Statistical optimization for lipase production from solid waste of vegetable oil industry

The production of biofuel using thermostable bacterial lipase from hot spring bacteria out of low-cost agricultural residue olive oil cake is reported in the present paper. Using a lipase enzyme from Bacillus licheniformis, a 66.5% yield of methyl esters was obtained. Optimum parameters were determined, with maximum production of lipase at a pH of 8.2, temperature 50.8°C, moisture content of 55.7%, and biosurfactant content of 1.693?mg. The contour plots and 3D surface responses depict the significant interaction of pH and moisture content with biosurfactant during lipase production. Chromatographic analysis of the lipase transesterification product was methyl esters, from kitchen waste oil under optimized conditions, generated methyl palmitate, methyl stearate, methyl oleate, and methyl linoleate.     

Laccase production in solid‐state and submerged fermentation by Pleurotus ostreatus

A solid‐state fermentation (SSF) system for production of an industrially important enzyme laccase by Pleurotus ostreatus was developed by using potato dextrose yeast extract medium and polyurethane foam as a supporting material. The maximum laccase production in the SSF system was as high as 3×10⁵ U/L. Addition of inducers, such as copper and ferulic acid, further enhanced the laccase production in SSF. Moreover, the time required for the maximum laccase production was reduced to 6 days compared to 10 days reported earlier. The improvement achieved by the SSF system was investigated by comparing it to a submerged fermentation system (SmF), both experimentally and by using a standard theoretical model along with a parameter sensitivity analysis. Laccase production in SSF was found to be twice of that in SmF. One of the main reasons for higher laccase production in SSF compared to SmF was possibly due to the presence of higher proteolytic activity in SmF. Strong proteolytic activity in SmF presumably caused subsequent laccase degradation, which lowered the ultimate laccase production in SmF compared to SSF.     

Improvement of production of citric acid from oil palm empty fruit bunches: Optimization of media by statistical experimental designs

A sequential optimization based on statistical design and one-factor-at-a-time (OFAT) method was employed to optimize the media constituents for the improvement of citric acid production from oil palm empty fruit bunches (EFB) through solid state bioconversion using Aspergillus niger IBO-103MNB. The results obtained from the Plackett–Burman design indicated that the co-substrate (sucrose), stimulator (methanol) and minerals (Zn, Cu, Mn and Mg) were found to be the major factors for further optimization. Based on the OFAT method, the selected medium constituents and inoculum concentration were optimized by the central composite design (CCD) under the response surface methodology (RSM). The statistical analysis showed that the optimum media containing 6.4% (w/w) of sucrose, 9% (v/w) of minerals and 15.5% (v/w) of inoculum gave the maximum production of citric acid (337.94 g/kg of dry EFB). The analysis showed that sucrose (p < 0.0011) and mineral solution (p < 0.0061) were more significant compared to inoculum concentration (p < 0.0127) for the citric acid production.     

Production and optimization of process parameters for alkaline protease production by a newly isolated Bacillus sp. under solid state fermentation

Production of alkaline protease employing the laboratory isolate, Bacillus sp. under solid state fermentation (SSF) was optimized. The effect of wheat bran and lentil husk was examined. Wheat bran showed highest enzyme production. The appropriate incubation time, inoculum size, moisture level and buffer solution level were determined. Maximum yields of 429.041 and 168.640 U g⁻¹ were achieved by employing wheat bran and lentil husk as substrates in 0.1 M carbonate/bicarbonate buffer at pH 10 with 30 and 40% initial moisture level at 24 h. Inoculum size and buffer solution level were found to be 20 and 25% and 0.5:1 for wheat bran and lentil husk, respectively.     

Production of biofuel from waste cooking palm oil using nanocrystalline zeolite as catalyst: process optimization studies

The catalytic cracking of waste cooking palm oil to biofuel was studied over different types of nano-crystalline zeolite catalysts in a fixed bed reactor. The effect of reaction temperature (400-500 °C), catalyst-to-oil ratio (6-14) and catalyst pore size of different nanocrystalline zeolites (0.54-0.80 nm) were studied over the conversion of waste cooking palm oil, yields of Organic Liquid Product (OLP) and gasoline fraction in the OLP following central composite design (CCD). The response surface methodology was used to determine the optimum value of the operating variables for maximum conversion as well as maximum yield of OLP and gasoline fraction, respectively. The optimum reaction temperature of 458 °C with oil/catalyst ratio=6 over the nanocrystalline zeolite Y with pore size of 0.67 nm gave 86.4 wt% oil conversion, 46.5 wt% OLP yield and 33.5 wt% gasoline fraction yield, respectively. The experimental results were in agreement with the simulated values within an experimental error of less than 5%.     

