الفهرس 
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Abstract
Bioethanol is a renewable and environmentally friendly biofuel because it is produced from renewable sources such as sugarcane molasses. One strategy for lowering production costs and making ethanol fuel economically competitive with fossil fuels could be to use overland yeast with somnolence and ethanol resistance. and low nutritional requirements. The collected raw materials such as molasses, stalks of Sesame and banana pseudo stems of healthy and virus infected and collected and used in these studies. This work focuses on the kinetics of ethanol production by Saccharomyces cerevisiae on untreated or treated molasses-based medium with the development of a mathematical model considering the effect of substrate concentration, inoculum size, and pretreatment of molasses on the growth rate, substrate consumption, and product concentration. This work includes a study of the production of fermentable ethanol from crop residues such as sesame stalks and Banana pseudostem virus infected and healthy by Candida tropicalis DSM70156 and Saccharomyces cerevisiae. Sesame stalks residue (SS) and Banana pseudostem (BPS) (healthy and infected virus) were smashed using a mechanical grinder, and further sieved to obtain the desired particle size. This step was considered as the first pretreatment (Step I) of SSR and BPS biomass. Raw biomass was pretreated with NaOH at pH 11 and 100oC for 1 h. The solid loading was 5% (w/v). After pretreatment, solid and liquid fractions were separated through a 15-lm pore-sized filter. The solid fractions were washed with distilled water until the pH of the solid fraction reach 7–The solid phase was dried in an oven at 60oC for 2 day.
The production medium was prepared from the digested sesame stalks and Banana pseudostem virus infected and healthy after treating them with caustic soda, followed by two steps with acid to obtain the sugars (glucose and xylose) as a source of energy and carbon.
Yeast was isolated from each sugar cane molasses, dates and figs and maintained on YMA agar slants and identified according to microscopically examinations, characteristics of fermentation and biochemical testing , antibiotic sensitivity test and conformed by VITEK2 system as well as Candida tropicalis ATCC 70156.
Results of the present study are summarized in the following points:
1. The percentages of chemical contents in Egyptian sugarcane molasses, Total soluble sugers (TSS), Reducing sugar, Total sugar & Total ash were varied pretreatment (70.20, 8.50, 50.6, 9.50 %) and post treatment (46.00 , 16.9 , 45.00 & 4.55 % ) respectively.
2. The three isolated yeast did not show any variation according to the morphological and biochemical characteristics, of the three isolates seemed to be S.cerevisiae. Morphological colonies were distinctive creamy, pasty colonies, smooth after 24-48 h at 37oC, white patches with glossy surface and Sabouraud’s Dextrose Agar and Nutrient agar media. The cell morphology microscopic characteristics oval cells with budding. Identification of the three isolates using MALDI-TOF MS (VITIK2 system )was provided the S. cerevisiae with above 99% . Biochemical Identification of isolates which belonging to S.cerevicia based on The Biochemical characteristics of S.cereviciaea was confirmed by VITIK2 system .
3. As observed, all isolates were able to ferment glucose, galactose, sucrose, maltose and fructose; while the other ones (lactose, xylose and arabinose) were not fermentable .
4. As observed, the presence of the salt in the medium reduced significantly the growth of the isolates. The decrease in growth cell was 57.1%, 46.9%, 48.6% and 47.1% for isolates S1, S2, S3, and S.cerevisiae, respectively, in the presence of 0.5M salt. The growth of the isolates decreased upon increasing the salt concentration to reach 85.7%, 87.5%, 82.9% and 76.5% for isolates S1, S2, S3, and S.cerevisiae, respectively, in the presence of 1.5M salt.
5. The results showed that all isolates grew at 5, 7, 9, 10 and 12% ethanol concentration. Regarding the isolates, S.cerevisiae isolate (S1) tolerated up to 12% (v/v) of ethanol, while interestingly the commercial S. cerevisiae were highly tolerant, up to 14% (v/v) ethanol.
6. The kinetic parameters of yeast cell growth specific growth rate (µmax), saturation constant (Ks), yield factor (Yx/s) and productivity (Po-x) for fermentation runs, the highest values of four parameters were recorded for sugar concentration 15% (group A) and 25% (group B).
7. The values substrate utilization efficiency, SUE for group A and B were (73.5 -100%) and (49.35 - 100 %), respectively maximum SUE was recorded 100% followed by 86.2% for group A at 10 & 15% reducing sugar, while 100% followed 96% for group B at 10 % &25 % reducing sugar. In growth associated products, the product is formed along with the growth of the microbial cells and product concentration is almost directly proportional to the microbial growth rate.
8. The estimated values of the specific ethanol production rate (µ) were (0.05, 0.12, 0.04, and 0.11 h-1) for group A and (0.03, 0.02. 0.04, and 0.05h-1) for group B at initial substrate concentrations of 100, 150, 200, and 250 g/L, respectively .The maximum ethanol concentration obtained with initial sugar concentration 150 g/l group A was 121 g/L and for initial sugar concentration, 250 /group B was 175 g/L after 72 h of fermentation. The highest value of Yd/s and Po-p were recorded with sugar concentrations of 150 gL-1 i.e., 1.19gg-1 and 1.68 gL-1h-1 and 107 gg-1 and 2.43 gal1h-1 for group A and group B, respectively. As for the most important parameter, which is fermentation efficiency (FE) is found that all fermentation runs achieved more than 100 % of theoretical ethanol concentration. The highest value was recorded with a sugar concentration of 10-15% (194-171%0 group A., respectively.
