White-rot fungi, namely Coriolus versicolor and Schizophyllum commune, were studied for the biodecolorization of textile dyeing effluent in shaker-flask experiments. The results showed that C. versicolor was able to achieve 68% color removal after 5 days of treatment while that of S. commune was 88% in 9 days. Both fungi achieved the above results in non-sterile condition with diammonium hydrogen phosphate as the nutrient supplement. On the other hand, the best COD removal of 80% was obtained with C. versicolor in 9 days in sterile effluent with yeast extract as nutrient supplement, while S. commune was able to remove 85% COD within 8 days in non-sterile textile effluent supplemented with diammonium hydrogen phosphate.
In this research, we modify a previously developed assay for the quantification molybdenum blue to determine whether inhibitors to molybdate reduction in bacteria inhibits cellular reduction or inhibit the chemical formation of one of the intermediate of molybdenum blue; phosphomolybdate. We manage to prove that inhibition of molybdate reduction by phosphate and arsenate is at the level of phosphomolybdate and not cellular. We also prove that mercury is a physiological inhibitor to molybdate reduction. We suggest the use of this method to assess the effect of inhibitors and activators to molybdate reduction in bacteria.
The incorporation of magnesium ions into the calcium phosphate structure is of great interest for the development of artificial bone implants. This paper investigates the preparation of magnesium-doped biphasic calcium phosphate (Mg-BCP) via sol gel method at various concentrations of added Mg. The effect of calcinations temperature (ranging from 500 degrees C to 900 degrees C) and concentrations of Mg incorporated into BCP has been studied by the aid of XRD, TGA and infrared spectroscopy (IR) in transmittance mode analysis. The study indicated that the powder was pure BCP and Mg-BCP with 100% purity and high crystallinity. The results also indicated that beta-tricalcium phosphate (beta-TCP) phase can be observed when the powder was calcined at 800 degrees C and above.
Putrajaya Wetlands in Malaysia, a 200ha constructed wetland system consisting of 24 cells, was created in 1997-1998 to treat surface runoff caused by development and agricultural activities from an upstream catchment before entering Putrajaya Lake (400ha). It was designed for stormwater treatment, flood control and amenity use. The water quality improvement performance of a section of the wetland cells is described. The nutrient removal performance was 82.11% for total nitrogen, 70.73% for nitrate-nitrogen and 84.32% for phosphate, respectively, along six wetland cells from Upper North UN6 to UN1 from April to December 2004. Nutrient removal in pilot scale tank systems, simulating a constructed wetland and planted with examples of common species at Putrajaya, the Common Reed Phragmites karka and Tube Sedge Lepironia articulata, and the capacity of these species to retain nutrients in above and below-ground plant biomass and substrate is reported. The uptake of nutrients by the Common Reed and Tube Sedge from the pilot tank system was 42.1% TKN; 28.9% P and 17.4% TKN; 26.1% P, respectively. The nutrient uptake efficiency of the Common Reed was higher in above-ground than in below-ground tissue. The results have implications for plant species selection in the design of constructed wetlands in Malaysia and for optimizing the performance of these systems.
The need to isolate efficient heavy metal reducers for cost effective bioremediation strategy have resulted in the isolation of a potent molybdenum-reducing bacterium. The isolate was tentatively identified as Serratia sp. strain DRY5 based on the Biolog GN carbon utilization profiles and partial 16S rDNA molecular phylogeny. Strain DRY5 produced 2.3 times the amount of Mo-blue than S. marcescens strain Dr.Y6, 23 times more than E. coli K12 and 7 times more than E. cloacae strain 48. Strain DRY5 required 37 degrees C and pH 7.0 for optimum molybdenum reduction. Carbon sources such as sucrose, maltose, glucose and glycerol, supported cellular growth and molybdate reduction after 24 hr of static incubation. The most optimum carbon source that supported reduction was sucrose at 1.0% (w/v). Ammonium sulphate, ammonium chloride, glutamic acid, cysteine, and valine supported growth and molybdate reduction with ammonium sulphate as the optimum nitrogen source at 0. 2% (w/v). Molybdate reduction was optimally supported by 30 mM molybdate. The optimum concentration of phosphate for molybdate reduction was 5 mM when molybdate concentration was fixed at 30 mM and molybdate reduction was totally inhibited at 100 mM phosphate. Mo-blue produced by this strain shows a unique characteristic absorption profile with a maximum peak at 865 nm and a shoulder at 700 nm, Dialysis tubing experiment showed that 95.42% of Mo-blue was found in the dialysis tubing suggesting that the molybdate reduction seen in this bacterium was catalyzed by enzyme(s). The characteristics of isolate DRY5 suggest that it would be useful in the bioremediation ofmolybdenum-containing waste.