Production of cellulases and xylanase by Aspergillus fumigatus SK1 using untreated oil palm trunk through solid state fermentation

Direct utilization of untreated oil palm trunk (OPT) for cellulases and xylanase production by Aspergillus fumigatus SK1 was conducted under solid-state fermentation (SSF). The highest activities of extracellular cellulases and xylanases were produced at 80% moisture level, initial pH 5.0, 1 × 10⁸ spore/g (inoculum) with 125 μm of OPT as sole carbon source. The cellulases and xylanase activities obtained were 54.27, 3.36, 4.54 and 418.70 U/g substrates for endoglucanase (CMCase), exoglucanase (FPase), β-glucosidase and xylanase respectively. The crude cellulases and xylanase required acidic condition to retain their optimum activities (pH 4.0). Crude cellulases and xylanase were more stable at 40 °C compared to their optimum activities conditions (60 °C for FPase and 70 °C for CMCase, β-glucosidase and xylanase). SDS-PAGE and zymogram analysis showed that Aspergillus fumigatus SK1 could secrete cellulases (endoglucanase, exoglucanase and β-glucosidase), xylanase and protease. Enzymatic degradation of alkaline treated OPT with concentrated crude cellulases and xylanases resulted in producing polyoses.     

Pediocin production by Pediococcus acidilactici in solid state culture on a waste medium: process simulation and experimental results

The production of pediocin by Pediococcus acidilactici was comparatively studied in submerged and solid-state culture, using polyurethane foam particles soaked in commercial (MRS) and waste media with various supplements, where product concentrations were 15 times higher in MRS medium. For the solid state analysis, cultures were treated by successive compression and refilling of tubular minireactors equipped with a piston, without the need for reinoculation. This method was found to be simple, reproducible, and easily controllable, allowing culture productivity to be maintained for long periods of time without alterations in the basic properties of the system. In addition, yields were found to be superior compared to those from submerged culture. The system kinetics were modeled on the basis of widely accepted assumptions with a good fit to the experimental results and observed biomass fluctuations less evident than those predicted by the kinetic model.     

Statistical optimization of enzymatic degradation process for oil palm empty fruit bunch (OPEFB) in rotary drum bioreactor using crude cellulase produced from Aspergillus niger EFB1

Oil palm empty fruit bunch (OPEFB) was pretreated with 2% (v/v) HNO₃ and degraded by Aspergillus niger EFB1 crude cellulase. Through 2 Level Factorial Design (2LFD), it was found that OPEFB concentration, temperature, incubation time, concentration of Tween 80 and agitation speed have significant effect in reducing sugar production. A standard Response Surface Methodology (RSM) design known as Central Composite Design (CCD) was used to optimize the enzymatic degradation condition of OPEFB in rotary drum bioreactor. Reducing sugar level of 1.183 g/L was obtained with the following optimized degradation conditions: 1.95% (w/v) OPEFB, 0.5% (v/v) Tween 80, 55 °C, 87.5 rpm in the incubation period of 3 days and 16 h. The optimal degradation condition improved reducing sugar production by 1.07 fold compared to that before optimization in shake flasks culture. The optimization strategy of enzymatic degradation of OPEFB inside rotary drum bioreactor led to increase in glucose, xylose, arabinose, galactose and mannose production by 3, 2.5, 1.64, 19.37 and 22.52 fold, respectively. The improvement in reducing sugar and polyoses production were comparable with the reduction in OPEFB cellulose and hemicellulose content by 89.32% and 48.17% respectively after enzymatic degradation in optimized condition.     

Utilisation of fruits waste for citric acid production by solid state fermentation

A solid state fermentation method was used to utilise pineapple, mixed fruit and maosmi waste as substrates for citric acid production using Aspergillus niger DS 1. Experiments were carried out in the presence and absence of methanol at different moisture levels. In the absence of methanol the maximum citric acid was obtained at 60% moisture level whereas in the presence of methanol the maximum citric acid was obtained at 70% moisture level. The stimulating effect of methanol was less at lower moisture level. The inhibitory effect of metal ions was also not observed and maximum citric acid yield of 51.4, 46.5 and 50% (based on sugar consumed) was obtained from pineapple, mixed fruit and maosmi residues, respectively.     

