Alkali-treated Sugarcane Bagasse Research Articles

Isolation and Characterization of Bacteria from Natural Hot Spring and Insights into the Thermophilic Cellulase Production.

A thermophilic cellulase-producing bacterium,Bacillus velezensisstrain MRC 5958, from Bakra natural hot Springs, India was characterized through genome sequencing. It has a genome size of 4,467,129bp and a GC content of 45.7%. A cellulase purified from its fermentation broth has a molecular weight of about 18kDa. The optimum temperature and pH for carboxymethyl cellulase activity were at 55°C and pH ~ 7.0. The enzyme is stable over a wide range of temperatures from 30°C to 70°C with maximum activity observed at 48h of incubation. The strain produces cellulase on alkali-treated sugarcane bagasse, rice straw, rice husk, rice bran, and sawdust. The sugarcane bagasse exhibited the most effective carbon source for cellulase production at (85 U/ml) followed by rice bran (68 U/ml), rice husk (60 U/ml), rice straw (48 U/ml), and sawdust (39 U/ml). Therefore, this strain can be a potential thermostable cellulase-producing candidate for converting the waste biomass into biofuel and other industrial enzymes.

A sustainable process for co-production of xylooligosaccharides and ethanol from alkali treated sugarcane bagasse: A strategy towards waste management

Present study aims at sustainable utilization of sugarcane bagasse (SCB) for production of valuable prebiotic xylooligosaccharides (XOS) along with second generation ethanol. Fractionation of SCB into hemicellulose rich liquid fraction and cellulose rich solid residue was achieved using alkaline treatment. Carbohydrate rich precipitate obtained from liquid fraction was utilized for XOS production using inhouse produced endoxylanase. XOS production from SCB xylan was optimized by employing response surface methodology. Under optimized conditions, maximum XOS yield was 227.72 mg/g of carbohydrate rich precipitates. The solid residue obtained after alkaline pretreatment was used for ethanol fermentation by prehydrolysis and simultaneous saccharification and fermentation (P-SSF) process using cellulolytic enzyme cocktail and Saccharomyces cerevisiae SM1. Maximum ethanol concentration, productivity and yield were 79.76 ± 0.16 g/L, 0.83 g/L/h and 69.38%, respectively by employing P-SSF process. Based on the experimental data it can be predicted that bioconversion of 100 g raw SCB can yield 6.26 g of XOS (DP 2-DP 5), 15.95 g ethanol and 1.44 g of xylitol. Present investigation reports an integrated process for effective bioconversion of SCB into value added products by maximum utilization of cellulosic and hemicellulosic fractions simultaneously using indigenously produced fungal enzymes.

Wastes recycling of non-sterile cellulosic ethanol production from low-temperature pilot-scale enzymatic saccharification of alkali-treated sugarcane bagasse

High energy consumption has been one of bottlenecks for bioconversion of lignocellulose into biofuels and biochemicals. A self-designed pilot-scale device with recycling of black liquor (BL) and waste washing water (WWW) was constructed to conduct low-temperature pretreatment and high-solid enzymatic hydrolysis of sugarcane bagasse (SCB) at ordinary atmospheric pressure. Results showed that enzymatic hydrolysis of WWW-washed BL-WWW-NaOH-treated SCB at 30% solid concentration for 72 h achieved 91.59 g/L glucose with glucan conversion of 70.94%. The pretreatment unit shared only 19.68%–22.43% of total energy consumption and 8.32%–8.81% of total cost. The non-sterile enzymatic hydrolysate could be directly fermented by BL-adapted yeasts to maximally produce 44.82 g/L ethanol at 48 h, while the sterile hydrolysate could not be fermented. 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one, furancarboxaldehyde and 5-hydroxymethylfurfural might be the dominant inhibitors in the sterile enzymatic hydrolysate for ethanol production. Finally, a low-emission strategy for cellulosic ethanol production with low energy consumption was proposed.

