Influence of water activity and temperature on xylanase biosynthesis in pilot-scale solid-state fermentation by Aspergillus sulphureus

Solid-state fermentation of brown seaweeds for the production of alginate lyase using marine bacterium Enterobacter tabaci RAU2C

Alginate lyases have countless potential for application in industries and medicine particularly as an appealing biocatalyst for the production of biofuels and bioactive oligosaccharides. Solid-state fermentation (SSF) allows improved production of enzymes and consumes less energy compared to submerged fermentation. Seaweeds can serve as the most promising biomass for the production of biochemicals. Alginate present in the seaweed can be used by alginate lyase-producing bacteria to support growth and can secrete alginate lyase. In this perspective, the current study was directed on the bioprocessing of brown seaweeds for the production of alginate lyase using marine bacterial isolate. A novel alginate-degrading marine bacterium Enterobacter tabaci RAU2C which was previously isolated in the laboratory was used for the production of alginate lyase using Sargassum swartzii as a low-cost solid substrate. Process parameters such as inoculum incubation period and moisture content were optimized for alginate lyase production. SSF resulted in 33.56 U/mL of alginate lyase under the static condition maintained with 75% moisture after 4 days. Further, the effect of different buffers, pH, and temperature on alginate lyase activity was also analyzed. An increase in alginate lyase activity was observed with an increase in moisture content from 60 to 75%. Maximum enzyme activity was perceived with phosphate buffer at pH 7 and 37 °C. Further, the residual biomass after SSF could be employed as biofertilizer for plant growth promotion based on the preliminary analysis. To our knowledge, this is the first report stating the usage of seaweed biomass as a substrate for the production of alginate lyase using solid-state fermentation.

Humidity Control Strategies for Solid-State Fermentation: Capillary Water Supply by Water-Retention Materials and Negative-Pressure Auto-controlled Irrigation

Solid-state fermentation (SSF) has regained interest owing to its advantages in solid waste treatment and fermentation industries. However, heterogeneous heat and mass transfer are often caused by the absence of free water and noticeable water loss from microbial utilization and moisture evaporation in SSF. It is necessary to explore more effective ways to solve issues of water loss and water supplement in SSF based on online capillary water monitoring, because capillary water is the dominant form of water that is present and lost in substrate. Two novel capillary-water supply strategies were proposed, established and evaluated using three selected reference strains, including water-retention materials and negative-pressure auto-controlled irrigation (NPACI). This study employed superabsorbent polymer, a kind of water-retention material to enhance enzyme productivity with the most significant increase of 2.47 times. Moreover, the combination of NPACI and 0.1% superabsorbent polymers increased productivity by 2.80-fold, together with lowered gradients of temperature, moisture and products. Furthermore, a modified liquid-supply SSF was constructed through successful capillary water control by proposed humidity control strategies. This modified SSF system could address the shortcomings of inhomogeneous culture of traditional SSF.

Secretory expression of β-mannanase in Saccharomyces cerevisiae and its high efficiency for hydrolysis of mannans to mannooligosaccharides

Degradation of mannans is a key process in the production of foods and prebiotics. β-Mannanase is the key enzyme that hydrolyzes 1,4-β-D-mannosidic linkages in mannans. Heterogeneous expression of β-mannanase in Pichia pastoris systems is widely used; however, Saccharomyces cerevisiae expression systems are more reliable and safer. We optimized β-mannanase gene from Aspergillus sulphureus and expressed it in five S. cerevisiae strains. Haploid and diploid strains, and strains with constitutive promoter TEF1 or inducible promoter GAL1, were tested for enzyme expression in synthetic auxotrophic or complex medium. Highest efficiency expression was observed for haploid strain BY4741 integrated with β-mannanase gene under constitutive promoter TEF1, cultured in complex medium. In fed-batch culture in a fermentor, enzyme activity reached ~ 24 U/mL after 36 h, and production efficiency reached 16 U/mL/day. Optimal enzyme pH was 2.0-7.0, and optimal temperature was 60 °C. In studies of β-mannanase kinetic parameters for two substrates, locust bean gum galactomannan (LBG) gave K_m = 24.13 mg/mL and V_max = 715 U/mg, while konjac glucomannan (KGM) gave K_m = 33 mg/mL and V_max = 625 U/mg. One-hour hydrolysis efficiency values were 57% for 1% LBG, 74% for 1% KGM, 39% for 10% LBG, and 53% for 10% KGM. HPLC analysis revealed that the major hydrolysis products were the oligosaccharides mannose, mannobiose, mannotriose, mannotetraose, mannopentaose, and mannohexaose. Our findings show that this β-mannanase has high efficiency for hydrolysis of mannans to mannooligosaccharides, a type of prebiotic, suggesting strong potential application in food industries.

