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The food wastage problem and its associated issues have become a significant threat to sustainable development, particularly in developing countries. Cooked rice, which has been reported to be one of the most abundant regional food wastes, is a substantial feedstock for biofuel production due to its rich carbon content. In this study, both solid-state and acetone–butanol–ethanol (ABE) fermentations were conducted in series with Aspergillus oryzae and aero-tolerant Clostridium acetobutylicum YM1 for the biobutanol production. To validate the process parameters for an industrial-scale process, it is critical to examine the effects of process parameters using a process simulation tool. To this end, by adapting lab-scale process results, a techno-economic evaluation of the biobutanol production from the cooked rice by two-step fermentation was performed using SuperPro Designer®. This study aims to examine various scenarios for cooked rice utilization to produce butanol while examining process optimization and minimization of operational expenses for the aerobic ABE fermentation and microbial saccharification. According to the simulation results, butanol production cost was estimated to be 1.24 $ kg−1, incorporating a cost reduction of 0.58 $ kg−1 from heat integration, steam and power generation, while eliminating costs for the unnecessary commercial enzymes and N2 gas for purging. Finally, sensitivity analysis was applied to demonstrate the plant feasibility concerning potential fluctuations in the changing biofuel market and environmental conditions.

Biosurfactants or microbial surfactants are structurally diverse and contribute to reducing surface and interfacial tension. Apart from being isolated from municipal waste and oil contaminated soil...

Bacteriological assessment of commercial weaning foods, traditional weaning foods in addition to cereals and legumes samples (ingredients that formed the traditional weaning foods) that consumed in Taiz city, Yemen was carried out. The results showed that the standard counts of mesophilic aerobic bacteria and mesophilic aerobic endospore-forming bacteria in commercial weaning foods were 4.83 ± 0.79 and 2.44 ± 0.57 log10 CFU g−1, respectively. Whereas, this type of food were free from coliform bacteria, Enterococcus spp. and Salmonella spp. On another side, the standard counts of mesophilic aerobic bacteria, mesophilic aerobic endospore forming bacteria, coliform bacteria, and Enterococcus spp. in traditional weaning food samples were 4.83 ± 0.79, 2.35 ± 0.46, 2.63 ± 1.41, and 1.41 ± 1.10 log10 CFU g−1, respectively. Moreover, Salmonella spp. were observed in 58.3% of these samples. The results indicated that the major most source of contamination was red sorghum and the lowest source of contamination was rice. This study showed that the tested commercial weaning foods were better quality than traditional weaning food samples. Keywords: Bacteriological evaluation, Weaning food, Cereals, Legumes

The effect of pH and butyric acid supplementation on the production of butanol by a new local isolate of Clostridium acetobutylicum YM1 during batch culture fermentation was investigated. The results showed that pH had a significant effect on bacterial growth and butanol yield and productivity. The optimal initial pH that maximized butanol production was pH 6.0 ± 0.2. Controlled pH was found to be unsuitable for butanol production in strain YM1, while the uncontrolled pH condition with an initial pH of 6.0 ± 0.2 was suitable for bacterial growth, butanol yield and productivity. The maximum butanol concentration of 13.5 ± 1.42 g/L was obtained from cultures grown under the uncontrolled pH condition, resulting in a butanol yield ( Y P / S ) and productivity of 0.27 g/g and 0.188 g/L h, respectively. Supplementation of the pH-controlled cultures with 4.0 g/L butyric acid did not improve butanol production; however, supplementation of the uncontrolled pH cultures resulted in high butanol concentrations, yield and productivity (16.50 ± 0.8 g/L, 0.345 g/g and 0.163 g/L h, respectively). pH influenced the activity of NADH-dependent butanol dehydrogenase, with the highest activity obtained under the uncontrolled pH condition. This study revealed that pH is a very important factor in butanol fermentation by C. acetobutylicum YM1.

Fermenting palm kernel cake (PKC) hydrolysate using C.acetobutylicum YM1 produces butanol. Firstly, PKC is exposed to acid pretreatment to release fermentable sugars. Besides sugar, PKC hydrolysate consists of a mixture of microbial inhibitors. Sulfuric acid-treated PKC (2% SAPKC) released 30 g/L of reducing sugars. The concentration of microbial inhibitors are measured and two decontamination techniques namely overliming and activated charcoal are used and studied for their effectiveness in decreasing the microbial inhibitors and thereby increase the production of butanol. The activated charcoal detoxification technique produced good results in decreasing furan aldehydes compounds compared to overliming method. Even though overliming method decreased the inhibitory elements, the end amount of butanol produced is comparatively lower than the non-detoxified SAPKC. Activated charcoal technique increased productivity and yield of acetone, butanol, and ethanol (ABE).