Biochar derived from mild temperature carbonization of alkali-treated sugarcane bagasse for efficient adsorption to organic and metallic pollutants in water

Biochar derived from mild temperature carbonization of alkali-treated sugarcane bagasse for efficient adsorption to organic and metallic pollutants in water

Characterization of post-consumer HDPE/sugarcane bagasse biocomposites

The enormous production of plastic wastes has gained a huge attraction of researchers in the development of eco-friendly biocomposite materials with the adoption of polymer recycling or reusing. This paper was aimed to investigate the influence of light fiber modification and fiber loadings (5–15 wt%) on the thermal, mechanical and physical properties of post-consumer high-density polyethylene (pHDPE)/sugarcane bagasse (SB) biocomposites. Three types of SB fibers were used, namely raw, washed and alkali-treated SB with sodium hydroxide. These coupling agent-free biocomposites were prepared via extrusion and followed by hot/cold pressing. Based on thermogravimetric analysis results, the thermal stability of biocomposites was not remarkably affected by the both fiber types and loading, however, the influence on the residues left after decomposition was shown. By incorporating raw SB onto pHDPE matrix without coupling agent, tensile strength (14.0–16.4 MPa) decreased but it was recovered upon alkali treatment (only for 5 wt% at 20.8 MPa) which was increased by 12% as compared to neat matrix (18.5 MPa). Interestingly, the stiffness of biocomposites increased linearly with fiber loading, as indicated by increment of experimental Youngs modulus results up to 515.5 MPa than that of pHDPE (302.2 MPa). As compared to raw SB fiber biocomposite, the alkali-treated biocomposite exhibited the lowered water absorption percentages of <2% weight gain after 48 h immersion.

Assembling mini-xylanosomes with Clostridium thermocellum XynA, and their properties in lignocellulose deconstruction

Lignocellulose is a prominent source of carbohydrates to be used in biorefineries. One of the main challenges associated with its use is the low yields obtained during enzymatic hydrolysis, as well as the high cost associate with enzyme acquisition. Despite the great attention in using the fraction composed by hexoses, nowadays, there is a growing interest in enzymatic blends to deconstruct the pentose-rich fraction. Among the organisms studied as a source of enzymes to lignocellulose deconstruction, the anaerobic bacterium Clostridium thermocellum stands out. Most of the remarkable performance of C. thermocellum in degrading cellulose is related to its capacity to assemble enzymes into well-organized enzymatic complexes, cellulosomes. A mini-version of a cellulosome was designed in the present study, using the xylanase XynA and the N-terminus portion of scaffolding protein, mCipA, harboring one CBM3 and two cohesin I domains. The formed mini-xylanosome displayed maximum activity between 60 and 70 °C in a pH range from 6 to 8. Although biochemical properties of complexed/non-complexed enzymes were similar, the formed xylanosome displayed higher hydrolysis at 60 and 70 °C for alkali-treated sugarcane bagasse. Lignocellulose deconstruction using fungal secretome and the mini-xylanosome resulted in higher d-glucose yield, and the addition of the mCipA scaffolding protein enhanced cellulose deconstruction when coupled with fungal enzymes. Results obtained in this study demonstrated that the assembling of xylanases into mini-xylanosomes could improve sugarcane deconstruction, and the mCipA protein can work as a cellulose degradation enhancer.

A Comparison of the Digestibility of Two Complete Rations Containing Either Raw or Alkali-Treated Sugarcane Bagasse

Two successive digestibility trials were conducted employing four Holstein steers and 8-day total fecal collection periods. Both rations studied had the same basic formula, differing only in that one contained raw bagasse, and the other, bagasse treated in a 2-percent NaOH solution. Feed intakes were restricted to 97 g. (about 83 g. of DM) per kg. of metabolic body weight. The mean apparent digestion coefficients determined in the treated-bagasse and raw-bagasse rations, respectively, were as follows: DM, 68.6 and 55.7; OM, 76.1 and 62.0; CP, 79.6 and 71.0; EE, 86.4 and 83.0; CF, 67.9 and 37.5; NFE, 77.6 and 64.6; TDN, 67.4 and 55.8; and calories, 74.0 and 58.9. The former ration contained 2.78 and the latter 2.27 Meal, of DE per kg. of DM. Excluding EE, all of these mean differences between rations were statistically significant; those for OM, CF, TDN and calories at P &lt; .01, and those for DM, CP, NFE and DE at P &lt; .05. Single samples of alkali-treated and raw bagasse were found to contain the following percentages: neutral-detergent fiber, 93.2 and 84.2; acid-detergent fiber, 75.6 and 58.0; lignin, 12.0 and 11.3; silica, 0.6 and 5.4; and in vitro DM digestibility, 51.1 and 31.9. The latter criterion was found to be 66.1 and 52.0 in single samples of the complete rations containing treated and raw bagasse, respectively.

