Implementation of batchwise bioscouring of cotton knits

The examination of critical factors determining the performance of bioscouring showed that a short treatment of the fabric at greater than 80°C after pectinase treatment at 60°C was essential for removal of waxes from the fabric as demonstrated by diminished intensities of methylene peaks in FT-IR measurements. Batch-wise bioscouring of cotton knits was carried out several times with post-treatment at 80°C using a rapid dyeing machine. The dye-ability of bioscoured knits was as good as the company's alkaline scoured ones with slightly higher K/S values. Water pollution caused by effluents of bioscouring and alkaline processes were estimated, as well as that due to the input of chemicals and enzymes. Higher BOD:COD_Cr ratios for enzymes indicated their biodegradable character. After calculation of energy consumption using a simulation program, an economic evaluation of the two processes was done on the basis of one ton production by considering the costs of chemicals and enzyme, water usage, energy consumption and waste water treatment charge.     

New development for combined bioscouring and bleaching of cotton-based fabrics

A thorough investigation into conditions appropriate for effecting combined eco-friendly bioscouring and/or bleaching of cotton-based fabrics was undertaken. Fabrics used include cotton, grey mercerized cotton, cotton/polyester blend 50/50 and cotton/polyester blend 35/65. The four cotton-based fabric were subjected to bioscouring by single use of alkaline pectinase enzymes or by using binary mixtures of alkaline pectinase and cellulase enzymes under a variety of conditions. Results of bioscouring show that, the bioscoured substrates exhibit fabrics performances which are comparable with these of the conventional alkali scouring. It has been also found that, incorporation of ethylenediaminetetraacetic acid (EDTA) in the bioscouring with mixture from alkaline pectinase and cellulase improves the performance of the bioscoured fabrics. Addition of β-cyclodextrin to the bioscouring solution using alkaline pectinase in admixtures with cellulase acts in favor of technical properties and performance of the bioscoured fabrics. Concurrent bioscouring and bleaching by in situ formed peracetic acid using tetraacetylethylenediamine (TAED) and H₂O₂ was also investigated. The results reveal unequivocally that the environmentally sound technology brought about by current development is by far the best. The new development involves a single-stage process for full purification/preparation of cotton textiles. The new development at its optimal comprises treatment of the fabric with an aqueous formulation consisting of alkaline pectinase enzyme (2 g/L), TAED (15 g/L), H₂O₂ (5 g/L), nonionic wetting agent (0.5 g/L) and sodium silicate (2 g/L). The treatment is carried out at 60 °C for 60 min. Beside the advantages of the new development with respect to major technical fabric properties, it is eco-friendly and reproducible. This advocates the new development for mill trials.     

Green bioprocess of degumming of jute fibers and bioscouring of cotton fabric by recombinant pectin methylesterase and pectate lyases from Clostridium thermocellum

Enzymatic processes are emerging as important green biotechnological processes in textile industry. The application of recombinant pectin methylesterase (CtPME) and pectate lyase (CtPL1B) from Clostridium thermocellum for enzymatic degumming of jute or bioscouring of cotton was evaluated. The effectiveness of processes by combination of two enzymes were evaluated that effective degumming of jute and bioscouring of cotton as compared with individual enzyme. The optimum concentrations of two enzymes mixture for both processes, degumming of jute and bio scouring of cotton were 5 mg/mL (2.1 U/mL) of CtPME and 5 mg/mL (3.0 U/mL) of CtPL1B under optimized conditions of 60 min, 100 rpm and 50 °C. FESEM images showed more effective removal of pectin from jute fiber and cotton fabric by enzyme mixture, nevertheless similar to NaOH treatment. Wettability analysis showed mixture of enzymes and NaOH treated cotton fabric absorbed a water drop in 10 s and 8 s, respectively. UTM analysis showed higher tensile strength and Young’s modulus for jute fiber and cotton fabric treated with enzyme mixture than untreated and were similar to those of NaOH treated. These results showed that the CtPME and CtPL1B mixture can be used for replacing the chemical process by green bioprocess in textile industry.     

