Abstract:In this work, the catalytic role of chrysotile support on the acceleration of alcoholic fermentation under non-aseptic conditions by Saccharomyces cerevisiae was investigated. The fermentation medium employed consisted only of diluted sugar-cane molasses. In the batch fermentations process with immobilized yeasts, the initial rate of CO 2 production increased roughly 27 % during the first 30 minutes, compared to systems containing no chrysotile. A study of continuous alcoholic fermentation with chrysotile in t… Show more
“…However, strains SDB, SHW, STISB, and SELK were selected as the best producer of ethanol and the production conditions of SDB were optimized. The ethanol content evolves gradually during the fermentation, reaching a maximum of 126.00 ± 1.81 g/l at 72 h. Therefore, the optimum fermentation period for maximum production of ethanol was 72 h. Our finding is in agreement with those obtained by [27,39]. However, [11] obtained optimum ethanol content for 48 h using a strain of Zymomonas mobilis.…”
Section: Resultssupporting
confidence: 91%
“…So, the optimal sugar concentration for maximum ethanol production is 180 g/l. These results are similar to those obtained by [11,27]. The sugar concentration (180 g/l) above which both the ethanol production and metabolism yield decrease are due to the combined effect of decreased water activity and plasmolysis of cell [11].…”
Section: Resultssupporting
confidence: 88%
“…On the other hand, the obtained results show an improvement of the ethanol content and metabolism yield with increasing ammonium phosphate concentration to stabilize at a maximum of 136.00 ± 0.66 g/l and 78.61 ± 0.75%, respectively, with a concentration greater than or equal to 1.0 g/l. So, the optimum ammonium phosphate concentration is 1.0 g/l, while several authors [8,11,27,39] advocate 2.0-2.5 g/l.…”
The present study deals with submerged ethanol, citric acid, and α-amylase fermentation by Saccharomyces cerevisiae SDB, Aspergillus niger ANSS-B5, and Candida guilliermondii CGL-A10, using date wastes as the basal fermentation medium. The physical and chemical parameters influencing the production of these metabolites were optimized. As for the ethanol production, the optimum yield obtained was 136.00 ± 0.66 g/l under optimum conditions of an incubation period of 72 h, inoculum content of 4% (w/v), sugars concentration of 180.0 g/l, and ammonium phosphate concentration of 1.0 g/l. Concerning citric acid production, the cumulative effect of temperature (30°C), sugars concentration of 150.0 g/l, methanol concentration of 3.0%, initial pH of 3.5, ammonium nitrate concentration of 2.5 g/l, and potassium phosphate concentration of 2.5 g/l during the fermentation process of date wastes syrup did increase the citric acid production to 98.42 ± 1.41 g/l. For the production of α-amylase, the obtained result shows that the presence of starch strongly induces the production of α-amylase with a maximum at 5.0 g/l. Among the various nitrogen sources tested, urea at 5.0 g/l gave the maximum biomass and α-amylase estimated at 5.76 ± 0.56 g/l and 2,304.19 ± 31.08 μmol/l/min, respectively after 72 h incubation at 30°C, with an initial pH of 6.0 and potassium phosphate concentration of 6.0 g/l.
“…However, strains SDB, SHW, STISB, and SELK were selected as the best producer of ethanol and the production conditions of SDB were optimized. The ethanol content evolves gradually during the fermentation, reaching a maximum of 126.00 ± 1.81 g/l at 72 h. Therefore, the optimum fermentation period for maximum production of ethanol was 72 h. Our finding is in agreement with those obtained by [27,39]. However, [11] obtained optimum ethanol content for 48 h using a strain of Zymomonas mobilis.…”
Section: Resultssupporting
confidence: 91%
“…So, the optimal sugar concentration for maximum ethanol production is 180 g/l. These results are similar to those obtained by [11,27]. The sugar concentration (180 g/l) above which both the ethanol production and metabolism yield decrease are due to the combined effect of decreased water activity and plasmolysis of cell [11].…”
Section: Resultssupporting
confidence: 88%
“…On the other hand, the obtained results show an improvement of the ethanol content and metabolism yield with increasing ammonium phosphate concentration to stabilize at a maximum of 136.00 ± 0.66 g/l and 78.61 ± 0.75%, respectively, with a concentration greater than or equal to 1.0 g/l. So, the optimum ammonium phosphate concentration is 1.0 g/l, while several authors [8,11,27,39] advocate 2.0-2.5 g/l.…”
The present study deals with submerged ethanol, citric acid, and α-amylase fermentation by Saccharomyces cerevisiae SDB, Aspergillus niger ANSS-B5, and Candida guilliermondii CGL-A10, using date wastes as the basal fermentation medium. The physical and chemical parameters influencing the production of these metabolites were optimized. As for the ethanol production, the optimum yield obtained was 136.00 ± 0.66 g/l under optimum conditions of an incubation period of 72 h, inoculum content of 4% (w/v), sugars concentration of 180.0 g/l, and ammonium phosphate concentration of 1.0 g/l. Concerning citric acid production, the cumulative effect of temperature (30°C), sugars concentration of 150.0 g/l, methanol concentration of 3.0%, initial pH of 3.5, ammonium nitrate concentration of 2.5 g/l, and potassium phosphate concentration of 2.5 g/l during the fermentation process of date wastes syrup did increase the citric acid production to 98.42 ± 1.41 g/l. For the production of α-amylase, the obtained result shows that the presence of starch strongly induces the production of α-amylase with a maximum at 5.0 g/l. Among the various nitrogen sources tested, urea at 5.0 g/l gave the maximum biomass and α-amylase estimated at 5.76 ± 0.56 g/l and 2,304.19 ± 31.08 μmol/l/min, respectively after 72 h incubation at 30°C, with an initial pH of 6.0 and potassium phosphate concentration of 6.0 g/l.
