network by chemical modulator based laboratory evolution doubles lipid production in Crypthecodinium cohnii

Dietary omega-3 long-chain polyunsaturated fatty acids docosahexaenoic acid (DHA, C22:6) can be synthesized in microalgae Crypthecodinium cohnii; however, its productivity is still low. Here, we established a new protocol termed as “chemical modulator based adaptive laboratory evolution” (CM-ALE) to enhance lipid and DHA productivity in C. cohnii. First, ACCase inhibitor sethoxydim based CM-ALE was applied to redirect carbon equivalents from starch to lipid. Second, CM-ALE using growth modulator sesamol as selection pressure was conducted to relive negative effects of sesamol on lipid biosynthesis in C. cohnii, which allows enhancement of biomass productivity by 30% without decreasing lipid content when sesamol was added. After two-step CM-ALE, the lipid and DHA productivity in C. cohnii was respectively doubled to a level of 0.046 g/L/h and 0.025 g/L/h in culture with addition of 1 mM sesamol, demonstrating that this two-step CM-ALE could be a valuable approach to maximize the properties of microalgae.

Atmospheric pCO2 impacts leaf structural and physiological traits in Quercus petraea seedlings.

Atmospheric p CO 2 impacts Quercus petraea biomass production and cell wall composition of the leaves in favor of cellulose at the expense of lignin, and enhances foliar non-structural carbohydrate levels and sucrose contents in a pCO 2 concentration-dependent manner. Sessile oak (Quercus petraea Liebl.) was grown for ca. half a year from seeds at ambient control (525ppm), 750, 900, and 1000ppm atmospheric pCO2 under controlled conditions. Increasing pCO2 enhanced biomass production, modified the cell wall composition of the leaves in favor of cellulose at the expense of lignin, and enhanced the foliar non-structural carbohydrate level, in particular the sucrose content; as well as total N content of leaves by increased levels of all major N fractions, i.e., soluble proteins, total amino acids, and structural N. The enhanced total amino acid level was largely due to 2-ketoglutarate and oxalo acetate-derived compounds. Increasing pCO2 alleviated oxidative stress in the leaves as indicated by reduced H2O2 contents. High in vitro glutathione reductase activity at reduced H2O2 contents suggests enhanced ROS scavenging, but increased lipid peroxidation may also have contributed, as indicated by a negative correlation between malone dialdehyde and H2O2 contents. Almost all these effects were at least partially reversed, when pCO2 exceeded 750 or 900ppm. Apparently, the interaction of atmospheric pCO2 with leaf structural and physiological traits of Q. petraea seedlings is characterized by a dynamic response depending on the pCO2 level.

Establishment of adventitious root cultures of Allamanda cathartica L. for the production of iridoid glycosides and its identification using HPTLC MS

This study attempts to develop a reproducible protocol for in vitro adventitious root regeneration for enhanced biomass production from nodal segments of Allamanda cathartica L., which may be of use as an alternative source for production of iridoid glycosides. Allamanda cathartica (Apocynaceae) is a medicinally rich vine, used in the treatment of human carcinoma, human immunodeficiency virus (HIV), jaundice and malaria. The roots of the plant are the main reservoir of secondary metabolites. The main active constituent in root is iridoid glycosides. The explant for root initiation was cultured in ½ strength Murashige and Skoog (MS) liquid medium augmented with different levels of Indole-3-butyric acid. 0.5 μM Indole-3-butyric acid with 4% sucrose resulted in 1.810 ± 0.049 g and 0.376 ± 0.053 g fresh and dry weight respectively. Among different levels of sodium chloride (80, 100, 120 and 150 mM) added to optimized media, 120 mM sodium chloride treatment increased the root biomass considerably compared with Indole-3-butyric acid alone and other combination, and recorded the fresh weight 2.090 ± 0.049 g and dry weight 0.400 ± 0.005 g after 12 weeks of incubation. The phytochemical investigations using high performance thin-layer liquid chromatography (HPTLC) and mass spectrometry (MS) analysis revealed concentration dependent modulation of selected iridoids in the cultures treated with sodium chloride. The protocol developed can be utilized as an alternative source for production of iridoid glycosides and the findings may be explored on industrial scale.

