The depletion of fossil fuel reserv

The depletion of fossil fuel reserves, the unstable panorama of the petrol prices and more recently, increasing environmental and political pressures (Davis et al., 2005) has increased industrial focus toward alternative fuel sources, and encouraged the search of products originated from biomass, as renewable sources of energy. In this context, fermentative processes stand out, where microbial metabolism is used for the transformation of simple raw materials in products with high aggregate value. Among these, ethanol is one of the best examples of how fermentation can match market needs satisfactorily. Even though the fermentative process for ethanol production is well known, the production costs are still the key impedi- ment wide use of ethanol as fuel. Therefore, the develop- ment of a fermentation process using economical carbon sources is important for the biofuel ethanol production on a commercial scale (Tanaka et al., 1999; Tao et al., 2005). Many studies have been done that focus on produc- tion improvement and decreasing its costs (Sreenath and Jeffries, 2000; Davis et al., 2005; Ruanglek et al., 2006; Mohagheghi et al., 2006). Zymomonas mobilis, a Gram-negative bacterium, have been attracting increasing attention for fuel ethanol. It is an osmo- and ethanol-tolerant bacterium and it has shown higher specific rates of glucose uptake and ethanol produc- tion (Rogers et al., 1982, 1997) via the Entner-Doudoroff pathway under anaerobic conditions. Z. mobilis may have a greater potential for industrial ethanol production from raw sugar, sugarcane juice and sugarcane syrup (Lee and Huang, 2000). Molasses is an agro-industrial by-product often used in alcohol distilleries (Jime ´nez et al., 2004) due to the presence of fermentative sugars, being an optimal carbon source for the microorganism metabolism. Sugar cane molasses is an abundant agro-industrial material produced in Brazil and other tropical countries and its low cost is an important factor for the economical viability of substances produc- tion by fermentation. The traditional one-at-a-time optimization strategy is relatively simple, and the individual effects of medium factors can be graphically depicted without the need of the statistical analysis. Unfortunately, it frequently fails to locate the region of optimum response in such procedures. In this case, fractional and/or full factorial design provides an efficient approach to optimization. A combination of factors generating a certain optimum response can be iden- tified though factorial design and the use of response sur- face methodology (RSM) (Box et al., 1978). The response-surface methodology is an empirical mod- eling system that assesses the relationship between a group of variables that can be controlled experimentally and the observed response (Sreekumar et al., 1999; Hamsaveni et al., 2001). Response surface methodology (RSM) is a useful model to study the effect of several factors influenc- ing the responses by varying them simultaneously and car- rying out a limited number of experiments (Hamsaveni et al., 2001). The aim of this work was to study the influ- ence between four factors and their interaction to optimize the ethanol production by Z. mobilis ATCC 29191 in sugar cane molasses using factorial design and analysis by RSM. The selected factors were sugar concentration on molasses, temperature, agitation rate and culture time. The measured responses were ethanol and biomass.

ผลลัพธ์ (อังกฤษ) 3:

The depletion of fossil, fuel reserves the unstable panorama of the petrol prices and more recently increasing environmental,, And political pressures (Davis et al, 2005) has increased industrial focus toward alternative fuel sources and encouraged,, The search of products originated, from biomass as renewable sources of energy. In this context fermentative processes,, Stand, outWhere microbial metabolism is used for the transformation of simple raw materials in products with high aggregate, value. Among these ethanol is, one of the best examples of how fermentation can match market needs satisfactorily. Even though. The fermentative process for ethanol production is well known the production, costs are still the key impedi - ment wide. Use of ethanol as, Therefore fuel.The develop - ment of a fermentation process using economical carbon sources is important for the biofuel ethanol production. On a commercial scale (Tanaka et al, 1999; Tao et al, 2005). Many studies have been done that focus on produc - tion improvement. And decreasing its costs (Sreenath and Je, ff ries 2000; Davis et al, 2005; Ruanglek et al, 2006; Mohagheghi et al, 2006).? Zymomonas, mobilisA, Gram-negative bacterium have been attracting increasing attention for fuel ethanol. It is an Osmo - and ethanol-tolerant. Bacterium and it has shown higher speci fi C rates of glucose uptake and ethanol produc - tion (Rogers et al, 1982 1997), via. The Entner-Doudoro ff pathway under anaerobic conditions. Z. Mobilis may have a greater potential for industrial ethanol production. From, raw sugarSugarcane juice and sugarcane syrup (Lee, and Huang 2000). Molasses is an agro-industrial by-product often used in alcohol. Distilleries (Jime pixel Nez et al, 2004) due to the presence of fermentative sugars being an, optimal carbon source for the. Microorganism metabolism.Sugar cane molasses is an abundant agro-industrial material produced in Brazil and other tropical countries and its low. Cost is an important factor for the economical viability of substances produc - tion by fermentation. The traditional one-at-a-time. Optimization strategy is, relatively simpleAnd the individual e ff ects of medium factors can be graphically depicted without the need of the statistical analysis, Unfortunately,. It frequently fails to locate the region of optimum response in such procedures. In, this case fractional and / or full factorial. Design provides an e ffi cient approach to optimization.A combination of factors generating a certain optimum response can be iden - Ti fi ed though factorial design and the use of. Response sur - face methodology (RSM) (Box et al, 1978). The response-surface methodology is an empirical mod - eling system. That assesses the relationship between a group of variables that can be controlled experimentally and the observed response. (Sreekumar et al, 1999;Hamsaveni et al, 2001). Response surface methodology (RSM) is a useful model to study the e ff ect of several factors in fl uenc -. Ing the responses by varying them simultaneously and car - rying out a limited number of experiments (Hamsaveni et al, 2001).? The aim of this work was to study the in fl U - ence between four factors and their interaction to optimize the ethanol production. By Z.Mobilis ATCC 29191 in sugar cane molasses using factorial design and analysis by RSM. The selected factors were sugar concentration. On, molasses temperature agitation rate, and culture time. The measured responses were ethanol and biomass.
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