“…In addition, immobilization prevents cell washout in continuous fermentation that avoids separation or recycle of cells in the process [ 85 ]. Several carriers have been reported for cell immobilization including apple pieces [ 83 ], k-carrageenan gel, polyacrylamide, g-alumina [ 86 ], chrysotile [ 87 ], calcium-alginate [ 88 , 89 ], sugarcane pieces [ 56 ], banana leaf sheath [ 90 ], and orange peel [ 91 ]. Immobilization of S. cerevisiae can easily be carried out by enriched cells from culture media and harvested at the log phase of growth followed by entrapping into the carriers [ 88 ].…”
Bioethanol production from renewable sources to be used in transportation is now an increasing demand worldwide due to continuous depletion of fossil fuels, economic and political crises, and growing concern on environmental safety. Mainly, three types of raw materials, that is, sugar juice, starchy crops, and lignocellulosic materials, are being used for this purpose. This paper will investigate ethanol production from free sugar containing juices obtained from some energy crops such as sugarcane, sugar beet, and sweet sorghum that are the most attractive choice because of their cost-effectiveness and feasibility to use. Three types of fermentation process (batch, fed-batch, and continuous) are employed in ethanol production from these sugar juices. The most common microorganism used in fermentation from its history is the yeast, especially, Saccharomyces cerevisiae, though the bacterial species Zymomonas mobilis is also potentially used nowadays for this purpose. A number of factors related to the fermentation greatly influences the process and their optimization is the key point for efficient ethanol production from these feedstocks.
“…In the present investigation, maximum ethanol concentration was achieved at temperature 30°C. Reed (1982) and Sedha and Verma (2002) have also recommended 30°C as optimal temperature for ethanol production. Most of the yeasts capable of producing ethanol are not thermotolerant and their growth and fermentation efficiency decreases at 40°C (Murata et al 2015;Antil et al 2015).…”
The current study was aimed at optimizing the fermentation conditions for efficient ethanol production from biologically pretreated paddy straw. The yeast strain Saccharomyces cerevisiae LN1 showed highest fermentation efficiency at pH 5.0 and temperature 30°C. Paddy straw pretreated with fungus Myrothecium roridum LG7 was saccharified with indigenous holocellulase from Aspergillus niger SH3 producing total sugar yield of 26.14 mg/ml with 19.23 mg/ml of glucose. Enzymatic hydrolysate was then fermented using S. cerevisiae LN1 to observe the effect of nutrient supplementation (yeast extract, MgSO 4 Á7H 2 O and (NH 4 ) 2 SO 4 ) on ethanol production. Higher ethanol was produced from saccharified material fermented without supplementation of any nutrient source. With the scale-up of ethanol production under optimized conditions in 7L bioreactor, 4.46 g/l of ethanol was produced with fermentation efficiency of 47.2 %. TLC of enzymatic hydrolysate confirmed the presence of p-coumaric acid, ferulic acid, vanillic acid, gallic acid and many other aromatic compounds and inhibitors in the saccharified material which limit fermentation efficiency of yeast strain. Thus, optimization of fermentation conditions can lead to development of a cost-effective process for efficient ethanol production, exploitation of which also requires removal of aromatic compounds and inhibitors which may hinder the ethanol production efficiency.
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