Butanol was produced from pretreated deoiled rice bran (DRB) in a batch culture of Clostridium acetobutylicum YM1. The DRB was pretreated by acetyl chloride to produce fermentable sugars prior to butanol fermentation. Pretreatment of DRB using 1% acetyl chloride (AC-DRB) resulted in sufficient fermentable sugars (30.88 g/L), which was comparable to that produced by using 1% sulfuric acid (33.5 g/L). Pretreated AC-DRB contained 18.08 g/L glucose, 9.95 g/L xylose, and 2.86 g/L cellobiose. Detoxification of AC-DRB was performed to remove the fermentation inhibitors, such as furfural, 5-hydroxymethyl furfural (HMF), acetic acid, formic acid, and levulinic acid with the removal efficiencies of 92.98%, 98.82%, 51.53%, 38.72%, and 96.21%, respectively, using charcoal. The detoxification with charcoal was more efficient compared to that with XAD-4 resin. Acetone-butanol-ethanol (ABE) fermentation of detoxified AC-DRB (with 1% AC) by XAD-4 produced 5.64 g/L butanol, while detoxification with charcoal of AC-DRB (with 1% AC) produced 6.48 g/L butanol. In detoxified AC-DRB with charcoal, the maximum butanol and ABE yield of 6.48 g/L and 11.82 g/L, respectively, were achieved. This study is the first reported treatment of biomass using acetyl chloride, which was used as a pretreatment method for successful butanol production.

In Asia, uneaten cooked rice is the highest portion amongst many forms of food wastes that are thrown away. In order to make use of the thrown-away rice and potentially use it for liquid fuels, steamed Japanese rice was evaluated on biobutanol production through a two-step fermentation by amylase-producingAspergillus oryzae, and solvent-producingClostridium acetobutylicumYM1. The effects of sterilization and providing anaerobic conditions on solvent production in acetone-butanol-ethanol (ABE) fermentation cannot be underestimated. Several conditions, including aerobic, anaerobic, sterile, and non-sterile were investigated concerning the solvent production capability ofClostridium acetobutylicumYM1. The maximum solvent production was 11.02 +/- 0.22 g/l butanol and 18.03 +/- 0.34 g/l total ABE from 75 g/l dried rice. The results confirmed that the solvent production performance of the YM1 strain was not affected by the sterilization conditions. In particular, 10.91 +/- 0.16 g/l butanol and 16.68 +/- 0.22 g/l ABE were produced under non-sterile and aerobic conditions, which can reduce industrial-scale production costs.

Hydrogen generation was studied using palm oil mill effluent (POME) as an agro-industrial waste obtained from the palm oil industry. POME was subjected to a dilute acid hydrolysis step by HCl (37% v/v) to release fermentable sugars from cellulosic content. POME hydrolysate obtained was used as a substrate for hydrogen generation. The composition of POME hydrolysate showed glucose and xylose were the main monomeric sugars liberated. Hydrogen production was performed in dark fermentation process, in which the new bacterial strain Clostridium acetobutylicum YM1 was cultivated on POME hydrolysate based on a central composite design (CCD). CCD was constructed by considering three pivotal process variables including incubation temperature, initial pH of culture medium and microbial inoculum size. An empirical model, namely second-order polynomial regression model was generated and adjusted to CCD data. The analysis of empirical model generated showed that the linear and quadratic terms of temperature had a highly significant effect on hydrogen generation (P < 0.01). Furthermore, the quadratic effects of initial pH value of culture medium and inoculum size had a significant effect on hydrogen production at 95% probability level (P < 0.05). The regression model also showed that the interaction effect between temperature and initial pH value of the culture medium on the hydrogen generation was highly significant (P < 0.01). The empirical model suggested that the optimum conditions for hydrogen production were an incubation temperature of 38 °C, initial pH value of 5.85 and inoculum size of 17.61% with predicting the production of a cumulative hydrogen volume of 334.2 ml under optimum conditions. In order to validate the optimum conditions determined, C. acetobutylicum YM1 was cultivated on POME hydrolysate in optimum conditions. Verification test results showed that a cumulative hydrogen volume of 333.5 ml and a hydrogen yield of 108.35 ml H2/g total reducing sugars consumed were produced.