Reinforcement of polypropylene with alkali-treated sugarcane bagasse fibers: Mechanism and consequences

Polypropylene composites were prepared from neat and alkali-treated sugarcane bagasse fibers. The results showed that alkali treatment leads to an increase in composite stiffness and strength. A maximum is achieved in these properties at around 5 wt% NaOH content of the treating solution. The increase in properties was assigned to the improvement in inherent fiber characteristics. Acoustic emission testing and electron microscopy showed that the two main local deformation processes related to the fibers are their fracture and debonding; the latter is accompanied by the shear yielding of the matrix. Increased inherent strength of the fibers results in an increase in the fracture initiation stress and fracture energy of the composites. Interfacial adhesion has a slight effect on stiffness, but more significant on strength and impact resistance. Changing adhesion modifies the relative importance of local deformation processes, the number of debonding events decreases, while fiber fracture increases with increasing adhesion. Increased interfacial adhesion improves stress transfer and the load bearing capacity of the fibers as well, but suppresses matrix yielding. Alkali treatment increases inherent fiber strength, which can be directly correlated with composite strength.

Effect of a Nonionic Surfactant on Enzymatic Hydrolysis of Lignocellulose Based on Lignocellulosic Features and Enzyme Adsorption.

Reduction in the adsorption of cellulase onto lignin has been thought to be the common reason for the improvement of enzymatic hydrolysis of lignocellulose (EHLC) by a nonionic surfactant (NIS). Few research studies have focused on the relationship between lignocellulosic features and NIS for improving EHLC. This study investigated the impact of Tween20 on the enzymatic hydrolysis and enzyme adsorption of acid-treated and alkali-treated sugarcane bagasse (SCB), cypress, and Pterocarpus soyauxii (PS) with and without being ground. After addition of Tween20, the adsorption of cellulase onto unground and ground alkali-treated SCB increased, and the unground acid-treated SCB exhibited little change in adsorption cellulase, while other unground and ground, treated samples showed decreased cellulase adsorption. Tween20 could improve the enzymatic hydrolysis of acid-treated SCB, while it had little influence on the enzymatic hydrolysis of other treated materials. After being ground, both cellulase adsorption and enzymatic hydrolysis of treated lignocelluloses increased, and Tween20 could enhance the enzymatic hydrolysis of acid-treated materials while hardly affected the enzymatic hydrolysis of alkali-treated materials. This indicated that the promotion effect of Tween20 on enzymatic hydrolysis of treated lignocellulose could not be mainly ascribed to the hindrance of Tween20 to cellulase adsorption on lignin but was related to the lignocellulosic features such as hemicellulose removal and surface morphology changes.

Characterization of a thermophilic cellulase from Geobacillus sp. HTA426, an efficient cellulase-producer on alkali pretreated of lignocellulosic biomass.

A themophilic cellulase-producing bacterium was isolated from a hot spring district and identified as Geobacillus sp. HTA426. The cellulase enzyme produced by the Geobacillus sp. HTA426 was purified through ammonium sulfate precipitation and ion exchange chromatography, with the recovery yield and fold purification of 10.14% and 5.12, respectively. The purified cellulase has a molecular weight of 40 kDa. The optimum temperature and pH for carboxymethyl cellulase (CMCase) activity of the purified cellulase were 60°C and pH 7.0, respectively. The enzyme was also stable over a wide temperature range of 50°C to 70°C after 5 h of incubation. Moreover, the strain HTA426 was able to grow and produce cellulase on alkali-treated sugarcane bagasse, rice straw and water hyacinth as carbon sources. Enzymatic hydrolysis of sugarcane bagasse, which was regarded as the most effective carbon source for cellulase production (CMCase activity = 103.67 U/mL), followed by rice straw (74.70 U/mL) and water hyacinth (51.10 U/mL). This strain producing an efficient thermostable cellulose is a potential candidate for developing a more efficient and cost-effective process for converting lignocellulosic biomass into biofuel and other industrial process.

Feasibility of reusing the black liquor for enzymatic hydrolysis and ethanol fermentation

The black liquor (BL) generated in the alkaline pretreatment process is usually thought as the environmental pollutant. This study found that the pure alkaline lignin hardly inhibited the enzymatic hydrolysis of cellulose (EHC), which led to the investigation on the feasibility of reusing BL as the buffer via pH adjustment for the subsequent enzymatic hydrolysis and fermentation. The pH value of BL was adjusted from 13.23 to 4.80 with acetic acid, and the alkaline lignin was partially precipitated. It deposited on the surface of cellulose and negatively influenced the EHC via blocking the access of cellulase to cellulose and adsorbing cellulase. The supernatant separated from the acidified BL scarcely affected the EHC, but inhibited the ethanol fermentation. The 4-times diluted supernatant and the last-time waste wash water of the alkali-treated sugarcane bagasse didn’t inhibit the EHC and ethanol production. This work gives a clue of saving water for alkaline pretreatment.

