Investigating the influence of pH,temperature and agitation speed on yellow pigment production by Penicillium aculeatum ATCC 10409

In this study, the combined effect of pH, temperature and agitation speed on yellow pigment production and mycelial growth of Penicillium aculeatum ATCC 10409 was investigated in whey media. Different pH levels (5, 6.5 and 8), temperatures (25, 30 and 35°C) and agitation speed levels (100 and 150 rpm) were tested to determine the best conditions to produce a fungal yellow pigment under submerged fermentation. The best production of yellow pigment (1.38 g/L) was obtained with a pH value of 6.5, a temperature of 30°C and an agitation speed of 150 rpm. In contrast, the maximal biomass concentration (11.12 g/L) was obtained at pH value of 8, a temperature of 30°C and an agitation speed of 100 rpm. These results demonstrated that biomass and yellow pigment production were not directly associated. The identification of the structure of unknown P. aculeatum yellow pigment was detected using UV absorption spectrum and FT-IR spectroscopy.     

A Study of the Effects of Aeration and Agitation on the Properties and Production of Xanthan Gum from Crude Glycerin Derived from Biodiesel Using the Response Surface Methodology

The effects of aeration and agitation on the properties and production of xanthan gum from crude glycerin biodiesel (CGB) by Xanthomonas campestris mangiferaeindicae 2103 were investigated and optimized using a response surface methodology. The xanthan gum was produced from CGB in a bioreactor at 28 °C for 120 h. Optimization procedures indicated that 0.97 vvm at 497.76 rpm resulted in a xanthan gum production of 5.59 g L^?1 and 1.05 vvm at 484.75 rpm maximized the biomass to 3.26 g L^?1. Moreover, the combination of 1.05 vvm at 499.40 rpm maximized the viscosity of xanthan at 0.5 % (m/v), 25 °C, and 25 s^?1 (255.40 mPa s). The other responses did not generate predictive models. Low agitation contributed to the increase of xanthan gum production, biomass, viscosity, molecular mass, and the pyruvic acid concentration. Increases in the agitation contributed to the formation of xanthan gum with high mannose concentration. Decreases in the aeration contributed to the xanthan gum production and the formation of biopolymer with high mannose and glucose concentrations. Increases in aeration contributed to increased biomass, viscosity, and formation of xanthan gum with greater resistance to thermal degradation. Overall, aeration and agitation of CGB fermentation significantly influenced the production of xanthan gum and its properties.     

Production and Characterization of a Milk-clotting Protease Produced in Submerged Fermentation by the Thermophilic Fungus Thermomucor indicae-seudaticae N31

Proteases are some of the most important industrial enzymes, and one of their main applications is for the production of cheese in the dairy industry. Due to a shortage of animal rennet, microbial coagulant proteases are being sought. In this work, the production of microbial rennet from Thermomucor indicae-seudaticae N31 was studied in submerged fermentation. The best enzyme production was obtained in a fermentation medium containing 4 % wheat bran as the substrate in 0.3 % saline solution, incubated for 72 h at 45 °C and 150 rpm. The value of the milk clotting activity (MCA) was 60.5 U/mL, and the ratio to proteolytic activity (MCA/PA) was 510. The crude enzyme showed optimum pH at 5.5 and two peaks of optimum temperature (MCA at 65 °C and PA at 60 °C). The MCA was stable in the pH range 4.0–4.5 for 24 h and up to 55 °C for 1 h. It was stable during storage at different temperatures (?20 to 25 °C) for 10 weeks. Based on these results, we conclude that microbial rennet from T. indicae-seudaticae N31 produced by submerged fermentation showed good prospects of replacing traditional rennet.     