Effect of inhibition treatment, type of inocula, and incubation temperature on batch H2 production from organic solid waste

Two types of induction treatments (heat-shock pretreatment, HSP, and acetylene, Ac), inocula (meso and thermophilic) and incubation temperatures (37 and 55 degrees C) were tested according to a full factorial design 2(3) with the aim of assessing their effects on cumulative H(2) production (P(H), mmol H(2)/mini-reactor), initial H(2) production rate (R(i,H), micromol H(2)/(g VS(i) x h)), lag time (T(lag), h), and metabolites distribution when fermenting organic solid waste with an undefined anerobic consortia in batch mini-reactors. Type of inocula did not have a significant effect on P(H), T(lag), and R(i,H) except for organic acids production: mini-reactors seeded with thermophilic inocula had the highest organic acid production. Concerning the induction treatment, it was found that on the average Ac only affected in a positive way the P(H) and T(lag). Thus, P(H) in Ac-inhibited units (6.97) was 20% larger than those in HSP-inhibited units (5.77). Also, Ac favored a shorter T(lag) for P(H) in comparison with HSP (180 vs. 366). Additionally, a positive correlation was found between H(2) and organic acid production. In contrast, solvent concentration in heat-shocked mini-reactors were slightly higher than in reactors spiked with Ac. Regarding the incubation temperature, on the average mesophilic temperature affected in a positive and very significant way P(H) (10.07 vs. 2.67) and R(i,H) (2.43 vs. 0.76) with minimum T(lag) (87 vs. 459). The positive correlation between H(2) and organic acids production was found again. Yet, incubation temperature did not seem to affect solvent production. A strong interaction was observed between induction treatment and incubation temperature. Thus, Ac-inhibited units showed higher values of P(H) and R(i,H) than that HSP-inhibited units only under thermophilic incubation. Contrary to this, HSP-inhibited units showed the highest values of P(H) and R(i,H) only under mesophilic conditions. Therefore, the superiority of an induction treatment seems to strongly depend on the incubation temperature.     

Utilization of tannery solid waste for protease production by Synergistes sp. in solid‐state fermentation and partial protease characterization

Synergistes sp. DQ560074 produced a protease in submerged fermentation (SmF) at 400–420 U/mL and in solid‐state fermentation (SSF) at 745–755 U/g. The protease, which belongs to the aspartic protease class, was active over a wide range of pH (5–7) and at high temperatures (25–45°C). The protease is stable and active in various polar protic solvents (50% v/v) like ethanol, isopropanol, n–butanol, in polar aprotic solvents (50% v/v) like acetonitrile, and in non‐polar solvents (50% v/v) such as ethylacetate and toluene, but not in hydrophilic organic solvents (methyl alcohol and acetone). As far as we know, this is the first contribution to the production of a mesophilic protease with solvent stability in SSF using a proteinaceous solid waste.     

樟绒枝霉(Malbranchea cinnamomea)固体发酵产木聚糖酶的发酵条件优化

[目的] 研究樟绒枝霉(Malbranchea cinnamomea) CAU521利用农业废弃物固体发酵产木聚糖酶的发酵条件.[方法]采用单因素试验法优化影响菌株产酶的各个条件,包括碳源种类、氮源种类、初始pH、初始水分含量、培养温度及发酵时间共6个因素.[结果]获得的最佳产酶条件为:稻草为发酵碳源、2％(W/W)的酵母提取物为氮源、初始pH 7.0、初始水分含量80％和发酵温度45℃.在此条件下发酵6d后木聚糖酶的酶活力达到13 120 U/g干基碳源.[结论]樟绒枝霉固体发酵产木聚糖酶的产酶水平高,生产成本低,具有潜在的工业化应用前景.     

Microwave-assisted preparation and adsorption performance of activated carbon from biodiesel industry solid reside: influence of operational parameters

Preparation of activated carbon has been attempted using KOH as activating agent by microwave heating from biodiesel industry solid residue, oil palm empty fruit bunch (EFBAC). The significance of chemical impregnation ratio (IR), microwave power and activation time on the properties of activated carbon were investigated. The optimum condition has been identified at the IR of 1.0, microwave power of 600 W and activation time of 7 min. EFBAC was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy and nitrogen adsorption isotherm. The surface chemistry was examined by zeta potential measurement, determination of surface acidity/basicity, while the adsorptive property was quantified using methylene blue as dye model compound. The optimum conditions resulted in activated carbon with a monolayer adsorption capacity of 395.30 mg/g and carbon yield of 73.78%, while the BET surface area and total pore volume were corresponding to 1372 m²/g and 0.76 cm³/g, respectively.     

