pH Of Growth Medium Research Articles

Controlling the growth of uncapped silver nanoparticles on poly methacrylic acid nanospheres: The effect of polymer’s free surface on the antimicrobial properties

In this study, the control over the growth of uncapped silver nanoparticles on the surface of poly methacrylic acid nanospheres is presented. The pH of the growth medium and the size of the polymer nanospheres were studied as parameters in relation to the antimicrobial activity of the resulting structures against Escherichia coli and Staphylococcus aureus. Adjustment of the growth medium pH has a direct effect on the number of silver nanoparticles grown on the surface of the nanospheres, while the size of the nanospheres affects the resulting silver nanoparticle size distribution. The minimum bactericidal concentration was determined to 8 and 32 μg/mL against E. coli and S. aureus respectively, whereas the antimicrobial efficiency of the resulting nanospheres was enhanced in structures with increased free surface. Hence, the contribution of the as synthesized structures to the antimicrobial activity is attributed to the polymer’s ability to form stable suspensions in the aqueous bacterial growth medium, thus promoting the dissolution of silver nanoparticles to Ag cations with antimicrobial activity.

Effects of Novel Dental Composites on Streptococcus mutans Biofilms.

With the phase-out of amalgam and the increase in minimally invasive dentistry, there is a growing need for high-strength composite materials that can kill residual bacteria and promote tooth remineralization. This study quantifies how antibacterial polylysine (PLS) and re-mineralizing monocalcium phosphate monohydrate (MCPM) affect Streptococcus mutans biofilms and the strength of dental composites. For antibacterial studies, the MCPM-PLS filler percentages were 0-0, 8-4, 12-6, and 16-8 wt% of the composite filler phase. Composite discs were immersed in 0.1% sucrose-supplemented broth containing Streptococcus mutans (UA159) and incubated in an anaerobic chamber for 48 h. Surface biomass was determined by crystal violet (CV) staining. Growth medium pH was measured at 24 and 48 h. Biofilm bacterial viability (CFU), exo-polysaccharide (water-soluble glucan (WSG) and water-insoluble glucan (WIG)), and extracellular DNA (eDNA) were quantified. This was by serial dilution plate counting, phenol-sulfuric acid microassay, and fluorometry, respectively. The biaxial flexural strengths were determined after water immersion for 1 week, 1 month, and 1 year. The MCPM-PLS wt% were 8-4, 8-8, 16-4 and 16-8. The normalized biomass, WSG, and WIG showed a linear decline of 66%, 64%, and 55%, respectively, as the PLS level increased up to 8%. The surrounding media pH (4.6) was all similar. A decrease in bacterial numbers with the 12-6 formula and a significant reduction with 16-8 compared to the 0-0 formulation was observed. The eDNA concentrations in biofilms formed on 12-6 and 16-8 formulations were significantly less than the 0-0 control and 8-4 formulations. Doubling MCPM and PLS caused a 14 and 19% reduction in strength in 1 week, respectively. Average results were lower at 1 month and 1 year but affected less upon doubling MCPM and PLS levels. Moreover, a 4% PLS may help to reduce total biomass and glucan levels in biofilms on the above composites. Higher levels are required to reduce eDNA and provide bactericidal action, but these can decrease early strength.

Acid adaptation alters Streptococcus mutans drug susceptibility profile

The ability of Streptococcus mutans, the primary causative agent of dental caries, to generate and tolerate an acidic environment is a leading factor in its capacity to outcompete other organisms within the oral cavity. The acid tolerance response (ATR) involves coordination of multiple pathways to upregulate macromolecule repair, maintenance of cytosolic pH, and restructuring the membrane. In this study, we asked if the changes associated with adaptation to a low pH environment would result in detectable changes to drug susceptibility. Accordingly, we screened using the Selleck library of 853 FDA approved drugs for agents that exhibit antimicrobial activity toward planktonic cultures of S. mutans or disrupt biofilm formation in growth medium titrated to pH 5 or in the presence of hydrogen peroxide. Results revealed that a total of 182 compounds displayed antimicrobial properties toward the test strain in at least one screening condition. Our findings provide evidence that the S. mutans ATR is characterized by a concerted shift in drug susceptibility. The presence of an intact ATR, associated with growth in continuous culture at pH 5, leads to increased sensitivity to 22 compounds and decreased sensitivity to a separate set of 20 compounds. Disruption of the ATR in a mutant lacking the fabM gene resulted in a susceptibility profile that was distinct from the result of our results. This suggests that loss of unsaturated fatty acids produces a physiological change that is not only measurable, but perhaps more significant than the process of ATR. Additional tests revealed that S. mutans exhibits a distinct drug susceptibility profile compared to a closely related, non-cariogenic bacterium, S. gordonii. Overall, shifts in S. mutans susceptibility patterns based on pH of growth medium or type of culture (batch vs. continuous culture), indicate that the ATR can be tracked using changes in drug susceptibility profile. Furthermore, our results provide clues that compounds could be useful in treatment of dental caries as well as providing molecular tools to study shifts in physiology of disease-associated bacteria.