A New Temperature Control Shifting Strategy for Enhanced Triterpene Production by <Emphasis Type="Italic">Ganoderma lucidum</Emphasis> G0119 Based on Submerged Liquid Fermentation

Temperature control is a very important factor on triterpene productivity in submerged liquid fermentation. Temperature effects from 23 to 32 °C on triterpene production by Ganoderma lucidum G0119 were investigated in 6-L stirred fermentor. Logistic and Luedeking-Piret equations were used to estimate the mycelial growth and triterpene production kinetics by regression analysis. On that basis, a temperature-shifting fermentation control strategy was established. From 0 to 61 h, culturing was performed at 32 °C to get high specific mycelial growth rate. Between 62 and 127 h, the temperature was decreased stepwise from 31 to 30 °C to maintain high triterpene productivity. After 128 h, temperature was maintained at 29 °C to minimize triterpene production inhibition and sustain high productivity. Elevated triterpene level (0.269 g L^?1), yield (0.0101 g g^?1), and productivity (0.00207 g (L h)^?1) were achieved representing 27.32, 13.94, and 37.11 % higher than submerged liquid fermentation at constant temperature of 29 °C, respectively, feasible for the industrial scale.     

Enhanced Fumaric Acid Production from Brewery Wastewater and Insight into the Morphology of Rhizopus oryzae 1526

The present work explores brewery wastewater as a novel substrate for fumaric acid production employing the filamentous fungal strain Rhizopus oryzae 1526 through submerged fermentation. The effects of different parameters such as substrate total solid concentrations, fermentation pH, incubation temperature, flask shaking speed, and inoculum size on the fungal morphologies were investigated. Different morphological forms (mycelium clumps, suspended mycelium, and solid/hairy pellets) of R. oryzae 1526 were obtained at different applied fermentation pH, incubation temperature, flask shaking speed, and inoculum size. Among all the obtained morphologies, pellet morphology was found to be the most favorable for enhanced production of fumaric acid for different studied parameters. Scanning electron microscopic investigation was done to reveal the detailed morphologies of the pellets formed under all optimized conditions. With all the optimized growth conditions (pH 6, 25 °C, 200 rpm, 5 % (v/v) inoculum size, 25 g/L total solid concentration, and pellet diameter of 0.465?±?0.04 mm), the highest concentration of fumaric acid achieved was 31.3?±?2.77 g/L. The results demonstrated that brewery wastewater could be used as a good substrate for the fungal strain R. oryzae 1526 in submerged fermentation for the production of fumaric acid.     

Development of Batch and Continuous Processes on Biodiesel Production in a Packed-Bed Reactor by a Mixture of Immobilized Candida rugosa and Rhizopus oryzae Lipases

In this study, transesterification and esterification were investigated in batch and continuous process using immobilized Candida rugosa and Rhizopus oryzae lipases. In the case of batch process, stepwise reaction method was investigated to prevent the lipase deactivation. Reaction conditions were as follows: temperature, 45 °C; agitation speed, 250 rpm; enzyme concentration, 20%; and water contents 10%. And then, conversion yield was 98.33% at 4 h. In the case of continuous process, circulation and long-term continuous system were investigated for development of efficient mass transfer system. Optimal reaction conditions were as follows: temperature, 45 °C; flow rate, 0.8 mL/min; and water contents, 10%. And then, conversion yield of biodiesel was 97.98% at 3 h. Especially, the maximum conversion yield using a mixture of immobilized lipases exceeded over 90% for 108 h in long-term continuous system under optimal reaction conditions (45 °C; flow rate, 0.8 mL/min; and water contents, 10%). These results should help in determining the best method for the biodiesel production and improving the design and operation of large scale by enzymatic systems.     

Bioethanol Production from Soybean Residue via Separate Hydrolysis and Fermentation

Bioethanol was produced using polysaccharide from soybean residue as biomass by separate hydrolysis and fermentation (SHF). This study focused on pretreatment, enzyme saccharification, and fermentation. Pretreatment to obtain monosaccharide was carried out with 20% (w/v) soybean residue slurry and 270 mmol/L H₂SO₄ at 121 °C for 60 min. More monosaccharide was obtained from enzymatic hydrolysis with a 16 U/mL mixture of commercial enzymes C-Tec 2 and Viscozyme L at 45 °C for 48 h. Ethanol fermentation with 20% (w/v) soybean residue hydrolysate was performed using wild-type and Saccharomyces cerevisiae KCCM 1129 adapted to high concentrations of galactose, using a flask and 5-L fermenter. When the wild type of S. cerevisiae was used, an ethanol production of 20.8 g/L with an ethanol yield of 0.31 g/g consumed glucose was obtained. Ethanol productions of 33.9 and 31.6 g/L with ethanol yield of 0.49 g/g consumed glucose and 0.47 g/g consumed glucose were obtained in a flask and a 5-L fermenter, respectively, using S. cerevisiae adapted to a high concentration of galactose. Therefore, adapted S. cerevisiae to galactose could enhance the overall ethanol fermentation yields compared to the wild-type one.     

