Modeling and steady state simulation: production of xanthan gum from sugarcane broth.

The work is focused on developing a mathematical model for continuous process of xanthan gum production. The main objective of the study is to simulate the model, observe the behavior of substrate consumption, biomass and product formation with respect to dilution rate and determine the optimum dilution rate for which the reactor is to be designed. Systems with and without recycling of cells are considered and the optimum dilution rate is found. For the kinetic parameters used, the optimum dilution rate for the system with no recycling is 0.205 and 0.35 h(-1) for the system that includes recycling of cells.

Investigation of Levan-Derived Nanoparticles of Dolutegravir: A Promising Approach for the Delivery of Anti-HIV Drug as Milk Admixture.

Nanoparticles composed of Levan and Dolutegravir (DTG) have been successfully synthesized using a spray drying procedure specifically designed for milk/food admixture applications. Levan, obtained from the microorganism Bacillus subtilis, was thoroughly characterized using MALDI-TOF and solid-state NMR technique to confirm its properties. In the present study, this isolated Levan was utilized as a carrier for drug delivery applications. The optimized spray-dried nanoparticles exhibited a smooth surface morphology with particle sizes ranging from 195 to 329 nm. In the in-vitro drug release experiments conducted in water media, the spray-dried nanoparticles showed 100 % release, whereas the unprocessed drug exhibited only 50 % release at the end of 24 h. Notably, the drug release in milk was comparable to that in plain media, indicating the compatibility. The improved dissolution rate observed for the nanoparticles could be attributed to the solid-state conversion (confirmed by XRD analysis) of DTG from its crystalline to amorphous state. The stability of the drug was verified using Fourier Transform Infra-Red Spectroscopy and Thermogravimetry-Differential Scanning Calorimetry analysis. To evaluate the in-vitro cellular toxicity, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay was conducted, which revealed the CC50 value of 88.88 ± 5.10 µg/mL for unprocessed DTG and 101.08 ± 37.37 µg/mL for DTG nanoparticles. These results indicated that the toxicity of the nanoparticles was comparable to the unprocessed drug. Furthermore, the anti-HIV activity of the nanoparticles in human cell lines was found to be similar to that of the pure drug, emphasizing the therapeutic efficacy of DTG in combating HIV.

Levan production from sucrose using chicken feather peptone as a low cost supplemental nutrient source.

Chicken feather peptone (CFP) derived from poultry waste is a rich source of essential minerals and amino acids. This, along with suitable carbon source, can be used as a low cost complex supplemental nutrient source for microbial fermentation. In the present work, CFP blended with sucrose was evaluated for the production of levan using Bacillus subtilis MTCC 441. Amount of CFP added to the medium significantly influenced levan production and it was found that at a concentration 2 g/L, maximum levan yield of 0.26 ±â€¯0.04 g/g sucrose was obtained. The levan yield obtained with CFP as a low cost supplemental nutrient source was comparable with that obtained from commercial medium (0.31 ±â€¯0.02 g/g sucrose). Levan produced using CFP was tested on primary cell lines at various concentrations (100-1000 µM) and found to be non-toxic and bio-compatible in nature. This indicates that CFP could be used as low cost nutrient source for levan production.

Corrigendum to "Studies on solvent precipitation of levan synthesized using Bacillus subtilis MTCC 441" [Heliyon 5 (9) (September 2019) e02414].

[This corrects the article DOI: 10.1016/j.heliyon.2019.e02414.].

Guava (Psidium guajava) leaf powder: novel adsorbent for removal of methylene blue from aqueous solutions.

Batch sorption experiments were carried out using a novel adsorbent, guava leaf powder (GLP), for the removal of methylene blue (MB) from aqueous solutions. Potential of GLP for adsorption of MB from aqueous solution was found to be excellent. Effects of process parameters pH, adsorbent dosage, concentration, particle size and temperature were studied. Temperature-concentration interaction effect on dye uptake was studied and a quadratic model was proposed to predict dye uptake in terms of concentration, time and temperature. The model conforms closely to the experimental data. The model was used to find optimum temperature and concentration that result in maximum dye uptake. Langmuir model represent the experimental data well. Maximum dye uptake was found to be 295mg/g, indicating that GLP can be used as an excellent low-cost adsorbent. Pseudo-first-order, pseudo-second order and intraparticle diffusion models were tested. From experimental data it was found that adsorption of MB onto GLP follow pseudo second order kinetics. External diffusion and intraparticle diffusion play roles in adsorption process. Free energy of adsorption (DeltaG degrees ), enthalpy change (DeltaH degrees ) and entropy change (DeltaS degrees ) were calculated to predict the nature of adsorption. Adsorption in packed bed was also evaluated.