Fungal Fight Club: phylogeny and growth rate predict competitive outcomes among ectomycorrhizal fungi.

Ectomycorrhizal fungi are among the most prevalent fungal partners of plants and can constitute up to one-third of forest microbial biomass. As mutualistic partners that supply nutrients, water, and pathogen defense, these fungi impact host plant health and biogeochemical cycling. Ectomycorrhizal fungi are also extremely diverse, and the community of fungal partners on a single plant host can consist of dozens of individuals. However, the factors that govern competition and coexistence within these communities are still poorly understood. In this study, we used in vitro competitive assays between five ectomycorrhizal fungal strains to examine how competition and pH affect fungal growth. We also tested the ability of evolutionary history to predict the outcomes of fungal competition. We found that the effects of pH and competition on fungal performance varied extensively, with changes in growth media pH sometimes reversing competitive outcomes. Furthermore, when comparing the use of phylogenetic distance and growth rate in predicting competitive outcomes, we found that both methods worked equally well. Our study further highlights the complexity of ectomycorrhizal fungal competition and the importance of considering phylogenetic distance, ecologically relevant traits, and environmental conditions in predicting the outcomes of these interactions.

Nitrogen Source Preference in Maize at Seedling Stage Is Mainly Dependent on Growth Medium pH

To improve crop nitrogen recovery efficiency (NRE), plants must be supplied with their preferred form of nitrogen (N). However, whether pH affects crop N-form preference remains unclear. Here, we aimed to explore how maize (Zea mays L.) preference for NH4+ and NO3− is affected by pH and to determine the critical pH controlling this preference. Maize plants were grown with NH4+ or NO3− in different soils (pH 4.32–8.14) and nutrient solutions (pH 4.00–8.00). After harvest, plant dry weights, N content, N uptake, NRE, soil pH, and exchangeable aluminum (Al) were measured. Compared with the effect of NO3−, NH4+ decreased maize dry weight, N uptake, and NRE by 28–94% at soil pHs of 4.32 and 4.36 and a solution pH of 4.00, whereas it increased these parameters by 10–88% at soil pHs of 6.52–8.02 and solution pHs of 7.00 and 8.00. NO3− increased soil pH and decreased soil exchangeable Al content at soil pHs of 4.32–6.68. Critical soil and solution pHs for changing plant growth and N uptake preference for NH4+ vs. NO3− ranged from 5.08 to 5.40 and from 5.50 to 6.59, respectively. In conclusion, the preference of maize seedling growth and N uptake for NH4+ vs. NO3− mainly depends on the pH of the growth medium, and maize seedlings generally prefer NO3− in strongly acid soils but NH4+ in neutral to alkaline soils.

The effect of DC electric field on the elongation growth, proton extrusion and membrane potential of Zea mays L. coleoptile cells; a laboratory study