Characterization of Cellulolytic Extract from Pycnoporus sanguineus PF-2 and Its Application in Biomass Saccharification

The aim of this work was to evaluate the biochemical features of the white-rot fungi Pycnoporus sanguineus cellulolytic complex and its utilization to sugarcane bagasse hydrolysis. When cultivated under submerged fermentation using corn cobs as carbon source, P. sanguineus produced high FPase, endoglucanase, β-glucosidase, xylanase, mannanase, α-galactosidase, α-arabinofuranosidase, and polygalacturonase activities. Cellulase activities were characterized in relation to pH and temperature. β-Glucosidase and FPase activities were higher at 55°C, pH4.5, and endoglucanase activity was higher at 60°C, in a pH range of 3.5-4.0. All cellulase activities were highly stable at 40 and 50°C through 48h of pre-incubation. Crude enzymatic extract from P. sanguineus was applied in a saccharification experiment using acid-treated and alkali-treated sugarcane bagasse as substrate, and the hydrolysis yields were compared to that obtained by a commercial cellulase preparation. Reducing sugar yields of 60.4% and 64.0% were reached when alkali-treated bagasse was hydrolyzed by P. sanguineus extract and commercial cellulase, respectively. Considering the glucose production, it was observed that P. sanguineus extract and commercial cellulase ensured yields of 22.6% and 36.5%, respectively. The saccharification of acid-treated bagasse was lower than that of alkali-treated bagasse regardless of the cellulolytic extract. The present work showed that P. sanguineus has a great potential as an enzyme producer for biomass saccharification.

Bioconversion and saccharification of some lignocellulosic wastes by Aspergillus oryzae ITCC-4857.01 for fermentable sugar production

The recent interest in bioconversion of agricultural and industrial wastes to chemical feedstock has led to extensive studies on cellulolytic enzymes produced by microorganisms. In the present study three lignocellulosic substrates viz. sugarcane bagasse, sawdust and water hyacinth were pre-treated with alkali and enzyme and their effect on bioconversion has been investigated. The ability of selected substrates for induction of cellulase enzyme by A. oryzae ITCC 4857.01 and for the potentiality of the induced enzyme to saccharify the substrates were also assessed. The maximum degree of conversion of substrate (0.415%) and improved specific substrate consumption (0.99 g substrate/g dry biomass) was exhibited in sugarcane bagasse after alkali treatment at 96 hrs. Both alkali-treatment and enzyme-treatment, water hyacinth was the best for cellulase induction and showed maximum endoglucanase activity of 11.42 U/ml. Reducing sugar yield ranged from 1.12 mg/ml for enzyme treated sawdust at 48 hrs to 7.53 mg/ml for alkali treated sugarcane bagasse at 96 hrs. Alkali-treated sugarcane bagasse gave the highest saccharification rate of 9.03% after 96 hrs. The most resistant substrate was sawdust which produced 5.92% saccharification by alkaline treatment. The saccharification of lignocellulosic substrates by enzyme produced by A. oryzae ITCC 4857.01 indicates the enzymes specificity towards the substrates. The use of such enzyme in lingo-cellulose hydrolysis will lead to efficient conversion of cellulose materials to other important products.

Saccharification of sugar-cane bagasse with enzymes from Aspergillus ustus and Trichoderma viride

Enzymic saccharification of alkali-treated sugar-cane bagasse was improved when a mixture of cellulases obtained from Aspergillus ustus and Trichoderma viride was used. Ninety per cent conversion was achieved when the substrate concentration was 8% suspended in 0.1 m citrate buffer and the enzyme dose was 1.0 U ml −1. The optimum reaction temperature was 50°C and the period of hydrolysis was 72 h. Glucose and xylose were the main products of hydrolysis and they were found in the ratio of 3 : 1. No cellobiose was detected in the hydrolysate.

