scholarly journals Residual Gas for Ethanol Production by Clostridium carboxidivorans in a Dual Impeller Stirred Tank Bioreactor (STBR)

Fermentation ◽  
2021 ◽  
Vol 7 (3) ◽  
pp. 199 ◽  
Author(s):  
Carolina Benevenuti ◽  
Marcelle Branco ◽  
Mariana do Nascimento-Correa ◽  
Alanna Botelho ◽  
Tatiana Ferreira ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Ethanol Production ◽  
Culture Medium ◽  
Biofuel Production ◽  
Stirred Tank ◽  
Low Flow ◽  
Syngas Fermentation ◽  
Stirred Tank Bioreactor ◽  
Industrial Gases ◽  
Clostridium Carboxidivorans

Recycling residual industrial gases and residual biomass as substrates to biofuel production by fermentation is an important alternative to reduce organic wastes and greenhouse gases emission. Clostridium carboxidivorans can metabolize gaseous substrates as CO and CO2 to produce ethanol and higher alcohols through the Wood-Ljungdahl pathway. However, the syngas fermentation is limited by low mass transfer rates. In this work, a syngas fermentation was carried out in serum glass bottles adding different concentrations of Tween® 80 in ATCC® 2713 culture medium to improve gas-liquid mass transfer. We observed a 200% increase in ethanol production by adding 0.15% (v/v) of the surfactant in the culture medium and a 15% increase in biomass production by adding 0.3% (v/v) of the surfactant in the culture medium. The process was reproduced in stirred tank bioreactor with continuous syngas low flow, and a maximum ethanol productivity of 0.050 g/L.h was achieved.

scholarly journals Effect of temperature and surfactant on biomass growth and higher-alcohol production during syngas fermentation by Clostridium carboxidivorans P7

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Shaohuang Shen ◽  
Guan Wang ◽  
Ming Zhang ◽  
Yin Tang ◽  
Yang Gu ◽  
...  
Keyword(s):  
Tween 80 ◽  
Biofuel Production ◽  
Effect Of Temperature ◽  
Biomass Growth ◽  
Syngas Fermentation ◽  
Higher Alcohol ◽  
Alcohol Production ◽  
Expression Of Genes ◽  
Genes Encoding ◽  
Clostridium Carboxidivorans

Abstract Hexanol–butanol–ethanol fermentation from syngas by Clostridium carboxidivorans P7 is a promising route for biofuel production. However, bacterial agglomeration in the culture of 37 °C severely hampers the accumulation of biomass and products. To investigate the effect of culture temperature on biomass growth and higher-alcohol production, C. carboxidivorans P7 was cultivated at both constant and two-step temperatures in the range from 25 to 37 °C. Meanwhile, Tween-80 and saponin were screened out from eight surfactants to alleviate agglomeration at 37 °C. The results showed that enhanced higher-alcohol production was contributed mainly by the application of two-step temperature culture rather than the addition of anti-agglomeration surfactants. Furthermore, comparative transcriptome revealed that although 37 °C promoted high expression of genes involved in the Wood–Ljungdahl pathway, genes encoding enzymes catalyzing acyl-condensation reactions associated with higher-alcohol production were highly expressed at 25 °C. This study gained greater insight into temperature-effect mechanism on syngas fermentation by C. carboxidivorans P7.

scholarly journals Effects of Ultrasound on Fermentation of Glucose to Ethanol by Saccharomyces cerevisiae

Fermentation ◽  
2019 ◽  
Vol 5 (1) ◽  
pp. 16 ◽  
Author(s):  
Luis Huezo ◽  
Ajay Shah ◽  
Frederick Michel
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mass Transfer ◽  
Glucose Uptake ◽  
Ethanol Production ◽  
Ethanol Yield ◽  
Biofuel Production ◽  
Inhibitory Effects ◽  
Negative Effects ◽  
Intraparticle Mass Transfer ◽  
Improve Mass Transfer

Previous studies have shown that pretreatment of corn slurries using ultrasound improves starch release and ethanol yield during biofuel production. However, studies on its effects on the mass transfer of substrates and products during fermentation have shown that it can have both beneficial and inhibitory effects. In this study, the effects of ultrasound on mass transfer limitations during fermentation were examined. Calculation of the external and intraparticle observable moduli under a range of conditions indicate that no external or intraparticle mass transfer limitations should exist for the mass transfer of glucose, ethanol, or carbon dioxide. Fermentations of glucose to ethanol using Saccharomyces cerevisiae were conducted at different ultrasound intensities to examine its effects on glucose uptake, ethanol production, and yeast population and viability. Four treatments were compared: direct ultrasound at intensities of 23 and 32 W/L, indirect ultrasound (1.4 W/L), and no-ultrasound. Direct and indirect ultrasound had negative effects on yeast performance and viability, and reduced the rates of glucose uptake and ethanol production. These results indicate that ultrasound during fermentation, at the levels applied, is inhibitory and not expected to improve mass transfer limitations.