BackgroundIn this study, we investigated the effect of an electric field, with an intensity similar to that of the Earth’s field, on plant cells growth. The molecular mechanism underlying this effect remains unclear.ResultsIt was found that the electric field, depending on the applied voltage, its duration and the polarization of the maize seedlings, stimulated or inhibited the growth of the seedling organs (root, mesocotyl and coleoptile). Moreover, it was also noticed that the gravitropic response of maize seedlings was inhibited at all voltages studied. Simultaneous measurements of growth and external medium pH show that auxin(IAA, indole-3-acetic acid)- and fusicoccin(FC)-induced elongation growth and proton extrusion of maize coleoptile segments were significantly inhibited at higher voltages. The ionic current flowing through the single coleoptile segment during voltage application was 1.7-fold lower in segments treated with cation channel blocker tetraethylammonium chloride (TEA-Cl) and 1.4-fold higher with IAA compared to the control. The electrophysiological experiments show that the electric field caused the depolarization of the membrane potential of parenchymal coleoptile cells, which was not reversible over 120 min.ConclusionIt is suggested that a DC electric field inhibits the plasma membrane H+ pump activity and K+ uptake through voltage-dependent, inwardly rectifying ZMK1 channels (Zea mays K+ channel 1). The data presented here are discussed, taking into account the “acid growth hypothesis” of the auxin action and the mechanism of gravitropic response induction.

Isolation, Mutagenesis, and Organic Acid Secretion of a Highly Efficient Phosphate-Solubilizing Fungus.

The highly effective phosphate-solubilizing microorganisms are significant for making full use of the potential phosphorus resources in the soil and alleviating the shortage of phosphorus resources. In this study, a phosphate-solubilizing fungus was isolated from wheat and cotton rhizosphere soils in the lower reaches of the Yellow River in China and was identified as Penicillium oxalicum by morphological and ITS sequencing analysis. In order to obtain a fungus with more efficient phosphorus solubilization ability, we tested three positive mutant strains (P1, P2, and P3) and three negative mutant strains (N1, N2, and N3) through low-energy nitrogen ion implantation mutagenesis. Compared with the parental strain, the phosphate-solubilizing capacity of P1, P2, and P3 was enhanced by 56.88%, 42.26%, and 32.15%, respectively, and that of N1, N2, and N3 was weakened by 47.53%, 35.27%, and 30.86%, respectively. Compared with the parental strain, the total amount of organic acids secreted significantly increased in the three positive mutant strains and decreased in the negative mutant strains; the pH of culture medium was significantly lower in the positive mutant strains and higher in the negative mutant strains. The capacity of phosphate-solubilizing fungus to secrete organic acids and reduce the growth-medium pH was closely related to its phosphate-solubilizing ability. The changes in the amount of organic acids secreted by mutants can alter their acidification and phosphate-solubilizing capacity. In conclusion, this study offers a theoretical basis and strain materials for the exploration and application of phosphate-solubilizing fungi.

Effect of pH on Schizochytrium limacinum Production Grown Using Crude Glycerol and Biogas Digestate Effluent

The ability of microalgae, such as the rich in docosahexaenoic acid (DHA) heterotrophic marine microalgae Schizochytrium limacinum SR21, to utilize nutrients in their culture media derived from low-cost nutrient sources makes them a promising low-cost alternative source for the production of useful substances used in aqua feeds. The assessment of culture parameters, one of which is the pH, for every different nutrient growth medium used for microalgae cultivation is important, as they affect the biomass and secondary metabolite microalgae production. This study assessed the effect of different growth medium pH levels (6, 7, 8 and 9), at laboratory and pilot scale systems, on S. limacinum biomass productivity, lipid accumulation, proximate composition, carbon assimilation and DHA. The microalgae were cultivated in growth media containing two different alternative low-cost nutrient sources: (a) crude glycerol derived from biofuel industry as carbon source and (b) effluent digestate from biogas production of livestock decomposition as a source of nutrients and trace elements. It was found that a neutral pH (7) was the optimum level, as it enhanced biomass productivity of the lab and pilot scale cultivation systems at 44.9 g L−1 and 11 g L−1 and DHA content at 7.5% and 19% of the total lipid content, respectively.

