Ethanol production from rice hull using Pichia stipitis and optimization of acid pretreatment and detoxification processes

Abstract

The goal of this study was to produce ethanol from rice hull hydrolysates (RHHs) using Pichia stipitis strains and to optimize dilute acid hydrolysis and detoxification processes by response surface methodology (RSM). The optimized conditions were found as 127.14°C, solid:liquid ratio of 1:10.44 (w/v), acid ratio of 2.52% (w/v), and hydrolysis time of 22.01 min. At these conditions, the fermentable sugar concentration was 21.87 g/L. Additionally, the nondetoxified RHH at optimized conditions contained 865.2 mg/L phenolics, 24.06 g/L fermentable sugar, no hydroxymethylfurfural (HMF), 1.62 g/L acetate, 0.36 g/L lactate, 1.89 g/L glucose, and 13.49 g/L fructose + xylose. Furthermore, RHH was detoxified with various methods and the best procedures were found to be neutralization with CaO or charcoal treatment in terms of the reduction of inhibitory compounds as compared to nondetoxified RHH. After detoxification procedures, the content of hydrolysates consisted of 557.2 and 203.1 mg/L phenolics, 19.7 and 21.60 g/L fermentable sugar, no HMF, 0.98 and 1.39 g/L acetate, 0 and 0.04 g/L lactate, 1.13 and 1.03 g/L glucose, and 8.46 and 12.09 g/L fructose + xylose, respectively. Moreover, the base-line mediums (control), and nondetoxified and detoxified hydrolysates were used to produce ethanol by using P. stipitis strains. The highest yields except that of base-line mediums were achieved using neutralization (35.69 and 38.33% by P. stipitis ATCC 58784 and ATCC 58785, respectively) and charcoal (37.55% by P. stipitis ATCC 58785) detoxification methods. Results showed that the rice hull can be utilized as a good feedstock for ethanol production using P. stipitis. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:872-882, 2016.

Effect of furfural concentration on ethanol production using Saccharomyces cerevisiae in an immobilized cells stirred‐tank bioreactor with glucose‐based medium and mathematical modeling

“…Nonetheless, when the k value was also optimum, the BF and AF values satisfied and were close to one. Besides, while the BF decreased with increasing in k value, the AF value increased after the optimum k value (data not showed) (Baranyi & Roberts, 1994;Germeç et al, 2016). Similar results were also determined for the other model parameters in Table 2 in this manner.…”

“…Today, most of the energy is obtained from fossil fuels such as oil, coal, and natural gas (Germeç et al, 2016). However, due to the increase of both energy consumption and the world population, the amount of fossil fuel has been gradually decreasing.…”

“…Moreover, ethanol production can be carried out using pure carbon sources such as glucose, xylose, fructose, and sucrose and renewable resources such as carob (Ilgın et al, 2019), rice straw (Germec and Turhan, 2018a), tea processing waste (Germec and Turhan, 2018b), barley husk, wheat bran, and rye bran (Germec et al, 2017). While the ethanol production from pure carbon sources consists of fermentation and distillation steps, the ethanol production from renewable resources is generally carried out in four steps: pretreatment, hydrolysis, fermentation, and distillation (Germeç et al, 2016). Among them, the pretreatment is one of the most important processes to produce fermentable sugars from renewable resources.…”

Structural and mechanistic insight into stem‐loop RNA processing by yeast Pichia stipitis Dicer

“…Given that PsDCR1 is likely the only catalytically active RNase III protein in our P. stipitis, our study paves the way to understanding the function of the RNase III family in a budding yeast valued for biofuel production. 24 4 | METHODS…”

Kinetic Modeling and Techno-economic Feasibility of Ethanol Production From Carob Extract Based Medium in Biofilm Reactor

“…Ethanol, a two-carbon aliphatic alcohol, can be produced from various renewable carbon resources such as rice hulls [1], tea processing wastes [2,3], carob pods [4][5][6][7], rice straw [8], barley husk, wheat bran, rye bran [9], waste potato mash [10][11][12], sugarcane [13], corn grain [14]. Among them, carob has been suggested to be an attractive raw material in the production of bioethanol from renewable sources due to its high carbohydrate content including sucrose, glucose, and fructose [5].…”