Fermentative hydrogen generation was studied using palm kernel cake (PKC) as sustainable cellulosic biomass. PKC was subjected to an acid hydrolysis approach using dilute H2SO4 (7% v/v). PKC hydrolysate obtained was then diluted (70%) and used as a substrate for hydrogen generation. Chemical analysis showed that the main fermentable sugars in diluted PKC hydrolysate were glucose, xylose and mannose with the concentrations of 2.75 g/L, 2.60 g/L and 27.75 g/L, respectively. Hydrogen production was carried out by the cultivation of Clostridium acetobutylicum YM1 on PKC hydrolysate. The effect of incubation temperature, the initial pH of culture medium and microbial inoculum size on hydrogen production was studied using a statistical model. The analysis of the model generated showed that the initial pH value of the culture medium and inoculum size had significant effects on the hydrogen production. The study showed that the optimum conditions for the biohydrogen production were 30.57 °C temperature, pH 5.5 and 20% inoculum size. A verification experiment was performed in the optimum conditions determined. Experimental results of the verification test showed that a cumulative hydrogen volume of 1575 ml/L was generated with consuming 2.75 g/L glucose, 2.20 g/L xylose and 16.31 g/L mannose.

Aurantiochytrium sp. has been developed for commercial docosahexaenoic (DHA) production but the production cost remains a major issue due to exorbitant cultivation substrates. In this study, we explore the capacity of locally isolated Aurantiochytrium sp. to produce DHA utilizing low-cost, safe and extensively abundant fruit extracts derived from rejected fruits as alternative carbon sources via development of several biotechnological processes including; (1) simple and cost-effective sugar extraction from the fruit extracts, (2) screening of the potential fruit extracts and (3) process optimization using selected fruit extract to enhance the DHA yield and (4) comparative study of the selected fruit extract with commercial glucose and fructose to evaluate its competency for large scale production. The capability of Aurantiochytrium sp. SW1 to utilize the fruit extracts were screened and results showed that Aurantiochytrium sp. SW1 produced 20–60% higher lipid and DHA when grown in autoclaved assisted Ananas comosus MD2 extracts in comparison to other fruit extracts. In addition, lipid and DHA production cultivated with Ananas comosus MD2 extract was also 15–50% higher than that of commercial glucose and fructose. This superior production of lipid and DHA of Aurantiochytrium sp. SW1 cultivated in Ananas comosus MD2 extract was shown to probably be caused by significant elevation of the key metabolic enzymes involved in lipid biosynthesis, including malic enzyme, glucose-6-phosphate and ATP citrate lyase and the lowering of the reactive oxygen species and lipid peroxidation activities. Efficient DHA biosynthetic capacity of 0.31 (g DHA/g Biomass) was achieved in this study, suggesting Ananas comosus MD2 extract as an ideal alternative carbon source for economic production of DHA by Aurantiochytrium sp.

A new solvent-producing Clostridium has been isolated from soil used in intensive rice cultivation. The 16S rRNA analysis of the isolate indicates that it is closely related to Clostridium acetobutylicum, with a sequence identity of 96%. The new isolate, named C. acetobutylicum YM1, produces biobutanol from multiple carbon sources, including glucose, fructose, xylose, arabinose, glycerol, lactose, cellobiose, mannitol, maltose, galactose, sucrose and mannose. This isolate can also utilize polysaccharides such as starch and carboxylmethyl cellulose (CMC) for the production of biobutanol. The ability of isolate YM1 to produce biobutanol from agro-industrial wastes was also evaluated for rice bran, de-oiled rice bran, palm oil mill effluent and palm kernel cake. The highest concentration of biobutanol (7.27 g/L) was obtained from the fermentation medium containing 2% (w/v) fructose, with a total acetone–butanol–ethanol (ABE) concentration of 10.23 g/L. The ability of isolate YM1 to produce biobutanol from various carbon sources and agro-wastes indicates the promise of the use of this isolate for the production of biobutanol, a renewable energy resource, from readily available renewable feedstocks.

In this work, hydrolysis of cellulose and hemicellulose content of palm kernel cake (PKC) by different types of hydrolytic enzymes was studied to evaluate monomeric sugars released for production of biobutanol by Clostridium saccharoperbutylacetonicum N1-4 (ATCC 13564) in acetone-butanol-ethanol (ABE) fermentation. Experimental results revealed that when PKC was hydrolyzed by mixed β-glucosidase, cellulase and mannanase, a total simple sugars of 87.81±4.78 g/L were produced, which resulted in 3.75±0.18 g/L butanol and 6.44±0.43 g/L ABE at 168 h fermentation. In order to increase saccharolytic efficiency of enzymatic treatment, PKC was pretreated by liquid hot water before performing enzymatic hydrolysis. Test results showed that total reducing sugars were enhanced to 97.81±1.29 g/L with elevated production of butanol and ABE up to 4.15±1.18 and 7.12±2.06 g/L, respectively which represented an A:B:E ratio of 7:11:1.