Potential of agroindustrial waste from olive oil industry for fuel ethanol production

Olive pulp (OP) is a highly polluting semi-solid residue generated from the two-stage extraction processing of olives and is a major environmental issue in Southern Europe, where 80% of the world olive oil is produced. At present, OP is either discarded to the environment or combusted with low calorific value. In this work, utilization of OP as a potential substrate for production of bioethanol was studied. Enzymatic hydrolysis and subsequent glucose fermentation by baker's yeast were evaluated for OP from 10% to 30% dry matter (i.e., undiluted). Enzymatic hydrolysis resulted in an increase in glucose concentration by 75%, giving final glucose yields near 70%. Fermentation of undiluted OP hydrolysate (OPH) resulted in the maximum ethanol produced (11.2 g/L) with productivity of 2.1 g/L/h. Ethanol yields were similar for all tested OPH concentrations and were in the range of 0.49-0.51 g/g. Results showed that yeast could effectively ferment OPH even without nutrient addition, revealing the tolerance of yeast to OP toxicity. Because of low xylan (12.4%) and glucan (16%) content in OP, this specific type of OP is not a suitable material for producing only ethanol and thus, bioethanol production should be integrated with production of other value-added products.     

Enzymatic production of N-acetyl-D-glucosamine by solid state fermentation of chitinase by Penicillium ochrochloron MTCC 517 using agricultural residues

The optimization studies for production of chitinase were carried out by response surface methodology (RSM) based on statistics experimental design using three substrates, which were wheat, rice and red gram bran. 2⁴ full factorial central composite design was applied to evaluate optimal combinations of variables. These variables were chitin concentration, initial moisture content, inoculum level, and incubation time. The results of second order polynomial showed that all four variables had significant effect on chitinase production. Maximum chitinase activity was recorded for wheat bran (2443.23 U g⁻¹) than rice (1216.65 U g⁻¹) and red gram bran (961.32 U g⁻¹). An overall 3-fold increase in chitinase activity was achieved using optimized strategies of RSM. Growth of the fungus on all bran particles have been visualized by scanning electron microscopy. These results indicated the potential of Penicillium ochrochloron for economical production of chitinase using agricultural residues. TLC and HPLC analysis of colloidal chitin hydrolysate with partially purified chitinases revealed that the major reaction product was monomeric GlcNAc indicating the potential of these enzymes for efficient production of GlcNAc.     

Long-term genomic selection for heterosis without dominance in multiplicative traits: case study of bunch production in oil palm

Background

To study the potential of genomic selection for heterosis resulting from multiplicative interactions between additive and antagonistic components, we focused on oil palm, where bunch production is the product of bunch weight and bunch number. We simulated two realistic breeding populations and compared current reciprocal recurrent selection (RRS) with reciprocal recurrent genomic selection (RRGS) over four generations. All breeding strategies aimed at selecting the best individuals in parental populations to increase bunch production in hybrids. For RRGS, we obtained the parental genomic estimated breeding values using GBLUP with hybrid phenotypes as data records and population specific allele models. We studied the effects of four RRGS parameters on selection response and genetic parameters: (1) the molecular data used to calibrate the GS model: in RRGS_PAR, we used parental genotypes and in RRGS_HYB we also used hybrid genotypes; (2) frequency of progeny tests (model calibration); (3) number of candidates and (4) number of genotyped hybrids in RRGS_HYB.

Results

We concluded that RRGS could increase the annual selection response compared to RRS by decreasing the generation interval and by increasing the selection intensity. With 1700 genotyped hybrids, calibration every four generations and 300 candidates per generation and population, selection response of RRGS_HYB was 71.8 % higher than RRS. RRGS_PAR with calibration every two generations and 300 candidates was a relevant alternative, as a good compromise between the annual response, risk around the expected response, increased inbreeding and cost. RRGS required inbreeding management because of a higher annual increase in inbreeding than RRS.

Conclusions

RRGS appeared as a valuable method to achieve a long-term increase in the performance for a trait showing heterosis due to the multiplicative interaction between additive and negatively correlated components, such as oil palm bunch production.     

