Optimum pH Range Research Articles

The global significance of abiotic factors affecting nitrate removal in woodchip bioreactors

Woodchip bioreactor (WBR) is one of the green infrastructures in the agriculture system to reduce nitrate from agricultural drainage and stormwater. A lot of abiotic factors have been reported that affect nitrate removal lacking a comprehensive understanding. In this study, we studied eight important abiotic factors, including media age, hydraulic retention time (HRT), influent nitrate concentration (Cin), temperature, dissolved organic carbon (DOC), dissolved oxygen (DO), pH, and effective porosity (ρe) of WBR-filling materials. Based on a database that included 10,179 sets of data from 63 peer-reviewed articles, the nitrate removal rate (NRR) and nitrate removal efficiency (NRE) corresponding to the eight abiotic factors by different categories were comprehensively reported. According to this database, this study found the optimal range of abiotic factors for NRR and NRE in WBR were different. Regarding NRR, the optimal range of media age, HRT, Cin, temperature, effluent DOC, DO, pH, and ρe were in the first year, 0–5 h, 10–20 mg L−1, 20–25 °C, 0–5 mg L−1, 0–0.5 mg L−1, 7–8, and 0.6–0.7, respectively. For NRE, the optimal range of media age, HRT, Cin, temperature, effluent DOC, DO, pH, and ρe were in the first year, 500–3000 h, 0–10 mg L−1, 10–15 °C, >50 mg L−1, 0–0.5 mg L−1, 4–5, and 0.4–0.5, respectively. Moreover, the principal component analysis (PCA) indicated the field studies' principal components were different from laboratory studies. Furthermore, the structural equation modeling (SEM) also revealed the causal relationship of the eight abiotic factors on NRR and NRE is totally different. Lessons from this study can be incorporated into DNBR designs, especially improving nitrate removal rates by optimizing different abiotic factors. It also provides insights regarding the contributions of different abiotic factors for NRR and NRE independently and comprehensively.

Modulation of extracellular Penicillium expansum-driven acidification by Papiliotrema terrestris affects biosynthesis of patulin and has a possible role in biocontrol activity.

The active regulation of extracellular pH is critical for the virulence of fungal pathogens. Penicillium expansum is the causal agent of green-blue mold on stored pome fruits and during its infection process acidifies the host tissues by secreting organic acids. P. expansum is also the main producer of patulin (PAT), a mycotoxin found in pome fruit-based products and that represents a serious health hazard for its potential carcinogenicity. While it is known that PAT biosynthesis in P. expansum is regulated by nutritional factors such as carbon and nitrogen and by the pH, the mechanistic effects of biocontrol on PAT production by P. expansum are not known. In this work, we assessed how optimal and suboptimal concentrations of the biocontrol agent (BCA) Papiliotrema terrestris LS28 affect both extracellular pH and PAT biosynthesis in P. expansum. In wounded apples, the optimal and suboptimal concentrations of the BCA provided almost complete and partial protection from P. expansum infection, respectively, and reduced PAT contamination in both cases. However, the suboptimal concentration of the BCA increased the specific mycotoxigenic activity by P. expansum. In vitro, the rate of PAT biosynthesis was strictly related to the extracellular pH, with the highest amount of PAT detected in the pH range 4–7, whereas only traces were detectable at pH 3. Moreover, both in vitro and in apple wounds the BCA counteracted the extracellular P. expansum-driven acidification maintaining extracellular pH around 4, which is within the pH range that is optimal for PAT biosynthesis. Conversely, in the absence of LS28 the pathogen-driven acidification led to rapidly achieving acidic pH values (<3) that lie outside of the optimal pH range for PAT biosynthesis. Taken together, these results suggest that pH modulation by LS28 is important to counteract the host tissue acidification and, therefore, the virulence of P. expansum. On the other hand, the buffering of P. expansum-driven acidification provided by the BCA increases the specific rate of PAT biosynthesis through the extension of the time interval at which the pH value lies within the optimal range for PAT biosynthesis. Nevertheless, the antagonistic effect provided by the BCA greatly reduced the total amount of PAT.

