Improvement of the glaB promoter expressed in solid-state fermentation (SSF) of Aspergillus oryzae

The glucoamylase-encoding gene (glaB) promoter should be very useful for recombinant protein production in solid-state fermentation (SSF) of Aspergillus oryzae. A 97-bp fragment containing the cis-element of the glaB promoter was inserted into the glaA promoter, which was little expressed in SSF. The chimeric promoter showed about a 24-fold increase in promoter activity in SSF. Eight copies of the 97-bp fragment were tandemly fused with the glaB promoter. The improved promoter showed about a 4.6-fold increase in promoter activity in SSF. The glaB gene was overexpressed under control of the improved glaB promoter in SSF. Recombinant glucoamylase production reached about 1524 mg/kg-broth for 2 d. The improved glaB promoter should be very useful for overproduction of a recombinant protein in SSF of A. oryzae.     

Bioprocess optimization for production of thermoalkali-stable protease from Bacillus subtilis K-1 under solid-state fermentation

Cost-effective production of proteases, which are robust enough to function under harsh process conditions, is always sought after due to their wide industrial application spectra. Solid-state production of enzymes using agro-industrial wastes as substrates is an environment-friendly approach, and it has several advantages such as high productivity, cost-effectiveness, being less labor-intensive, and less effluent production, among others. In the current study, different agro-wastes were employed for thermoalkali-stable protease production from Bacillus subtilis K-1 under solid-state fermentation. Agricultural residues such as cotton seed cake supported maximum protease production (728?U?ml^?1), which was followed by gram husk (714?U?ml^?1), mustard cake (680?U?ml^?1), and soybean meal (653?U?ml^?1). Plackett–Burman design of experiment showed that peptone, moisture content, temperature, phosphates, and inoculum size were the significant variables that influenced the protease production. Furthermore, statistical optimization of three variables, namely peptone, moisture content, and incubation temperature, by response surface methodology resulted in 40% enhanced protease production as compared to that under unoptimized conditions (from initial 728 to 1020?U?ml^?1). Thus, solid-state fermentation coupled with design of experiment tools represents a cost-effective strategy for production of industrial enzymes.     

Comparative studies on the production of cellulases by thermophilic fungi in submerged and solid-state fermentation

Summary Six thermophilic fungi were examined for their ability to produce cellulolytic enzymes in liquid (LF) and solid-state fermentation (SSF). The best cellulase activities were achieved by Thermoascus aurantiacus and Sporotrichum thermophile. Taking into consideration that solid-state medium obtained from 100 g of dry sugar-beet pulp occupies about 11 of fermentor volume equivalent to 11 of LF, it was confirmed that enzyme productivity per unit volume from both fungi was greater in SSF than in LF. The cellulase system obtained by SSF with T. aurantiacus contained 1.322 IU/1 of exo--d-glucanase, 53.269 IU/1 of endo--d-glucanase and 8.974 IU/1 of -d-glucosidase. The thermal and pH characteristics of cellulases from solid-state fermentation of T. aurantiacus and S. thermophile are described.     

Evaluation of culture conditions for cellulase production by two Trichoderma reesei mutants under solid-state fermentation conditions

Response surface methodology (RSM) was used to evaluate the effects of fermentation parameters for cellulase production by Trichoderma reesei QM9414 and T. reesei MCG77 in solid-state fermentation using rice bran as substrate. Initial pH, moisture content and temperature were optimized using filter paper activity (FPA) as response. Statistical analysis of the results for T. reesei QM9414 showed that only moisture content had significant effect on cellulase activity and had a linear effect on enzyme activity (maximum enzyme activities were obtained at 70% moisture content). The results for T. reesei MCG77 showed that temperature and moisture content were the most significant parameters for cellulase activity. The optimum cellulase production was in the temperature range of 25-30 degrees C and moisture content between 55% and 70%. After the optimization, the FPA in T. reesei MCG77 was increased by 2.5 folds compared to that of T. reesei QM9414.     

Improved polygalacturonase production from Bacillus sp. MG-cp-2 under submerged (SmF) and solid state (SSF) fermentation