Solid-state fermentation of co-products from palm oil processing: Production of lipase and xylanase and effects on chemical composition

The palm oil industry generates large amounts of lignocellulosic co-products. Palm kernel cake (PKC) and palm pressed fibre (PPF) have nutritional limitations as ingredients in animal feed, and are therefore little used. Solid-state fermentation (SSF) is one alternative treatment to improve the nutritional value of these co-products and to increase their possible use, through the production of enzymes such as lipases and xylanases. These enzymes can reduce the contents of undesirable compounds, such as lipids, and degrade some components of the fibres to improve the digestibility of these co-products. The fungi Aspergillus niger, Aspergillus oryzae and Aspergillus awamori were able to grow in PKC/PPF (40/60 w/w) culture medium by SSF, and to produce xylanase and lipase. A. niger showed the highest lipase activity (20.7?U g^?1) at 72?h. A. awamori higher xylanase activity than the other fungi at all culture periods, reaching a maximum activity of 134.2?U g^?1 at 72?h. The unfermented co-products contained 7.49% lipids and 7.38% non-fibrous carbohydrates (NFC). Lipase produced by these fungi during SSF reduced the lipid content by 36%, 40% and 45% for A. oryzae, A. awamori and A. niger, respectively. The production of xylanases by SSF probably increased the NFC contents by up to 64%. Fermented solids with A. oryzae and A. awamori had the highest levels of NFC, 20.3% and 13.94%, respectively, which improved the nutritional value of these co-products.     

Life cycle greenhouse gas emissions of furniture and bioenergy production from oil palm trunks

The palm oil industry constantly attempts to increase the sustainability along the entire palm oil value chain. One important strategy is to utilize all co‐products. Oil palm trunks, which become available upon replanting of existing plantations, represent an important and increasing flow of underexploited biomass. In recent years, innovative technologies are emerging to use them for producing furniture or plywood or providing bioenergy. We assessed the life cycle greenhouse gas emissions of such products and the greenhouse gas emission savings due to replaced alternative products. Although challenging material properties result in a relatively high energy demand and related greenhouse gas emissions in the oil palm wood processing, substantial reductions in greenhouse gas emissions can arise from producing furniture or bioenergy from oil palm trunks, especially if the process energy demand is met by the energy recovery from oil palm wood‐processing residues.     

Nutritional value and proteases of Lentinus citrinus produced by solid state fermentation of lignocellulosic waste from tropical region

This paper examined the growth and yield performance of Lentinus citrinus on cupuaçu exocarp (Theobroma grandiflorum) mixed with litter (CE + LI) or rice bran (Oryza sativa) (CE + RB) in the ratio of 2:1 (800 g:200 g) to investigate the nutritional composition and proteolytic potential of the fruiting body produced. Significance values of yield were determined on substrate combinations. In CE + LI the biological efficiency of the mushrooms was 93.5% and the content of fat (4.5%), fiber (11.0%), protein (27.0%) and amino acids were higher when compared with CE + RB. Among the amino acids, the amount of glutamic acid, aspartic acid, alanine, arginine and leucine was high. The biological efficiency on CE + RB reduced to 84.2% and based on the nutritional value, carbohydrates (53.59%), energy (324.33 kcal) and minerals such as zinc, iron, copper, potassium and phosphorus were higher in this substrate combination. Protease activity from fruiting body was significant in CE + LI (463.55 U/mL). This protease showed an optimal activity at 50 °C in neutral and alkaline pH with maximum stability at 30 °C at alkaline pH. This is the first report of L. citrinus fruiting body nutritional composition with potential for human food and application in industrial processes.     

Novozym 435 for production of biodiesel from unrefined palm oil: Comparison of methanolysis methods

Biodiesel (BD) is commonly produced from refined vegetable oils by alkali-catalyzed methanolysis. Unrefined vegetable oils are economically attractive but not suitable for alkali catalysis because of their high content of free fatty acids (FFAs). Novozym 435 (immobilized Candida antarctica lipase B), which accepts both FFA and oil as substrates, was, therefore, employed to convert unrefined palm oil to BD. Three different methanolysis methods, namely, t-butanol mediated system (method-1), LiCl solution based controlled release system for methanol (method-2) and solvent-free system with three successive additions of methanol (method-3), were compared. The optimal methanol to oil molar ratios in the method-1, -2 and -3 are 6:1, 3:1 and 3:1, respectively. BD yield at an optimal methanol concentration reaches 91–92% after 10, 20 and 24 h in the method-1, -2 and -3, respectively. BD yield remains the same over five repeated cycles in the method-1, while it drops to 68 and 71% by the fifth cycle in the method-2 and -3, respectively. The results show that the method-1 is the most effective for production of BD from a low cost feedstock like unrefined palm oil.