This research aimed to study the fermentative production of hydrogen using de-oiled rice bran (DRB) as renewable biomass. DRB was obtained by the extraction of oil content of rice bran samples. DRB was then hydrolyzed by dilute H2SO4 (1% v/v) to obtain DRB hydrolyzate as substrate for hydrogen generation. The composition of DRB hydrolyzate showed that glucose and xylose formed the main fermentable sugars released from acid hydrolysis of DRB. Hydrogen production was performed by the cultivation of new strain Clostridium acetobutylicum YM1 on DRB hydrolyzate in an anaerobic fermentation process. The effect of pivotal operating variables (incubation temperature, initial pH of culture medium and microbial inoculum amount) on hydrogen production was studied using response surface methodology. A second-order polynomial regression model was generated to evaluate hydrogen generation trend under conditions tested. The model analysis revealed the high significance of linear effects of incubation temperature (P < 0.01) and inoculum amount (P < 0.05) on hydrogen generation. The process model also showed that the quadratic effects of the incubation temperature and pH value were significant at 99% probability level and 95% probability level, respectively. Similar results indicated that the interaction effect between incubation temperature and inoculum amount was highly significant (P < 0.01). The regression model suggested that the optimum conditions were an incubation temperature, pH value and inoculum amount of 35.2 °C, 5.5 and 11.6% (v/v), respectively. In order to validate the optimum conditions determined by the model, Clostridium acetobutylicum YM1 was cultivated on DRB hydrolyzates under optimum conditions determined. Verification experiment showed that a cumulative hydrogen volume of 572.5 ml and a hydrogen yield of 132.2 ml H2/g total sugars consumed were generated.

Improvement in the butanol production selectivity or enhanced butanol:acetone ratio (B:A) is desirable in acetone-butanol-ethanol (ABE) fermentation by Clostridium strains. In this study, artificial electron carriers were added to the fermentation medium of a new isolate of Clostridium acetobutylicum YM1 in order to improve the butanol yield and B:A ratio. The results revealed that medium supplementation with electron carriers changed the metabolism flux of electron and carbon in ABE fermentation by YM1. A decrease in acetone production, which subsequently improved the B:A ratio, was observed. Further improvement in the butanol production and B:A ratios were obtained when the fermentation medium was supplemented with butyric acid. The maximum butanol production (18.20 ± 1.38 g/L) was gained when a combination of methyl red and butyric acid was added. Although the addition of benzyl viologen (0.1 mM) and butyric acid resulted in high a B:A ratio of 16:1 (800% increment compared with the conventional 2:1 ratio), the addition of benzyl viologen to the culture after 4 h resulted in the production of 18.05 g/L butanol. Manipulating the metabolic flux to butanol through the addition of electron carriers could become an alternative strategy to achieve higher butanol productivity and improve the B:A ratio.

A newly isolated strain of Clostridium acetobutylicum YM1 has a unique property of producing biobutanol from glucose under aerobic conditions. This strain exhibited the capability to grow and produce high concentrations of biobutanol under different concentrations of dissolved oxygen (DO). The growth profile and solvent production in a 5 L bioreactor were similar under anaerobic and aerobic conditions (100% initial DO saturation), and the final biobutanol production was 12.18 and 12.30 g/L, respectively. The addition of reducing chemical agents, without creating anaerobic conditions, to the culture of YM1 enhanced the production of biobutanol. Strain YM1 possesses different enzymes that are responsible for oxygen scavenging, such as superoxide dismutase (SOD), catalase and NADH/NADPH oxidases. This study provides a simple operation strategy for more efficient biobutanol production by using an aerotolerant strain of C. acetobutylicum YM1 without the need to flush the medium with nitrogen gas to ensure anaerobic conditions.

Palm oil mill effluent (POME), an abundant and low-cost agro-industrial residue, was utilized for the production of butanol in the anaerobic process of acetone–butanol–ethanol (ABE) fermentation. The ABE process was performed by the cultivation of Clostridium saccharoperbutylacetonicum N1-4 (ATCC 13564) in raw POME medium without supplementation. The effect of various process parameters, including pH, incubation temperature, agitation and inoculums size on butanol production, was studied. Experimental results showed that the highest butanol levels could be produced when the initial pH of culture medium, incubation temperature, agitation speed and inoculums size were set at 5.8, 30 °C, 100 rpm and 15% (v/v), respectively. Results revealed that the existence of crude palm oil (CPO) in the POME composition had an adverse effect on butanol synthesis by Clostridial cells. The highest butanol and ABE concentrations of 0.9 g/L and 2.09 g/L were produced, respectively, when operating variables tested were set at their optimum levels under the absence of CPO.