Biodiesel Production from Various Oils Under Supercritical Fluid Conditions by Candida antartica Lipase B Using a Stepwise Reaction Method

In this study, we evaluate the effects of various reaction factors, including pressure, temperature, agitation speed, enzyme concentration, and water content to increase biodiesel production. In addition, biodiesel was produced from various oils to establish the optimal enzymatic process of biodiesel production. Optimal conditions were determined to be as follows: pressure 130 bar, temperature 45 °C, agitation speed 200 rpm, enzyme concentration 20%, and water contents 10%. Among the various oils used for production, olive oil showed the highest yield (65.18%) upon transesterification. However, when biodiesel was produced using a batch system, biodiesel conversion yield was not increased over 65%; therefore, a stepwise reaction was conducted to increase biodiesel production. When a reaction medium with an initial concentration of methanol of 60 mmol was used and adjusted to maintain this concentration of methanol every 1.5 h during biodiesel production, the conversion yield of biodiesel was 98.92% at 6 h. Finally, reusability was evaluated using immobilized lipase to determine if this method was applicable for industrial biodiesel production. When biodiesel was produced repeatedly, the conversion rate was maintained at over 85% after eight reuses.     

Effectiveness of Sal Deoiled Seed Cake as an Inducer for Protease Production from Aeromonas sp. S1 for its Application in Kitchen Wastewater Treatment

The present study is an attempt to demonstrate the feasibility of sal (Shorea robusta) deoiled cake—a forest-based industrial by-product—as a cheaper media supplement for augmented protease production from Aeromonas sp. S1 and application of protease in the treatment of kitchen wastewater. Under optimized conditions, protease production could successfully be enhanced to 5.13-fold (527.5 U mL^?1) on using sal deoiled seed cake extract (SDOCE), as medium additive, compared to an initial production of 102.7 U mL^?1 in its absence. The culture parameters for optimum production of protease were determined to be incubation time (48 h), pH (7.0), SDOCE concentration (3 % (v/v)), inoculum size (0.3–0.6 % (v/v)), and agitation rate (100 rpm). The enzyme was found to have an optimum pH and temperature of 8.0 and 60 °C, respectively. The protease preparation was tested for treatment of organic-laden kitchen wastewater. After 96 h of wastewater treatment under static condition, enzyme preparation was able to reduce 74 % biological oxygen demand, 37 % total suspended solids, and 41 % oil and grease. The higher and improved level of protease obtained using sal deoiled seed cake-based media hence offers a new approach for value addition to this underutilized biomass through industrial enzyme production. The protease produced using this biomass could also be used as pretreatment tool for remediation of organic-rich food wastewater.     

High Cell Density Process for Constitutive Production of a Recombinant Phytase in Thermotolerant Methylotrophic Yeast <Emphasis Type="Italic">Ogataea thermomethanolica</Emphasis> Using Table Sugar as Carbon Source

The yeast Ogataea thermomethanolica has recently emerged as a potential host for heterologous protein expression at elevated temperature. To evaluate the feasibility of O. thermomethanolica as heterologous host in large-scale fermentation, constitutive production of fungal phytase was investigated in fed-batch fermentation. The effect of different temperatures, substrate feeding strategies, and carbon sources on phytase production was investigated. It was found that O. thermomethanolica can grow in the temperature up to 40 °C and optimal at 34 °C. However, the maximum phytase production was observed at 30 °C and slightly decreased at 34 °C. The DOT stat control was the most efficient feeding strategy to obtain high cell density and avoid by-product formation. The table sugar can be used as an alternative substrate for phytase production in O. thermomethanolica. The highest phytase activity (134 U/mL) was obtained from table sugar at 34 °C which was 20-fold higher than batch culture (5.7 U/mL). At a higher cultivation temperature of 38 °C, table sugar can be used as a low-cost substrate for the production of phytase which was expressed with an acceptable yield (85 U/mL). Lastly, the results from this study reveal the industrial favorable benefits of employing O. thermomethanolica as a host for heterologous protein production.     