Chelating cellulose functionalized with four amino acids: A comparative study on the enhanced adsorptive removal of cadmium and lead ions

Cellulose, a regenerative superior material, has been attracted an increased interest for extending its area to use. Here, some chelating celluloses functionalized with four amino acids: cysteine, histidine, aspartic acid, and methionine (as named Cys-CL, His-CL, Asp-CL and Met-CL) were prepared through a Schiff base reaction, and analyzed by several means of characterization for the purpose of enhanced adsorptive removal of Cd2+ and Pb2+ from aqueous solution. For the Cd2+ ions, the saturated adsorptive capacities of the Cys-CL, His-CL, Asp-CL and Met-CL at 30 °C in the optimal pH range of 4.5–5.5 were found to be 130.7, 87.0, 75.5 and 37.1 mg g−1, respectively. For the Pb2+ions, the saturated adsorptive capacities of the Cys-CL, His-CL, Asp-CL and Met-CL at 30 °C in the optimal pH range of 4.0–5.5 were found to be 180.9, 119.0, 111.0 and 51.1 mg g−1, respectively. The results clearly illustrated adsorption capacities conformed to Cys-CL > His-CL > Asp-CL > Met-CL. Cys-CL exhibited the obvious advantages and was sensitive to the initial concentrations of both the metal ions, solution pH and temperature. The rapid uptakes of the Cd2+ and Pb2+ by the Cys-CL were observed within 30 min. The adsorption of both the metal ions by the Cys-CL was described reliably by the Langmuir and pseudo second-order models and occurred spontaneously and endothermically in nature. The Cys-CL with good adsorptive characteristics and recyclability owns great potential for the adsorptive removal of the Cd2+ and Pb2+ from aqueous solution.

Pb2+ potentiometric chemical sensors based on lead and silver doped thioaresenate glasses

Lead doped chalcogenide glass compositions, in the pseudo-ternary AgI-PbS-As2S3, were examined as active membrane materials for the construction of Pb(II) ion-selective sensors, Pb(II)−ISE. The basic glass properties of the synthesised bulk samples such as vitreous state, macroscopic, thermal and electric properties were studied. To this end, several techniques were used, including X-ray powder diffraction, density measurements, differential scanning calorimetry, scanning electron microscopy and impedance complex spectroscopy. It is found that the density increases with increased AgI and PbS contents. The glass transition temperatures for the studied compositions were also reported. The electrical measurement show the conductivity increases with increasing AgI content. Meanwhile, for the glasses with same AgI content and increasing PbS content, the conductivity decreases. For the fabricated sensors, several key analytical parameters were investigated to evaluate the different glass compositions as active membranes in Pb(II)−ISE, including detection limit, sensitivity, linearity, ionic selectivity (in the presence of K+, Na+, Ni2+, Ca2+, Cd2+, Cu2+ and Hg2+ interfering cations), reproducibility and optimal pH-range.

Methanococcoides orientis sp. nov., a methylotrophic methanogen isolated from sediment of the East China Sea.

A novel methylotrophic methanogen Methanococcoides orientis sp. nov. was isolated from East China Sea sediment. Type strain LMO-1T of Methanococcoides orientis sp. nov. was irregular 1-2 µm cocci without flagella. Strain LMO-1T could utilize a variety of methylated compounds including methanol, methylamine, dimethylamine and trimethylamine for growth and methanogenesis, while H2/CO2 or acetate could not be used for growth or methanogenesis. Optimum growth temperature was 30-35 °C, optimum pH range for growth was 7.0-7.5, while the optimum salinity spectrum for growth was 1.0%-5.0% NaCl. Based on 16S rRNA gene similarity, strain LMO-1T belongs to Methanococcoides, with the highest sequence similarity to Methanococcoides methylutens DSM 2657T (99.8 %), Methanococcoides vulcani SLH33T(99.4 %), followed by Methanococcoides alaskense AK-5T(98.1 %), Methanococcoides burtonii DSM 6242T (98.0 %). Digital DNA-DNA hybridization also showed highest similarity with Methanococcoides methylutens DSM 2657T, with the value of 58.4 %. The average nucleotide identity between strain LMO-1T and Methanococcoides methylutens DSM 2657T was 94.06 %. In summary, LMO-1T represents a novel species of the genus Methaococcoides, for which the name Methanococcoides orientis sp. nov. is proposed. The type strain is LMO-1T (=MCCC 4K00106T=JCM 39195T).

