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Journal ArticleDOI

Optimization of batch fermentation conditions for dextran production

01 Oct 1996-Bioprocess Engineering (Springer Berlin Heidelberg)-Vol. 15, Iss: 5, pp 247-251
TL;DR: The nutrient medium, temperature and initial pH conditions were optimised for batch dextran production in shake flask fermentations using a strain of Leuconostoc mesenteroides NRRL B 512 (F) and the optimal values of tested variables were found to be sucrose, yeast extract and K2HPO4.
Abstract: The nutrient medium (containing sucrose, yeast extract and K2HPO4), temperature and initial pH conditions were optimised for batch dextran production in shake flask fermentations using a strain of Leuconostoc mesenteroides NRRL B 512 (F). A 25−1 fractional factorial central composite experimental design was attempted. Multistage Monte Carlo optimization program was used to maximize the multiple regression equation obtained. The optimal values of tested variables for maximal dextran production were found to be: sucrose, 300 g/l; yeast extract, 10 g/l; K2HPO4, 30 g/l; temperature, 23°C and initial pH 8.3 with a predicted dextran yield of 154 g/l.
Citations
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TL;DR: The combined effects of macronutrients of media on α-amylase production by Bacillus sp.

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TL;DR: Data is summarized on their use, biodegradability, commercial reliability and production from renewable resources from a variety of sources including microbial fermentations and chemically modified natural products.
Abstract: Plastic waste disposal is a huge ecotechnological problem and one of the approaches to solving this problem is the development of biodegradable plastics This review summarizes data on their use, biodegradability, commercial reliability and production from renewable resources Some commercially successful biodegradable plastics are based on chemical synthesis (ie polyglycolic acid, polylactic acid, polycaprolactone, and polyvinyl alcohol) Others are products of microbial fermentations (ie polyesters and neutral polysaccharides) or are prepared from chemically modified natural products (eg, starch, cellulose, chitin or soy protein)

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TL;DR: The coefficient determination (R(2)) was good for the second-order model and the optimal conditions for levulinic acid production from wheat straw were 209.3 degrees C, 3.5% acid concentration, 15.6 liquid:solid ratio and 37.6 min of reaction time resulted 19.86% yield.

247 citations

Journal ArticleDOI
TL;DR: The results indicates that the highest percentage removal of Pb can be achieved at pH 5, 40 mg/L of CNTs, contact time 80 min, and agitation speed 50 r/min, and the highest correlation coefficients from Langmuir isotherm model indicates the strong adsorptions of P b(II) on the surface of C NTs.
Abstract: The capability of carbon nanotubes (CNTs) to adsorb lead (Pb) in aqueous solution was investigated. Batch mode adsorption experiment was conducted to determine the effects of pH, agitation speed, CNTs dosage and contact time. The removal of Pb(II) reached maximum value 85% or 83% at pH 5 or 40 mg/L of CNTs, respectively. Higher correlation coefficients from Langmuir isotherm model indicates the strong adsorptions of Pb(II) on the surface of CNTs (adsorption capacity Xm = 102.04 mg/g). The results indicates that the highest percentage removal of Pb (96.03%) can be achieved at pH 5, 40 mg/L of CNTs, contact time 80 min, and agitation speed 50 r/min.

209 citations


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Journal ArticleDOI
TL;DR: The ultrasound-assisted extraction (UAE) of FC from HS was investigated and the optimum levels of these significant parameters were determined using response surface methodology (RSM), which revealed these as follows.

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References
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Journal ArticleDOI
TL;DR: High yields of the enzyme dextransucrase have been produced repeatedly by fed‐batch fermentation techniques and different types of yeast extract have been found to have significant effect on the final cell concentration and more especially on the enzyme activity.
Abstract: High yields of the enzyme dextransucrase have been produced repeatedly by fed-batch fermentation techniques. Activities in excess of 21.9 U/cm(3) have been obtained by culturing Leuconostoc mesenteroides NRRL B-512(F) under nonaerated fed-batch fermentation conditions. Aerobic fermentations carried out under identical conditions have consistently produced enzyme of less than 17 U/cm(3), but with no difference in the final cell concentration in the broth. Different types of yeast extract have been found to have significant effect on the final cell concentration and more especially on the enzyme activity with enzyme yields varying by as much as 50% when different types of yeast extracts were used.

45 citations

Journal ArticleDOI
TL;DR: It was found that the use of a partially saccharified starch substrate markedly increased yields and attainable alcohol levels and balancing the degree of initial saccharification with the level of glucoamylase used to complete hydrolysis was found necessary to obtain optimum yields.
Abstract: The quantitative effects of carbohydrate levels, degree of initial saccharification, glucoamylase dosage, temperature, and fermentation time were investigated using a Box-Wilson central composite design protocol. With Saccharomyces cerevisiae ATCC 4126, it was found that the use of a partially saccharified starch substrate markedly increased yields and attainable alcohol levels. Balancing the degree of initial saccharification with the level of glucoamylase used to complete hydrolysis was found necessary to obtain optimum yields. The temperature optimum was found to be 36 degrees C. The regression equations obtained were used to model the fermentation in order to determine optimum fermentation conditions.

23 citations

Journal ArticleDOI
TL;DR: In this paper, poly-β-hydroxybutyrate was produced in shake cultures by Alcaligenes eutrophus H16 on fructose, xylose, and fumaric, itaconic, lactic and propionic acids in a three-stage process.
Abstract: Poly-β-hydroxybutyrate was produced in shake cultures by Alcaligenes eutrophus H16 on fructose, xylose, and fumaric, itaconic, lactic and propionic acids in a three-stage process. The maximum polymer concentration of 6.9 g l−1 (69% of cell dry matter) was obtained with 20g l−1 of fructose with a volumetric productivity of about 0.22 g l−1 h−1 at 24h. Up to about 3 g l−1 (about 50% of cell dry matter) of polymer was also produced on lactic and propionic acids as the sole carbon source during the production phase. In multivatiate optimization employing an orthogonal 23-factorial central composite experimental design with fructose as the substrate in a single-stage process, the optimal initial fructose concentration decreased from 35 g l−1 to 24 g l−1 when the incubation time was increased from about 35 h to 96 h. The optimal shaking speed range was 90–113 rpm.

17 citations