Acclimation to NaCl and H2O2 develops cross tolerance to saline-alkaline stress in Rice (Oryza sativa L.) by enhancing fe acquisition and ROS homeostasis

ABSTRACT Plants are known to develop cross-tolerance in which plants tolerate to one stress following prior exposure to another stress. In this study, we investigated this phenomenon in rice (Oryza sativa L.) to elucidate the underlying physiological mechanisms. Twenty-one (21) day-old seedlings were pre-exposed to various concentrations of NaCl, NaHCO3, and H2O2 for 7 days and then subjected to saline-alkaline stress (SAS) for 14 days. The present findings report that pre-exposure to 10 mM NaCl and 10 µM H2O2 develops cross-tolerance to SAS by triggering systemic physiological processes involved in Fe uptake and ROS homeostasis. While the mechanisms of this tolerance vary among pre-treatments, a consensus suggests the relevance of the following processes: (1) the ability to maintain a lower growth medium pH, (2) ability to suppress root K+ losses, (3) maintenance of a stable acquisition of Fe and P and (4) regulated generation of reactive oxygen species (ROS) via enhanced antioxidant enzyme activities. Taken together, these results are consistent with the hypothesis that a crosstalk exists between salinity stress, oxidative stress, and SAS, triggering adaptive physiological responses that develop tolerance to SAS in rice, a phenomenon that offers a prospect for developing plants tolerant to multiple stressors.

Knockdown of Succinate Dehydrogenase Assembly Factor 2 Induces Reactive Oxygen Species-Mediated Auxin Hypersensitivity Causing pH-Dependent Root Elongation.

Metabolism, auxin signaling and reactive oxygen species (ROS) all contribute to plant growth, and each is linked to plant mitochondria and the process of respiration. Knockdown of mitochondrial succinate dehydrogenase assembly factor 2 (SDHAF2) in Arabidopsis thaliana lowered succinate dehydrogenase activity and led to pH-inducible root inhibition when the growth medium pH was poised at different points between 7.0 and 5.0, but this phenomenon was not observed in wildtype (WT). Roots of sdhaf2 mutants showed high accumulation of succinate, depletion of citrate and malate and up-regulation of ROS-related and stress-inducible genes at pH 5.5. A change of oxidative status in sdhaf2 roots at low pH was also evidenced by low ROS staining in root tips and altered root sensitivity to H2O2. sdhaf2 had low auxin activity in root tips via DR5-GUS staining but displayed increased indole-3-acetic acid (IAA, auxin) abundance and IAA hypersensitivity, which is most likely caused by the change in ROS levels. On this basis, we conclude that knockdown of SDHAF2 induces pH-related root elongation and auxin hyperaccumulation and hypersensitivity, mediated by altered ROS homeostasis. This observation extends the existing evidence of associations between mitochondrial function and auxin by establishing a cascade of cellular events that link them through ROS formation, metabolism and root growth at different pH values.

Key aroma compounds and metabolic profiling of Debaryomyces hansenii L1-1-fermented Flos Sophorae.

The extract from Debaryomyces hansenii L1-1-fermented Flos Sophorae has a unique aroma and could be used as a natural spice. The influence of yeast growth and culture medium pH on organoleptic properties of fermented substrates, as well as on the content of volatile aromatic compounds, total sugars, polysaccharides, reducing sugars, total proteins, and amino acids, were analyzed. Metabolic pathways were annotated to compare and contrast key aromatic compounds and metabolic profiles of water and ethanol extracts of D. hansenii L1-1-fermented Flos Sophorae. We found that cells grew most rapidly, pH values changed significantly, and the largest consumption of sugars and amino acids occurred within 48hr, producing bouquet-like, fruity, and sweet odors, as well as the highest content of volatile aromatic compounds in the extracts. The main aroma metabolites were 2-phenylethanol, linalool, and α-terpineol. The sensory quality of the ethanol extracts was superior to that of the water extracts. Five aromatic compounds, isoamyl alcohol, 2-methylbutan-1-ol, isobutyric acid, 2,3-hexanedione, and 1-hexanol, were positively correlated with the water extract group and negatively correlated with the ethanol extract group, whereas 13 aromatic compounds, styrene, acetophenone, 2-octen-1-ol, linalool, naphthalene, α-terpineol, dihydrocarveol, (-)-myrtenol, methyl anthranilate, eugenol, γ-nonanolactone, jasmone, and β-ionone, showed the converse trend. Although 2-phenylethanol displayed the highest concentration in the extracts, it did not significantly contribute to the separation of ethanol and water extracts. In Flos Sophorae medium, D. hansenii mainly produces 2-phenylethanol from phenylalanine by the Ehrlich reaction, whereas it produces linalool and α-terpineol by the terpenoid backbone and monoterpenoid biosynthetic pathways; the variable contents of proline, arginine, and glutamate could respond to the arginine and proline metabolic pathways. PRACTICAL APPLICATIONS: Flos Sophorae, a collection of buds of Sophora japonica L., is a traditional Chinese medicinal and edible plant for its good aroma, taste, and nutritional value. Debaryomyces hansenii is a common, aroma-producing yeast. D. hansenii L1-1-fermented Flos Sophorae had a unique, bouquet-like aroma, slightly softer than the typical Flos Sophorae-like aroma. This study enriches our understanding of predominant aroma components and determines their contribution to the profiles of Flos Sophorae ferments obtained using D. hansenii L1-1. Researchers and manufacturers specializing in spices making can use these data to improve the aromatic profiles of natural spices produced by microorganisms, thereby obtaining unique aromas.

