scholarly journals Enhancement of very high gravity bioethanol production via fed-batch fermentation using sago hampas as a substrate

2020 ◽  
pp. 44-51
Author(s):  
Nur Adila Muradi ◽  
Dayang Salwani Awang Adeni ◽  
Nurashikin Suhaili
Keyword(s):  
Batch Culture ◽  
Batch Fermentation ◽  
Stirred Tank ◽  
High Gravity ◽  
Fed Batch ◽  
Stirred Tank Bioreactor ◽  
Very High Gravity ◽  
Fed Batch Fermentation ◽  
Fed Batch Culture ◽  
Very High

Very high gravity (VHG) ethanolic fermentation is a promising technology used for producing bioethanol. However, the technology is often associated with the excessive amount of glucose that is entirely supplied in the beginning of the culture causing the fermentation process to be sluggish and therefore inhibits complete utilisation of glucose. The high concentration of glucose in the fermentation medium also elevates the osmotic pressure, which has a destructive effect on yeast cells. This study aims to enhance the production of VHG bioethanol from sago hampas hydrolysate (SHH) via fed-batch fermentation. The fermentations were performed in a 2-L stirred tank bioreactor. Batch fermentation was conducted as a control. Our results showed that the maximum yeast cell concentration achieved was significantly improved by 1.5-fold when the fermentation was carried out in fed-batch mode. The ethanol yield attained in the fed-batch culture represents an enhancement of 22% over that achieved in the batch culture. Moreover, the ethanol productivity achieved in the fed-batch culture was found to be increased by 1.8 times in comparison to the productivity attained in the batch culture. In general, this work provides useful insights into promising techniques for enhancing VHG fermentations in the stirred tank bioreactor employing agricultural residues as feedstocks.

scholarly journals Bacterial Cellulose Synthesis by Gluconacetobacter xylinus: Enhancement via Fed-batch Fermentation Strategies in Glycerol Media

2021 ◽  
Vol 18 (22) ◽  
pp. 453
Author(s):  
Azila Adnan ◽  
Giridhar Nair ◽  
Mark Lay ◽  
Janis Swan
Keyword(s):  
Carbon Source ◽  
Bacterial Cellulose ◽  
Batch Culture ◽  
Batch Fermentation ◽  
Operation Mode ◽  
Volumetric Productivity ◽  
Fed Batch ◽  
Fed Batch Fermentation ◽  
Pulse Feed ◽  
Fed Batch Culture

Bacterial cellulose (BC) is an abundant polysaccharide, which is secreted by several genera of bacteria. It has remarkable characteristics, which include high purity, high tensile strength, high biocompatibility and non-toxic. The main feature that differentiates BC and plant cellulose (PC) is the absence of contaminants such as lignin, hemicellulose and pectin. However, the main drawbacks in producing BC are low yield and expensive carbon source. Due to that, this study was carried out to enhance BC volumetric productivity in fed-batch operation mode using glycerol as a carbon source. BC was produced in fill-and-draw and pulse-feed fed-batch cultures of Gluconacetobacter xylinus DSM 46604 in a 3-L bench-top bioreactor. The fed-batch fermentation trials were conducted in agitated and aerobic conditions at 30 ºC. For fill-and-draw fed-batch culture, a total of 24.2 g/L of BC accumulated in the bioreactor after 9 days, which corresponded to a yield and productivity of 0.2 g/g and 2.69 g/L/day, respectively. Pulse-feed fed-batch fermentation resulted in a yield and volumetric productivity of 0.38 g/g and 2.71 g/L/day, respectively. The pulse-feed fed-batch culture proved to be a better fermentation system for utilizing glycerol, which is a low-cost and abundant carbon source. HIGHLIGHTS Komagataeibacter species, which were formerly known as Acetobacter or Gluconacetobacter is one of the Gram-negative BC producers that secretes a large quantity of BC microfibrils extracellularly One of the main challenges in bacterial cellulose (BC) production is low productivity and high processing cost As fed-batch fermentation is one of the operation modes in bioprocess that can control the microbial growth rate, this operation mode is conducted to enhance the yield of BC, substrate consumption and also volumetric productivity Fill-and-draw and pulse feed fed-batch culture were conducted to enhance yield and volumetric productivity. The pulse-feed fed-batch culture resulted to be a favorable operation mode for utilizing glycerol, which is a low-cost and abundant carbon source GRAPHICAL ABSTRACT

Very high gravity ethanol fermentation from sweet sorghum stem juice using a stirred tank bioreactor coupled with a column bioreactor

2021 ◽  
Author(s):  
Benjaporn Sriputorn ◽  
Pattana Laopaiboon ◽  
Niphaphat Phukoetphim ◽  
Nawapol Uppatcha ◽  
Witchuta Phuphalai ◽  
...  
Keyword(s):  
Ethanol Fermentation ◽  
Sweet Sorghum ◽  
Stirred Tank ◽  
High Gravity ◽  
Stirred Tank Bioreactor ◽  
Very High Gravity ◽  
Column Bioreactor ◽  
Very High

Strong stability of an optimal control hybrid system in fed-batch fermentation

2018 ◽  
Vol 11 (04) ◽  
pp. 1850045 ◽  
Author(s):  
Zhenyu Dong ◽  
Bing Tan ◽  
Yuduo Zhang ◽  
Jinlong Yuan ◽  
Enmin Feng ◽  
...  
Keyword(s):  
Optimal Control ◽  
Batch Fermentation ◽  
Equilibrium Points ◽  
Strong Stability ◽  
Fed Batch ◽  
Initial State ◽  
Variational System ◽  
Fed Batch Fermentation ◽  
Fed Batch Culture ◽  
Nonlinear Hybrid

In this paper, we consider a nonlinear hybrid dynamic (NHD) system to describe fed-batch culture where there is no analytical solutions and no equilibrium points. Our goal is to prove the strong stability with respect to initial state for the NHD system. To this end, we construct corresponding linear variational system (LVS) for the solution of the NHD system, also prove the boundedness of fundamental matrix solutions for the LVS. On this basis, the strong stability is proved by such boundedness.

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