Optimizing the Growth Conditions of the Selected Plant-Growth-Promoting Rhizobacteria Paenibacillus sp. MVY-024 for Industrial Scale Production.

Simple SummaryNitrogen is one of the most important elements for plant growth and development. However, irrational fertilization causes many environmental problems: high rates of nitrogen fertilizers change the soil pH, encourage nitrate and nitrite accumulation in plants and the soil, leached nitrogen compounds cause water eutrophication and drinking water contamination, and gaseous losses of nitrogen contribute to global warming. The biological nitrogen fixation (BNF) process, in which atmospheric nitrogen is converted to ammonia by microorganisms, has a significant role in the global nitrogen cycle and agriculture. Nitrogen-fixing-bacteria inoculants could help to reduce the losses of consistently rising prices of mineral fertilizers and help to implement green revolution strategies. In this research, we found the bacteria strain Paenibacillus sp. MVY-024 that has a positive impact on nitrogen accumulation in spring wheat and was easily applied on an industrial scale.In this study, thirteen isolates, which were possibly expected to fix nitrogen, were isolated from soil and pea root nodules and identified by the gene analysis of 16S rDNA sequences. Two of these isolates that were able to form endospores and grow on nitrogen-free media were selected for spring wheat development research. The isolate Paenibacillus sp. S7 identified as Paenibacillus polymyxa was found to significantly increase the amount of ammonium and mineral N amounts in the soil. Furthermore, increased nitrogen accumulation in grains and a chlorophyll index were obtained after wheat treatment. Paenibacillus sp. S7 isolate was selected for further studies and the accession number MT900581 and strain name MVY-024 in NCBI nucleotide bank for this isolate were assigned. During the cultivation of Paenibacillus sp. MVY-024, sugarcane molasses and a yeast extract were determined as the most suitable carbon and nitrogen sources, whose optimal concentrations were 100 g L−1 and 10 g L−1, respectively. The optimal pH range for the cell culture was between 6.5 and 7.0, and the optimal air flow rate was 0.4 vvm. It was found that the air flow has an effect on biomass production and endospore formation. After Paenibacillus sp. MVY-024 biomass cultivation optimization, the cultured cell number was, on average, 2.2 × 109 cfu m L−1.

Polymeric Electrochemical Sensor for Calcium Based on DNA.

Plastic membranes containing deoxyribonucleic acid (DNA) as an electroactive material were acting as Ca2+ selective sensors. Diethyl phthalate (DEP), dioctyl Phthalate (DOP), or nitrophenyl octyl ether (NPOE) were used as plasticizers and polyvinyl chloride (PVC) was the membrane matrix. A sensor with a membrane composition of 120 mg PVC, 60 mg DOP plasticizer, and 2 mg DNA ionophore (DNA: DOP: PVC, 1.0:29.2:0.1 mole) was found to have the best performance. The slope of the calibration graph was 30 mV decade−1. The optimum pH range was 5.7–9.5 for 0.01 M Ca2+. The sensor response time was fast (2–3 s) with a long working period (up to 3 weeks). Excellent selectivity for Ca2+ was indicated by the values of selectivity coefficients for different selected interference. The sensor was used effectively for the estimation of calcium in real samples (fruits, calcium syrup, milk, and dairy products).

Biotechnological Applications of Manganese Peroxidases for Sustainable Management

Microbial manganese peroxidases (MnPs) are ligninolytic enzymes primarily responsible for degrading lignin, but they are also capable of degrading dyes, organic pollutants, and emerging contaminants in wastewater. They have been isolated and characterized from many white-rot fungi and few bacteria. For microbial MnPs, the optimum pH range is between 3.5 and 9.0; the optimum temperature range is between 25°C and 70°C. Their molecular weights range between 25 kDa and 68 kDa. By oxidizing Mn2+ to Mn3+, they can oxidize a wide range of phenolic and non-phenolic substrates. MnPs can be used in a wide range of industrial applications, including delignification of pulp, wastewater treatment, biofuel production, dye removal, biopulping, biobleaching, and juice extract clarification. The purpose of this review is to summarize biotechnological applications of manganese peroxidases.