Optimization of poly (lactic-co-glycolic acid)-bioactive glass composite scaffold for bone tissue engineering using stem cells from human exfoliated deciduous teeth

ObjectiveThe aim of this study was to develop a composite scaffold with the optimal poly(lactic-co-glycolic acid) (PLGA) and bioactive glass proportions to provide an environment for bone tissue regeneration and repair. DesignPLGA-bioactive glass composite scaffolds were prepared using a salt-leaching technique with different percentages of bioactive glass (0%, 10 %, and 15 % [w/w]) with PLGA. The resulting scaffolds were characterized using scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDS), and water contact angle, dynamic mechanical, and pH analysis. The scaffold biocompatibility was investigated using stem cells from human exfoliated deciduous teeth (SHED) and rat experiments. ResultsSEM-EDS confirmed the successful fabrication of three-dimensional PLGA-bioactive glass scaffolds. The results showed that 10 % bioactive glass with PLGA exhibited favorable properties including increased pore size, hydrophilicity, and mechanical properties. The growth medium pH was increased for scaffolds containing bioactive glass. All scaffolds were biocompatible, and 10 % bioactive glass composite scaffolding showed better attachment, growth, and proliferation of SHED compared to the other scaffolds. Moreover, it enhanced osteogenic differentiation of SHED in vitro and in vivo. ConclusionsSalt-leaching-derived PLGA-bioactive glass composite scaffolds were successfully established. PLGA with 10 % bioactive glass had adequate physical properties and bioactivity, and it could be considered as a composite for bone tissue engineering applications.

Research and Development of Process Conditions for Growing Young Plants Iris sibirica L. Aimed at Bio-Synthesis of Tannins, Flavonoids and Xanthones

The reported paper presents process conditions providing a maximal output of biomass and accumulated biologically active substances when growing young plants Iris sibirica (Sterh variety): growth medium composition according to Murashige and Skoog Media Formulation, growth medium pH 5.6-5.8, temperature of growing 24-26 0C, 16-hour photoperiod, illumination intensity (2000 - 4000 lux), and relative air humidity 70%. It is recommended to use growth media containing 1.0-2.5 uM BAP and auxin compounds 1.0 uM NAA+0.1 uM IB A for an optimal build-up of biomass and phenol compounds (flavonoids, tannins, xanthones) in Iris sibirica.

Conditions of nisin production by Lactococcus lactis subsp. lactis and its main uses as a food preservative.

Nisin is a small peptide produced by Lactococcus lactis ssp lactis that is currently industrially produced. This preservative is often used for growth prevention of pathogenic bacteria contaminating the food products. However, the use of nisin as a food preservative is limited by its low production during fermentation. This low production is mainly attributed to the multitude of parameters influencing the fermentation progress such as bacterial cells activity, growth medium composition (namely carbon and nitrogen sources), pH, ionic strength, temperature, and aeration. This review article focuses on the main parameters that affect nisin production by Lactococcus lactis bacteria. Moreover, nisin applications as a food preservative and the main strategies generally used are also discussed.

E-monitoring of in vitro culture parameters for prediction of maximal biomass yields

An e-monitoring system was established and modeled by object-oriented methodology for prediction of the maximal biomass yields based on in vitro culture parameters. The system calculates the maximal biomass yields through neuro-fuzzy or adaptive neuro-fuzzy inference system (ANFIS) methodology. The final biomass fresh weight was considered as a function of culture parameters. ANFIS models were created for the prediction of the maximal biomass yields. According to the prediction accuracy of the models, the inputs’ influence was determined on the biomass fresh weight. It was determined that the pH of growth medium has the highest impact on the biomass fresh weight (RMSE = 0.8302) while the medium culture vessel has the smallest influence on the biomass fresh weight (RMSE = 0.9556). The designed e-monitoring system could have the potential for practical applications.