Continuous fermentation of dilute acid-pretreated de-oiled rice bran (DRB) to butanol by the Clostridium acetobutylicum YM1 strain was investigated. Pretreatment of DRB with dilute sulfuric acid (1%) resulted in the production of 42.12 g/L total sugars, including 25.57 g/L glucose, 15.1 g/L xylose and 1.46 g/L cellobiose. Pretreated-DRB (SADRB) was used as a fermentation medium at various dilution rates, and a dilution rate of 0.02 h−1 was optimal for solvent production, in which 11.18 g/L of total solvent was produced (acetone 4.37 g/L, butanol 5.89 g/L and ethanol 0.92 g/L). Detoxification of SADRB with activated charcoal resulted in the high removal of fermentation inhibitory compounds. Fermentation of detoxified-SADRB in continuous fermentation with a dilution rate of 0.02 h−1 achieved higher concentrations of solvent (12.42 g/L) and butanol (6.87 g/L), respectively, with a solvent productivity of 0.248 g/L.h. This study showed that the solvent concentration and productivity in continuous fermentation from SADRB was higher than that obtained from batch culture fermentation. This study also provides an economic assessment for butanol production in continuous fermentation process from DRB to validate the commercial viability of this process.

This study investigated the effect of different organic solvents, temperatures and pH levels for dye extraction from Areca catechu. The optimum conditions for the maximum yield of extracted natural dye were further determined using D-optimal design. The extracted dye at optimum conditions was used together with TiO2 as photosensitiser and the performance of dye-sensitised solar cell (DSSC) was further investigated. Analysis of variance ANOVA results showed that all factors significantly affect dye extraction. The optimum conditions of dye extraction were at 80 °C, pH 10 and ethanol as extraction solvent. The validation experimental at the optimum conditions showed the absorbance of the extracted dye was 1.832 with an error of less than 5%. The DSSC performance showed high energy conversion efficiency of 0.38% and the fill factor of 62.9%.

In this study, response surface methodology (RSM) was applied to optimize and investigate the ability of yeast extract, CaCO3, MgSO4, and K2HPO4 to maximize biobutanol production by a novel local isolate of Clostridium acetobutylicum YM1. A central composite design was applied as the experimental design, and analysis of variance (ANOVA) was used to analyze the experimental data. A quadratic polynomial equation was obtained for biobutanol production by multiple regression analysis. ANOVA analysis showed that the model was significant (p < 0.0001), and the yeast extract, CaCO3, and MgSO4 concentrations had a significant effect on biobutanol production. However, K2HPO4 did not have a significant effect on biobutanol production. The estimated optimum combinations for biobutanol production using C. acetobutylicum YM1 were 2 g/L yeast extract, 6 g/L CaCO3, 0.1 g/L MgSO4, and 1.1 g/L K2HPO4. Subsequently, the model was validated through use of the estimated optimum conditions, which confirmed the model validity ...

In view of increasing attempts for the production of renewable energy, the production of biohydrogen energy by a new mesophilic bacterium Clostridium sp. YM1 was performed for the first time in the dark fermentation. Experimental results showed that the fermentative hydrogen was successfully produced by Clostridium sp. YM1 with the highest cumulative hydrogen volume of 3821 ml/L with a hydrogen yield of 1.7 mol H 2 /mol glucose consumed. Similar results revealed that optimum incubation temperature and pH value of culture medium were 37 °C and 6.5, respectively. The study of hydrogen production from glucose and xylose revealed that this strain was able to generate higher hydrogen from glucose compared to that from xylose. The profile of volatile fatty acids produced showed that hydrogen generation by Clostridium sp. YM1 was butyrate-type fermentation. Moreover, the findings of this study indicated that an increase in head space of fermentation culture positively enhanced hydrogen production.

This study reviews the role of Plant Growth Promoting Rhizobacteria (PGPR), Plant Growth Promoting Fungi (PGPF) and Mycorrhizal Fungi in the enhancement of rice growth and yield. A total 70 papers spanning from 1970 to 2013 was screened and noted its conclusion to enhance rice growth and yield. The mechanisms employed by microbes in enhancing rice growth and yield includes; the production of growth regulating substances, phosphate solubilization, N-fixation, cellulose degradation and side rophore production. Some microbes are also involved in cell regulation and signaling in rice plants. We can conclude that there are significant influences on the growth and yield of rice plant by microbes.

