Ragi tapai and Saccharomyces cerevisiae as potential coculture in viscous fermentation medium for ethanol production

A comparison study on the ethanol production from 20% (w/v) of unhydrolyzed raw cassava starch using  Saccharomyces cerevisiae and Candida tropicalis was performed and compared with the commercialized ragi tapai. The findings showed that S. cerevisiae, C. tropicalis and ragi tapai produced 23, 20 mg/l and 26 g/l of ethanol in 72 h, respectively. Subsequent coculturing of the two best performing strains namely ragi tapai and S. cerevisiae were performed to improve ethanol production and to reduce the accumulation of inhibitory concentration of reducing sugar with 10% (w/v) unhydrolyzed raw cassava starch. The coculture of ragi tapai with S. cerevisiae using the unhydrolyzed raw starch in a single step-fermentation produced an ethanol concentration of 35 g/l when the starch was inoculated with ragi tapai and cocultured with S. cerevisiae. The yield was 46% higher than the one inoculated with ragi tapai only (24 g/l). The glucose concentration was maintained at a low concentration in the coculture medium as compared to the medium with pure ragi tapai. The findings suggested that coculture of ragi tapai with S. cerevisiae is capable of enhancing the ethanol production and prevention of the inhibitory effect of reducing sugars on amylolytic activity.Key words: Cassava starch, ethanol, Candida tropicalis, ragi tapai, Saccharomyces cerevisiae, single-stepbioconversion

Single-Step Bioconversion of Unhydrolyzed Cassava Starch in the Production of Bioethanol and Its Value-Added Products

The global economic recession that began in 2008 and continued into 2009 had a profound impact on world income (as measured by GDP) and energy use. Since then the price of the energy supply by conventional crude oil and natural gas production has been fluctuating for years which has resulted in the need to explore for other alternative energy sources. One of the fastest-growing alternative energy sources is bioethanol, a renewable energy which can reduce imported oil and refined gasoline, thus creates energy security and varies energy portfolio. Global biofuel demand is projected to grow 133% by 2020 (Kosmala, 2010). However, the biofuel supply is estimated deficit by more than 32 billion liters over the same period and the deficit is worse for ethanol than biodiesel. Ethanol may serve socially desirable goals but its production cost is still remained as an issue. Extensive research has been carried out to obtain low cost raw material, efficient fermentative enzyme and organism, and optimum operating conditions for fermentation process. In addition to that, researchers have been trying to capitalize certain features of the plant equipment and facilities to increase the throughput of ethanol and other high value by products as well as to apply suitable biorefinery for the product recovery. At the same time, effort has been made to reduce utilities costs in water usage, cooling or heating, and also consumables usage via minimizing the effluent production. Aimed to provide an alternative means for ethanol production, this book chapter introduces a single-step or direct bioconversion production in a single reactor using starch fermenting or co-culture microbes. This process not only eliminates the use of enzymes to reduce the production cost but also yield added value by-products via co-culture of strains. Before further elaboration on this single-step fermentation, we will visit the conventional process, the substrate preparation and microbe used. By this way a clear picture of the differences between conventional process and the proposed single-step fermentation with the advantages and disadvantages of both processes will be discussed

Natural deep eutectic solvent-assisted pectin extraction from pomelo peel using sonoreactor: experimental optimization approach

Background: Natural deep eutectic solvents (NADESs) can be used for extracting a wide range of biomaterials, such as pectin. This study introduces a new generation of natural solvents for pectin extraction which could replace the conventional solvents in the food industry. Methods: In this study, NADESs were used for pectin extraction from pomelo (Citrus grandis (L.) Osbeck) peels using a sonoreactor. Definitive screening design (DSD) was used to screen the influence of time, temperature, solid/liquid ratio, and NADES/water ratio on the pectin yield and degree of esterification (DE). Results: The primary screening revealed that the best choices for the extraction were choline chloride–malonic acid (ChCl-Mal) and choline chloride–glucose–water (ChCl:Glc:W). Both co-solvents yielded 94% pectin and 52% DE after optimization at 80 ◦C, with 60 min of sonication, pH < 3.0, and a NADES-to-water ratio of 1:4.5 (v/v). Morphological screening showed a smooth and compact surface of the pectin from ChCl-Mal where glucose-based pectin had a rough surface and lower DE. Conclusions: NADESs proved to be promising co-solvents for pectin extraction with a high degree of esterification (>55%)

The isolation and amplification of full length cDNA of oleosins from oil palm (Elaeis guineensis Jacq.)