A major weakness of current orthopedic implant materials, for instance sintered hydroxyapatite (HA), is that they exist as a hardened form, requiring the surgeon to fit the surgical site around an implant to the desired shape. This can cause an increase in bone loss, trauma to the surrounding tissue, and longer surgical time. A convenient alternative to harden bone filling materials are injectable bone substitutes (IBS). In this article, recent progress in the development and application of calcium phosphate (CP)-based composites use as IBS is reviewed. CP materials have been used widely for bone replacement because of their similarity to the mineral component of bone. The main limitation of bulk CP materials is their brittle nature and poor mechanical properties. There is significant effort to reinforce or improve the mechanical properties and injectability of calcium phosphate cement (CPC) and this review resumes different alternatives presented in this specialized literature.
This paper presents the development of novel alternative injectable calcium phosphate cement (CPC) composites for orthopaedic applications. The new CPC composites comprise β-tri-calcium phosphate (β-TCP) and di-calcium phosphate anhydrous (DCPA) mixed with bovine serum albumin (BSA) and incorporated with multi-walled carbon nanotubes (MWCNTs) or functionalized MWCNTs (MWCNTs-OH and MWCNTs-COOH). Scanning electron microscopy (SEM), compressive strength tests, injectability tests, Fourier transform infrared spectroscopy and X-ray diffraction were used to evaluate the properties of the final products. Compressive strength tests and SEM observations demonstrated particularly that the concomitant admixture of BSA and MWCNT improved the mechanical properties, resulting in stronger CPC composites. The presence of MWCNTs and BSA influenced the morphology of the hydroxyapatite (HA) crystals in the CPC matrix. BSA was found to act as a promoter of HA growth when bounded to the surface of CPC grains. MWCNT-OH-containing composites exhibited the highest compressive strengths (16.3 MPa), being in the range of values for trabecular bone (2-12 MPa).
Use of phosphate-solubilizing bacteria (PSB) as inoculants has concurrently increased phosphorous uptake in plants and improved yields in several crop species. The ability of PSB to improve growth of aerobic rice (Oryza sativa L.) through enhanced phosphorus (P) uptake from Christmas island rock phosphate (RP) was studied in glasshouse experiments. Two isolated PSB strains; Bacillus spp. PSB9 and PSB16, were evaluated with RP treatments at 0, 30 and 60 kg ha(-1). Surface sterilized seeds of aerobic rice were planted in plastic pots containing 3 kg soil and the effect of treatments incorporated at planting were observed over 60 days of growth. The isolated PSB strains (PSB9 and PSB16) solubilized significantly high amounts of P (20.05-24.08 mg kg(-1)) compared to non-inoculated (19-23.10 mg kg(-1)) treatments. Significantly higher P solubilization (24.08 mg kg(-1)) and plant P uptake (5.31 mg plant(-1)) was observed with the PSB16 strain at the highest P level of 60 kg ha(-1). The higher amounts of soluble P in the soil solution increased P uptake in plants and resulted in higher plant biomass (21.48 g plant(-1)). PSB strains also increased plant height (80 cm) and improved root morphology in aerobic rice. The results showed that inoculation of aerobic rice with PSB improved phosphate solubilizing activity of incorporated RP.
