Characteristics of Aspergillus niger xylanases produced on rice husk and wheat bran in submerged culture and solid‐state fermentation for an applicability proposal

Xylanolytic rich filtrates were obtained by A. niger sp in both submerged and solid‐state culture using rice husk or wheat bran as the only carbon source. Filtrates obtained on rice husk showed the highest activities (~6500 and 5200 U g^?1, respectively). Independent of carbon source, these filtrates were very stable in an acidic pH range (4–7) and mild temperatures, with high half‐life time values (more than 7 h at 50 °C) in the corresponding inactivation kinetic models. Also the effect of different metallic ions and denaturing substances was verified finding that these enzymes are not metaloproteins, and metals as Hg²⁺ and Pb²⁺ caused the greatest loss of xylanolytic activity (not higher than 30%). Xylanases produced by this A. niger strain showed important features that make them potential candidates for applications on human and livestock food industries.     

Production of α‐amylase by Aspergillus oryzae As 3951 in solid state fermentation using spent brewing grains as substrate

BACKGROUND: The optimisation of nutrient levels for the production of α‐amylase by Aspergillus oryzae As 3951 in solid state fermentation (SSF) with spent brewing grains (SBG), an inexpensive substrate and solid support, was carried out using response surface methodology (RSM) based on Plackett–Burman design (PBD) and Box–Behnken design (BBD). RESULTS: In the first optimisation step a PBD was used to evaluate the influences of related factors. Corn steep liquor, CaCl₂ and MgSO₄ were found to be the most compatible supplements to the substrate of SBG and influenced α‐amylase activity positively. In the second step the concentrations of these three nutrients were optimised using a BBD. The final concentrations (g/g dry substrate basis) in the medium optimised with RSM were 1.8% corn steep liquor, 0.22% CaCl₂ and 0.2% MgSO₄ · 7H₂O using SBG as the solid substrate. The average α‐amylase activity reached 6186 U g^?1 dry substrate under the optimised conditions at 30 °C after 96 h. Under the optimised conditions of SSF an approximately 17.5% increase in enzyme yield was observed. CONCLUSION: SBG was found to be a good substrate for the production of α‐amylase by A. oryzae As 3951 under SSF. Copyright © 2007 Society of Chemical Industry     

Production of feed enzymes from citrus processing waste by solid‐state fermentation with Eupenicillium javanicum

Bingtang sweet orange processing waste was utilised to produce four feed enzymes (Endoglucanase, β‐glucosidase, pectinase and xylanase) by the solid‐state fermentation (SSF) with Eupenicillium javanicum. The factors related with SSF including moisture content, temperature, initial pH, time, carbon source (0.5 g), nitrogen sources (0.05 g), inorganic mineral salts (0.1 g) were investigated separately. The corresponding optimal condition was: moisture content 80% (w/w), temperature 30 °C, natural pH, time 96 h, wheat bran 0.5 g, (NH₄)₂SO₄ 0.05 g or NaNO₃ 0.05 g, CaCl₂ 0.1 g. The L₉(3⁴) orthogonal experiment results showed that the optimal condition for producing above multiple enzymes was: moisture content 80% (w/w), temperature 30 °C, wheat bran 1 g, (NH₄)₂SO₄ 0.05 g, NaNO₃ 0.05 g, CaCl₂ 0.1 g, fermentation time 96 h and natural pH. Under this condition, the average activity of Endoglucanase (CMCase), β‐glucosidase, pectinase and xylanase by E. javanicum could reach 46.80, 49.64, 51.87 and 106.42 U g^?1, respectively, which was significantly higher than those in single factor experiments. Our present results demonstrated that E. javanicum could also be an effective and useful fungus for multienzyme preparation especially for β‐glucosidase and xylanase from citrus processing wastes.     

Improvement of flavour compound synthesis in a mixed culture system at high temperature by solid‐state fermentation

In order to enhance the synthesis of flavour compounds in solid‐state fermentation (SSF) at a high temperature, Bacillus subtilis XJ‐013 and Saccharomyces cerevisiae Z‐06 were used as a mixed culture with Monascus HQ‐3. The culture temperature was enhanced from 37°C to 56°C by the synergetic effect, and the synthesis of esterase was enhanced from 85.43 U/g to 129.65 U/g in the mixed culture system (over 50% higher than that of the culture using a single strain). This resulted in the synthesis of favourable flavour compounds in the solid‐state fermentation. These results signified that a mixed culture of Monascus and S. cerevisiae was favourable for enzyme production. The mixed culture of Monascus and B. subtilis resulted in a high culture temperature that promoted flavour compound synthesis in the solid‐state fermentation system dramatically. These results present a model to explain the synergetic effects between the fungus and the Bacillus in the solid‐state fermentation. Copyright © 2015 The Institute of Brewing & Distilling     

黑曲霉固态发酵橘皮生产纤维素酶及淀粉酶

以橘皮为原料,以黑曲霉AS3.3928为生产菌株,采用固态发酵法生产纤维素酶和淀粉酶。通过单因素试验考察固态发酵培养基中橘皮含量、培养基含水量、接种量及发酵时间4个因素对纤维素酶和淀粉酶活力的影响。在单因素试验基础上,通过正交试验最终确定最优产酶条件为：固态发酵培养基中添加16g橘皮,并加入5mL无菌水使培养基初始含水量为64mL/100g,黑曲霉接种量15%,发酵60h。在此发酵条件下所产纤维素酶活力可达1816U/g,淀粉酶活力达196U/g。结果表明,利用黑曲霉固态发酵橘皮,非常有利于纤维素酶和淀粉酶的生产。     