Biopolymer Synthesized by Strains of Xanthomonas sp Isolate from Brazil Using Biodiesel-Waste

The future supplies and usage of glycerol are expected to increase as biodiesel plants increase production, and the output will greatly outpace demand. Biodiesel production has already had a significant impact on the price of refined glycerol. A major concern of glycerol producers is the reduced price of glycerol resulting from the increased production of biodiesel. Some alternative uses for this glycerol that have been investigated are substrates for fermentation process or the production of biosurfactants, fatty acids, biopolymers, and others products. This work had as objective to evaluate two strains of Xanthomonas sp isolate from Brazil for xanthan gum in orbital agitator, analizing the apparent viscosity of aqueous solutions and selecting viscosity. The experiments of xanthan gum production were realized in orbital agitator with 120 rpm agitation, for cells production, and 180rpm, for biopolymer production, under a 28 °C temperature. The rheology of the fermentation broth was analyzed by apparent viscosity and the polymer was recovered with ethanol (1:3, v/v). After its recovery, the productivity evaluation was performed. The productivity were 0.157 and 0.363 gL⁻¹ for C1 and 0.186 and 0.363 gL⁻¹ for C9 to media glycerol or glycerol and sucrose, respectively. The viscosity analysis was performed for aqueous solutions 3%, at 25 °C, the best apparent viscosity was obtained using gum synthesized with glycerol and sucrose (50:50) at 25 °C, 143 mPa.s⁻¹ from Xanthomonas sp C1.     

Selection of a Thermotolerant Kluyveromyces marxianus Strain with Potential Application for Cellulosic Ethanol Production by Simultaneous Saccharification and Fermentation

The development of technologies for cellulosic ethanol production by simultaneous saccharification and fermentation (SSF) depends on the use of microorganisms with high fermentative rates and thermotolerance. In this study, the ability of five Kluyveromyces marxianus strains to produce ethanol from glucose at 45 °C was investigated. The highest fermentative parameters were observed with K. marxianus NRRL Y-6860, which was then further studied. An initial evaluation of the oxygen supply on ethanol production by the selected yeast and a comparison of SSF process from acid pretreated rice straw between K. marxianus NRRL Y-6860 and Saccharomyces cerevisiae at 30 and 45 °C were carried out. Under the lowest evaluated conditions of aeration and agitation, K. marxianus NRRL Y-6860 produced 21.5 g/L ethanol from 51.3 g/L glucose corresponding to Y_P/S of 0.44 g/g and Q_P of 3.63 g/L h. In the SSF experiments, K. marxianus NRRL Y-6860 was more efficient than S. cerevisiae at both evaluated temperatures (30 and 45 °C), attained at the highest temperature an ethanol yield of 0.24 g/g and productivity of 1.44 g/L h.     

The Influence of Initial Xylose Concentration, Agitation, and Aeration on Ethanol Production by Pichia stipitis from Rice Straw Hemicellulosic Hydrolysate

Rice straw hemicellulosic hydrolysate was used as fermentation medium for ethanol production by Pichia stipitis NRRL Y-7124. Shaking bath experiments were initially performed aiming to establish the best initial xylose concentration to be used in this bioconversion process. In the sequence, assays were carried out under different agitation (100 to 200 rpm) and aeration (V _flask/V _medium ratio varying from 2.5 to 5.0) conditions, and the influence of these variables on the fermentative parameters values (ethanol yield factor, Y _P/S; cell yield factor, Y _X/S; and ethanol volumetric productivity, Q _P) was investigated through a 2² full-factorial design. Initial xylose concentration of about 50 g/l was the most suitable for the development of this process, since the yeast was able to convert substrate in product with high efficiency. The factorial design assays showed a strong influence of both process variables in all the evaluated responses. The agitation and aeration increase caused a deviation in the yeast metabolism from ethanol to biomass production. The best results (Y _P/S?= 0.37 g/g and Q _P?=?0.39 g/l.h) were found when the lowest aeration (2.5 V _flask/V _medium ratio) and highest agitation (200 rpm) levels were employed. Under this condition, a process efficiency of 72.5% was achieved. These results demonstrated that the establishment of adequate conditions of aeration is of great relevance to improve the ethanol production from xylose by Pichia stipitis, using rice straw hemicellulosic hydrolysate as fermentation medium.     