9. The chemical components of three different sizes of dried sesame stalks were evaluated in three steps and found to have 18 to 23.3 percent phenol, 26 to 29 percent hemicellulose, and 41 to 43.2 percent cellulose.
10. The solid recoveries of NaOH pretreatment ranged from 18% to 23.3% (w/w).
11. The maximum holocellulose hydrolysis (72.2 %) was achieved by using 1% H2SO4 at 110°C for 30 minutes in stage I and 3% H2SO4 at 130°C for 60 minutes in stage II, with a particle size of 30 mesh generating 25.40 and 85 g/L reducing sugars, respectively.
12. The highest of Sf, SUE, Po-s, and Yx/s were 58.09gL-1, 83 %, 1.9 gg-1L-1, and.63 gg-1, respectively, for hydrolysate 1, while C. tropicalis DSM 70156 grown on hydrolysate 2 showed superiority in Smax, Rs, s (SSCR) recorded values of 18.5 gL-1, 0.32 h-1, and 0.15 h-1Pmax of 11,02 g L-1, Pf of 49.21 gl-1 h-1, p(SSPR) of 0.14 h-1, Po=p of 1.03 gl-1h-1, Yp/s of 0.93 gg-1, Yp/x of 1.35 gg-1, and PT of 62,57 % were obtained with first stage hydrolysate 1.
13. The first stage hydrolysate of SS by C. tropicalis DSM 70156 in a batch of xylose fermentation system show that after 36 hours of incubation (1st batch of fermentation), the maximum bioethanol concentration (49.21 gL-1) was achieved with 1.03 gL-1h-1 volumetric ethanol productivity and 0.93 gg-1 ethanol yield.
14. Saccharomyces cerevisiae growth on the second stage dilute acid hydrolysate-base medium was carried out in the same manner as C. tropicals growth on the first stage dilute acid hydrolysate-base medium, with the exception that the smallest particle size of SS was used. The greatest values were reported for growing biomass (Xf. Po-x), sugar consumption (Sf, SUE, s-SSCR-, Po-s, Yx/s), and product production (Pf. p -SSPR- Po-p, Yp/s, and Yp/x) of (70.75 gl-1, 1.47 gl-1h-1, 0.07 h-1), (87.15 gl-1, 87 %, 0. 09h-1, 1.82 gl-1h-1, 0/82 gg-1) and (88 gl-1, 0.03 h-1, 1.8 hl-1h-1, 1.3 gg-1, 1.6 gg-1,) ,respectively.
15. The largest influence on SS pretreatment was found to be particle size. The microbial cells and acid solution displayed the greatest surface area, promoting pretreatment reactions for the smallest particle size . Larger particle size may have less easily available reactive sites, resulting in slower pretreatment, as demonstrated by two distinct treatments (850 and 1300 m).
16. The solid recoveries of NaOH pretreatment ranged from 19% to 23.5% (w/w). For (specifically 10 mesh and.3% NaOH; 1 h).
17. The percentages of chemical contents in Banana pseudo Stems, cellulose, Hemicellulose, lignin, Pectin and Ash contents were decreased in BbTV and BMV viruses infected (48.23, 11.31, 2.22 & 1.61 mg) than healthy ones (53.38 and 17.96, 3.26 & 2.5 mg) respectively.
18. The maximum holocellulose hydrolysis (73 %) for healthy pseudostem was achieved by using 1% H2SO4 at 110°C for 30 minutes in stage I and 3% H2SO4 at 130°C for 60 minutes in stage II, with a particle size of 10 mesh generating 28.6 and 88 g/L reducing sugars, respectively, and on the other side the infected pseudostem achived maximum holocellulose hydrolysis was 70.7% by the previous conditions, with a particle size of 10 mesh generating 25.3 and 84 g/L reducing sugars, respectively,
19. The ethanol production from the first stage hydrolysate of healthy banana stem by C. tropicalis DSM 70156 in a batch of xylose fermentation system show that after 36 h of incubation (1st batch of fermentation), the maximum bioethanol concentration (64.21 gL-1) was achieved with 1.08 gL-1h-1 volumetric ethanol productivity and 0.98 gg-1 ethanol yield. The infected pseudostem (1st batch of fermentation), the maximum bioethanol concentration (52.44 gL-1) was achieved with 1.08 gL-1h-1 volumetric ethanol productivity and 0.93 gg-1 ethanol yield .
20. Saccharomyces cerevisiae growth on the second stage dilute acid hydrolysate-base medium was carried out in the same manner as C. tropicals growth on the first stage dilute acid hydrolysate-base medium, with the exception that the smallest particle size of BS was used. for Ethanol production from the second stage hydrolysate of healthy banana stem by Saccharomyces cerevisiae in a batch of glucose fermentation system show that after 36 hours of incubation (2sec batch of fermentation), the maximum bioethanol concentration (102.5 gL-1) was achieved with 1.09 gL-1h-1 volumetric ethanol productivity and 0.98 gg-1 ethanol yield. The infected pseudostem (2sec batch of fermentation), the maximum bioethanol concentration (88.5 gL-1) was achieved with 1.05 gL-1h-1 volumetric ethanol productivity and 0.93 gg-1 ethanol yield.