Preliminary studies on tannin degradation by Aspergillus niger van Tieghem MTCC 2425

A tannin-degrading strain of Aspergillus niger van Tieghem was grown at pH 5·0 and 30°C in a defined medium where tannins were the sole source of carbon and energy. The fungus had variable growth in tannic acid- and quebracho tannin-medium and could tolerate these tannins even up to 150 g⁻¹ without showing any growth inhibition.     

Isolation,purification and properties of tannase from Aspergillus niger van Tieghem

Tannase (tannin acyl hydrolase E.C. 3.1.1.20) has been isolated from Aspergillus niger van Tieghem and purified 29-fold. The enzyme had a temperature optimum of 60^°C, pH optimum of 6.0 with a second peak at pH 4.5, K_m of 0.20mM and V_max of 5.0mol min^–1 mg^–1protein.     

黑曲霉固态发酵生产单宁酶的条件优化

研究采用响应面法优化黑曲霉固态发酵生产单宁酶的培养条件。应用Plackett—Burman试验筛选出重要影响因子：五倍子粉含量、（NH4）2SO4浓度以及接种孢子量,最陡爬坡试验逼近最大响应区域。应用Box．Behnken响应面试验对重要影响因子进一步优化。得到最佳培养条件：每250mL三角瓶中装入1．0g五倍子粉、4．4g稻壳和0．5g麸皮、液固比（mL／g）2：1且营养盐溶液组成为（NH4）2s0421g/L、MgSO4·7H2O1g／L、NaCl1g／L,培养基pH自然,接种5．7×10^7个孢子后在30℃温度下培养4d。在此条件下,单宁酶产量从40U／g提高到114U／g,3次重复验证性试验平均值为115U／g,验证了模型的可靠性。     

Removal of hydrocarbons from liquid media by Aspergillus niger van Tieghem

This study investigated the abiliy of Aspergillus niger van Tieghem to utilize crude oil and kerosene. Hydrocarbons are molecules that pose serious environmental problem because of their toxic, carcinogenic or teratogenic properties. The fate of these pollutants in the environment is mainly governed by the biodegradation process. The existence of these phenomena depends on the inherent biodegradability of the pollutant but also the presence of microflora-degrading competent.The microbial strain were isolated and identified from industrial wastewater samples from Sonatrach Skikda (North-east of Algeria), we selected them for their ability to grow in the presence of hydrocarbons. To test the ability to biodegrade the two selected hydrocarbons in 6 days, the study of the evolution of such parameters as the microbial kinetics, pH, the final dry weight of the population, oxygen concentration, and finally, biodegradation rate of crude oil and kerosene was conducted by high performance liquid chromatography (HPLC). A control test was performed to quantify the losses caused by abiotic factors.The filamentous fungus was found to degrade crude oil and kerosene, when previously grown mycelium was incubated 6 days in the Galzy and Slonimski media containing hydrocarbon. The results showed that these organisms were able to utilize crude oil more than kerosene and the degradation rate was 52.01% and 32.67%, respectively. Thus Aspergillus niger van Tieghem plays a major role in the detoxification of polluted natural environments and these capabilities could be explored in bioremediation processes.     

Mixed substrate solid state fermentation for production and extraction of lipase from Aspergillus niger MTCC 2594

A novel mixed substrate solid-state fermentation (SSF) process has been developed for Aspergillus niger MTCC 2594 using wheat bran (WB) and gingelly oil cake (GOC) and the results showed that addition of GOC to WB (WB : GOC, 3 : 1, w/w) increased the lipase activity by 36.0% and the activity was 384.3+/-4.5 U/g dry substrate at 30 degrees C and 72 h. Scale up of lipase production to 100 g and 1 kg tray-level batch fermentation resulted in 95.0% and 84.0% of enzyme activities respectively at 72 h. A three-stage multiple contact counter-current extraction yielded 97% enzyme recovery with a contact time of 60 min. However, extraction by simple percolation and plug-flow methods resulted in decreased enzyme recoveries. The mixed substrate SSF process has resulted in a significant increase in specific activity (58.9%) when compared to a submerged fermentation (SmF) system. Furthermore, an efficient process of extraction has been standardized with this process. Use of GOC along with WB as potential raw materials for enzyme production could be of great commercial significance. This is the first report on the production and extraction of lipase from Aspergillus niger using mixed solid substrates, WB and GOC, which are potential raw materials for the production of enzymes and other value-added products.     