Optimization of pectinolytic hydrolysis in Caatinga passion fruit wine must with commercial pectinase, according to the central composite rotatable design approach

The Passiflora cincinnata Mast. has high flavor and potential for wine and other alcoholic beverages production. However, for wine production, the presence of pectin becomes undesirable, as it influences the efficiency of the fermentation process and the clarity of the final product. The objective of this study was to optimize the pectin hydrolysis process in Caatinga passion fruit must for wine production with pectinolytic enzymes, using a Central Composite Rotatable Design (CCRD). The 2³ factorial CCRD, E01 to E17 assays, was applied with six axial tests and three replications in the central point. Caatinga passion fruit must was obtained with pulp and distilled water (40:60 proporcion). Commercial enzyme with high concentration of pectinase was tested. Concentration of enzyme (0.014-0.056 g L-1), working temperature (43-57°C) and reaction time (12-139min) were the independent variables in the optimization process; and the soluble pectin content (mg 100g-1) corresponded to a process-dependent variable. Prior to the beginning of the assays, in order to provide the optimum working pH range for the pectinase, correction of the must pH to 3.9. The initial Caatinga passion fruit wine must had 24.06 mg 100g-1 of soluble pectin in its composition. After the optimization using CCRD, the treatments presented pectin contents ranging from 6.81 (E16: 0.014g L-1/50°C/75min) to 0.00 mg 100 g-1 (E05: 0.05 g L-1/45°C/ 30min and E06: 0.05 g L-1/45°C/120min). According to the results, to a satisfactory process of pectin hydrolysis in Caatinga passion fruit wine must be added 0.05 g L-1 of pectinase at 45°C for 30min.

Novel Application for Activated Carbon Pharmaceutical Formulation as an Efficient Adsorbent of Iron (III) from Contaminated Canned Food

Additional medical indication has been realized for the active carbon commercialized in pharmaceutical stores for the first time. In this study, the active carbon was used to remove iron (III) from real canned food samples contaminated with iron by an adsorption process, in a new approach. Different parameters affecting the adsorption behavior of active carbon towards iron (III) have been optimized. Under the optimized conditions, namely, pH 4, 5 h contact time, 40 ppm iron initial concentration, and 2 g carbon, the study was applied to some of the real canned food samples. Black olive and green bean canned food samples containing relatively high iron levels of 698.0 and 1168 mg kg-1, respectively, have been selected for this study due to their levels which were above the maximum permitted levels 48 mg kg-1 according to the Joint FAO/WHO Expert Committee on Food Additives (JECFA). These samples were digested and treated, and their iron concentration was determined using ICP-AES under the specified optimum conditions. The removal percentage of the real samples was ~91%. In a novel approach, this study simulates the adsorption behavior of active carbon towards iron (III) in the human stomach when canned food with relatively high iron levels has been digested, since the pH value of the human stomach (~3) comes in good agreement with the adsorption optimized pH range (2-4). Moreover, the overall tolerability and safety of active carbon are worldwide known and traditionally documented. These application studies realize the applicability of utilizing active carbon commercially available in pharmaceutical stores to eliminate the toxicity of canned food contaminated by high levels of the investigated elements.

Optimizing the Effect of pH and Temperature on Atrazine Degradation by Bacillus safensis strain BUK_BCH_BTE6 an Efficient Atrazine Tolerating Bacteria from an Agricultural Soil in Kura Local Government Area of Kano State, Nigeria

The widespread and long term use of atrazine results in high residue levels of atrazine in soil, which further causes water contamination, it is considered as an endocrine disruptor and is potentially carcinogenic. Microbial degradation of herbicide represents a time cost effective way of eco-restoration. This research was aimed at isolating and characterizing bacteria capable of degrading and utilizing atrazine as a sole carbon source. An enrichment method was used to isolate the bacteria on mineral salt media (MSM) following serial dilution. The isolate was identified morphologically, biochemically and molecularly as Bacillus safensis strain BUK_BCH_BTE6 based on 16S rRNA gene sequence and molecular phylogenetic analysis. The effect of pH and temperature on the degradation of atrazine was studied in MSM medium supplemented with atrazine as sole carbon source. Growth and degradation of atrazine in this isolate was optimal at pH 7.5 and temperature of 35 °C. Bacillus safensis is highly efficient in atrazine degradation with an optimum range of pH and temperature. Bacillus safensis could be a suitable candidate for bioremediation of atrazine polluted sites.

