RESUMEN
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.
Asunto(s)
Acetatos/síntesis química , Glucanos/síntesis química , Modelos Estadísticos , Nanopartículas/química , Análisis de Varianza , Reactores Biológicos/microbiología , Carbono/farmacología , Fermentación/efectos de los fármacos , Glucanos/biosíntesis , Tamaño de la Partícula , Espectroscopía de Protones por Resonancia Magnética , Termogravimetría , Factores de Tiempo , Difracción de Rayos XRESUMEN
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 (1â6) 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.
Asunto(s)
Ascomicetos/química , Glucanos/química , Reactores Biológicos , Carbono/química , Fermentación , Concentración de Iones de Hidrógeno , Peso Molecular , Nitrógeno/química , Polímeros/química , Cloruro de Sodio/química , Temperatura , Resistencia a la TracciónRESUMEN
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.
Asunto(s)
Celulosa/química , Glucanos/biosíntesis , Manihot/química , Saccharomycetales/metabolismo , Residuos Sólidos , Carbono/metabolismo , Cromatografía en Gel , Medios de Cultivo/química , Disacáridos/metabolismo , Fermentación , Concentración de Iones de Hidrógeno , Espectroscopía de Resonancia Magnética , Monosacáridos/metabolismo , Nitrógeno/metabolismo , Espectroscopía Infrarroja por Transformada de FourierRESUMEN
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.
Asunto(s)
Bacillus/enzimología , Endo-1,4-beta Xilanasas/biosíntesis , Glucuronatos/biosíntesis , Oligosacáridos/biosíntesis , Carbono/metabolismo , Metabolismo Energético , Activación Enzimática , Fermentación , Concentración de Iones de Hidrógeno , Hidrólisis , Nitrógeno/metabolismo , Temperatura , Xilanos/metabolismoRESUMEN
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).
Asunto(s)
Artocarpus/metabolismo , Técnicas de Cultivo/métodos , Fermentación , Glucanos/biosíntesis , Glucanos/química , Semillas/metabolismo , Estadística como Asunto/métodos , Artocarpus/crecimiento & desarrollo , Medios de Cultivo/química , Peso MolecularRESUMEN
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.