Recovery of Gold and Other Precious Metal Resources from Environmental Polluted E-waste Printed Circuit Board by Bioleaching Frankia

The physicochemical profiling of e-waste was done by AAS, XRD, and SEM with EDX that reveals the composition of valuable metals like Au−, Ag−, Zn−, and Cu−. Thus, the present findings provide the important resource of precious metal in the e-waste (PCBs) as pollutant in the environment and human impact. The native isolates Frankia sp. DDNSF-01 and Frankia casuarinae DDNSF-02 were subjected for bioleaching of gold and precious elements bearing e-waste under one and two-step leaching methods. The two-step bioleaching protocol was found effectual in expression with high level of metal leaching within the culture medium of Frankia metabolites and organic acids which were obtained by the leaching of metals. The presence of organic acids functional groups was determined by FT-IR spectrum and by low pH of growth medium. The AAS analysis quantified the initial concentration of metals and their significant increase brought by the leaching. The initial concentration of precious metal elements was found in the e-waste like Au−, Ag−, Cu−, and Zn− (0.04, 0.05, 0.35, 0.1 mg/g) respectively. Frankia sp. leached out precious metals like Au−, Ag−, Cu−, and Zn− (0.2, 0.14, 0.68, 0.2 mg/g) respectively. Frankia casuarinae leached out precious metals like Au−, Ag−, Cu−, and Zn− (0.25, 0.15, 0.55, and 0.2 mg/g) respectively. The precious metal gold was highly leached out by F. casuarinae than Frankia sp.. The valuable metal copper was significantly increased by Frankia sp. than F. casuarinae. Higher gold recovery, at 75%, was obtained for F. casuarinae and copper 94% recovery by Frankia sp. bioleaching of the biooxidised e-waste at 0.2% low pulp densities. The results were confirmed by XRD and SEM with EDX analysis.

SLC26A7 protein is a chloride/bicarbonate exchanger and its abundance is osmolarity- and pH-dependent in renal epithelial cells

Acid-secreting intercalated cells of the collecting duct express the chloride/bicarbonate kidney anion exchanger 1 (kAE1) as well as SLC26A7, two proteins that colocalize in the basolateral membrane. The latter protein has been reported to function either as a chloride/bicarbonate exchanger or a chloride channel. Both kAE1 and SLC26A7 are detected in the renal medulla, an environment hyper-osmotic to plasma. Individuals with mutations in the SLC4A1 gene encoding kAE1 and mice lacking Slc26a7 develop distal renal tubular acidosis (dRTA). Here, we aimed to (i) confirm that SLC26A7 can function as chloride/bicarbonate exchanger in Madin-Darby canine kidney (MDCK) cells, and (ii) examine the behavior of SLC26A7 relative to kAE1 wild type or carrying the dRTA mutation R901X in iso- or hyper-osmotic conditions mimicking the renal medulla. Although we found that SLC26A7 abundance increases in hyper-osmotic growth medium, it is reduced in low pH growth conditions mimicking acidosis when expressed at high levels in MDCK cells. In these cells, SLC26A7 exchange activity was independent from extracellular osmolarity. When SLC26A7 protein was co-expressed with kAE1 WT or the R901X dRTA mutant, the cellular chloride/bicarbonate exchange rate was not additive compared to when proteins are expressed individually, possibly reflecting a decreased overall protein expression. Furthermore, the cellular chloride/bicarbonate exchange rate was osmolarity-independent. Together, these results show that (i) in MDCK cells, SLC26A7 is a chloride/bicarbonate exchanger whose abundance is up-regulated by high osmolarity growth medium and (ii) acidic extracellular pH decreases the abundance of SLC26A7 protein.