Screening of gamma-aminobutyric acid-producing lactic acid bacteria and the characteristic of glutamate decarboxylase from Levilactobacillus brevis F109-MD3 isolated from kimchi

This study aimed to screen the γ-aminobutyric acid (GABA)-producing lactic acid bacteria (LAB) from kimchi, and investigate the glutamate decarboxylase (GAD) activity of the highest GABA-producing strain. Seven strains of LAB were screened from kimchi with GABA-producing activity. Strain Levilactobacillus brevis F109-MD3 showed the highest GABA-producing ability. It produced GABA at a concentration of 520mmoll-1 with a 97.4% GABA conversion rate in MRS broth containing 10% monosodium glutamate for 72h. The addition of pyridoxal 5'-phosphate had no significant effect on the GAD activity of L. brevis F109-MD3. The optimal pH range of GAD was 3.0-5.0 and the optimal temperature was 65°C. The D value of GAD at 50, 60 and 70°C was 7143, 971 and 124min respectively and Z value was 11.36°C. Seven strains isolated from kimchi, especially F109-MD3, showed high GABA-production ability even in the high concentrations of MSG at 7.5% and 10%. The GAD activity showed an effective broad pH range and higher optimal temperature. These seven strains could be potentially useful for food-grade GABA production and the development of healthy foods.

Structure and stability analysis of antibacterial substance produced by selenium enriched Bacillus cereus BC1.

Microorganisms can produce many antibiotics against bacteria and fungi, which have been used as a potential choice of new antibiotics. In this paper, we studied the characteristics of antibacterial substances by Bacillus cereus BC1. The results showed that the acid-precipitated substance played the main role in antibacterial activity, and further characterization indicated that the antibacterial substance might be a lipopeptide substance. Then the antibacterial spectrum suggested that the antibacterial substance had an inhibitory effect on Gram-positive bacteria and fungi, while selenium-riched antibacterial substance of Bacillus cereus BC1 could significantly enhance the inhibition. Then the morphological effects of the antibacterial substance to indicator bacteria were determined. The effects of different treatment methods on the stability of antibacterial substances were studied and the results showed that the antibacterial substance was stable to heat, ultrasonic, and ultraviolet treatment, and their antibacterial activity would not be greatly affected. However, they were sensitive to pepsin. The optimum pH range of antibacterial activity was 3-5. This study may contribute to reusing the fermentation supernatant often discarded in the previous fermentation process. At the same time, the lipopeptide antibacterial substance extracted from the fermentation broth of selenium-enriched Bacillus cereus BC1 can be used in the development of antibiotics and biopesticides, and open up a new way for the control of plant diseases.

Effects of poultry waste as an additive in biogas production using cow dung

Globally, there is need for the proper utilization of animal waste products (such as cow dung, poultry waste and so on), which can be used as an alternative source of energy. Herein, the effects of poultry waste as an additive in the production of biogas using substrate (cow dung and poultry waste) and pH value were investigated. The substrate (cow dung and poultry waste) was prepared via simple dry method. Different set up (1, 2, 3,4 and 5) were designed using local materials (based on the floating drum plant type of digester). The gas produced through an anaerobic digestion method of the different set ups were recorded daily at a fixed time (14 hr) for the periods of 10 days. Set up 2 produced the highest volume of gas (89 cm3), a ~2, ~1.1, ~1.4 and ~1.6 -folds enhancement compared with set up 1, 3, 4 and 5, respectively. It observed that the gas produced decrease with an increase of the poultry waste, indicating that poultry waste played significant role in boosting the production of the gas. The pH of the digester and temperature were kept within pH optimum range of 6.5-8.0 and mesophilic temperature range 20-40 oC, respectively. Thus, the substrate developed (2:1 ratio) was economical, non-hazardous and environmentally friendly.