Enhancing vorticity magnitude of turbulent flow to promote photochemical efficiency and trichome helix pitch of Arthrospira platensis in a raceway pond with conic baffles

In order to clarify vortex mechanisms under a turbulent flow field to explain enhanced biomass productivity, computational fluid dynamics and a miniature Doppler velocimeter were employed to investigate the promoted vorticity magnitude and turbulent kinetic energy to support the increased actual photochemical efficiency of Arthrospira platensis in a raceway pond with alternatively permutated conic baffles. Results showed that whereas the first two parameters increased by 5.9 and 13.9 times, respectively, the third rose on an average by 28% to the value of 0.59 measured on pulse-modulated fluorometer. Furthermore, it was detected on a Nikon inverted-fluorescence microscope that the average helix pitch and trichome length increased by 14% and 10% respectively, resulting in higher biomass productivity (34.8%).

Nitrogen supply – A determinant in water use efficiency of winter wheat grown under free air CO2 enrichment

Global warming and associated decrease of summer precipitation will intensify the limitation of crop growth through water unavailability in Europe. Concomitantly, the rise of atmospheric CO2 concentration ([CO2]) decreases stomatal conductance and thus transpiration as evident at the leaf level. However, knowledge about the effect of elevated [CO2] ([eCO2]) on seasonal water use of crops is rather poor. In a two year field study, winter wheat was grown under ambient [CO2] (393 ppm) and [eCO2] (600 ppm) using free air CO2 enrichment (FACE). In addition, subplots were established with three levels of nitrogen (N) supply (35, 190, 320 kg N ha−1). Soil moisture was continuously measured and wheat was irrigated when necessary to keep field capacity at between 50% to 90%. Evapotranspiration (ET) from stem elongation until maturity was calculated using a soil water balance approach. Water use efficiency (WUE) was determined from the ratio of aboveground biomass production and ET during this period.Increasing N supply increased canopy size and decreased radiation transmission to the soil surface. Moreover increasing N supply enhanced biomass production from 771–1569 g m−2, ET from 227 to 336 mm and WUE from 4.07 to 6.20 g kg−1. Biomass was increased under [eCO2] by 17% among all N levels. [eCO2] increased soil moisture especially in the upper soil layer (0–20 cm) and thus irrigation was reduced under [eCO2] compared to [aCO2]. This effect was intensified by rising N supply leading to a significant CO2×N interaction on ET and WUE. Thus, the [eCO2] effect was for ET −2, −9 and −10% and for WUE + 20,+ 30 and +29% under 35, 190, 320 kg N ha-1, respectively. Simultaneously, there seems to be a greater increase of evaporation by [eCO2] under low than high N supply.

Bioenergy production and nutrients removal by green microalgae with cultivation from agro-wastewater palm oil mill effluent (pome) - a review

Environmental pollution specifically wastewater is gaining attention both in the developed and developing countries. Malaysia is considered as one of the major palm oil producers in the world. Therefore, it is important to develop an environmental friendly and economic method to treat palm oil mill effluent (POME). The wastewater can serve as an economical nutrient source or substrate that can support the cultivation of microalgae. This can be a great nutrient for algal cultivation at the same time as remediating effluent and generating biomass. Nowadays, many microalgae species are being investigated to determine their potential and effectiveness for phytoremediation application, especially high growth rate. However, using synthetic media for growing microalgae in a mass scale is costly. It is acknowledged that POME (as nutrients enriched media) assisted enhanced microalgae growth under certain condition can considerably reduce the presence of organic and inorganic compounds. In this review, the potential of wide range of the predominant microalgae species with main focus on green microalgae (high removal efficiency): Chlamydomonas sp and Chlorella sp were investigated. Moreover, we discussed about the history, methods and future prospects in nutrients removal by green microalgae comprehensively. This review discusses several potential strategies for tackling the environmental issue generated by agro-waste water POME with enhancement of biomass productivity which can be used as an alternative for energy production.