Improved thermostability of an acidic xylanase from Aspergillus sulphureus by combined disulphide bridge introduction and proline residue substitution

As a feed additive, xylanase has been widely applied in the feed of monogastric animals, which contains multiple plant polysaccharides. However, during feed manufacture, the high pelleting temperatures challenge wild-type xylanases. The aim of this study was to improve the thermostability of Aspergillus sulphureus acidic xylanase. According to the predicted protein structure, a series of disulphide bridges and proline substitutions were created in the xylanase by PCR, and the mutants were expressed in Pichia pastoris. Enzyme properties were evaluated following chromatographic purification. All the recombinant enzymes showed optima at pH 3.0 and 50 °C or 55 °C and better resistance to some chemicals except for CuSO₄. The specific activity of the xylanase was decreased by introduction of the mutations. Compared to the wild-type enzyme, a combined mutant, T53C-T142C/T46P, with a disulphide bond at 53–142 and a proline substitution at 46, showed a 22-fold increase of half-life at 60 °C. In a 10-L fermentor, the maximal xylanase activity of T53C-T142C/T46P reached 1,684 U/mL. It was suggested that the T53C-T142C/T46P mutant xylanase had excellent thermostability characteristics and could be a prospective additive in feed manufacture.

Optimization of cellulase production by Penicillium sp

The production of cellulolytic enzymes (β-exoglucanase, β-endoglucanase and β-glucosidase) by Penicillium sp. on three different media in liquid shake culture conditions was compared. The organism exhibited relatively highest activity of endoglucanase among three enzymes measured at 7-day interval during the course of its growth on Czapek-Dox medium supplemented with 0.5 % (w/v) cellulose. Cellulose at 0.5 %, lactose at 0.5 %, sawdust at 0.5 %, yeast extract at 0.2 % as a nitrogen source, pH 5.0 and 30 °C temperature were found to be optimal for growth and cellulase production by Penicillium sp. Yields of Fpase, CMCase and β-glucosidase, attained on optimized medium with Penicillium sp. were 8.7, 25 and 9.52 U/ml, respectively with increment of 9.2, 5.9 and 43.8-folds over titers of the respective enzyme on unoptimised medium. Cellulase of the fungal culture with the ratio of β-glucosidase to Fpase greater than one will hold potential for biotechnological applications.

Olive pomace valorization by Aspergillus species: lipase production using solid-state fermentation

BACKGROUND

Pollution by olive mill wastes is an important problem in the Mediterranean area and novel solutions for their proper management and valorization are needed. The aim of this work was to optimize a solid-state fermentation (SSF) process to produce lipase using olive pomace (OP) as the main source of nutrients by several Aspergillus spp. Optimized variables in two different designs were: ratio between olive pomace and wheat bran (OP:WB), NaNO3 , Czapek nutrients, fermentation time, moisture content (MC) and temperature.

RESULTS

Results showed that the mixture OP:WB and MC were the most significant factors affecting lipase production for all fungi strains tested. With MC and temperature optimization, a 4.4-fold increase in A. ibericus lipase was achieved (90.5 ± 1.5 U g(-1) ), using a mixture of OP and WB at 1:1 ratio, 0.02 g NaNO3 g(-1) dry substrate, absence of Czapek nutrients, 60% of MC and incubation at 30 °C for 7 days. For A. niger and A. tubingensis, highest lipase activity obtained was 56.6 ± 5.4 and 7.6 ± 0.6 U g(-1) , respectively.