The viability of most fermentation processes is very much dependent on the cheap fermentation medium used. Palm kernel cake (PKC) is an abundant biomass generated from the palm oil processing industry that can be used as the carbon source for the growth and production of acetone-butanol-ethanol fermentation (ABE) by Clostridia. In this study, ABE production from the fermentation of PKC using Clostridium acetobutylicum YM1 in a batch culture was conducted. The PKC was subjected to treatment with acids (sulphuric and hydrochloric acids), alkali (sodium hydroxide and alkaline peroxide), enzymatic hydrolysis, and hydrothermal treatment (in autoclave). The sulphuric acid-treated PKC (2% SAPKC) method produced the highest concentration of reducing sugars (30 g/L) compared with the other methods applied. The results showed that increasing the concentration of H2SO4 up to 3% decreased the amounts of generated reducing sugars to 20.4 g/L, which is about 32% less. The fermentation of 1%, 2%, and 3% SAPKC resulted in the production of ABE of 1.07, 5.72, and 3.48 g/L, respectively. This study showed that the pretreatment of PKC improved the content of fermentable sugars and subsequently enhanced the production of ABE by C. acetobutylicum YM1. This study also revealed that PKC can be regarded as a potentially low cost substrate for ABE fermentation.

The anaerobic production of biohydrogen from different pretreated agroindustrial wastes, including rice bran (RB), de-oiled RB (DRB), sago starch (SS), and palm oil mill effluent (POME) via Clostridium saccharoperbutylacetonicum N1-4 was investigated in a batch culture system at 30 °C and a pH of 6.2. A yield of 7627, 6995, and 6,363 mL H2/L was obtained from H2SO4 (1 %)-treated DRB (10 %), enzymatically hydrolyzed DRB (10 %) and HCl (1 %)-treated DRB (10 %), respectively; however, untreated DRB (10 %) was able to produce only 3,286 mL H2/L. A strategic treatment of RB (10 %) with HCl (1 %) followed by enzymatic hydrolysis could produce 3,172 mL H2/L. An enzymatically hydrolyzed mixture of each POME and SS (5 %) produced 3,474 mL H2/L, and a remarkable enhancement of H2 production (7,020 mL H2/L) was achieved when the same mixture was subjected to XAD-4 resin treatment. In contrast, the enzymatically hydrolyzed SS (5 %) could produce only 4,628 mL H2/L. Conclusively, it can be stated that agricultural wastes have a potential as substrates for biohydrogen production and that pretreatment with C. saccharoperbutylacetonicum N1-4 can contribute positively to enhancing the production.

The interaction between sucrose, yeast extract and initial pH was investigated to optimize critical medium components for mycelium biomass and production of exopolysaccharide (EPS) of Lentinus squarrosulus using Response Surface Methodology (RSM). A central composite design (CCD) was applied and a polynomial regression model with quadratic term was used to analyse the experimental data using analysis of variance (ANOVA). ANOVA analysis showed that the model was very significant (p Lentinus squarrosulus are as follows: sucrose concentration 114.61 g/L, yeast extract 1.62 g/L and initial pH of 5.81; sucrose concentration 115.8 g/L, yeast extract of 3.39 g/L and initial pH of 6.44 respectively.

Catalytic depolymerization of mannan composition of palm kernel cake (PKC) by mannanase was optimized to enhance the release of mannan-derived monomeric sugars for further application in acetone-butanol-ethanol (ABE) fermentation. Efficiency of enzymatic hydrolysis of PKC was studied by evaluating effects of PKC concentration, mannanase loading, hydrolysis pH value, reaction temperature and hydrolysis time on production of fermentable sugars using one-way analysis of variance (ANOVA). The ANOVA results revealed that all factors studied had highly significant effects on total sugar liberated (P0.01). The optimum conditions for PKC hydrolysis were 20% (w/v) PKC concentration, 5% (w/w) mannanase loading, hydrolysis pH 4.5, 45°C temperature and 72h hydrolysis time. Enzymatic experiments in optimum conditions revealed total fermentable sugars of 71.54±2.54g/L were produced including 67.47±2.51g/L mannose and 2.94±0.03g/L glucose. ABE fermentation of sugar hydrolysate by Clostridium saccharoperbutylacetonicum N1-4 resulted in 3.27±1.003g/L biobutanol.