Sugarcane Silage, Sodium Hydroxide- and Steam Pressure-Treated Sugarcane Bagasse, Corn Silage, Cottonseed Hulls, Sodium Bicarbonate, and Aspergillis oryzae Product in Complete Rations for Lactating Cows

Five experiments compared silages, by-product roughages, and added sodium bicarbonate. Thirty-four cows were fed diets containing 1) 30% cottonseed hulls, 2) corn silage to supply 25% of dry matter intake from nongrain portion, 3) alkali-treated sugarcane bagasse silage, or 4) sugarcane silage both to supply 25% of dry matter intake. Only dry matter intake differed for diets 1 and 2 which excelled 3 and 4 for daily dry matter intake, milk yield, and protein percent. With 36 cows, sugarcane silage, enzyme-treated sugarcane silage, nongrain portion of corn silage, and pelleted cottonseed hulls with sodium bicarbonate (0 or 1%) and an enzyme product from Aspergillus oryzae (0 or 56.7 g/day) were compared. Milk yield was decreased and fat percent increased by silage compared with pelleted cottonseed hulls. Bicarbonate increased milk fat percent and fat-corrected milk in silage-containing rations. For the effect of sodium bicarbonate in early lactation, 36 cows were in a continuous feeding trial of corn silage, cottonseed hulls, or steam pressure-treated sugarcane bagasse, with sodium bicarbonate (0 or 170 g/cow per day). Lactation curves for feed intake, milk yield, and milk fat percent showed no effects of sodium bicarbonate. Cottonseed hull diets excelled corn silage diets. For the same cows and diets plus additional forms of steam pressure-treated bagasse (pelleted and wetter), bicarbonate was detrimental to feed intake and milk yield in pelleted bagasse diets but tended to be beneficial to milk yield in corn silage. Four groups of cows (152 cows/group) receiving 0 or 150g sodium bicarbonate in a corn silage-based ration for 30 days did not differ in a field study.

Effect of nutritional factors on cellulase enzyme and microbial protein production by Aspergillus terreus and its evaluation

The biomass yield, cellulolytic activity, and protein recovery using Aspergillus terreus GN1 with alkali-treated sugarcane bagasse was studied using different levels (250-600 mg of N/L of broth) of organic and inorganic nitrogen sources. e.g., cattle urine, urea, cornsteep liquor, ammonium sulfate, ammonium nitrate, ammonium iron sulfate, ammonium chloride, and sodium nitrate. Among different levels of alkali-treated bagasse substrate concentrations (0.5-4.0% w/v) tested, 1.0% substrate yielded the highest crude protein content, protein recovery, and cellulolytic activity. The biomass recovery with 1.0% substrate ranged from 290-380 mg/500 mg bagasse substrate in a 50-mL broth with a nitrogen level of 250-600 mg of N/L in all the sources except ammonium iron sulfate, which yielded 402-439 mg/500 mg bagasse substrate. However, crude protein content of biomass obtained with an ammonium iron sulfate nitrogen source was the lowest. Cornsteep liquor nitrogen source at the rate of 600 mg of N/L yielded the maximum crude protein of 32.9%, protein recovery of 22.2 g/100 g of bagasse, and carboxymethyl cellulase and filter paper enzyme activities of 1.1 and 0.09 units/mL, among the organic and inorganic nitrogen sources studied. In general, the organic nitrogen sources and inorganic nonammonium nitrogen sources were utilized preferentially for protein production over the inorganic ammonium nitrogen sources. The fermentation time required under optimum cultural and nutritional conditions for A. terreus GN1 was also evaluated. The crude protein content of the biomass increased gradually up to the seventh day of fermentation, but the protein recovery rate was high up to two or three days. It was observed that the cellulose utilization rate increased after an initial lag of one day up to the third day and gradually increased further, which corresponded positively with protein content, biomass protein recovery, and cellulase enzyme activity. On the seventh day of fermentation, the crude protein content, biomass protein recovery, water-soluble carbohydrate, bagasse cellulose utilization, CMCase, and FPase activities were 32.8%, 20.1 g/100 g of bagasse, 6.2%, 82.7%, 1.0. and 0.08 U/mL, respectively. The final biomass recovered contained 32.8% crude protein content and had an in vitro rumen digestibility (IVRD) coefficient of 68.8%. The biomass contained almost all the essential and nonessential amino acids and was comparable with FAO reference protein. It is concluded that a fermentation time of 72 h gave a faster rate of protein production of 16.9 g/100 g of bagasse with 69.8% bagasse cellulose utilization with 76.0% IVRD. and contained almost all the essential and nonessential amino acids.