Phytosterols Elevation in Bamboo Shoot Residue through Laboratorial Scale Solid-State Fermentation Using Isolated Aspergillus niger CTBU

Aspergillus niger CTBU isolated from local decayed bamboo shoot residue was employed to solid-state fermentation (SSF) of bamboo shoot residue to elevate the content of phytosterols. Strain acclimatization was carried out under the fermentation condition using bamboo shoot as substrate for fermentation performance improvement. The optimal fermentation temperature and nitrogen level were investigated using acclimatized strain, and SSF was carried out in a 500-ml Erlenmeyer flask feeding 300-mg bamboo shoot residue chips under the optimal condition (33 °C and feeding 4 % urea), and 1,186 mg (100 g)^?1 of total phytosterol was attained after 5-day fermentation, in comparison, only 523 mg (100 g)^?1 of phytosterol was assayed in fresh shoots residue. HPLC analysis of the main composition of total phytosterols displays that the types of phytosterols and composition ratio of main sterols keep steady. This laboratorial scale SSF unit could be scaled up for raw phytosterols production from discarded bamboo shoot residue and could reduce its cost.     

Xanthan gum production by Xanthomonas campestris w.t. fermentation from chestnut extract

Xanthomonas campestris w.t. was used for production of xanthan gum in fermentations with chestnut flour for the first time. Fermentations were carried out with either chestnut flour or its soluble sugars (33.5%) and starch (53.6%), respectively, at 28°C and 200 rpm at initial pH 7.0 in flasks. The effect of agitation rate (at 200, 400, and 600 rpm) on xanthan gum production was also studied in a 2-L batch reactor. It was found that xanthan production reaches a maximum value of 3.3 g/100 mL at 600 rpm and 28°C at 45 h.     

Effect of Agitation Rate on Ethanol Production from Sugar Maple Hemicellulosic Hydrolysate by Pichia stipitis

Concentrated dilute acid hydrolysate was obtained from hot water extracts of Acer saccharum (sugar maple) and was fermented to ethanol by Pichia stipitis in a 1.3-L-benchtop bioreactor. The conditions under which the highest ethanol yield was achieved were when the air flow rate was set to 100?cm³ and the agitation rate was set to 150?rpm resulting in an overall mass transfer coefficient (K _L a) of 0.108?min^?1. A maximum ethanol concentration of 29.7?g/L was achieved after 120?h of fermentation; however, after 90?h of fermentation, the ethanol concentration was only slightly lower at 29.1?g/L with a yield of 0.39?g ethanol per gram of sugar consumed. Using the same air flow rate and adjusting the agitation rate resulted in lower ethanol yields of 0.25?g/g at 50?rpm and 0.30?g/g at 300?rpm. The time it takes to reach the maximum ethanol concentration was also affected by the agitation rate. The ethanol concentration continued to increase even after 130?h of fermentation when the agitation rate was set at 50?rpm, whereas the maximum ethanol concentration was reached after only 68.5?h at 300?rpm.     

Production and Characterization of a Halo-, Solvent-, Thermo-tolerant Alkaline Lipase by Staphylococcus arlettae JPBW-1, Isolated from Rock Salt Mine