Characterization of Biosurfactants Produced by Bacillus Subtilis using Fresh and Waste Cooking Oil Enriched Medium

This study aims to compare and analyze the chemical structures of bacterial biosurfactants produced by an indigenous Bacillus subtillis strain cultured in minimal salt medium (MSM) enriched with fresh cooking oil and used cooking oils that are cheaper and easy to obtained in huge quantities. Optimization of biosurfactants was successfully conducted in two MSMs enriched with 2% (v/v) fresh cooking oil and 2% (v/v) waste cooking oil respectively. The initial pH of growth medium was fixed at pH 7.64 and the whole fermentation process was maintained in a constant temperature of 30 °C. Chemical structures analysis of biosurfactants produced at 1L scale in bioreactor were conducted using spectroscopic methods such as Nuclear Magnetic Resonance (NMR) and Fourier-Transform Infrared spectroscopy (FTIR). The chemical compound isolated from the biosurfactant produced from the waste cooking oil was pentyl 2-ureidobut-3-enoate (1) while (1-hydroxyethyl)amino)methyl heptanoate (2) was isolated from the biosurfactant produced from fresh cooking oil. This study demonstrated the ability of Bacillus subtilis to produce a low-cost biosurfactant characterized as lipopeptide.

Cellulase Production by Fusarium graminearum and its Application in Ruminant's Diets Degradation.

Cellulase as a fibrolytic enzyme is a highly effective tool for agricultural waste treatments. Production of cellulase enzyme on medium of agricultural wastes by Fusarium graminearum to be used in ruminant feeding was the main objective of this study. Impact of initial pH of growth medium, different nitrogen sources and variety of agriculture by products as a carbon sources on cellulase production have been studied. Electron microscope was used for investigate the impact of the resultant cellulase on corn stover degradation, while batch culture technique was used for investigate impact of different levels of the produced and commercial cellulases on total mixed ration digestibility by rumen microorganisms (in vitro). Cellulase maximum production by F. graminearum was obtained at 20% corn stover, initial pH of growth medium 5.0 and peptone as a nitrogen source. All addition levels of the produced cellulase increased dry matter (DM), neutral detergent fiber (NDF), acid detergent fiber (ADF), cellulose and hemicellulose degradability of the treated diets, but the maximum produced cellulase efficiency% for dry matter degradability was obtained at 1200 IU kg-1 DM reached 23.19% over the control. Utilization of the produced cellulase in enrichment of the feeding value of the agricultural by-products may help in overcome of the feed gap with good impact on environment and public health.

Ammonium Alleviates Manganese Toxicity and Accumulation in Rice by Down-Regulating the Transporter Gene OsNramp5 Through Rhizosphere Acidification.

Ammonium () alleviates manganese (Mn) toxicity in various plant species, but the underlying mechanisms are still unclear. In this study, we compared the effects of and nitrate () on rice (Oryza sativa L.) growth, accumulation and distribution of Mn, accumulation of iron (Fe), zinc (Zn) and copper (Cu), root cell wall components, and expression of Mn and Fe transporter genes. After rice seedlings were grown in non-pH-buffered nutrient solution for 2 days, the pH of growth medium changed from an initial value of 4.5 to 3.5 and to 5.5 in the presence of and in the presence of , respectively. Compared with , ammonium decreased nutrient-solution pH and alleviated Mn toxicity and accumulation in rice under non-pH-buffered conditions. This alleviation disappeared when 5 mM Homo-PIPES pH buffer was added. Regardless of N form, roots, shoots, root cell sap, and xylem sap accumulated much lower Mn at pH 3.5 than at pH 5.5, whereas Mn distribution in different leaves and Mn accumulation in root cell walls was affected by neither N form nor pH. Ammonium decreased the expression of the Mn influx transporter gene OsNramp5 in roots under non-pH-buffered conditions, but not under pH-buffered ones. OsNramp5 expression was down-regulated at pH 3.5 compared with pH 5.5. Another efflux Mn transporter gene, OsMTP9, was not regulated by either N form or pH. High pH (5.5) enhanced the expression of the Fe transporter gene OsIRT1 and increased the accumulation of Zn but not Fe or Cu in shoots compared with pH 3.5. Taken together, our results indicate that alleviates Mn toxicity and accumulation in rice through the down-regulatory effects of rhizosphere acidification on the Mn influx transporter gene OsNramp5. In addition, the up-regulation of OsIRT1 expression may contribute to the increased Zn uptake by rice at high pH of nutrient solution.