CONCLUSION

Aspergillus ibericus was found to be the most promising microorganism for lipase production using mixtures of OP and WB. © 2015 Society of Chemical Industry.

A multi-tolerant low molecular weight mannanase from Bacillus sp. CSB39 and its compatibility as an industrial biocatalyst

Bacillus sp. CSB39, isolated from popular traditional Korean food (Kimchi), produced a low molecular weight, thermostable mannanase (MnCSB39); 571.14U/mL using locust bean gum galactomannan as a major substrate. It was purified to homogeneity using a simple and effective two-step purification strategy, Sepharose CL-6B and DEAE Sepharose Fast Flow, which resulted in 25.47% yield and 19.32-fold purity. The surfactant-, NaCl-, urea-, and protease-tolerant monomeric protein had a mass of ∼30kDa as analyzed by SDS-PAGE and galactomannan zymography. MnCSB39 was found to have optimal activity at pH 7.5 and temperature of 70°C. The enzyme showed ˃55% activity at 5.0-15% (w/v) NaCl, and ˃93% of the initial activity after incubation at 37°C for 60min. Trypsin and proteinase K had no effect on MnCBS39. The enzyme showed ˃80% activity in up to 3M urea. The N-terminal amino acid sequence, ALKGDGX, did not show identity with reported mannanases, which suggests the novelty of our enzyme. Activation energy for galactomannan hydrolysis was 26.85kJmol(-1) with a Kcat of 142.58×10(4)s(-1). MnCSB39 had Km and Vmax values of 0.082mg/mL and 1099±1.0Umg(-1), respectively. Thermodynamic parameters such as ΔH, ΔG, ΔS, Q10, ΔGE-S, and ΔGE-T supported the spontaneous formation of products and the high hydrolytic efficiency and feasibility of the enzymatic reaction, which strengthen its novelty. MnCSB39 activity was affected by metal ions, modulators, chelators, and detergents. Mannobiose was the principal end-product of hydrolysis. Bacillus subtilis CSB39 produced a maximum of 1524.44U mannanase from solid state fermentation of 1g wheat bran. MnCSB39 was simple to purify, was active at a wide pH and temperature range, multi-stress tolerant and catalyzes a thermodynamically possible reaction, characteristics that suggests its suitability for application as an industrial biocatalyst.

Review of lignocellulolytic enzyme activity analyses and scale-down to microplate-based assays

With the increasing use of enzymes in environmental applications, there is a need for analytical methods adapted to large factorial experiments. Existing reference methods are chemical and labor intensive and unsuitable to analyze in parallel a large number of samples. Based on an extensive literature review and on experimental results, this work compares reference and microplate adapted methods to define the most adequate filter paper, carboxymethylcellulase, β-glucosidase and xylanase activity tests. In the adapted methods, the total reaction volume was reduced from 2.2-24.5 mL to 0.21-0.24 mL. Statistical analysis of the activities measured on enzyme mixtures by applying the 96-well plate reduced methods showed that they were not significantly different to the activities obtained with reference tests.

Saccharification and hydrolytic enzyme production of alkali pre-treated wheat bran by Trichoderma virens under solid state fermentation

Background

In continuation of our previously interest in the saccharification of agriculture wastes by Bacillus megatherium in solid state fermentation (SSF), we wish to report an investigation and comparative evaluation among Trichoderma sp. for the saccharification of four alkali-pretreated agricultural residues and production of hydrolytic enzymes, carboxymethyl cellulase (CMCase), filter paperase (FPase), pectinase (PGase) and xylanase (Xylase) in SSF. The optimization of the physiological conditions of production of hydrolytic enzymes and saccharification content from Trichoderma virens using alkali-pretreated wheat bran was the last goal.

