Orientador: Crispin Humberto Garcia-Cruz / Banca: Eleni Gomes / Banca: Ranulfo Monte Alegre / Banca: Vanildo Luiz Del Bianchi / Banca: Hamilton Cabral / Resumo: O principal produto da fermentação de açúcares por Zymomonas mobilis é o etanol quando glicose e frutose são utilizadas como fontes de carbono. Entretanto, quando sacarose é empregada na fermentação, o rendimento do etanol diminui devido à formação de subprodutos como levana, sorbitol, acetaldeído, ácido acético, pequenas quantidades de alguns álcoois superiores e fenol. A utilização de produtos agroindustriais, como o caldo e melaço de cana-deaçúcar, é uma alternativa para reduzir o custo final dos produtos de fermentação devido à disponibilidade de aquisição e composição química desses substratos. Este trabalho teve como objetivo utilizar substratos alternativos e otimizar as condições de fermentação para a produção de etanol, levana e sorbitol por Zymomonas mobilis CCT 4494. Também foi considerado o efeito da variação do substrato e de sais minerais adicionados nos meios de produção (sintético, caldo e melaços de cana-de-açúcar). Para a obtenção dos produtos de fermentação, foi aplicada a metodologia de superfície de resposta, seguindo um planejamento fatorial do tipo 27-2, de acordo com o modelo proposto por Box e Hunter, onde as variáveis independentes estudadas foram: pH inicial do meio de cultivo, temperatura de incubação, concentração do substrato e efeito da adição de KCl, K2SO4, MgSO4, CaCl2. Durante a realização das fermentações foi observado que a bactéria Zymomonas mobilis CCT 4494 se adaptou nos meios de fermentação contendo altas concentrações de sacarose e suportou a variação do pH e da temperatura de fermentação. O aumento da concentração da fonte de carbono favoreceu a formação dos produtos levana e etanol, entretanto, não houve produção de sorbitol. O meio sintético proporcionou maior rendimento de levana e etanol, enquanto que, os meios alternativos caldo e melaços de cana-de-açúcar... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The main product from fermentation of sugars by Zymomonas mobilis is ethanol when glucose and fructose are used as carbon sources. However, when sucrose is used in the fermentation medium, ethanol yield decreases due to the formation of by-products such as levan, sorbitol, acetaldehyde, acetic acid, small amounts of some superior alcohols and phenol. The use of agro industrial by products, such as sugarcane juice and molasses, is an alternative to reduce the final cost of fermentation products due to the constant availability and to the chemical composition of these by substrates. This study had the aim of using alternative substrates and of optimizing fermentation conditions for the production of ethanol, levan and sorbitol by Zymomonas mobilis CCT 4494. The effect of variation of substrate and mineral salts added to the production media (synthetic, sugarcane juice and molasses) was also considered. To obtain the fermentation products, response surface methodology was employed, following a 27-2 factorial planning, according to the model proposed by Box and Hunter, where the independent variables studied were: initial medium pH, incubation temperature, substrate concentration and effect of the addition of KCl, K2SO4, MgSO4, CaCl2. During the fermentations, it was noted that the bacteria Zymomonas mobilis CCT 4494 well adapted in the media containing high concentrations of sucrose and tolerated pH and temperature variations. The increase of carbon source concentration favored the formation of levan and ethanol, however, there was no sorbitol production. The synthetic medium offered higher levan and ethanol yield, whereas alternative media sugarcane juice and molasses, favored cellular growth. Among the independent variables analyzed with the best medium (synthetic) for biosynthesis of the biopolymer and ethanol, the ones that significantly (p<0.05) affected were KCl, K2SO4, CaCl2... (Complete abstract click electronic access below) / Doutor

In the diploma thesis are discussed the process of enzymatic hydrolysis of waste paper as a source for the production of bioethanol by bacteria Zymomonas mobilis. In the theoretical part summarize basic information about particular methods of hydrolysis, about paper used as a raw material for enzymatic hydrolysis, about possibilities of the fermentative production of bioethanol focusing on the method of simultaneous saccharification and fermentation comparison with enzymatic hydrolysis and fermentation. Suitable microorganisms for ethanolic fermentation and simultaneous saccharification and fermentation and their advantages and disadvantages, are further discussed in this part as well. The theoretical part ends with the suggestion of the technological process for production of bioetanol. It covers all necessary steps from the input of raw material to the separation of produced ethanol. In the experimental part various parameters of hydrolysis, fermentation and simultaneous saccharification and fermentation were optimized using enzymes from Novozymes® company and the Zymomonas mobilis CCM2770 and Zymomonas mobilis LMG457 bacterium. The conversion rate of paper cellulose to gluckose and production of ethanol were observed by HPLC/RI method. Type of buffer, quantity of cells, enzyme and substrate were optimized in order to maximize the efficiency of the process. All experiments were performed on paper containing high amount of cellulose and for comparison on standard medium which contains gluckose. The highest yields was achieved with the use of Novozymes® Cellulosic ethanol enzyme Kit. The strain Zymomonas mobilis LMG457 has demonstrated as a better producer.

Diploma thesis deals with use of Zymomonas mobilis for the production of bioethanol from waste paper. There were used three kinds of substrate (cardboard, drawing and office paper) to optimize of bioethanol production. Individual papers were subjected to the same pre treatment, namely a milling, a combination of microwave irradiation and NaOH, a combination of microwave irradiation and H2SO4 and combination microwave irradiation, H2SO4 and NaOH. The substrates were decomposed by enzymatic hydrolysis after pre treatment to evaluate the best pre-treatment. Simultaneous saccharification and fermentation was carried out for each substrate (with two of the best pre-treatment). The samples were taken during the hydrolysis and the simultaneous saccharification and fermentation, and were determined by HPLC. Growth curves of Zymomonas mobilis were constructed, as the most appropriate for SSF was chosen temperature of 40 ° C in which the exponential phase took place at the time of 6 15 hours. During hydrolysis was monitored glucose concentration in the solution. The maximum concentration of glucose was in the cardboard (microwaves + H2SO4 + NaOH) 16.46 gdm-3, a drawing (microwaves + H2SO4 + NaOH) 31.78 gdm-3, and office paper (microwaves + H2SO4) 25.04 gdm-3. The concentration of ethanol for SSF was highest in the same cases as in the hydrolysis. The cardboard was the maximum concentration of bio ethanol 9.5 gdm-3, for the drawing 16.1 gdm-3 and for the office paper 12.13 gdm-3.