A capillary electrophoresis (CE)-capacitively coupled contactless conductivity detection (C(4)D) method for the simultaneous separation of eleven underivatized fatty acids (FAs), namely, lauric, myristic, tridecanoic (internal standard), pentadecanoic, palmitic, stearic, oleic, elaidic, linoleic, linolenic and arachidic acids is described. The separation was carried out in normal polarity mode at 20 °C, 30 kV and using hydrodynamic injection (50 mbar for 1 s). The separation was achieved in a bare fused-silica capillary (70 cm × 75 μm i.d.) using a background electrolyte of methyl-β-cyclodextrin (~6 mM) and heptakis-(2,3,6-tri-O-methyl)-β-cyclodextrin (~8 mM) dissolved in a mixture of Na2HPO4/KH2PO4 (5 mM, pH 7.4):ACN:MeOH:n-octanol (3:4:2.5:0.5, v/v/v/v). C(4)D parameters were set at fixed amplitude of 100 V and frequency of 1000 kHz. The developed method was validated. Calibration curves of the ten FAs were well correlated (r(2)>0.99) within the range of 5-250 μg mL(-1) for lauric acid, and 3-250 μg mL(-1) for the other FAs. The method was simple and sensitive with detection limits (S/N=3) of 0.9-1.9 μg mL(-1) and good relative standard deviations of intra- and inter-day for migration times and peak areas (≤9.7%) were achieved. The method was applied to the determination of FAs in margarine samples. The proposed method offers distinct advantages over the GC and HPLC methods, especially in terms of simplicity (without derivatization) and sensitivity.
Various materials have been used as scaffolds to suit different demands in tissue engineering. One of the most important criteria is that the scaffold must be biocompatible. This study was carried out to investigate the potential of HA or TCP/HA scaffold seeded with osteogenic induced sheep marrow cells (SMCs) for bone tissue engineering.
Palm sugar-like flavouring (PSLF) is a type of flavour product that is formed by heating amino acids and sugar under specific heating conditions. Unfortunately, PSLF has a salty taste and contains high amounts of acrylamide. Hence, the objective of this research was to reduce saltiness and acrylamide without negatively affecting the aroma properties of PSLF. A decrease in the sodium phosphate (NaHPO₄) buffer concentration from 0.20 to 0.02 M was found to reduce sodium to approximately 15% of the level found in original PSLF. A further decrease (~25%) in the sodium content was achieved by removing monobasic sodium phosphate (NaH₂PO₄) from the buffer system. Meanwhile, the addition of CaCl₂ at 20-40 mg/L reduced the acrylamide content in PSLF by as much as 58%. A CaCl₂ concentration of 20 mg/mL was most favourable as it most efficiently suppressed acrylamide formation while providing an acceptably high flavour yield in PSLF. In view of the high acrylamide content in PSLF, additional work is necessary to further reduce the amount of acrylamide by controlling the asparagine concentration in the precursor mixture.
Molybdenum is very toxic to agricultural animals. Mo-reducing bacterium can be used to immobilize soluble molybdenum to insoluble forms, reducing its toxicity in the process. In this work the isolation of a novel molybdate-reducing Gram positive bacterium tentatively identified as Bacillus sp. strain A.rzi from a metal-contaminated soil is reported. The cellular reduction of molybdate to molybdenum blue occurred optimally at 4 mM phosphate, using 1% (w/v) glucose, 50 mM molybdate, between 28 and 30 °C and at pH 7.3. The spectrum of the Mo-blue product showed a maximum peak at 865 nm and a shoulder at 700 nm. Inhibitors of bacterial electron transport system (ETS) such as rotenone, sodium azide, antimycin A, and potassium cyanide could not inhibit the molybdenum-reducing activity. At 0.1 mM, mercury, copper, cadmium, arsenic, lead, chromium, cobalt, and zinc showed strong inhibition on molybdate reduction by crude enzyme. The best model that fitted the experimental data well was Luong followed by Haldane and Monod. The calculated value for Luong's constants p max, K(s), S(m), and n was 5.88 μmole Mo-blue hr(-1), 70.36 mM, 108.22 mM, and 0.74, respectively. The characteristics of this bacterium make it an ideal tool for bioremediation of molybdenum pollution.
Partially phosphorylated polyvinyl alcohol (PPVA) with aluminum phosphate (ALPO4) composites was synthesized by solution casting technique to produce (PPVA)(100-y) - (ALPO4)(y) (y = 0, 1, and 2). The surface structure and thermal properties of the films were characterized using Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). The results showed that the films have higher thermal stability with strong bonding between PPVA and ALPO4.