Methods

The physico-chemical parameters of SSF include incubation time, incubation temperature, moisture content of the substrate, incubation pH, supplementation with carbon and nitrogen sources were optimized.

Results

Saccharification of different solid state fermentation sources wheat bran, date's seeds, grass and palm leaves, were tested for the production of fermentable sugar by Trichoderma sp. The maximum production of hydrolytic enzymes CMCase, FPase, PGase and Xylase and saccharification content were obtained on wheat bran. Time course, moisture content, optimum temperature, optimum pH, supplementation with carbon and nitrogen sources were optimized to achieve the maximum production of the hydrolytic enzymes, protein and total carbohydrate of T. virens using alkali pre-treated wheat bran. The maximum production of CMCase, FPase, PGase, Xylase, protein and carbohydrate content was recorded at 72 h of incubation, 50-70 % moisture, temperature 25-35 °C and pH 5. The influence of supplementary carbon and nitrogen sources was studied. While lactose and sucrose enhanced the activity of PGase from 79.2 to 582.9 and 632.6 U/g, starch inhibited all other enzymes. This was confirmed by maximum saccharification content. Among the nitrogen sources, yeast extract and urea enhanced the saccharification content and CMCase, PGase and Xylase.

Conclusions

The results of this study indicated that alkali pre-treated wheat bran was a better substrate for saccharification and production of hydrolytic enzymes CMCase, FPase, PGase and xylase by T. virens compared to other alkali-pretreated agricultural residues tested.

Expression of manganese peroxidase by Lentinula edodes and Lentinula boryana in solid state and submerged system fermentation

The production of ethanol from lignocellulosic biomass is referred as a second generation biofuel, whose processing is one of the most promising technologies under development. There are few available studies on the use of enzymes produced by fungi as active for the biodegradation of lignocellulosic biomass. However, the manganese peroxidase (MnP) enzyme presents high potential to degrade lignin and the basidiomycetes are the major producers of this oxidase. Thus, this study aimed at evaluating the ability of fungi Lentinula edodes and Lentinula boryana to produce this enzyme when cultivated in submerged fermentation system (SS) and also in solid-state fermentation system (SSF) containing Eucalyptus benthamii sawdust with or without corn cob meal. In the SS the greatest MnP expression occurred on the 25th day, being of 70 UI.L-1 for L. boryana and of 20 UI.L-1 for L. edodes. In the SSF, the best results were obtained on the 10th day for L. edodes, while for L. boryana it happened between the 20th and the 25th days, despite both species presented values close to 110 UI.L-1. Therefore, the results indicated that the studied fungi express the enzyme of interest and that its production is enhanced when cultivated in solid system.

Changes in selected physical property and enzyme activity of rice and barley koji during fermentation and storage

Koji are solid-state fermentation products made by inoculating steamed grains with the spores of fungi, particularly Aspergillus spp. This research was undertaken to identify the fermentation and storage conditions optimal for the production and maintenance of selected hydrolytic enzymes, such as α-amlyase and protease, in koji. Steamed rice and barley were inoculated with 2 × 10 ¹¹ Aspergillus oryzae spores per kilogram of grains and fermented for 118 h in a growth chamber at 28 to 32 °C with controlled relative humidities. Samples were drawn periodically during fermentation and storage at -20, 4, or 32 °C, and α-amylase and protease activity, mold counts, a(w), moisture contents, and pH of collected samples were determined. It was observed that the a(w), moisture contents, and pH of the koji were influenced by the duration of fermentation and temperature of storage. The α-amylase activity of both koji increased as the populations of A. oryzae increased during the exponential growth phase. The enzyme activity of barley koji was significantly higher than that of rice koji, reaching a peak activity of 211.87 or 116.57 U at 46 and 58 h, respectively, into the fermentation process. The enzyme activity in both products started to decrease once the mold culture entered the stationary growth phase. The protease activities of both koji were low and remained relatively stable during fermentation and storage. These results suggest that rice and barley koji can be used as sources of α-amylase and desired enzyme activity can be achieved by controlling the fermentation and storage conditions.