Solid‐state fermentation for the production of debittering enzyme naringinase using Aspergillus niger MTCC 1344

Aspergillus niger produced high levels of naringinase using easily available, inexpensive industrial waste residues such as rice bran, wheat bran, sugar cane bagasse, citrus peel, and press mud in solid‐state fermentation (SSF). Among these, rice bran was found to be the best substrate. Naringinase production was highest after 96 h of incubation at 27°C and at a substrate‐to‐moisture ratio of 1:1 w/v. Supplementation of the medium with 10% naringin caused maximum induction. An inoculum age of 72 h and an inoculum level of 15% resulted in maximum production of naringinase. Enzyme production was stimulated by the addition of nutrients such as naringin and peptone. Thus, A. niger produced a very high level of naringinase within a short time in solid‐state fermentation using inexpensive agro‐residues, a level that is much higher than reported for any other microbes.     

Optimization of tannase production by Aspergillus niger in solid-state packed-bed bioreactor

Tannin acyl hydrolase, also known as tannase, is an enzyme with important applications in the food, feed, pharmaceutical, and chemical industries. However, despite a growing interest in the catalytic properties of tannase, its practical use is very limited owing to high production costs. Several studies have already demonstrated the advantages of solid-state fermentation (SSF) for the production of fungal tannase, yet the optimal conditions for enzyme production strongly depend on the microbial strain utilized. Therefore, the aim of this study was to improve the tannase production by a locally isolated A. niger strain in an SSF system. The SSF was carried out in packed-bed bioreactors using polyurethane foam as an inert support impregnated with defined culture media. The process parameters influencing the enzyme production were identified using a Plackett–Burman design, where the substrate concentration, initial pH, and incubation temperature were determined as the most significant. These parameters were then further optimized using a Box-Behnken design. The maximum tannase production was obtained with a high tannic acid concentration (50 g/l), relatively low incubation temperature (30°C), and unique low initial pH (4.0). The statistical strategy aided in increasing the enzyme activity nearly 1.97-fold, from 4,030 to 7,955 U/l. Consequently, these findings can lead to the development of a fermentation system that is able to produce large amounts of tannase in economical, compact, and scalable reactors.     

Purification and physicochemical properties of polygalacturonase from Aspergillus niger MTCC 3323

Polygalacturonases are the pectinolytic enzymes that catalyze the hydrolytic cleavage of the polygalacturonic acid chain. In the present study, polygalacturonase from Aspergillus niger (MTCC 3323) was purified. The enzyme precipitated with 60% ethanol resulted in 1.68-fold purification. The enzyme was purified to 6.52-fold by Sephacryl S-200 gel-filtration chromatography. On SDS–PAGE analysis, enzyme was found to be a heterodimer of 34 and 69 kDa subunit. Homogeneity of the enzyme was checked by NATIVE-PAGE and its molecular weight was found to be 106 kDa. The purified enzyme showed maximum activity in the presence of polygalacturonic acid at temperature of 45 °C, pH of 4.8, reaction time of 15 min. The enzyme was stable within the pH range of 4.0–5.5 for 1 h. At 4 °C it retained 50% activity after 108 h but at room temperature it lost its 50% activity after 3 h. The addition of Mn²⁺, K⁺, Zn²⁺, Ca²⁺ and Al³⁺ inhibited the enzyme activity; it increased in the presence of Mg²⁺ and Cu²⁺ ions. Enzyme activity was increased on increasing the substrate concentration from 0.1% to 0.5%. The K_m and V_max values of the enzyme were found to be 0.083 mg/ml and 18.21 μmol/ml/min. The enzyme was used for guava juice extraction and clarification. The recovery of juice of enzymatically treated pulp increased from 6% to 23%. Addition of purified enzyme increased the %T₆₅₀ from 2.5 to 20.4 and °Brix from 1.9 to 4.8. The pH of the enzyme treated juice decreased from 4.5 to 3.02.     