This study focused on the isolation and amplification of the cDNA clone of oleosin from oil palm. The oil palm cDNA library constructed from the kernel tissues 10 weeks after anthesis (WAA) produced a clone of pO1A containing partial 563 bp sequence of oleosin. The polymerase chain reaction for the rapid amplification of cDNA ends (RACE-PCR) was performed to obtain full length cDNA of oleosin from the RNA transcripts using forward gene-specific primers that is, primer Oleo 3. The product was then cloned into pCR 4 TOPO vector and subjected to sequencing using M13 forward and reverse primers. The end-to-end PCR method was performed to amplify the complete cDNA sequence of oleosin and it produce a 750 bp PCR product. The BLAST results showed that the cDNA from oil palm kernel isolated exhibited high similarities with low molecular weight isoforms of oleosin cDNA from crops like rice, maize and barley

A brief review on anti diabetic plants: Global distribution, active ingredients, extraction techniques and acting mechanisms

A study has been conducted with the aim to provide researchers with general information on anti diabetic extracts based on relevant research articles collected from 34 reliable medical journals. The study showed that Asian and African continents have 56% and 17% share of the worldwide distribution of therapeutic herbal plants, respectively. In Asia, India and China are the leading countries in herbal plants research, and there has been an increase in medicinal research on plants extract for diabetes treatment since 1995 in these regions. The information collected shows that plant leaves are about 20% more favorable for storing active ingredients, as compared to other parts of herbal plants. A brief review on the extraction techniques for the mentioned parts is also included. Furthermore, the acting mechanisms for the anti diabetic activity were described, and the related active ingredients were identified. The findings reveal that most of the anti diabetic research is focused on the alteration of glucose metabolism to prevent diabetes

Optimization of Single-step Bioconversion Process using Taguchi’s method for the production of Multiple Valuable Fermentation-products

The significant of fermentation parameters for multiple valuable fermentation-products from co-culture fermentation of raw unhydrolyzed cassava starch were determined using Taguchi’s methodology in an orthogonal array of L8 using Design Expert v8.0.1. Seven factors were varied at two levels for each factor. The significant factors for the production of multiple valuable fermentation-products, namely ethanol, glycerol and lactic acids, were determined. The result shown that the optimum level for two nutrients which were NPK and urea were at 0.09% (w/w) and 0.8% (w/w), respectively. The optimum concentration of the dry starter of ragi tapai was 10% (w/w) which was best subsequent co-cultured at 3 h later with 10% (w/w) of Saccharomyces cerevisiae. The process was best operated at 30oC of fermentation temperature with 100 rpm of agitation speed

Assessment of scale-up parameters of microwave-assisted extraction via the extraction of flavonoids from cocoa leaves

Microwave-assisted extraction (MAE) is a promising technique for the extraction of flavonoid compounds from plants. However, it is difficult to scale up due to the complex mass transfer involved. This has prompted the study of parameters for scaling up the system by considering energy-related parameters, i.e. the nominal power density and the absorbed power density (APD). Modeling of MAE of flavonoid compounds from cocoa (Theobroma cacao L.) leaves using the film theory model was performed for this purpose. Operating parameters such as the sample particle size, the solvent-to-feed ratio, and the microwave irradiation power were also included in the kinetic study. The APD exhibited its aptitude as scaling-up parameter as it can characterize both the extraction kinetics and the extraction yields of MAE. Furthermore, it can be used as a reference for predicting the optimum extraction time of MAE under various heating conditions