AIMS: To investigate the effect of amino acids, vitamins and surfactants on polygalacturonase production from Bacillus sp. MG-cp-2 under submerged (SmF) and solid state fermentation (SSF). METHODS AND RESULTS: Bacillus sp. MG-cp-2 was isolated from the outer covering of the seeds of Celastrus paniculatus. Out of the various surfactants, amino acids and vitamins, Tween-60, DL-serine and folic acid maximally enhanced polygalacturonase production by 2.7-fold (240.0 U x ml(-1)), 4.0-fold (360.0 U x ml(-1)) and 3.8-fold (342.0 U x ml(-1)) respectively, under submerged fermentation (SmF). In solid state fermentation (SSF), Tween-80, pyridoxine and DL-ornithine monohydrochloride induced highest enzyme production up to 1.73-fold (6956.5 U x g(-1)), 5.3-fold (21224.4 U x g(-1)) and 5.74-fold (23076.9 U x g(-1)), respectively. CONCLUSION: Amino acids and their analogues, vitamins and surfactants effect significantly polygalacturonase production by Bacillus sp. MG-cp-2 when grown under submerged (SmF) and solid state fermentation (SSF) conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: The study provides useful information about regulation of polygalacturonase biosynthesis in Bacillus sp. MG-cp-2, which appears to be an interplay of nutritional and physical factors. Alkaline polygalacturonase from Bacillus sp. MG-cp-2 will be extremely useful in the treatment of alkaline pectic waste waters from vegetable and fruit processing industries and in degumming of bast fibres.     

Exploitation of biological wastes for the production of value-added products under solid-state fermentation conditions

Biological wastes contain several reusable substances of high value such as soluble sugars and fibre. Direct disposal of such wastes to soil or landfill causes serious environmental problems. Thus, the development of potential value-added processes for these wastes is highly attractive. These biological wastes can be used as support-substrates in solid-state fermentation (SSF) to produce industrially relevant metabolites with great economical advantage. In addition, it is an environmentally friendly method of waste management. This paper reviews the reutilization of biological wastes for the production of value-added products using the SSF technique.     

Cellulase production by trichoderma harzianum in static and mixed solid-state fermentation reactors under nonaseptic conditions

Cellulase production from lignocellulosic materials was studied in solid-state cultivation by both static and mixed techniques under nonaseptic conditions. The effects of fermentation conditions, such as moisture content, pH, temperature, and aeration, on cellulase production by Trichoderma harzianum using a mixture of wheat straw (80%) and bran (20%) were investigated. With a moisture content of 74% and a pH of 5.8., 18 IU filter paper activity and 198 IU endoglucanase activity/g initial substrate content were obtained in 66 h. The extension from static column cultivation to stirred tank reactor of 65 L capacity gave similar yields of cellulase.     

2-phenylethanol (rose aroma) production potential of an isolated pichia kudriavzevii through solid-state fermentation

2-phenylethanol (2-PE) is a higher alcohol widely used in industry that can be obtained by solid-state fermentation (SSF) using low-cost raw materials. This report describes the 2-PE production potential of an indigenous Pichia kudriavzevii isolated from solid-state fermented sugarcane bagasse that possesses attractive characteristics for processing waste streams such as its low-pH tolerance, high growth rate and temperature resistance. Besides, 2-PE production was optimized in batch-SSF using sugarcane bagasse supplemented with l-phenylalanine as substrate. Full factorial design allowed identifying the pH adjustment, micronutrient addition, inoculum and co-substrate load effects, and response surface methodology served to identify the maximum production based on temperature, initial moisture content (MC₀) and specific airflow rate (S_AFR). While the pH adjustment and micronutrient addition did not affect the 2-PE production, temperature and MC₀ resulted critical for the process. After optimization, the maximum 2-PE content was 27.2 ± 0.2 mg per gram of dry substrate at 31 °C, 76 % MC₀ and 0.129 L h⁻¹ g⁻¹ S_AFR. This result was 23.8 % higher than the sub-optimal condition, and it is the highest 2-PE production via SSF reported so far. These results confirm the ability of P. kudriavzevii for producing 2-PE, and its potential for using waste streams as substrate.     

High-level of xylanase production by the thermophilic Paecilomyces themophila J18 on wheat straw in solid-state fermentation

The production of extracellular xylanase by a newly isolated thermophilic fungus, Paecilomyces themophila J18, on the lignocellulosic materials was studied in solid-state fermentation (SSF). The strain grew well at 50 degrees C and produced a high-level of xylanase activity using the selected lignocellulosic materials, especially wheat straw. Production of xylanase by P. themophila J18 on wheat straw was enhanced by optimizing the particle size of wheat straw, nitrogen source, initial moisture level, growth temperature and initial pH of the culture medium. Under the optimized conditions, yield as high as 18,580 Ug(-1) of carbon source of xylanase was achieved. No CMCase activity was observed. The xylanase exhibited remarkable stability and retained more than 50% of its original activity at 70 degrees C for 4h at pH 7.0-8.0. Therefore, P. themophila J18 could to be a promising microorganism for thermostable, cellulase-free xylanase production in SSF.     