Nanocrystalline structure and microhardness of cobalt-chromium alloys electrochemically synthesized using a metal hydroxide coprecipitation technique

The effect of glycine as a complexing agent on metal hydroxide formation, such as Co(OH)2 and Cr(OH)3, was investigated based on potential-pH diagrams and titration curves for Co2+-H2O and Cr3+−H2O systems. Using a potentiostatic electrodeposition technique, Co–Cr alloy-based composite films containing Cr2O3 were synthesized from a non-suspended aqueous solution within an optimized pH range. Chromium content in the composite films was controlled up to 38.9% by adjusting the cathode potential during the alloy electrodeposition. Based on the XRD profiles and electron diffraction patterns, an amorphous-like nanocrystalline structure was observed in the composite films with high chromium content. The average crystal grain size declined due to Cr2O3 particles and hydrogen evolution during the electrodeposition process. Saturation magnetization of the composite films decreased with an increase in the chromium content. Synergistic contribution of increasing dislocation density and refining crystal grain size improved the microhardness of the composite films. The microhardness reached 624.2 kgf mm−2 and greatly exceeded that of pure cobalt (ca. 250–300 kgf mm−2).

Characterization of the Novel Phage vB_VpaP_FE11 and Its Potential Role in Controlling Vibrio parahaemolyticus Biofilms.

Vibrio parahaemolyticus causes aquatic vibriosis. Its biofilm protects it from antibiotics; therefore, a new different method is needed to control V. parahaemolyticus for food safety. Phage therapy represents an alternative strategy to control biofilms. In this study, the lytic Vibrio phage vB_VpaP_FE11 (FE11) was isolated from the sewers of Guangzhou Huangsha Aquatic Market. Electron microscopy analysis revealed that FE11 has a typical podovirus morphology. Its optimal stability temperature and pH range were found to be 20–50 °C and 5–10 °C, respectively. It was completely inactivated following ultraviolet irradiation for 20 min. Its latent period is 10 min and burst size is 37 plaque forming units/cell. Its double-stranded DNA genome is 43,397 bp long, with a G + C content of 49.24% and 50 predicted protein-coding genes. As a lytic phage, FE11 not only prevented the formation of biofilms but also could destroy the formed biofilms effectively. Overall, phage vB_VpaP_FE11 is a potential biological control agent against V. parahaemolyticus and the biofilm it produces.

Investigation on mechanism of Hexavalent chromium bioreduction by Escherichia sp. TH-1 and the stability of reduction products

Hexavalent chromium (Cr(VI)) was proved to be a carcinogen to organisms and threaten health of human beings through food chains. In order to detect a more economical and efficient method to remove Cr(VI) from contaminated sites, a Cr(VI) reducing strain named TH-1 was isolated from aerobic activated sludge and identified as Escherichia sp. by 16 S rDNA sequence analysis. The Cr(VI) removing performance of TH-1 was elucidated under different environmental conditions (temperature, pH, initial Cr (VI) concentration and metal ions) to detect the optimum condition, and the potential mechanisms of Cr(VI) reduction were explained including micro-characterization and stability test of reduction product. As the result, while inhibited by Cd2+ existence, TH-1 could grow and remove Cr(VI) in a wide range of temperature and pH (optimum at 37 ℃ and pH7.0), with the process being promoted by Cu2+, Ni2+ and Fe3+. The results of X-ray Diffraction, X-ray photoelectron spectroscopy confirmed that the reduced Cr(VI) product was mainly organic-Cr (III) complex, and Fourier Transform infrared spectroscopy showed that functional groups such as –OH, -COOH and CO etc. were Cr binding sites. Afterwards, the stability of the organic-Cr (III) complex reduced by strain TH-1 were much more stable than Cr (III) chemically reduced by FeS, the stability of which decreased significantly from pH 9 to pH 14, but rarely changed under near-neutral and acidic condition. Hence, TH-1 had great prospects for reducing Cr (VI) under different environmental conditions with long-term effect, which was significant for the remediation of Cr (VI) influenced environmental sites.