A study was conducted to determine the total microbial population, the occurrence of growth promoting bacteria and their beneficial traits in acid sulfate soils. The mechanisms by which the bacteria enhance rice seedlings grown under high Al and low pH stress were investigated. Soils and rice root samples were randomly collected from four sites in the study area (Kelantan, Malaysia). The topsoil pH and exchangeable Al ranged from 3.3 to 4.7 and 1.24 to 4.25 cmol(c) kg(-1), respectively, which are considered unsuitable for rice production. Total bacterial and actinomycetes population in the acidic soils were found to be higher than fungal populations. A total of 21 phosphate-solubilizing bacteria (PSB) including 19 N2-fixing strains were isolated from the acid sulfate soil. Using 16S rRNA gene sequence analysis, three potential PSB strains based on their beneficial characteristics were identified (Burkholderia thailandensis, Sphingomonas pituitosa and Burkholderia seminalis). The isolated strains were capable of producing indoleacetic acid (IAA) and organic acids that were able to reduce Al availability via a chelation process. These PSB isolates solubilized P (43.65%) existing in the growth media within 72 hours of incubation. Seedling of rice variety, MR 219, grown at pH 4, and with different concentrations of Al (0, 50 and 100 µM) was inoculated with these PSB strains. Results showed that the bacteria increased the pH with a concomitant reduction in Al concentration, which translated into better rice growth. The improved root volume and seedling dry weight of the inoculated plants indicated the potential of these isolates to be used in a bio-fertilizer formulation for rice cultivation on acid sulfate soils.
In this study, randomly oriented hydroxyethyl cellulose/polyvinyl alcohol (HEC/PVA) nanofibers were fabricated by electrospinning. The blend solutions of HEC/PVA with different weight ratio of HEC to PVA were prepared using water as solvent to fabricate nanofibers. These nanofibrous scaffolds were coated with bone-like apatite by immersing into 10x simulated body fluid (SBF) for different time periods. The morphology and structure of the nanofibers were characterized by SEM, FTIR and DSC. FESEM-EDS and FTIR analysis were used to confirm the deposition of apatite on the surface of nanofibers. The results of this study suggest that this apatite coated nanofibrous scaffolds could be a suitable biomaterial for bone tissue engineering.
The effect of the addition of an ionic dopant to calcium phosphates for biomedical applications requires specific research due to the essential roles played in such processes. In the present study, the mechanical and biological properties of Ni-doped hydroxyapatite (HA) and Ni-doped HA mixed with graphene nanoplatelets (GNPs) were evaluated. Ni (3wt.% and 6wt.%)-doped HA was synthesized using a continuous precipitation method and calcined at 900°C for 1h. The GNP (0.5-2wt.%)-reinforced 6% Ni-doped HA (Ni6) composite was prepared using rotary ball milling for 15h. The sintering process was performed using hot isostatic pressing at processing conditions of 1150°C and 160MPa with a 1-h holding time. The results indicated that the phase compositions and structural features of the products were noticeably affected by the Ni and GNPs. The mechanical properties of Ni6 and 1.5Ni6 were increased by 55% and 75% in hardness, 59% and 163% in fracture toughness and 120% and 85% in elastic modulus compared with monolithic HA, respectively. The in-vitro biological behavior was investigated using h-FOB osteoblast cells in 1, 3 and 5days of culture. Based on the osteoblast results, the cytotoxicity of the products was indeed affected by the Ni doping. In addition, the effect of GNPs on the growth and proliferation of osteoblast cells was investigated in Ni6 composites containing different ratios of GNPs, where 1.5wt.% was the optimum value.