Performance of indigenous yeasts in the processing of Chinese strong‐flavoured liquor during spontaneous mixed solid‐state or submerged fermentation

To explore the in situ metabolic characteristics of yeasts involved in the spontaneous fermentation process of Chinese strong‐flavoured liquor, a comparison was conducted between solid‐state fermentation (SSF) and submerged fermentation (SmF) when supplemented with 24 indigenous yeast strains, with a focus on the production of ethanol and a broad range of volatile compounds responsible for the characteristics of Chinese strong‐flavoured liquor. Under the various experimental conditions, the 24 indigenous yeast strains showed different influences on the mixed fermentation system. The fluctuations caused by different yeast strains in the mixed system were less than those caused by the different fermentation modes relative to the formation of flavour compounds. SSF was found to be more suitable for the production of ethanol, methanol and ethyl lactate, whereas SmF was more suitable for the production of 10 higher alcohols, four esters and four acids. This study revealed the relationships amongst the indigenous yeasts, SSF, and the distinctive flavour profiles of Chinese strong‐flavoured liquor. This work provides evidence of the existence of internal stability in spontaneous SSF, thereby facilitating a better understanding of the fermentative mechanism in the SSF process for Chinese strong‐flavoured liquor production Copyright © 2015 The Institute of Brewing & Distilling     

Production,partial purification and properties of β‐mannanases obtained by solid substrate fermentation of spent soluble coffee wastes and copra paste using Aspergillus oryzae and Aspergillus niger

In order to achieve a higher added value of two galactomannan‐containing wastes, copra paste and spent coffee from the soluble coffee industry (SCW), solid substrate fermentation (SSF) was used. Filamentous fungi Aspergillus oryzae and A niger were used to evaluate the feasibility of producing β‐mannanase by SSF. A 2³ factorial design was used to select the best interaction among the two fungi, the two substrates and two fermentation times. The treatment ‘A niger–copra–2.5 days’ produced a significantly higher (p < 0.05) β‐mannanase activity, having five different isoforms of the enzyme, one of which was partially purified to a specific activity of 764 U mg⁻¹ (U = nmol of mannose released per second from a galactomannan substrate). Copra paste had a higher mannose/galactose ratio (14:1) than SCW (6:1), and low oil content, which led to higher β‐mannanase production from SSF. A β‐mannanase from SSF of copra produced by A oryzae was highly purified using acetone precipitation and cation exchange and size exclusion chromatographies. This enzyme had an MW of 110 kDa, a pI between 3.5 and 4.5 and a specific activity of 1760 U mg⁻¹; purification achieved was 90.7 times. The temperature and pH for optimal activity were 40 °C and 6.0 respectively. The optimal temperature was lower and the optimal pH higher than others previously reported (produced by submerged fermentation), which could be important for viscosity reduction of concentrated coffee extract in instant coffee manufacture. Copra is an interesting alternative for β‐mannanase production, since it is readily available in Mexico; moreover, the residue after SSF has a reduced galactomannan content and may be used for monogastric animal feed. © 2000 Society of Chemical Industry     

Influence of aeration and agitation modes on solid‐state fermentation of apple pomace waste by Phanerochaete chrysosporium to produce ligninolytic enzymes and co‐extract polyphenols

The effect of different types of agitation (i) continuous agitation (C); (ii) continuous, discontinuous, continuous agitation (C/D/C); (iii) discontinuous, continuous, discontinuous agitation (D/C/D) and aeration (0.87, 1.25, 1.66 vvm) on ligninolytic enzyme production and polyphenolic compounds extraction by solid‐state cultures of Phanerochaete chrysosporium BKM‐F‐1767 was investigated. Higher production of manganese peroxidase (MnP) (1690.3 ± 87.6), lignin peroxidase (LiP) (387.9 ± 14.3) and laccase (898.9 ± 53.3 U gds^?1) and liberation of total polyphenolics (ranging from 12.22 ± 1.1 to 30.12 ± 0.88 mg gallic acid equivalents per gram DW) was obtained after 195, 147, 219 and 204 h of fermentation, respectively, using 1.66 vvm as airflow and (C/D/C) agitation mode. Maximal enzyme production and total polyphenolic content were influenced by aeration, and higher values were obtained using 1.66 vvm as airflow rate, followed by 1.25 and 0.83 vvm, respectively. They were also influenced by agitation, and maximal values were obtained using C/D/C, followed by D/C/D and continuous agitation, respectively. The agitation modes influenced the production of ligninolytic enzymes and simultaneous extraction of polyphenols.     

Biochemical characterisation and application of lipases produced by Aspergillus sp. on solid‐state fermentation using three substrates

Lipase from Aspergillus sp. obtained by solid‐state fermentation (SSF) on wheat bran (LWB), soybean bran (LSB) and soybean bran combined with sugarcane bagasse (LSBBC) were 67.5, 58 and 57.3 U of crude lipase per gram substrate, respectively. The optimum pH of activity and stability of the LWB was between 8 and 9, and the optimum temperature of activity and stability was 50 °C and up to 60 °C, respectively. The LSB and LSBBC showed two peaks of optimum pH (4 and 6) and optimal values of temperature and stability at 50 °C. The LSB was stable in the pH range of 6–7, while LSBBC in the range of pH 4–7. All the enzymes show activities on p‐nitrophenyl esters (butyrate, laurate and palmitate). LWB stood out either on the hydrolysis of sunflower oil, presenting 66.1% of the activity over commercial lipase and on the esterification of oleic acid and ethanol, surpassing the activities of the commercial lipases studied. The thin layer chromatography showed that LWB and LSB have produced ethyl esters from corn oil, while LWB produced it from sunflower oil.