De-hairing protease production by an isolated Bacillus cereus strain AT under solid-state fermentation using cow dung: Biosynthesis and properties

Agro-industrial residues and cow dung were used as the substrate for the production of alkaline protease by Bacillus cereus strain AT. The bacterial strain Bacillus cereus strain AT produced a high level of protease using cow dung substrate (4813 ± 62 U g⁻¹). Physiological fermentation factors such as the incubation time (72 h), the pH (9), the moisture content (120%), and the inoculum level (6%) played a vital role in the enzyme bioprocess. The enzyme production improved with the supplementation of maltose and yeast extract as carbon and nitrogen sources, respectively. Sodium dodecyl sulfate–polyacrylamide gel electrophoresis and zymogram analysis of the purified protease indicated an estimated molecular mass of 46 kDa. The protease enzyme was stable over a temperature range of 40–50 °C and pH 6–9, with maximum activity at 50 °C and pH 8. Among the divalent ions tested, Ca²⁺, Na⁺ and Mg²⁺ showed activities of 107 ± 0.7%, 103.5 ± 1.3%, and 104.6 ± 0.9, respectively. The enzyme showed stability in the presence of surfactants such as sodium dodecyl sulfate and on various commercially available detergents. The crude enzyme effectively de-haired goat hides within 18 h of incubation at 30 °C. The enzymatic properties of this protease suggest its suitable application as an additive in detergent formulation and also in leather processing. Based on the laboratory results, the use of cow dung for producing and extracting enzyme is not cumbersome and is easy to scale up. Considering its cheap cost and availability, cow dung is an ideal substrate for enzyme bioprocess in an industrial point of view.     

Optimization of saccharification and ethanol production by simultaneous saccharification and fermentation (SSF) from seaweed, Saccharina japonica

Ethanol was produced using the simultaneous saccharification and fermentation (SSF) method with macroalgae polysaccharide from the seaweed Saccharina japonica (Sea tangle, Dasima) as biomass. The seaweed was dried by hot air, ground with a hammer mill and filtered with a 200-mesh sieve prior to pretreatment. Saccharification was carried out by thermal acid hydrolysis with H(2)SO(4) and the industrial enzyme, Termamyl 120 L. To increase the yield of saccharification, isolated marine bacteria were used; the optimal saccharification conditions were 10% (w/v) seaweed slurry, 40 mM H(2)SO(4) and 1 g dcw/L isolated Bacillus sp. JS-1. Using this saccharification procedure, the reducing sugar concentration and viscosity were 45.6 ± 5.0 g/L and 24.9 cp, respectively, and the total yield of the saccharification with optimal conditions and S. japonica was 69.1%. Simultaneous saccharification and fermentation was carried out for ethanol production. The highest ethanol concentration, 7.7 g/L (9.8 ml/L) with a theoretical yield of 33.3%, was obtained by SSF with 0.39 g dcw/L Bacillus sp. JS-1 and 0.45 g dcw/L of the yeast, Pichia angophorae KCTC 17574.     

Enhancement of ethanol production by simultaneous saccharification and fermentation (SSF) of rice straw using ethoxylated span 20

In this work, four nonionic surfactants based on sorbitan monolaurate (Span 20) were synthesized by introducing ethylene oxide gas (n?=?20, 40, 60, 80 ethylene oxide units) into Span 20 to give four new surfactants with different hydrophilic-lipophilic balance (HLB), namely, E(20), E(40), E(60), and E(80). The structures of the prepared nonionic surfactants were elucidated using Fourier-transform infrared (FT-IR) and (1)H-nuclear magnetic resonance (NMR) spectroscopy. The surface-tension measurements were recorded. The effects of the prepared nonionic surfactants on the simultaneous saccharification and fermentation (SSF) of microwave/alkali-pretreated rice straw to produce ethanol were investigated. From the obtained data, it was found that the addition of the nonionic surfactants at 2.5?g/L had a positive effect on SSF. The maximum ethanol yield (76 and 55%) was obtained after 72?hr for rice straw using Kluyveromyces marxianus and Saccharomyces cerevisiae, respectively. Also, it was found that the ethanol yield increases with increasing HLB of the prepared nonionic surfactants by increasing ethylene oxide units. The adsorption of nonionic surfactants on lignocelluloses is proposed to be due to hydrophobic and hydrogen bonding interactions between nonionic surfactants and the lignin part in the lignocelulose. It can be concluded that additions of surface-active compounds, such as nonionic surfactants, increase enzymatic conversion of rice straw for bioethanol purposes.     