Palm oil mill effluent (POME) was used as an acetone–butanol–ethanol (ABE) fermentation medium using Clostridium saccharoperbutylacetonicum N1-4. Various pretreatment methods were applied on POME to increase the amount of fermentable sugars leading to enhanced ABE production. Sulfuric acid-treated POME (SA-POME) method was found to give the highest yield of total reducing sugars (glucose, cellobiose, xylose, and arabinose) as compared to other pretreatment methods. An increment in the concentration of H2SO4 from 1 to 2% resulted in the enhanced release of reducing sugars (18.3, 26.3 g/L, respectively). However, the treatment of POME with 3% H2SO4, decreased the reducing sugars to 21.6 g/L and consequently, the total ABE production was also reduced. The highest yield of ABE was observed from a culture grown with POME treated by 1% H2SO4. The total ABE production from 1, 2, and 3% SA-POME was obtained as 2.2, 0.45, and 0.41 g/L, respectively. Although, enzymatically treated POME (EH-POME) could produce 4.42 g/L glucose, sulfuric acid treatment (1%) was able to liberate only 1.76 g/L glucose, ABE production was higher when 1% SA-POME was used. Low yield of ABE from enzymatically treated POME can be attributed to the production of some inhibitors during hydrolysis of POME. When EH-POME was treated with XAD-4 resin to nullify the inhibitors, the production of ABE was increased to 4.29 g/L, and ABE yield was also increased to 0.29 g/g. In conclusion, enzymatic hydeolysis of POME followed by elution to XAD-4 column can be proposed as the best pretreatment method for highest productivity of ABE. It was found that addition of P2 medium to the POME hydrolysates was able to improve the production of butanol except in raw POME and sulfuric acid hydrolysates.

Acetone–butanol–ethanol (ABE) was produced in Clostridium saccharoperbutylacetonicum N1-4 using sago starch as a substrate, and the effects of nutrient supplementation on ABE production were studied. Using sago starch as a substrate led to higher butanol production in C. saccharoperbutylacetonicum N1-4 when compared to other starchy materials as substrates. TYA medium supplemented with sago starch led to enhanced ABE and butanol production; however, P2 medium improved ABE production more than TYA medium. The highest ABE and butanol production was achieved with P2 medium supplemented with 70 g/L of sago starch. Using these fermentation conditions, ABE and butanol were produced at 16.65 and 9.83 g/L, respectively, and productivity was 0.15 g/L h for ABE and 0.09 g/L h for butanol. Using P2 medium supplemented with either 50 g/L enzymatically hydrolyzed sago starch or 70 g/L sago starch without hydrolysis, 9.81 and 9.83 g/L butanol were produced, respectively. These results reveal the importance of media formulation in the biobutanol fermentation of sago starch by C. saccharoperbutylacetonicum N1-4.

This study was designed to investigate the ability of Clostridium saccharoperbutylacetonicum N1-4 to produce butanol in a limited nutrient medium using mixtures of glucose and butyric acid as substrates. Specific combinations of glucose and butyric acid were found to influence the enhancement and retardation of butanol production as well as the reduction and modulation of the number of bacterial cells. Increasing the butyric acid concentration leads to the inhibition of bacterial growth, whereas the presence of (0–5 g/L) butyric acid and (0–10 g/L) glucose enhances the butanol production. The combination of 5 g/L butyric acid with 5 and 10 g/L of glucose was found to be the most suitable, but the use of glucose at concentrations greater than 10 g/L shifted the optimal butyric acid concentrations to 10 and 15 g/L for maximum butanol production signifying the requirement of a specific combination of glucose and butyric acid for enhanced butanol production in the fermentation process. C. saccharoperbutylacetonicum N1-4 demonstrated the ability to produce butanol in the absence of glucose, but no acetone or ethanol was produced under these conditions, reflecting the nature of the pathways involved in the production of butanol using only butyric acid. Ten grams per litre of butyric acid was found able to produce 13 g/L of butanol in the presence of 20 g/L of glucose, and 0.7 g/L butanol was produced in the absence of glucose. This study indicates the importance of the glucose to butyric acid ratio to the enhancement of butanol production.

A new isolate of the solvent-producing Clostridium acetobutylicum YM1 was used to produce butanol in batch culture fermentation. The effects of glucose concentration, butyric acid addition and C/N ratio were studied conventionally (one-factor-at-a-time). Moreover, the interactions between glucose concentration, butyric acid addition and C/N ratio were further investigated to optimize butanol production using response surface methodology (RSM). A central composite design was applied, and a polynomial regression model with a quadratic term was used to analyze the experimental data using analysis of variance (ANOVA). ANOVA revealed that the model was highly significant (p