A recently reported stable and efficient EBPR system at high temperatures around 30 °C has led to characterization of kinetic and stoichiometric parameters of the Activated Sludge Model no. 2d (ASM2d). Firstly, suitable model parameters were selected by identifiability analysis. Next, the model was calibrated and validated. ASM2d was found to represent the processes well at 28 and 32 °C except in polyhyroxyalkanoate (PHA) accumulation of the latter. The values of the kinetic parameters for PHA storage (q PHA), polyphosphate storage (q PP) and growth (μ PAO) of polyphosphate-accumulating organisms (PAOs) at 28 and 32 °C were found to be much higher than those reported by previous studies. Besides, the value of the stoichiometric parameter for the requirement of polyphosphate for PHA storage (Y PO4) was found to decrease as temperature rose from 28 to 32 °C. Values of two other stoichiometric parameters, i.e. the growth yield of heterotrophic organisms (Y H) and PAOs (Y PAO), were high at both temperatures. These calibrated parameters imply that the extremely active PAOs of the study were able to store PHA, store polyphosphate and even utilize PHA for cell growth. Besides, the parameters do not follow the Arrhenius correlation due to the previously reported unique microbial clade at 28 and 32 °C, which actively performs EBPR at high temperatures.
With inoculum sludge from a conventional activated sludge wastewater treatment plant, three sequencing batch reactors (SBRs) fed with synthetic wastewater were operated at different high temperatures (30, 40 and 50±1°C) to study the formation of aerobic granular sludge (AGS) for simultaneous organics and nutrients removal with a complete cycle time of 3h. The AGS were successfully cultivated with influent loading rate of 1.6CODg(Ld)(-1). The COD/N ratio of the influent wastewater was 8. The results revealed that granules developed at 50°C have the highest average diameter, (3.36mm) with 98.17%, 94.45% and 72.46% removal efficiency observed in the system for COD, ammonia and phosphate, respectively. This study also demonstrated the capabilities of AGS formation at high temperatures which is suitable to be applied for hot climate conditions.
In this paper, a linear relationship is proposed relating the natural logarithm of partition coefficient, ln K for protein partitioning in poly (ethylene glycol) (PEG)-phosphate aqueous two-phase system (ATPS) to the square of tie-line length (TLL(2)). This relationship provides good fits (r(2) > 0.98) to the partition of bovine serum albumin (BSA) in PEG (1450 g/mol, 2000 g/mol, 3350 g/mol, and 4000 g/mol)-phosphate ATPS with TLL of 25.0-50.0% (w/w) at pH 7.0. Results also showed that the plot of ln K against pH for BSA partitioning in the ATPS containing 33.0% (w/w) PEG1450 and 8.0% (w/w) phosphate with varied working pH between 6.0 and 9.0 exhibited a linear relationship which is in good agreement (r(2) = 0.94) with the proposed relationship, ln K = α' pH + β'. These results suggested that both the relationships proposed could be applied to correlate and elucidate the partition behavior of biomolecules in the polymer-salt ATPS. The influence of other system parameters on the partition behavior of BSA was also investigated. An optimum BSA yield of 90.80% in the top phase and K of 2.40 was achieved in an ATPS constituted with 33.0% (w/w) PEG 1450 and 8.0% (w/w) phosphate in the presence of 8.5% (w/w) sodium chloride (NaCl) at pH 9.0 for 0.3% (w/w) BSA load.
Interconnected porous tricalcium phosphate ceramics are considered to be potential bone substitutes. However, insufficient mechanical properties when using tricalcium phosphate powders remain a challenge. To mitigate these issues, we have developed a new approach to produce an interconnected alpha-tricalcium phosphate (α-TCP) scaffold and to perform surface modification on the scaffold with a composite layer, which consists of hybrid carbonate apatite / poly-epsilon-caprolactone (CO3Ap/PCL) with enhanced mechanical properties and biological performance. Different CO3Ap combinations were tested to evaluate the optimal mechanical strength and in vitro cell response of the scaffold. The α-TCP scaffold coated with CO3Ap/PCL maintained a fully interconnected structure with a porosity of 80% to 86% and achieved an improved compressive strength mimicking that of cancellous bone. The addition of CO3Ap coupled with the fully interconnected microstructure of the α-TCP scaffolds coated with CO3Ap/PCL increased cell attachment, accelerated proliferation and resulted in greater alkaline phosphatase (ALP) activity. Hence, our bone substitute exhibited promising potential for applications in cancellous bone-type replacement.