Studies on lipase production and characterization were carried out with a bacterial strain Staphylococcus arlettae JPBW-1 isolated from rock salt mine, Darang, HP, India. Higher lipase activity has been obtained using 10 % inoculum with 5 % of soybean oil as carbon source utilizing a pH 8.0 in 3 h at 35 °C and 100 rpm through submerged fermentation. Partially purified S. arlettae lipase has been found to be active over a broad range of temperature (30–90 °C), pH (7.0–12.0) and NaCl concentration (0–20 %). It has shown extreme stability with solvents such as benzene, xylene, n-hexane, methanol, ethanol and toluene up to 30 % (v/v). The lipase activity has been found to be inhibited by metal ions of K⁺, Co²⁺ and Fe ²⁺ and stimulated by Mn²⁺, Ca²⁺ and Hg²⁺. Lipase activity has been diminished with denaturants, but enhanced effect has been observed with surfactants, such as Tween 80, Tween 40 and chelator EDTA. The K _m and V _max values were found to be 7.05 mM and 2.67 mmol/min, respectively. Thus, the lipase from S. arlettae may have considerable potential for industrial application from the perspectives of its tolerance towards industrial extreme conditions of pH, temperature, salt and solvent.     

Enzymatic Fractionation of SAA-Pretreated Barley Straw for Production of Fuel Ethanol and Astaxanthin as a Value-Added Co-Product

Barley straw was used to demonstrate an integrated process for production of fuel ethanol and astaxanthin as a value-added co-product. Barley straw was pretreated by soaking in aqueous ammonia using the previously determined optimum conditions, which included 77.6 °C treatment temperature, 12.1 h treatment time, 15 wt% ammonia concentration, and 1:8 solid-to-liquid ratio. In the newly developed process, the pretreated barley straw was first hydrolyzed with ACCELLERASE® XY (a commercial hemicellulase product) to generate a xylose-rich solution, which contained 3.8 g/l glucose, 22.9 g/l xylose, and 2.4 g/l arabinose, with 96 % of the original glucan being left intact. The xylose-rich solution was used for production of astaxanthin by the yeast Phaffia rhodozyma without further treatment. The resulting cellulose-enriched solid residue was used for ethanol production in a fed-batch simultaneous saccharification and fermentation using ACCELLERASE® 1500 (a commercial cellulase product) and the industrial yeast Saccharomyces cerevisiae. At the end of the fermentation, 70 g/l ethanol was obtained, which was equivalent to 63 % theoretical yield based on the glucan content of the solid substrate.     

Regional Differences in Rice Hulls Supply for Bioethanol Production

Agricultural by-products are becoming an attractive substrate for bioethanol production. The aim of this study was to evaluate the effects of regional differences in the rice hulls using Escherichia coli KO11 for bioethanol production. The rice hulls coded Edirne were obtained from Thrace Region, and the rice hulls coded Izmir were obtained from Aegean Region in Turkey. Rice hulls were treated by dilute acid before using them as substrates. The cells were incubated on an orbital shaker at 160 rpm under 30 °C during 96 h of the fermentation period. It was found that the maximum yield of ethanol from sugar (0.44 g ethanol/g reducing sugar) was obtained with the substrate C/N ratio of 29.16 in Izmir medium. The main difference was the dominant carbon source available as a substrate. It was detected that glucose concentration was about 2.5 times higher in Izmir medium, whereas xylose concentration was about two times higher in Edirne medium. The different results obtained with rice hulls from different origins could depend on the type of paddy as well as different cultivation conditions. These findings provide a valuable indicator for identifying suitable agricultural waste materials to be used as substrates for bioethanol production.     

Experimental Investigation and Optimization of Process Variables Affecting the Production of Extracellular Lipase by Kluyveromyces marxianus IFO 0288

In this study, the production and optimization of extracellular lipase from Kluyveromyces marxianus IFO 0288 was investigated by using optimized nutritional and cultural conditions in a yeast medium containing glucose as the carbon source in fully aerobic batch fermentation (150?rpm). The influence of four fermentation parameters (type of lipidic source, initial culture pH, temperature, and length of fermentation) on growth and lipase production was investigated and evaluated using the conventional ??one variable at a time?? approach and response surface methodology. An 18-fold increase in lipase production during 65?h of fermentation was obtained with optimized nutritional (0.5?% olive oil) and cultivation (pH?6.5, 35?°C) conditions by employing the conventional optimization method. By applying the response surface methodology technique the initial pH value of 6.4 and temperature of 32.5?°C were identified as optimal and led to further improvements (up to 18-fold) of extracellular lipase production. The results provide, for the first time, evidence that K. marxianus has the potential to be used as an efficient producer of extracellular lipase with prospective application in a variety of industrial and biotechnological areas.