Sugarcane Bagasse Hemicellulosic Hydrolysate Research Articles

Aspects of the cell growth of Candida guilliermondii in sugar cane bagasse hydrolysate.

In this work the behavior of the growth of Candida guilliermondii FTI 20037 in sugar cane bagasse hemicellulosic hydrolysate on various oxygen transfer rates was investigated. The yeast was able to grow and produced xylitol at different performance levels. At 1.0 vvm (volume of air per volume of medium per minute) the highest growth with 24.4 g/l was observed, but no xylitol was produced. At aeration rate of 0.5 vvm the growth was lower, but therefore slight amounts of xylitol (xylitol yield factor-Yp/s = 0.15 g/g) were observed. The lowest cell concentration (10.7 g/l) and the highest xylitol yield (Yp/s = 0.46 g/g) was observed when aeration was changed from 0.5 vvm to 0.05 vvm after 14 h.

Pretreatment of sugar cane bagasse hemicellulose hydrolysate for xylitol production by yeast.

A total of six known xylitol-producing yeast strains were screened for production of xylitol from xylose. Candida sp. 11-2 proved to be the best producer. It was chosen to study its ability to produce xylitol from hemicellulose hydrolysate derived from sugar cane bagasse. The hydrolysate was prepared by dilute sulfuric acid (2-3% [w/v]) hydrolysis, with a high-solid, low-liquid ratio followed by leaching. Owing to the inhibitors present in the hydrolysate, different treatments were studied to overcome its effect. In order to reach higher xylitol productivity, treated hydrolysates were concentrated by vacuum evaporation in rotavapor to provide a higher initial xylose concentration. After treatment, Candida sp. 11-2 was able to ferment xylose in hemicellulose hydrolysate to produce xylitol.

Xylitol formation by Candida guilliermondii grown in a cane bagasse hemicellulosic hydrolysate: Effect of aeration and inoculum adaptation

AbstractThe xylose conversion into by Candida guilliermondii was evaluated in sugar cane bagasse hemicellulosic hydrolysate. The effect of air flow rates of 0.4, 0.6 and 0.8 vvm cn xylitol formation was studied. In addition, inoculum previously adapted to the hydrolysate was also tested in the fermentation carried out at 0.6 vvm. The results showed that xylitol production depends markedly on the aeration rate and on the previous adaptation of the yeast to the hydrolysate. When the highest productivity of xylitol was 0.39 g/l × h. However, during the fermentation carried out at an air flow rate of 0.6 vvm with adapted inoculum, the productivity increased to 0.65 g/l × h. Furthermore, the adapted cells performed quite well in the presencel of acetic concentrations of about 4.5 g/l in the medium.

Influence of aeration and agitation rate on the xylanase activity from Penicillium janthinellum

Penicillium janthinellum was cultivated in sugar cane bagasse hemicellulosic hydrolysate. The maximum xylanase activity obtained in shake flasks was 98 U ml −1 at 60 min −1 agitation rate, 30°C and pH 5·5. The growth of the P. janthinellum in a 4 litre fermentor was studied to determine the influence of aeration and agitation rate on xylanase production. Three agitation rates (100, 300 and 400 min −1) and three aeration rates (0·2, 0·4 and 0·6 vvm) were used. Xylanase synthesis was growth associated and a function of K L a. The highest enzymic activity (8·9 U ml −1) was obtained at a very low oxygen supply, at a K L a of 1·24 h −1.

Chemostat cultivation of Candida blankii on sugar cane bagasse hemicellulose hydrolysate

A Candida blankii yeast isolate was grown in sugar cane bagasse hemicellulose hydrolysate at 38 degrees C in carbon-limited chemostat culture. The pretreatment of the acid hydrolysate prior to microbial cultivation consisted of partial neutralization with ammonia and sodium hydroxide, plus the addition of phosphorus, which was the only other growth-limiting nutrient apart from nitrogen. The cell yield coefficient on nitrogen was 16.78. The critical dilution rate was higher (0.35 h(-1)) in diluted hydrolysate than in undiluted hydrolysate (0.21 h(-1)). In undiluted hydrolysate at a dilution rate of 0.1 h(-1) and pH 4, where aseptic procedures proved unnecessary, the cell and protein yield coefficients were 0.53 and 0.26, respectively, and no residual carbon substrates (D-xylose, L-arabinose, D-glucose, and acetic acid) were detected. The cell yield on oxygen increased linearly as a function of dilution rate. The cellular content of protein, carbohydrate, and RNA also increased with an increase in dilution rate, whereas the DNA content decreased slightly. C. blankii has considerable potential for the production of single cell protein from hemicellulose hydrolysate, because of its ability to utilize all of the major carbon substrates in the hydrolysate at a low pH and at a relatively high temperature with a high protein yield.

Utilization of sugar cane bagasse hemicellulosic hydrolysate by pichia stipitis for the production of ethanol

The production of ethanol by Pichia stipitis CBS 5773 in semi-synthetic xylose-containing media and in sugar cane bagasse hemicellulosic hydrolysate was investigated. The effect of xylose concentration upon fermentation was determined for P. stipitis and three other yeasts. An effective method of hydrolysate treatment employing neutralization with NaOH and activated charcoal was established. Fermentation of hydrolysate thus treated showed an extended lag phase and a 20% lower maximum volumetric productivity ( i.e., 0·82 g l −1 h −1) relative to fermentation of semi-synthetic media; however, yield (0·35 g g −1) and final ethanol concentration (24 g l −1) did not differ. Recycling of the yeast four times in treated hydrolysate-containing medium did not improve efficiency.

Fermentation of Sugarcane Bagasse Hemicellulose Hydrolysate to Xylitol by a Hydrolysate‐Acclimatized Yeast

ABSTRACTThe yeast strain, Candida sp B‐22, which has an increased tolerance to untreated neutralized sugarcane bagasse hemicellulose hydrolysate has been isolated by a continuous adaptation‐selection technique which allows yeasts to overcome the inhibitory effect of extraneous chemicals in hydrolysate. With this yeast, xylitol is produced from untreated full‐strength hydrolysate in a yield of over 85% of the theoretical value. A final xylitol concentration of 94.74 g/L was obtained from 105.35 g/L D‐xylose in hemicellulose hydrolysate after 96 hr of incubation.

Ethanol production from pentoses and sugar-cane bagasse hemicellulose hydrolysate by Mucor and Fusarium species

The fermentation of carbohydrates and hemicellulose hydrolysate by Mucor and Fusarium species has been investigated, with the following results. Both Mucor and Fusarium species are able to ferment various sugars and alditols, including d-glucose, pentoses and xylitol, to ethanol. Mucor is able to ferment sugar-cane bagasse hemicellulose hydrolysate to ethanol. Fusarium F5 is not able to ferment sugar-cane bagasse hemicellulose hydrolysate to ethanol. During fermentation of hemicellulose hydrolysates, d-glucose was utilized first, followed by d-xylose and l-arabinose. Small amounts of xylitol were produced by Mucor from d-xylose through oxidoreduction reactions, presumably mediated by the enzyme aldose reductase 1 (alditol: NADP + 1-oxidoreductase, EC 1.1.1.21). For pentose fermentation, d-xylose was the preferred substrate. Only small amounts of ethanol were produced from l-arabinose and d-arabitol. No ethanol was produced from l-xylose, d-arabinose or l-arabitol.