Soil Erosion Susceptibility Assessment of the Lower Himachal Himalayan Watershed

ABSTRACT Assessment of erosion status of a watershed is an essential prerequisite for integrated watershed management. It not only assists in chalking out suitable soil and water conservation measures to arrest erosion and conserve water but also helps in devising best management practices to enhance biomass production in watersheds. Keeping this in view, the present study has been undertaken by involving geospatial-statistical techniques to determine the critical and priority areas for soil and water conservation in Suketi watershed of the lower Himachal Himalayan region. A novel weighted sum analysis technique was used for ranking each of hydrological unit by obtaining the weightages from various morphometric parameters. This technique offers dynamic, effective and sustainable approach over traditional prioritization methods in which significance of each parameter were considered equally. Considering this approach, sub-watersheds were delineated into low, medium and high priority zones. The results illustrate that about 52 % of sub-watersheds of Suketi watershed are in moderate to high erosion and runoff susceptible zones. Therefore, these potential areas can be considered for preferential soil and water conservation planning. The results obtained from the study will be useful for various stakeholders such as agriculturists, water resource managers, conservation measures planners and decision policy makers for better management practices and decision making. The geospatial-statistical technique can be used for effective estimation of erosion status of watersheds leading to watershed prioritization for taking up soil and water conservation measures in watershed systems. Finally, this technique can be very useful in remote, rugged and inaccessible watersheds with absence of soil erosion and runoff monitoring.

Transcriptional responses of soybean roots to colonization with the root endophytic fungus Piriformospora indica reveals altered phenylpropanoid and secondary metabolism

Piriformospora indica, a root endophytic fungus, has been shown to enhance biomass production and confer tolerance to various abiotic and biotic stresses in many plant hosts. A growth chamber experiment of soybean (Glycine max) colonized by P. indica compared to uninoculated control plants showed that the fungus significantly increased shoot dry weight, nutrient content, and rhizobial biomass. RNA-Seq analyses of root tissue showed upregulation of 61 genes and downregulation of 238 genes in colonized plants. Gene Ontology (GO) enrichment analyses demonstrated that upregulated genes were most significantly enriched in GO categories related to lignin biosynthesis and regulation of iron transport and metabolism but also mapped to categories of nutrient acquisition, hormone signaling, and response to drought stress. Metabolic pathway analysis revealed upregulation of genes within the phenylpropanoid and derivative pathways such as biosynthesis of monolignol subunits, flavonoids and flavonols (luteolin and quercetin), and iron scavenging siderophores. Highly enriched downregulated GO categories included heat shock proteins involved in response to heat, high-light intensity, hydrogen peroxide, and several related to plant defense. Overall, these results suggest that soybean maintains an association with this root endosymbiotic fungus that improves plant growth and nutrient acquisition, modulates abiotic stress, and promotes synergistic interactions with rhizobia.

Arbuscular mycorrhizal fungi mitigates heavy metal toxicity adverse effects in sewage water contaminated soil on Tagetes erecta L

ABSTRACTThe aim of this experiment was to evaluate the impact of colonization with arbuscular mycorrhizal (AM) fungus Glomus constrictum on the biomass production, flower quality, chlorophyll content, macronutrients and heavy metals content of marigold (Tagetes erecta L.) planted under uncontaminated soil and watered with various rates of sewage water. Sewage water utilization significantly decreased biomass production, characters of flower, nutrient concentration and rates of mycorrhizal colonization of mycorrhizal (M) and non-mycorrhizal (NM) marigold as compared to control untreated plants especially at the higher rates, but the reduction rate was proportionally higher in non-AM treatments. Mycorrhizal plants had significantly greater yield, relative chlorophyll content, leaf area, flower quality and element (P, N, K and Mg) content compared to non-inoculated marigold plants irrigated with or without sewage water. Furthermore, AM inoculation had highly decreased heavy metal (Zn, Co, Mn, Cu) content in tissues as compared to equivalent non-inoculated plants grown under sewage water application. Growing marigold with AM inoculum can reduce toxicity of heavy metals and enhance biomass production and P uptake. The results support the view that AM have a protective function for the host plant, hence playing a potential function in soil polluted immobilization processes, and thus are of assessing the potential of phytoremediation of heavy metals in sewage water contaminated soil.