Production and optimization of polyhydroxyalkanoates from non-edible Calophyllum inophyllum oil using Cupriavidus necator.

Polyhydroxyalkanoates (PHA) are biodegradable polymers found in the cellular masses of a wide range of bacterial species and the demand for PHA is steadily growing. In this work we have produced PHA from a low-cost substrate, Calophyllum inophyllum oil, using Cupriavidus necator. Effects of various process parameters such as Oil concentration, Nitrogen source and inoculum size on the production of PHA were studied using Response Surface Methodology. A quadratic equation was used in the model to fit the experimental data. It was found that the model could satisfactorily predict the PHA yield (R2=99.17%). Linear, quadratic and interaction terms used in the model were found to be statistically significant. Maximum PHA yield of 10.6gL-1 was obtained under the optimized conditions of oil concentration - 17.5%, inoculum concentration - 50mL/L and nitrogen content - 1.125gL-1, respectively. The product obtained was characterized using FTIR and NMR to confirm that it was PHA. The results demonstrate that C. inophyllum oil, a non-edible oil, can be potentially used as a low-cost substrate for the production of PHA.

Biosorption of reactive dye using acid-treated rice husk: factorial design analysis.

A factorial experimental design technique was used to investigate the biosorption of reactive red RGB (lambda(max)=521 nm) from water solution on rice husk treated with nitric acid. Biosorption is favored because of abundance of biomass, low cost, reduced sludge compared to conventional treatment techniques and better decontamination efficiency from highly diluted solutions. Factorial design of experiments is employed to study the effect of four factors pH (2 and 7), temperature (20 and 40), adsorbent dosage (5 and 50mg/L) and initial concentration of the dye (50 and 250 mg/L) at two levels low and high. The efficiency of color removal was determined after 60 min of treatment. Main effects and interaction effects of the four factors were analyzed using statistical techniques. A regression model was suggested and it was found to fit the experimental data very well. The results were analyzed statistically using the Student's t-test, analysis of variance, F-test and lack of fit to define most important process variables affecting the percentage dye removal. The most significant variable was thus found to be pH.

Production of biodiesel by enzymatic transesterification of waste sardine oil and evaluation of its engine performance.

Waste sardine oil, a byproduct of fish industry, was employed as a low cost feedstock for biodiesel production. It has relatively high free fatty acid (FFA) content (32 mg KOH/g of oil). Lipase enzyme immobilized on activated carbon was used as the catalyst for the transesterification reaction. Process variables viz. reaction temperature, water content and oil to methanol molar ratio were optimized. Optimum methanol to oil molar ratio, water content and temperature were found to be 9:1, 10 v/v% and 30 °C respectively. Reusability of immobilized lipase was studied and it was found after 5 cycles of reuse there was about 13% drop in FAME yield. Engine performance of the produced biodiesel was studied in a Variable Compression Engine and the results confirm that waste sardine oil is a potential alternate and low-cost feedstock for biodiesel production.

Production and optimization of xylooligosaccharides from corncob by Bacillus aerophilus KGJ2 xylanase and its antioxidant potential.

The aim of the present study is to produce xylooligosaccharides (XOS) from corncob xylan. The xylan was extracted from corncob using methods like dilute acid, dilute alkali and sodium hypochlorite treatment. Corncob xylan extracted using alkali was characterized by FT-IR and TG-DSC. The extracted xylan was subjected to enzymatic hydrolysis using Bacillus aerophilus KGJ2 xylanase for XOS production. To increase the yield of XOS, the effects of various process parameters like substrate concentration, reaction time, and enzyme concentration on XOS production were investigated. XOS prepared was characterized by HPTLC. Anti oxidant potential of produced XOS was evaluated and the DPPH assay showed that XOS possessed concentration dependent free radical scavenging activity.

Statistical modeling of pullulan production and its application in pullulan acetate nanoparticles synthesis.

This work focused on the optimization of exo-polysaccharide, pullulan production by exploiting cassava bagasse, an agricultural solid waste residue by solid state fermentation and its application in the preparation of pullulan acetate nanoparticles. Statistical approach was investigated to maximize the pullulan production using C/N ratio, initial pH, NaCl and ZnSO4·5H2O. The optimum conditions for maximum yield of pullulan (39.42±0.62mg/gds) were found to be: C/N=25.94, initial pH=5.5 and NaCl=0.55g/L. Using the optimized medium variables, the production of pullulan was investigated in lab scale solid state fermentation. The pullulan produced was characterized by thermo gravimetric and XRD analysis. Also pullulan acetate nanoparticles were synthesized from chemical modification of pullulan and the average particle size of nanoparticles was examined by zeta particle sizer.