PRACTICAL APPLICATION

Amylases and proteases are 2 important hydrolytic enzymes. In the food industry, these enzymes are used to break down starches and proteins while reducing the viscosity of foods. Although amylases and proteases are found in plants and animals, commercial enzymes are often produced using bacteria or molds through solid state fermentation, which is designed to use natural microbial process to produce enzymes in a controlled environment. A properly produced and maintained koji with a high hydrolytic enzyme activity can serve as an important source of the enzymes for the food industry.

Optimization for the production of cellulase enzyme from municipal solid waste residue by two novel cellulolytic fungi

The main purpose of this study is to reduce the production cost of cellulase by optimizing the production medium and using an alternative carbon source such as municipal solid waste residue. In the present investigation, we aim to isolate the two novel cellulase producing fungi (Aspergillus niger and Trichoderma sp.) from municipal solid waste. Municipal solid waste residue (4-5% (w/v)) and peptone and yeast extract (1.0% (w/v)) were found to be the best combination of carbon and nitrogen sources for the production of cellulase by A. niger and Trichoderma sp. Optimum temperature and pH of the medium for the cellulase production by A. niger were 40°C and 6-7, whereas those for the production of cellulase by Trichoderma sp. were 45°C and 6.5. Cellulase production from A. niger and Trichoderma sp. can be an advantage as the enzyme production rate is normally higher as compared to other fungi.

Key technologies for bioethanol production from lignocellulose

Controversies on bioethanol produced from straw mainly revolve around the unfitted economical feasibility and environmental concerns of the process, which attribute mainly to unilateral researches from own specialties of each scholar without regard to the characteristics of the straws themselves. To achieve an economical and environmentally-friendly system of bioethanol production from straw, a number of breakthroughs are needed, not only in individual process steps, but also in the balance and combination of these processes. This article gives an overview of the new technologies required and the advances achieved in recent years, especial progresses achieved in our group, based on the concept of fractional conversions. An eco-industrial multi-production pattern is established, by which the maximum efficacy and benefit of process can be achieved due to the production of many high-value co-products simultaneously with ethanol. We believed that, in the future, the bioethanol production from straw will be competitive economically and environmentally.

Optimization of xylanase production by Thermomyces lanuginosus in solid state fermentation

Extracellular xylanase production by the thermophilic fungus Thermomyces lanuginosus 195 in solid state fermentation (SSF) was found to be significantly affected by fermentation temperature, duration, and inoculum volume (p < or = 0.001). Optimization of these parameters corresponded to a 21.7% increase in xylanase yield. Maximum activity (2,335 U/g of wheat bran) was obtained when 10 g of wheat bran was inoculated with 10 ml of liquid culture and cultivated at 45 degrees C for 40 h. The influence of supplemental carbon and nitrogen sources (3% w/v) on xylanase production was also assessed. Wheat bran, supplemented with glucose and cellulose, facilitated 10% and 7% increases in relative activity respectively. Ammonium based salts, nitrates, and a number of organic nitrogen sources served only to reduce xylanase production (p < or = 0.005) significantly. The enhanced xylanase titers achieved in the present study emphasize the need for optimizing growth conditions for maximum enzyme production in SSF.

Improvement of Aspergillus sulphureus endo-beta-1,4-xylanase expression in Pichia pastoris by codon optimization and analysis of the enzymic characterization

The gene xynB from Aspergillus sulphureus encoding the endo-beta-1,4-xylanase was de novo synthesized by splicing overlap extension polymerase chain reaction according to Pichia pastoris protein's codon bias. The synthetic DNA and wild-type DNA were placed under the control of a glyceraldehyde-3-phosphate dehydrogenase gene promoter (GAP) in the constitutive expression vector plasmid pGAPzalphaA and electrotransformed into the P. pastoris X-33 strain, respectively. The transformants screened by Zeocin were able to constitutively secrete the xylanase in YPD liquid medium. The maximum yield of the recombinant xylanase produced by the synthetic DNA was 105 U ml(-1), which was about 5-fold higher than that by wild-type DNA under the flask culture at 28 degrees Celsius for 3 days. The enzyme showed optimal activity at 50 degrees Celsius and pH 5.0. The residual activity remained above 90% after the recombinant xylanase was pretreated in Na(2)HPO(4)-citric acid buffer (pH 2.4) for 2 h. The xylanase activity was significantly improved by Zn(2+). These biochemical characteristics suggest that the recombinant xylanase has a prospective application in feed industry as an additive.