Comparison of the kinetics of lipopeptide production by Bacillus amyloliquefaciens XZ-173 in solid-state fermentation under isothermal and non-isothermal conditions

This study aimed to compare the kinetics of lipopeptide production in solid-state fermentation (SSF) under isothermal and non-isothermal conditions. Models based on the logistic, modified Gompertz and Luedeking–Piret-like equations were developed to describe the time course of fermentation under different conditions. The experiments were conducted in 250 mL flasks and a 50 L fermenter. The results showed that the non-isothermal process had higher levels of product formation rate and substrate utilization rate compared to the isothermal process. The part of substrate carbon to meet microbial maintenance—energy, biomass and lipopeptides formation requirements got increased using the non-isothermal technique. In addition, fermenter conditions positively influenced the lipopeptides formation rate with significantly higher levels of substrate for the microbial growth and product formation, though the product productivity and biomass both decreased as compared to flask. This is the first report that investigates the effects of temperature changing on the kinetics of lipopeptide production by Bacillus amyloliquefaciens strain under SSF condition using soybean flour and rice straw as major substrates in flask and in fermenter.     

辅酶Q_(10)产生菌发酵条件的优化

对辅酶Q10生产菌株鞘氨醇单胞菌YZ0803的发酵条件进行优化,确定发酵时间为90 h,250 mL摇瓶装液量为30 mL。培养基组成(质量分数,下同):葡萄糖1.5%,淀粉2.5%,黄豆饼粉2.5%,(NH4)2SO40.5%,NaCl0.03%,K2HPO40.02%,MgSO40.005%。优化后的辅酶Q10产量达到192 mg/L,比采用基础培养基的产量(138mg/L)提高了39.13%。     

Ethanol production from sunflower meal biomass by simultaneous saccharification and fermentation (SSF) with Kluyveromyces marxianus ATCC 36907

The lignocellulosic materials are considered promising renewable resources for ethanol production, but improvements in the processes should be studied to reduce operating costs. Thus, the appropriate enzyme loading for cellulose saccharification is critical for process economics. This study aimed at evaluating the concentration of cellulase and β-glucosidase in the production of bioethanol by simultaneous saccharification and fermentation (SSF) of sunflower meal biomass. The sunflower biomass was pretreated with 6 % H₂SO₄ (w/v), at 121 °C, for 20 min, for hemicellulose removal and delignificated with 1 % NaOH. SSF was performed with Kluyveromyces marxianus ATCC 36907, at 38 °C, 150 rpm, for 72 h, with different enzyme concentrations (Cellulase Complex NS22086-10, 15 and 20 FPU/g_substrate and β-Glucosidase NS22118, with a cellulase to β-glucosidase ratio of 1.5:1; 2:1 and 3:1). The best condition for ethanol production was cellulase 20 FPU/g_substrate and β-glucosidase 13.3 CBU/g_substrate, resulting in 27.88 g/L ethanol, yield of 0.47 g/g and productivity of 0.38 g/L h. Under this condition the highest enzymatic conversion of cellulose to glucose was attained (87.06 %).     

Impact of operating conditions on performance of a novel gas double-dynamic solid-state fermentation bioreactor (GDSFB)

A self-designed novel solid-state fermentation (SSF) bioreactor named “gas double-dynamic solid-state fermentation bioreactor (GDSFB)” showed great success in processes for the production of several valuable products. For the present study, a simple GDSFB (2 L in volume) was designed to investigate the impact of exhaust time on SSF performance. Both air pressure and vent aperture significantly influenced the exhaust time. The production of cellulase by Penicillium decumbens JUA10 was studied in this bioreactor. When the vent aperture was maintained at 0.2 cm, the highest FPA activity of 17.2 IU/g dry solid-state medium was obtained at an air pressure of 0.2 MPa (gauge pressure). When the air pressure was maintained at 0.2 MPa, a vent aperture of 0.3 cm gave the highest FPA activity of 18.0 IU/g dry solid-state medium. Further analysis revealed that the exhaust time was a crucial indicator of good performance in GDSFB.     

Application of simultaneous saccharification and fermentation (SSF) from viscosity reducing of raw sweet potato for bioethanol production at laboratory, pilot and industrial scales

The aim of this work was to research a bioprocess for bioethanol production from raw sweet potato by Saccharomyces cerevisiae at laboratory, pilot and industrial scales. The fermentation mode, inoculum size and pressure from different gases were determined in laboratory. The maximum ethanol concentration, average ethanol productivity rate and yield of ethanol after fermentation in laboratory scale (128.51 g/L, 4.76 g/L/h and 91.4%) were satisfactory with small decrease at pilot scale (109.06 g/L, 4.89 g/L/h and 91.24%) and industrial scale (97.94 g/L, 4.19 g/L/h and 91.27%). When scaled up, the viscosity caused resistance to fermentation parameters, 1.56 AUG/g (sweet potato mash) of xylanase decreased the viscosity from approximately 30000 to 500 cp. Overall, sweet potato is a attractive feedstock for be bioethanol production from both the economic standpoints and environmentally friendly.