Feasibility Study and Structural Analysis of Cellulose Isolated from Rice Husk: Microwave Irradiation, Optimization, and Treatment Process Scheme

The goal of this study was to pretreat rice husk (RH) using a microwave-assisted pretreatment process coupled with chlorite delignification and alkaline treatment to facilitate the isolation of cellulose. The isolated cellulose was characterized and subjected to structural analysis and a thermal stability test to ascertain the efficiency of the isolation from a visual perspective. The optimum condition for the microwave-assisted pretreatment of RH was determined by response surface methodology (RSM). The effects of three independent variables—microwave power, irradiation time, and solvent ratio—were investigated based on the maximum content of the RH being pretreated. At the optimum parameters of microwave power of 400 w, a 10-min duration, and a solvent ratio of 80.0% v/v, the pretreatment efficiency of RH was 10.0%. Compared with the conventional Soxhlet technique, the microwave pretreatment was superior. The X-ray powder diffraction (PXRD) result for the isolated cellulose showed that cellulose was highly crystalline (CrI = 65.0%). Fourier transform infrared spectroscopy (FT-IR) verified that most of the lignin and hemicelluloses were removed from the isolated cellulose after the chemical treatment. Furthermore, the TGA study revealed that the thermal stability of RH cellulose was higher than the original RH

Ragi tapai and saccharomyces cerevisiae as potential coculture in viscous fermentation medium for ethanol production

A comparison study on the ethanol production from 20% (w/v) of unhydrolyzed raw cassava starch using Saccharomyces cerevisiae and Candida tropicalis was performed and compared with the commercialized ragi tapai. The findings showed that S. cerevisiae, C. tropicalis and ragi tapai produced 23, 20 mg/l and 26 g/l of ethanol in 72 h, respectively. Subsequent coculturing of the two best performing strains namely ragi tapai and S. cerevisiae were performed to improve ethanol production and to reduce the accumulation of inhibitory concentration of reducing sugar with 10% (w/v) unhydrolyzed raw cassava starch. The coculture of ragi tapai with S. cerevisiae using the unhydrolyzed raw starch in a single step-fermentation produced an ethanol concentration of 35 g/l when the starch was inoculated with ragi tapai and cocultured with S. cerevisiae. The yield was 46% higher than the one inoculated with ragi tapai only (24 g/l). The glucose concentration was maintained at a low concentration in the coculture medium as compared to the medium with pure ragi tapai. The findings suggested that coculture of ragi tapai with S. cerevisiae is capable of enhancing the ethanol production and prevention of the inhibitory effect of reducing sugars on amylolytic activity

Transformation of Starchy Lignocellulosic Biomass to Ethanol using Ragi Tapai Synergized with Microwave Irradiation Pretreatment

Ethanol production strategy was studied using multiple strain microbes from microwave irradiation (MI) pretreated sago waste. Sago waste (SW) was MI-pretreated for reducing sugars production using 2 heating media (water and sulfuric acid) under pretreatment conditions including MI power, pretreatment duration, and solid loading. When water was used, the pretreatment parameters were optimized using Box-Behnken Design (BBD). However, gelatinized starch and charring of SW led to an insignificant quadratic model. To mitigate the gelatinization problem while determining the best MI pretreatment conditions, water was substituted by sulfuric acid using single factor method. The highest reducing sugar yield of 261.5 mg/g SW was achieved at 7.5% solid loading, 6 min pretreatment duration, and 300 W MI power. The effectiveness of the pretreatment was ascertained by field-emission scanning electron microscopy (FESEM) and chemical-composition analysis. When fermenting MI-pretreated SW using ragi tapai, simultaneous saccharification of starch and ethanol production was evidenced from the sugar/ethanol profile. A resulted yield of 7.24 g ethanol/100 g SW confirmed the fermentability of MI-pretreated SW. The ethanol production was well fitted into the modified Gompertz model