Biohydrogen and polyhydroxyalkanoate co-production by Enterobacter aerogenes and Rhodobacter sphaeroides from Calophyllum inophyllum oil cake.

The feasibility of coupled biohydrogen and polyhydroxyalkanoate production by Enterobacter aerogenes and Rhodobacter sphaeroides using Calophyllum inophyllum oil cake was studied under dark and photo fermentation conditions. The utilization of a non-edible acidic oil cake (C. inophyllum), and exploitation of a modified minimal salt media led to reduction in the cost of media. Cost of fermentation is reduced by implementation of alternate dark-photo fermentative periods and through the use of a co-culture consisting of a dark fermentative (E. aerogenes) and a photo fermentative (R. sphaeroides) bacterium. The biohydrogen and polyhydroxyalkanoate produced were 7.95 L H2/L media and 10.73 g/L media, respectively, under alternate dark and photo fermentation and were 3.23 L H2/L media and 5.6g/L media, respectively under complete dark fermentation. The characteristics of the oil cake and alternate dark (16 h) and photo (8h) fermentative conditions were found to be supportive in producing high biohydrogen and polyhydroxyalkanoate (PHA) yield.

Bioconversion of industrial solid waste--cassava bagasse for pullulan production in solid state fermentation.

The purpose of the work was to produce commercially important pullulan using industrial solid waste namely cassava bagasse in solid state fermentation and minimize the solid waste disposal problem. First, influence of initial pH on cell morphology and pullulan yield was studied. Effect of various factors like fermentation time, moisture ratio, nitrogen sources and particle size on pullulan yield was investigated. Various supplementary carbon sources (3%, w/w) namely glucose, sucrose, fructose, maltose, mannose and xylose with cassava bagasse was also studied to improve the pullulan yield. After screening the suitable supplement, effect of supplement concentration on pullulan production was investigated. The pullulan from cassava bagasse was characterized by FTIR, (1)H-NMR and (13)C-NMR. Molecular weight of pullulan from cassava bagasse was determined by gel permeation chromatography. Thus, cassava bagasse emerged to be a cheap and novel substrate for pullulan production.

Xanthan from sulphuric acid treated tapioca pulp: influence of acid concentration on xanthan fermentation.

Xanthan gum was produced by fermentation of sulphuric acid pre-treated tapioca pulp. Effect of sulphuric acid concentration (0.5%, 2.5% and 5.0%) on xanthan fermentation was investigated. Maximum xanthan yield (7.1g/l) was obtained with 0.5% sulphuric acid pre-treatment. Further, increase in sulphuric acid concentration caused formation of inhibitory substance and lowered xanthan yield. The product was confirmed as xanthan using FTIR, (1)H NMR analyses. Viscosity was measured by Brookfield viscometer and the molecular weight was determined from the intrinsic viscosity. The results confirmed that the yield and quality of xanthan produced were strongly influenced by the acid concentration.

Statistical optimization of pullulan production from Asian palm kernel and evaluation of its properties.

Pullulan, a biodegradable exopolysaccharide, was produced from Asian Palmyra palm kernel by solid-state fermentation. Levels of medium variables, namely carbon to nitrogen ratio (C/N), pH, NaCl concentration and ZnSO4·5H2O concentration were optimized to maximize pullulan production using Box-Behnken design of experiments. Optimal values were predicted as: C/N ratio - 28.1, pH - 6.6, NaCl - 0.78 g/l and ZnSO4·5H2O - 0.37 g/l. Theoretical pullulan yield predicted under optimum condition was 30.4 mg/gds. Pullulan was produced under optimum condition and an experimental yield of 28.7 ± 0.3mg/gds was obtained. (13)C NMR spectra of the exopolysaccharide produced from Asian palm kernel revealed the presence of anomeric α (1→6) linked maltosyl units. The weight-average molecular weight of the polymer was determined to be 8.4×10(6)Da by gel permeation chromatography. Thermal decomposition temperature of pullulan was obtained to be 245°C. The tensile strength of pullulan film (0.5mm thick) was found to be 27 MPa.

Xylanase production from Bacillus aerophilus KGJ2 and its application in xylooligosaccharides preparation.