On the Modes of Action of Three Xylanases Produced by a Strain of Aspergillus niger van Tieghem

The modes of action of three xylanases (I, II and III) produced by Aspergillus niger van Tieghem on several substrates were investigated. Xylanase I possesed the strongest activity against xylooligosaccharides among the three enzymes and converted them into xylose and xylobiose. Xylanase II and III catalyzed a glycosylating reaction and produced higher polymerized xylooligosaccharides from xylotetraose or xylopentaose. Among three enzymes, xylanase II could split α1,3-arabinofuranosidic bond of arabinose-xylose mixed oligosaccharides.

In the case of hydrolysis by three xylanases on xylan and arabinoxylan, the maximum hydrolysis degree and the reaction products were compared with each other. From the results, some speculation were made concerning the modes of action of the enzymes.     

Synthesis of antioxidant propyl gallate using tannase from Aspergillus niger van Teighem in nonaqueous media

Tannase from Aspergillus niger van Teighem has been used for synthesis of food additive antioxidant propyl gallate by direct transesterification of tannic acid. The optimized yield of 86% was obtained by using simultaneously pH tuned enzyme, immobilized on Celite and using the right amount of water in the non aqueous media.     

Enhancement of inulinase production by Aspergillus niger van Teighem

P. VISWANATHAN AND P.R. KULKARNI. 1995. Aspergillus niger van Teighem, a soil isolate, was mutagenized by u.v. light. A mutant strain with 3 times increased productivity was generated on exposure of the parent strain to u.v. for 15 min. This mutant on further exposure to u.v. yielded second generation mutants with only marginal increase in inulinase productivity with respect to the parent mutant, but the best yield of 377 U ml⁻¹ was considered promising for industrial use.     

Sequential optimization and large scale production of lipase using tri-substrate mixture from Aspergillus niger MTCC 872 by solid state fermentation

Tri-substrate mixture of Prosopis juliflora (PJ), red gram husk (RGH) and cotton seed cake (CSC) has been studied for the production of lipase (E.C. 3.1.1.3) using Aspergillus niger MTCC 872 in solid state fermentation. Simplex centroid mixture design (SCMD) was implemented to optimize the tri-substrate mixture composition consisting of PJ, RGH and CSC. Mixture taken in the ratio of 6.66:1.66:1.66 for PJ:RGH:CSC has shown highest lipase activity of 212.20 ± 6.36 U/gds at 30 °C, 7 pH and 70 % initial moisture content (v/w). Sequential optimization of physical parameters was done using the central composite face-centered design (CCFD). The optimum mixture composition has shown the highest lipase activity of 269.87 ± 8.09 U/gds at 35 °C, 7 pH and 70 % initial moisture content (v/w). ANOVA analysis for SCMD and CCFD confirms the model’s significance with R² values of 0.9989 and 0.968. A 1.27 fold increased lipase activity was obtained after physical parameters optimization. Large scale production using 1 kg substrate was carried out in tray bioreactor with different bed heights and the highest lipase activity of 208.79 ± 6.26 U/gds was obtained. This study signifies the enhancement of lipase production using substrate PJ for lipase production along with the other agricultural residues.     

Absorbed substrate fermentation for pectinase production with Aspergillus niger

Summary A 130 litre packed-bed bioreactor was used for pectinase production with Aspergillus niger using absorbed substrate fermentation techniques. Pectinolytic enzyme activity and relative CO₂ production were used as indicators of metabolic activity. Absorbed substrate fermentation is an efficient process for pectinase production and is also an interesting model because the culture medium, water, nutrients and specific inducers, can be designed at the desired concentrations.     