γ-PGA Fermentation by Bacillus subtilis PG-001 with Glucose Feedback Control pH-stat Strategy.

Poly-γ-glutamic acid (γ-PGA) is an important biopolymer with many applications due to its biodegradable and non-toxic characteristics. γ-PGA is produced industrially by fermentation of Bacillus species. The optimal pH range for producing γ-PGA by Bacillus subtilis PG-001 was firstly studied by glucose fed-batch fermentation with non-controlled pH. Result showed that both cell growth and γ-PGA synthesis were repressed when pH was lower than pH 6. Further investigation with γ-PGA fed-batch fermentation showed that pH 6.5 is more suitable for γ-PGA fermentation than pH 7. Under comparable consumption of glutamic acid and glucose, 11.8 g/L γ-PGA and 0.7 g/g yield were achieved by fermentation at pH 6.5, which was significantly higher than 10.5 g/L and 0.56 g/g yield of fermentation at pH 7. In addition, γ-PGA degradation during later phase of fermentation was repressed at pH 6.5 as 9238cP of final broth viscosity was achieved from fermentation at pH 6.5 while it was only 346 cP for fermentation at pH 7. Finally, a glucose feedback control pH-stat strategy was performed for reducing alkali consumption during γ-PGA fermentation, which further increased final γ-PGA concentration to 15.5 g/L with much higher viscosity (11458 cP); meanwhile the consumption of alkali decreased 57%. The fed-batch γ-PGA fermentation with glucose feedback control pH-stat strategy showed high feasibility for industrial scaling-up.

Development of an integrating coagulation and reverse osmosis system to treat highly turbid water using synthesized coagulants.

In the present study a coagulation process was used as a pretreatment for a reverse osmosis (RO) membrane with turbid raw water collected from Bisalpur dam, Rajasthan, India. To optimize the coagulation performance, three kinds of coagulant, namely, alum (commercially available), synthesized inorganic polymeric coagulant-medium basicity (IPC-M), and inorganic polymeric coagulant-ultrahigh basicity (IPC-UH) were examined for turbidity removal with varying operating parameters. It was observed that in the optimum pH range of 6-7, the IPC-UH was the best performing coagulant with a 0.99 mg/L equivalent Al2O3 dose, revealing 2 NTU residual turbidity and residual aluminium of 0.001 mg/L. Moreover, the Langelier saturation index and Ryznar stability index values were evaluated at optimum conditions for all the three coagulants providing negligible scaling potential. Furthermore, the coagulant-treated water (100 L) was fed to the RO membrane, and the performance was noted in terms of flux, pressure, and total dissolved solids. It was observed that IPC-UH had the lowest reduction in permeate flux of 0.78 L/min/m2 compared with the commercially available coagulant alum (0.90 L/min/m2). Also, an increased feed pressure was observed for all the coagulant-treated waters with the lowest value of 2.3 kg/cm2 for IPC-UH, which was 2.5 kg/cm2 for alum (commercially available coagulant). Therefore, integration of coagulation before the RO system resulted in effective pretreatment of turbid water with very minute scaling.

Synthesis and characterization of graphene nanosheets for electrochemical quantification of chlorpheniramine maleate drugs using a modified glassy carbon electrode

The development of innovative sensors for the detection of analytes at extremely low concentrations with great sensitivity and selectivity has been a major focus of this study. The electrochemical activity of chlorpheniramine maleate (CPRM) in the presence of a graphene modified GCE has been investigated. Cyclic voltammograms (CV) have been obtained in the linear dynamic range 3.5- 156 μM while the optimum pH range and the maximum peak current (IPa) have been measured at pH 7.3. The process on the electrode's surface, diffusion regulated, heterogeneous rate constant, charge transfer coefficient, and the number of electrons transferred among the physicochemical properties have been obtained. Differential pulse voltammetry (DPV) of CPRM at the modified has electrode revealed a good linear calibration curve with a linear range of 10 to 60 μM and limit of detection of 0.062 μM. The suggested sensor has been fabricated and utilized to determine CPRM in medicines as well as serum samples.