Xylanolytic enzyme was produced using a newly isolated Bacillus aerophilus KGJ2 and low cost lignocellulosic sources in solid state fermentation. Seven different agricultural residues (wheat bran, tea dust, saw dust, paper waste, cassava bagasse, rice straw and rice husk) and six nitrogen source namely yeast extract, beef extract, peptone, ammonium nitrate, ammonium sulphate, and ammonium chloride were examined for xylanase production. Upon initial screening, wheat bran and ammonium chloride were chosen as suitable carbon source and nitrogen source respectively. Plackett-Burman fractional factorial design was employed to screen the important process variables affecting enzyme production. Substrate concentration, nitrogen source, moisture content and MgSO4·7H2O were identified as statistically significant variables. Subsequently Box-Behnken method was used to optimize the process conditions to achieve maximum xylanase yield. Under optimized conditions xylanase yield was 45.9 U/gds. Best xylanase activity was obtained at 70 °C and pH 4.0. It retained more than 90% activity after incubation at 80-90 °C for 60 min. The hydrolytic efficiency of xylanase on xylan was examined and xylobiose, xylotriose and xylotetrose were obtained as hydrolytic products.

Statistical studies on high molecular weight pullulan production in solid state fermentation using jack fruit seed.

The purpose of the work was to optimize the medium variables for maximizing pullulan production using jack fruit seed as a low cost substrate by Aureobasidium pullulans in solid state fermentation. Effects of K2HPO4, KH2PO4, ZnSO4·5H2O, MgSO4·7H2O, NaCl, (NH4)2SO4·5H2O, yeast extract, moisture content (%, w/w) in the production medium on pullulan production were studied using Plackett-Burman design. Production of pullulan was significantly affected by the medium variables namely KH2PO4, ZnSO4·5H2O, NaCl and moisture content (%, w/w). Then screened variables were optimized by Box Behnken experiment design. The pullulan obtained was characterized and confirmed by FTIR, (1)H NMR and (13)C NMR. Molecular weight of pullulan was found to be 1.733×10(6) g/mol by gel permeation chromatography (GPC).

Production of pullulan by Aureobasidium pullulans from Asian palm kernel: a novel substrate.

Production of a commercially important biodegradable polymer, pullulan, by Aureobasidium pullulans from four agricultural wastes namely wheat bran, rice bran, coconut kernel and palm kernel was evaluated in solid state fermentation. Under the experimental conditions, palm kernel resulted in highest concentration of pullulan (16 g/L) among the four solid substrates. Optimum initial pH and moisture content for pullulan production were found out to be 6.5 and 50% respectively. 18.43 g/L of pullulan was produced from Asian palm kernel with initial pH 6.5 after 7 days of fermentation and yeast like morphology was predominant under this condition. Among different nitrogen sources tried in this study, yeast extract was found to the best. The pullulan produced from palm kernel was characterized by FTIR and (1)H NMR. The results were matching with that of commercial pullulan. Thus, Asian palm kernel appears to be an attractive low cost carbon source for the production of pullulan.

Studies on application of teak leaf powders for the removal of color from synthetic and industrial effluents.

Batch studies were conducted to investigate the potential of untreated teak leaf powder (TLP) to remove color from synthetic and industrial effluents. Langmuir and Freundlich isotherms were used to analyze the equilibrium data. Langmuir isotherm was found to be the best-fitting isotherm. The monolayer adsorption capacity was found to be 99.1, 145.2, 188.7 and 207.9 mg methyleneblue/gTLP at 293, 303, 313 and 323 K, respectively. It was also found from the thermodynamic analysis that the adsorption of methylene blue onto TLP was spontaneous, chemisorption and exothermic in nature. The color of the effluent was quantified in terms of the area under absorbance spectrum. Percentage color, COD and total dissolved solids (TDS) removed from a diluted effluent (10% effluent by vol.) were found to be 57.41, 45.95 and 49.46, respectively. The monolayer capacity was calculated in terms of TDS and was found to be 219 mg/g.

Kinetics of methylene blue removal from aqueous solution using gulmohar (Delonix regia) plant leaf powder: multivariate regression analysis.

Effects of process variables namely pH, dye concentration, adsorbent dosage, temperature, particle size and agitation speed on kinetics of methylene blue adsorption onto gulmohar plant leaf powder were investigated. Quadratic models were proposed to predict pseudo second order rate constant and equilibrium uptake in terms of the process variables. Model coefficients were determined by multiple regression analysis. Statistical tools like Student's t-test, F-test, ANOVA and lack-of-fit were used to define the most important process variables. The proposed models could predict the rate constant and equilibrium dye uptake with high R(2) values (0.94 and 0.947). It was found that rate constant increased with decrease in concentration, decrease in particle size, increase in adsorbent dosage, increase in agitation speed and increase in temperature. Meanwhile, it was found that equilibrium dye uptake increased with increase in concentration and decrease in dosage. Apart from these combined effects of the process variables were established through multiple regression analysis. Langmuir monolayer adsorption capacity of GUL was found to be 186.22 mg/g.