In this study investigation was made to evaluate the effects of different algal media components to get optimized cell count of Scenedesmus dimorphus . Five different fresh water algal media such as Bold’s Basal Medium (BBM), M4N medium, BG-11 medium, N-8 medium and M-8 medium were used for culturing S. dimorphus in flask culture. A set of environmental factors including light, temperature, air flow rate and nutritional components was standardized to obtain the highest productivity of 0.1406 g/L with specific growth rate of 0.10483/day. This study designates the bold basal medium as advantageous one for S. dimorphus and also reveals that production of metabolites by the same algal strain depends mostly on the nature of constituents of media and might have different influence on the pH. Keywords: Scenedesmus dimorphus , bold basal medium, algal growth African Journal of Biotechnology , Vol 13(16), 1714-1720

In this study, three factors (fructose concentration, agitation speed and monosodium glutamate (MSG) concentration) were optimized to enhance DHA production by Schizochytrium SW1 using response surface methodology (RSM). Central composite design was applied as the experimental design and analysis of variance (ANOVA) was used to analyze the data. The experiments were conducted using 500 mL flask with 100 mL working volume at 30°C for 96 hours. ANOVA analysis revealed that the process was adequately represented significantly by the quadratic model (p

Palm kernel cake (PKC) was used for biobutanol production by Clostridium saccharoperbutylacetonicum N1-4 in acetone-butanol-ethanol (ABE) fermentation. PKC was subjected to acid hydrolysis pretreatment and hydrolysates released were detoxified by XAD-4 resin. The effect of pH, temperature and inoculum size on butanol production was evaluated using an empirical model. Twenty ABE fermentations were run according to an experimental design. Experimental results revealed that XAD-4 resin removed 50% furfural and 77.42% hydroxymethyl furfural. The analysis of the empirical model showed that linear effect of inoculums size with quadratic effect of pH and inoculum size influenced butanol production at 99% probability level (P

Increasing demand of energy and awareness about environmental pollution has led to increase interest in alternative, clean and renewable energy sources. Biobutanol is considered as the candidate liquid biofuel to replace gasoline. In this study, the capability of a newly isolated strain of local Clostridium acetobutylicum YM1 was tested to produce biobutanol in batch fermentation. Various culture conditions including glucose concentration, initial pH, incubation temperature and inoculum size were investigated for their effects on production of biobutanol using strain YM1. The results showed that the optimal biobutanol production was obtained at glucose concentration 50 g/L, initial pH 6.2, temperature 30°C and inoculum size 10%. These results show that C. acetobutylicum YM1 as a mesophilic bacterium is a potential candidate for biobutanol production.

A Plackett-Burman design was used to pre-optimize the medium composition for biobutanol production using a unique isolate of solvent-producing Clostridium YM1. Various nutrient factors affecting biobutanol production were screened using the Plackett-Burman design. These factors included: glucose, tryptone, yeast extract, peptone, ammonium acetate, KH2PO4, K2HPO4, MgSO4, FeSO4, Na2CO3, and NaCl. The results were analyzed by an analysis of variance (ANOVA), which showed that glucose, tryptone, yeast extract, peptone, K2HPO4, Na2CO3, and MgSO4 had significant effects on biobutanol production. However, ammonium acetate, KH2PO4, and FeSO4 had insignificant effects. The established model from the ANOVA analysis had a significant value of Pmodel>F = 0.0245 and an R2 value of 0.999. The estimated maximum biobutanol production was 9.01 g/L, whereas the optimized medium produced 10.93 g/L of biobutanol.

Rice bran (RB) and de-oiled rice bran (DRB) have been treated and used as the carbon source in acetone–butanol–ethanol (ABE) production using Clostridium saccharoperbutylacetonicum N1-4. The results showed that pretreated DRB produced more ABE than pretreated RB. Dilute sulfuric acid was the most suitable treatment method among the various pretreatment methods that were applied. The highest ABE obtained was 12.13 g/L, including 7.72 g/L of biobutanol, from sulfuric acid. The enzymatic hydrolysate of DRB (ESADRB), when treated with XAD-4 resin, resulted in an ABE productivity and yield of 0.1 g/L h and 0.44 g/g, respectively. The results also showed that the choice of pretreatment method for RB and DRB is an important factor in butanol production.

The green microalgae Haematococcus pluvialis is one of the most beneficial microalgae due to its production of astaxanthin that has great commercial interest because of its antioxidant properties. A two level factorial design (2LFD) was used to pre-optimize conditions to grow H. pluvialis. The variables involved were pH, inoculum size, temperature and presence or absence of light. The results were analyzed by analysis of variance (ANOVA). ANOVA analysis showed that inoculum size of 40%, temperature of 30oC and presence of light had significant effects on H. pluvialis growth whereas production pH had insignificant effect. The established model from the ANOVA analysis had a significant value with Pmodel > F = 0.0074 and the R² value of 0.9989. The expected growth was 1.08879 (Table 5) and the optimized growth was 1.178 (Table 5).