Fertilizer Management for a Rye Cover Crop to Enhance Biomass Production

Core Ideas Additional N can enhance cereal cover crop biomass production and maximize benefits. Cover crop N fertilizer recovery efficiency averaged 37% across all treatments. Commercial N fertilizer increased biomass for less money compared to poultry litter. Winter cereal cover crops are necessary to achieve maximum benefits of conservation tillage in the southeastern United States. These benefits generally increase as cover crop biomass increases; therefore, we conducted a study to evaluate N application times, sources, and optimal rates to maximize cover crop biomass production at Headland, AL, on a Fuquay sand (loamy, kaolinitic, thermic Arenic Plinthic Kandiudults) during the 2006–2008 growing seasons. Treatments were arranged in a split‐split plot treatment restriction in a randomized complete block design with four replications. Main plots were time of fertilizer application (fall and spring), subplots were N source (commercial fertilizer and poultry [Gallus gallus domesticus] litter), and sub‐subplots were N rate (0, 34, 67, and 101 kg N ha−1 as commercial fertilizer and 0, 2.2, 4.5, and 6.7 Mg ha−1 as poultry litter [as‐sampled basis]) for a cereal rye (Secale cereale L.) cover crop. Commercial fertilizer produced 13% greater biomass compared to poultry litter across all rates and application times. Lower biomass production and higher costs for poultry litter reduced the feasibility of poultry litter as an N source compared with commercial N. Higher C/N ratios were measured for fall‐applied N compared to spring‐applied N, while N fertilizer recovery efficiency (REN) averaged 37% across the experiment. Results indicated fall application of commercial fertilizer N produced superior results across cover crop responses examined in this study, while providing general information about N fertilizer requirements to increase surface residue associated with cover crops across the southeastern United States.

Predicted Glycerol 3-Phosphate Dehydrogenase Homologs and the Glycerol Kinase GlcA Coordinately Adapt to Various Carbon Sources and Osmotic Stress in Aspergillus fumigatus.

Glycerol plays an important role in the adaptation of fungi to various microenvironments and stressors, including heat shock, anoxic conditions and osmotic stress. Glycerol 3-phosphate dehydrogenase (G3PDH) is able to catalyze dihydroxyacetone phosphate to glycerol 3-phosphate (G3P), which is subsequently dephosphorylated into glycerol. However, current knowledge about the functions of G3PDH homologs in glycerol biosynthesis in Aspergillus fumigatus is limited. Here, we show that the A. fumigatus G3PDH gene, gfdA, is crucial for normal colony growth in glucose media under both normoxic and hypoxic conditions. In addition, failure of the overexpression of the gfdA homolog, gfdB, to rescue the phenotype of a gfdA null mutant suggests that gfdA plays a predominant role in the synthesis of G3P and glycerol. However, in a wild-type background, overexpressing either gfdA or gfdB is able to significantly enhance biomass production of mycelia, suggesting that gfdA and gfdB have similar functions in promoting the use of glucose. Interestingly, overexpression of the gene encoding the predicted glycerol kinase, GlcA, which is capable of phosphorylating glycerol to form G3P, significantly rescues the growth defects of gfdA null mutants in glucose media, indicating that the growth defects of gfdA null mutants might be due to the absence of G3P rather than glycerol. Moreover, Western blotting analysis revealed that gfdA is inducibly expressed by osmotic mediators. However, in the absence of gfdA, osmotic stress can rescue colony growth defects and allow colonies to partially bypass the gfdA requirement in a high osmolarity glycerol pathway-dependent manner. Therefore, the findings of this study elucidate how saprophytic filamentous fungi have developed pathways distinct from those of budding yeasts to adapt to varied carbon sources and survive environmental stresses.