Production of xylanase by Aspergilli using alternative carbon sources: application of the crude extract on cellulose pulp biobleaching

The ability of xylanolytic enzymes produced by Aspergillus fumigatus RP04 and Aspergillus niveus RP05 to promote the biobleaching of cellulose pulp was investigated. Both fungi grew for 4-5 days in liquid medium at 40 degrees C, under static conditions. Xylanase production was tested using different carbon sources, including some types of xylans. A. fumigatus produced high levels of xylanase on agricultural residues (corncob or wheat bran), whereas A. niveus produced more xylanase on birchwood xylan. The optimum temperature of the xylanases from A. fumigatus and A. niveus was around 60-70 degrees C. The enzymes were stable for 30 min at 60 degrees C, maintaining 95-98% of the initial activity. After 1 h at this temperature, the xylanase from A. niveus still retained 85% of initial activity, while the xylanase from A. fumigatus was only 40% active. The pH optimum of the xylanases was acidic (4.5-5.5). The pH stability for the xylanase from A. fumigatus was higher at pH 6.0-8.0, while the enzyme from A. niveus was more stable at pH 4.5-6.5. Crude enzymatic extracts were used to clarify cellulose pulp and the best result was obtained with the A. niveus preparation, showing kappa efficiency around 39.6% as compared to only 11.7% for that of A. fumigatus.

Solid-state fermentation of xylanase from Penicillium canescens 10-10c in a multi-layer-packed bed reactor

Xylanase is produced by Penicillium canescens 10-10c from soya oil cake in static conditions using solid-state fermentation. The impact of several parameters such as the nature and the size of inoculum, bed-loading, and aeration is evaluated during the fermentation process. Mycelial inoculum gives more production than conidial inoculum. Increasing the quantity of inoculum enhances slightly xylanase production. Forced aeration induces more sporulation of strain and reduces xylanase production. However, forced moistened air improves the production compared to production obtained with forced dry air. In addition, increasing bed-loading reduces the specific xylanase production likely due to the incapacity of the Penicillium strain to grow deeply in the fermented soya oil cake mass. Thus, the best cultivation conditions involve mycelial inoculum form, a bed loading of 1-cm height and passive aeration. The maximum xylanase activity is obtained after 7 days of fermentation and attains 10,200 U/g of soya oil cake. These levels are higher than those presented in the literature and, therefore, show all the potentialities of this stock and this technique for the production of xylanase.

Prokaryotic expression, purification and characterization of Aspergillus sulphureus beta-mannanase and site-directed mutagenesis of the catalytic residues

Wild type (WT) DNA sequence, which encoded a mature beta-mannanase of Aspergillus sulphureus, composed of 1,152 nucleotides (nt), was amplified from pUCm-T-mann by polymerase chain reaction (PCR). Based on this DNA fragment, mutants designated as E(206)G and E(314)G were constructed by overextension PCR (OE-PCR). Glutamic acids of the 206th and 314th sites in the amino acid sequence of beta-mannanase were separately replaced by glycine in these two mutants. The WT and mutant genes were ligated into prokaryotic vector pET-28a (+) and transformed into the Escherichia coli BL21 strain, respectively. The recombinant enzyme proteins were expressed by IPTG induction and detected by Western blot. The recombinant proteins purified with Ni-NTA column were dialyzed to correctly refold. The WT recombinant beta-mannanase showed optimal activity at 50 degrees C and pH 2.4. The kinetic parameters of K (m) and V (max) for purified beta-mannanase were 1.38 mg/ml and 72.99 U/mg, respectively. However, the mutant proteins did not show any activity. It was demonstrated that E(206) and E(314) were the catalytic residues of beta-mannanase.