Isolation and Characterization of a Xylan-Degrading Enzyme from Aspergillus niger van Tieghem LPM 93 with Potential for Industrial Applications

Aspergillus niger van Tieghem LPM 93 was shown in an earlier study to produce the most thermostable ??-xylanase, which was effective for improving brightness and delignification of non-delignified and oxygen-bleached samples of eucalyptus kraft pulp. Here, we report the production, purification, and characterization of a xylan-degrading enzyme (XynI) from this strain grown in submerged liquid cultivation on medium containing sugar cane bagasse as the carbon source. XynI was isolated by ultrafiltration and gel-filtration chromatography and characterized. The fungus displayed high levels of xylanolytic activity after the second day of cultivation, and this activity remained constant up to the 50th day. The molecular mass of XynI was in the range of 32?C33?kDa as determined by mass spectrometry and SDS-PAGE. The two-dimensional gel electrophoresis analysis showed the existence of multiple forms of ??-xylanases in XynI. XynI showed the highest activity at 50°C and pH?4.5 and was stable in sodium acetate buffer at pH?4.5. The K _m and V _max values were 47.08?mg/ml and 3.02?IU/ml, respectively. Salts inhibited the activity of XynI to different degrees. N-Bromosuccinimide caused marked inhibition of XynI. On the other hand, ??-mercaptoethanol and l-tryptophan were the best enzyme activators.     

Invertase production by Aspergillus niger in submerged and solid-state fermentation

Three Aspergillus nigerstrains were grown in submerged and solid state fermentation systems with sucrose at 100 g l^–1. Average measurements of all strains, liquid vs solid were: final biomass (g l^–1), 11 ± 0.3 vs 34 ± 5; maximal enzyme titres (U l^–1) 1180 ± 138 vs 3663 ± 732; enzyme productivity (U l^–1h^–1) 20 ± 2 vs 87 ± 33 and enzyme yields (U/gX) 128 ± 24 vs 138 ± 72. Hence, better productivity in solid-state was due to a better mould growth.     

Bioaccumulation and biosorption of chromium by Aspergillus niger MTCC 2594

Chromium toxicity is of prime concern due to chrome tanning processes in the leather sector. Chrome tanning results in the discharge of toxic levels of chromium causing pollution hazards. Chromium levels of Cr(III) and Cr(VI) were high above permissible limits in chrome samples after chrome tanning. The potential of Aspergillus niger MTCC 2594 to accumulate chromium as well as its biosorption capacity is investigated in this study. Bioaccumulation of Cr(III) and Cr(VI) in the spent chrome liquor has resulted in a 75-78% reduction of the initial Cr content in 24-36 h. A. niger biomass is found to be very effective in the biosorption of Cr(III) and Cr(VI) in spent chrome liquor. Maximum adsorption of 83% for biosorption of Cr(III) at 48 h and 79% of Cr(VI) at 36 h in spent chrome liquor is observed. The biosorption characteristics fit well with Langmuir and Freundlich isotherms and the adsorption parameters are evaluated. The biosorption of Cr also follows Lagergren kinetics. A. niger biomass is effectively used for the biosorption of chromium with 79-83% Cr removal in 36-48 h.     

Production of tannase by Aspergillus niger Aa-20 in submerged and solid-state fermentation: influence of glucose and tannic acid

Tannase production by Aspergillus niger Aa-20 was studied in submerged (SmF) and solid-state (SSF) fermentation systems with different tannic acid and glucose concentrations. Tannase activity and productivity were at least 2.5 times higher in SSF than in SmF. Addition of high tannic acid concentrations increased total tannase activity in SSF, while in SmF it was decreased. In SmF, total tannase activity increased from 0.57 to 1.03 IU/mL, when the initial glucose concentration increased from 6.25 to 25 g/L, but a strong catabolite repression of tannase synthesis was observed in SmF when an initial glucose concentration of 50 g/L was used. In SSF, maximal values of total tannase activity decreased from 7.79 to 2.51 IU when the initial glucose concentration was increased from 6.25 to 200 g/L. Kinetic results on tannase production indicate that low tannase activity titers in SmF could be associated to an enzyme degradation process which is not present in SSF. Tannase titers produced by A. niger Aa-20 are fermentation system-dependent, favoring SSF over SmF. Journal of Industrial Microbiology & Biotechnology (2001) 26, 296–302. Received 07 July 2000/ Accepted in revised form 15 February 2001