Screening of plant growth promoting traits in heavy metals resistant bacteria: Prospects in phytoremediation.

Phytoremediation is considered as a novel environmental friendly technology, which uses plants to remove or immobilize heavy metals. The use of metal-resistant plant growth-promoting bacteria (PGPB) constitutes an important technology for enhancing biomass production as well as tolerance of the plants to heavy metals. In this study, we isolated twenty seven (NF1-NF27) chromium resistant bacteria. The bacteria were tested for heavy metals (Cr, Zn, Cu, Ni, Pb and Co) resistance, Cr(VI) reduction and PGPB characters (phosphate solubilization, production of IAA and siderophores). The results showed that the bacterial isolates resist to heavy metals and reduce Cr(VI), with varying capabilities. 37.14% of the isolates have the capacity of solubilizing phosphate, 28.57% are able to produce siderophores and all isolates have the ability to produce IAA. Isolate NF2 that showed high heavy metal resistance and plant growth promotion characteristics was identified by 16S rDNA sequence analysis as a strain of Cellulosimicrobium sp.. Pot culture experiments conducted under greenhouse conditions showed that this strain was able to promote plant growth of alfalfa in control and in heavy metals (Cr, Zn and Cu) spiked soils and increased metal uptake by the plants. Thus, the potential of Cellulosimicrobium sp. for both bioremediation and plant growth promotion has significance in the management of environmental pollution.

Chromatin interacting factor OsVIL2 increases biomass and rice grain yield.

SummaryGrain number is an important agronomic trait. We investigated the roles of chromatin interacting factor Oryza sativa VIN3‐LIKE 2 (OsVIL2), which controls plant biomass and yield in rice. Mutations in OsVIL2 led to shorter plants and fewer grains whereas its overexpression (OX) enhanced biomass production and grain numbers when compared with the wild type. RNA‐sequencing analyses revealed that 1958 genes were up‐regulated and 2096 genes were down‐regulated in the region of active division within the first internodes of OX plants. Chromatin immunoprecipitation analysis showed that, among the downregulated genes, OsVIL2 was directly associated with chromatins in the promoter region of CYTOKININ OXIDASE/DEHYDROGENASE2 (OsCKX2), a gene responsible for cytokinin degradation. Likewise, active cytokinin levels were increased in the OX plants. We conclude that OsVIL2 improves the production of biomass and grain by suppressing OsCKX2 chromatin.

Acceleration of saturated porous media clogging and silicon dissolution due to low concentrations of Al(III) in the recharge of reclaimed water

The recharge of reclaimed water is an effective strategy for addressing the issues of water quality deterioration and groundwater level decline simultaneously. Residual Al coagulants are normally remained in the recovered water at low concentrations, and may induce clogging problems during the recharging process. However, this issue has been ignored in the past. In this study, we investigated the mechanisms of Al(III)-induced aquifer bio-clogging, the role of Al(III) in quartz sand media (SiO2) dissolution and re-precipitation in the series of aquifer columns. We determined that Al(III) resulted in serious clogging in ∼140 h at low concentrations that satisfied the national drinking water standard of China. The corresponding hydraulic conductivity decreased by more than ∼90% in the bacteria-containing aquifer, which was ∼30% greater than that for the bacteria-free trials. The enhanced Al(III)-related clogging was caused by modifying quartz sand to form Si-O-Al(OH)n and improving microbes attachment. Microbes retention kinetic coefficients (k) of the Al recharged simulated aquifer could increase by 3.0–8.3 times. The Al(III) also enhanced biomass production and clogging by binding to microbial extracellular polymeric substances. In turn, the greater amount of biomass accelerated the Si dissolution and re-precipitation, this may potentially damage the stability of aquifer structure. The results showed that reclaimed water treated with Al coagulation should be employed with caution for recharging.