Continuous ethanol production from sago starch using immobilized amyloglucosidase and Zymomonas mobilis

doi:10.1016/0385-6380(87)90112-9

Journal of Fermentation Technology

Volume 65, Issue 5, 1987, Pages 531-535

https://doi.org/10.1016/0385-6380(87)90112-9 Get rights and content

Abstract

To produce ethanol more economically than in a conventional process, it is necessary to attain high productivity and low production cost. To this end, a continuous ethanol production from sago starch using immobilized amylogucosidase (AMG) and Zymomonas mobilis cells was studied. Chitin was used for immobilization of AMG and Z. mobilis cells were immobilized in the form of sodium alginate beads. Ethanol was produced continuously in an simultaneous saccharification and ethanol fermentation (SSF) mode in a pacekd bed reactor. The maximum ethanol productivity based on the void volume, V_v, was 37 g/l/h with ethanol yield, Y_p/s, 0.43 g/g (84% of the theoretical ethanol yield) in this system. The steady-state concentration of ethanol (46 g/l could be maintained in a stable manner over two weeks at the dilution rate of 0.46 h⁻.

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Use of Zymomonas mobilis immobilized in doped calcium alginate threads for ethanol production
2018, Energy
Citation Excerpt :
Alginate has been one of the most widely deployed methods for immobilization due to its simplicity, non-toxic character and versatile use with both aerobic and anaerobic microorganisms [6,7]. The formation of alginate beads has been studied extensively with different, microorganisms, feed stocks, feed rates, alginate concentrations, crosslinking reagents and concentrations [8–14]. Although cellular immobilization has many benefits, there are some potential disadvantages, including unwanted side reaction [15], contamination by cell leakage [16], concentration gradients of the nutrients and products within the reactor [17], and the creation of microenvironments [18].
Zymomonas mobilis immobilized in doped calcium alginate (Ca-alginate) threads was successfully employed for the production of ethanol in immobilized cell reactors operated with both vertical and horizontal flow. Polyethylene oxide (PEO) as a dopant for Ca-alginate threads was used to increase thread porosity. The influence of the direction of the flow into the reactor and the use of a dopant on the effectiveness of microbe immobilized Ca-alginate threads to produce ethanol was studied and results were compared to the widely used 2% Ca-alginate beads. Threads were able to obtain a similar ethanol yield to beads achieving 90.7% in vertical and 88% in horizontal flow reactors, while beads obtained 91% and 74.7%, respectively. The addition of PEO decreased the lag phase of the threads in both the horizontal and vertical flow reactors compared to a Ca-alginate standard over a 24 h period. The horizontal flow reactor's ethanol yield increased from 10.5% to 41.2% with the addition of PEO while the vertical flow reactor's ethanol yield increased from 15.5% to 69.6%. Additionally, doping with PEO lead to higher ethanol yield. This study demonstrates the use of threads for immobilization of microbes and the effectiveness of PEO as a dopant.
Industrial production, processing, and utilization of sago palm-derived products
2008, Carbohydrate Polymers
With a deep concern over the probable global food shortage in the years to come, underutilized plant resources are now being extensively tapped by scientists throughout the world. In this regard, sago palm is gaining much importance as a crop par excellence and a starch crop of the 21st century, due to its being an extremely sustainable plant with an ability to thrive in most soil conditions. The review focuses on sago palm as an invaluable resource of starchy foods and of innumerable other products of significant commercial value such as modified starches, lactic acid, cyclodextrins, and ethanol. Several important aspects of the properties and applications of sago palm-derived products that could be exploited commercially are also covered.
Efficient production of acetic acid from glucose in a mixed culture of Zymomonas mobilis and Acetobacter sp.
1996, Journal of Fermentation and Bioengineering
Efficient production of acetic acid from glucose was investigated in a mixed culture of Zymomonas mobilis ATCC10988 and Acetobacter sp. TC-1. The culture was initially incubated under low aeration and low agitation conditions to allow ethanol fermentation. A shift from ethanol fermentation to acetic acid fermentation was achieved by enhancing the aerobic conditions when the glucose, whose concentration was monitored using an on-line glucose sensor, dropped below a certain level. Ethanol production decreased when a higher aeration rate and agitation speed were used during the early stage of the cultivation. Acetic acid production was also markedly dependent on agitation and aeration during the early stage. The acetic acid yield from glucose was 0.64 g/g (95.5% of the theoretical value) under the optimum conditions.
Process development for simultaneous starch saccharification and ethanol fermentation by Zymomonas mobilis
1993, Process Biochemistry
Various simultaneous starch saccharification and ethanol fermentation (SSSF) processes were developed and evaluated on batch, semibatch and continuous modes of fermentation in laboratory and pilot scale fermentors using Zymomonas mobilis. Compared with a two-step process involving separate saccharification and fermentation stages, the SSSF reduced the total process time by half. In order to produce ethanol from sago starch economically, the immobilization of amyloglucosidase and Z. mobilis cells was studied. Among the various immobilization methods tested, a co-immobilized system using chitin and sodium alginate appeared most promising with respect to ethanol productivity and operational stability. In order to scale-up the SSSF process, large scale SSSF processes were studied in batch and semibatch fermentation modes. In pilot scale SSSFs, the kinetic results were found to be similar to those from laboratory scale fermentation. Finally, a mathematical model was described for the SSSF process. Simulations of glucose concentration and other fermentation parameters agreed closely with experimental results.
Ethanol production by Zymomonas mobilis using natural rubber waste as a nutritional source
1992, Journal of Fermentation and Bioengineering
The feasibility of using natural rubber serum powder (NRSP) as a nutritional source instead of yeast extract on ethanol fermentation by Zymomonas mobilis was carried out. The results showed that NRSP either as it is or hydrolyzed with pronase has the potential to be used as a nutritional source. The optimum NRSP hydrolysate and mieki concentration supporting better growth rate and biomass yield are 0.3% and 1%, respectively. Comparative kinetic studies of Z. mobilis grown on yeast extract medium (10% glucose), NRSP hydrolysate-mieki medium (10% glucose) and NRSP hydrolysate-mieki medium (10% glucose from sago starch) were studied. It was found that specific glucose uptake rate, specific ethanol production rate and ethanol yield on NRSP hydrolysate-mieki (10% glucose and 10% glucose from sago starch) are comparable to those values on yeast extract medium. The cell viability of cells grown on NRSP hydrolysate-mieki medium was also observed as being comparable to values for yeast extract medium.
The potential of sago as a local food ingredient to support the food security in South Konawe
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Continuous ethanol production from sago starch using immobilized amyloglucosidase and Zymomonas mobilis

Abstract

Biomass

J. Ferment. Technol.

Biotechnol. Bioeng.

Biotechnol. Lett.

Biotechnol. Lett.

File Number A5170-GB