De novo synthesis, constitutive expression of Aspergillus sulphureus beta-xylanase gene in Pichia pastoris and partial enzymic characterization

The endo-beta-1, 4-xylanase gene xynA from Aspergillus sulphureus, encoded a lack-of-signal peptide protein of 184 amino acids, was de novo synthesized by splicing overlap extension polymerase chain reaction according to Pichia pastoris protein's codon bias. The synthetic DNA, composed of 572 nucleotides, was ligated into the downstream sequence of an alpha-mating factor in a constitutive expression vector pGAPzalphaA and electrotransformed into the P. pastoris X-33 strain. The transformed yeast screened by Zeocin was able to constitutively secrete the xylanase in yeast-peptone-dextrose liquid medium. The heterogenous DNA was stabilized in the strain by 20-times passage culture. The recombinant enzyme was expressed with a yield of 120 units/mL under the flask culture at 28 degrees C for 3 days. The enzyme showed optimal activity at 50 degrees C and pH 2.4-3.4. Residual activity of the raw recombinant xylanase was not less than 70% when fermentation broth was directly heated at 80 degrees C for 30 min. However, the dialyzed xylanase supernatant completely lost the catalytic activity after being heated at 60 degrees C for 30 min. The recombinant xylanase showed no obvious activity alteration by being pretreated with Na(2)HPO(4)-citric acid buffer of pH 2.4 for 2 h. The xylanase also showed resistance to certain metal ions (Na(+), Mg(2+), Ca(2+), K(+), Ba(2+), Zn(2+), Fe(2+), and Mn(2+)) and EDTA. These biochemical characteristics suggest that the recombinant xylanase has a prospective application in feed industry as an additive.

Production of cellulase-free endoxylanase from novel alkalophilic thermotolerent Bacillus pumilus by solid-state fermentation and its application in wastepaper recycling

The present study aimed at optimization of culture condition for the enhanced production of extra cellular thermostable cellulase-free xylanase from Bacillus pumilus by solid-state fermentation. Batch studies were carried out to evaluate various agro-industrial residues such as rice bran, rice husk, rice straw, sawdust, coconut pith, sugarcane bagasse and wheat bran for enzyme production by the bacterial culture. The endoxylanase production was highest on wheat bran media (5582 U/gds), which was enhanced 3.8-fold (21,431 U/gds) by optimization of cultivation conditions. The enzymatic extracts was used in mixed wastepaper recycling, which resulted in a considerable improvement of the paper strength with high drainage and easy drying up. The results of enzyme application with recycled paper clearly indicated that the effective use of enzymes in fiber separation could reduce the cost of carton paper production.

Influence of cultivating conditions on the alpha-galactosidase biosynthesis from a novel strain of Penicillium sp. in solid-state fermentation

AIMS

The work is intended to achieve optimum culture conditions of alpha-galactosidase production by a mutant strain Penicillium sp. in solid-state fermentation (SSF).

METHODS AND RESULTS

Certain fermentation parameters involving incubation temperature, moisture content, initial pH value, inoculum and load size of medium, and incubation time were investigated separately. The optimal temperature and moisture level for alpha-galactosidase biosynthesis was found to be 30 degrees C and 50%, respectively. The range of pH 5.5-6.5 was favourable. About 40-50 g of medium in 250-ml flask and inoculum over 1.0 x 10(6) spores were suitable for enzyme production. Seventy-five hours of incubation was enough for maximum alpha-galactosidase production. Substrate as wheat bran supplemented with soyabean meal and beet pulp markedly improved the enzyme yield in trays.

CONCLUSIONS

Under optimum culture conditions, the alpha-galactosidase activity from Penicillium sp. MAFIC-6 indicated 185.2 U g(-1) in tray of SSF.

SIGNIFICANT AND IMPACT OF THE STUDY

The process on alpha-galactosidase production in laboratory scale may have a potentiality of scaling-up.