scholarly journals Experimental Design to Improve Cell Growth and Ethanol Production in Syngas Fermentation by Clostridium carboxidivorans

Catalysts ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 59 ◽  
Author(s):  
Carolina Benevenuti ◽  
Alanna Botelho ◽  
Roberta Ribeiro ◽  
Marcelle Branco ◽  
Adejanildo Pereira ◽  
...  
Keyword(s):  
Cell Growth ◽  
Ethanol Production ◽  
Yeast Extract ◽  
Biomass Gasification ◽  
Culture Collection ◽  
Medium Composition ◽  
Syngas Fermentation ◽  
The Cost ◽  
Clostridium Carboxidivorans ◽  
Peptone Yeast Extract Glucose

Fermentation of gases from biomass gasification, named syngas, is an important alternative process to obtain biofuels. Sequential experimental designs were used to increase cell growth and ethanol production during syngas fermentation by Clostridium carboxidivorans. Based on ATCC (American Type Culture Collection) 2713 medium composition, it was possible to propose a best medium composition for cell growth, herein called TYA (Tryptone-Yeast extract-Arginine) medium and another one for ethanol production herein called TPYGarg (Tryptone-Peptone-Yeast extract-Glucose-Arginine) medium. In comparison to ATCC® 2713 medium, TYA increased cell growth by 77%, reducing 47% in cost and TPYGarg increased ethanol production more than four-times, and the cost was reduced by 31%. In 72 h of syngas fermentation in TPYGarg medium, 1.75-g/L of cells, 2.28 g/L of ethanol, and 0.74 g/L of butanol were achieved, increasing productivity for syngas fermentation.

Optical Approach for Measuring Oxygen Mass Transfer in Stirred Tank Bioreactors

2017 ◽  
Vol 15 (4) ◽  
Author(s):  
Jorge Isaac Martínez-Corona ◽  
Rubén Rogelio Cisneros-Garza ◽  
Felipe Robledo-Padilla ◽  
Roberto Parra-Saldívar ◽  
Andrés Sebastián Treviño-Martínez ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Bubble Diameter ◽  
Real Life ◽  
Digital Camera ◽  
Close Correlation ◽  
Stirred Tank ◽  
Oxygen Mass Transfer ◽  
Stirred Tank Bioreactor ◽  
Sensing Systems ◽  
And Control

Abstract Bioreactor engineering allows modeling the conditions of real life biological processes. Particularly, oxygen represents one of the most important factors for life, and the understanding and control of its mass transfer in bioreactors is one of the most challenging problems in the industry. The aim of this study was to develop an optical approach for measuring the oxygen mass transfer coefficient (kLa). An assembly was constructed for this purpose, consisting of a stirred tank bioreactor, a high-intensity light source, a luminometer and a digital camera. Air flux supply and stirring velocity of the bioreactor were tested over a range of thirty-five values. The air bubbles generated were counted and their diameters were measured from photographs. The luminometer measured light obstruction due to bubbles. A polarography electrode sensor measured the dissolved oxygen in water to correlate it with the optical approach. The results showed a close correlation between kLa and light obstructed due to bubbles of air. The bubble diameter and holdup results suggest that the size of the bubbles decreases and becomes more homogeneous as stirring speed increases. A multivariable linear model for kLa as a function of the measured light obstruction and air flux injection was constructed. A strong correlation between this model and results was obtained. This approach avoids the need for chemical sensors for sensing systems, with a noninvasive and nondestructive methodology to determine the kLa for dilute solutions. This technique could be developed to evaluate a scaled-up bioreactor before running a bioprocess.

Optimization of Continuously Stirred Tank Bioreactor Design for Cost Minimization: Effect of Microbial Species and Operating Conditions

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Erin E Powell ◽  
Gordon A Hill
Keyword(s):  
Culture Medium ◽  
Operating Cost ◽  
Oxygen Demand ◽  
Design Strategy ◽  
Aeration Rate ◽  
Operating Conditions ◽  
Stirred Tank ◽  
Optimum Operating ◽  
Stirred Tank Bioreactor ◽  
Microbial Species

The operation of continuously stirred tank bioreactors (CSTBs) at minimum cost is a major concern of operators. In this work, a CSTB design strategy is presented where impeller stirring speed and aeration rate are optimized to meet the oxygen demand of growing cells, simultaneously minimizing the capital and operating cost. The operating cost is limited to the cost of utilities. The optimization scheme assumes a given fermentor tank size, and that the properties of the culture medium and the oxygen respiratory requirements of the microorganisms being cultivated are known. It is possible to choose between two different turbine impellers during the design process. The equations, constraints, and the CSTB design strategy employed by the program are described. The effect of microbial species, ions in the culture medium, impeller style, as well as changing CSTB size and biomass input density on the optimum operating conditions, is examined. The mass transfer coefficient, gas holdup, mixing speed, and aeration rate are all reported at optimized cost conditions. A study of the effects of various parameters on the CSTB design are shown.

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