Application of Thermostable Xylanase of Bacillus pumilus in Textile Processing

Desizing of cotton and micropoly fabrics was done using thermostable xylanase from Bacillus pumilus ASH. Micropoly fabric showed better desizing than cotton under same conditions. Violet scale readings from the TEGEWA test after enzymatic desizing for 90 min at pH 7.0 and at 60°C showed the readings falling in the range of 4–5, indicating good desizing efficiency. During bioscouring the weight loss values and liberation of reducing sugars were highest when EDTA was used along with xylanase. The weight loss value of 1.5% was observed for dry cotton fabric after 1 h in case of agitated system at pH 7.0 and at an optimal enzyme dosage of 5 IU/g. The weight loss values and the liberation of reducing sugars were higher in case of cotton fabrics. Wetting time of fabrics was lowered significantly after 60 min of bioscouring using xylanase. Increase in temperature or concentration of surfactant led to further reduction in the wetting time. The whiteness values of fabrics after bioscouring were 0.9% higher than the chemically scoured fabrics indicating good efficacy of xylanase during the scouring process.     

Effects of some thermal, chemical and mechanical treatments on lipase activity in Shammi goat milk

The effects of heating (20, 37 or 50 °C), cooling (5 °C), pasteurisation (71 °C for 15 s), boiling (100 °C), agitation (5 or 10 min), pH (acid or alkaline), and addition of chemicals such as silver and lead nitrates, copper sulphate and sodium chloride on lipase activity in Shammi goat milk were studied. There were non-significant differences (P < 0.01) in chemical composition between Shammi goat milk and Arabi cow milk. Lipase activity in Shammi goat milk was non-significantly (P < 0.01) lower than in Arabi cow milk. Lipase activity in milk of Shammi goats and Arabi cows was reduced when the milk was subjected to heating, cooling, pasteurisation, boiling, or when chemicals or acid was added, whereas in agitated and alkaline milk, the lipase activity was increased. The increase following agitation was greater after 10 min than 5 min. It can be concluded that heating, pasteurising, boiling, cooling, addition of certain chemicals and acidity are means by which lipase activity in milk can be reduced.     

A Celloidin Infiltration-Frozen Section Sequence for Enhanced Preservation of Phosphatases in Bone

The effect of the following embedding procedures on the acid and alkaline phosphatase content of decalcified mouse tibiae has been studied: embedding in 23% gelatine for 18 hr at 37° C, embedding in paraffin wax in vacuo for 1 hr at 58° C, and impregnation with 4% celloidin in diethyl ether and ethanol at 4° C for 2-3 days. Unsupported tissues were also used to demonstrate these enzymes for comparison with the above procedures. Tibiae were first fixed in 10% neutral formalin at 4° C for 15 hr, decalcified in equal volumes of 2% formic acid and 20% sodium citrate at pH 4.9 for not more than 5 days and then washed in distilled water before carrying out the embedding schedules. The celloidin-impregnated tibiae were placed in 70% ethanol to harden the celloidin and then washed in distilled water for 1-2 hr. These tibiae and those embedded in gelatine were cast in a gelatine block which was then hardened in 10% neutral formalin at 4° C for 2 hr. Sections of these and unsupported tibiae were cut at 15 μ on a freezing microtome. Decalcified tibiae embedded and blocked in paraffin wax were sectioned at 15 μ on a base sledge microtome. The enzymes were demonstrated using the coupling azo dye method given by Pearse (Histochemistry, 1st Ed. 1954). The stable diazotates of 4 benzoyl amino 2-5 diethoxyanilene, 3 nitro toluidine and o-dianisidine were used. Of the embedding procedures paraffin wax embedding produced the greatest loss of both enzymes. Gelatine embedding and infiltration with celloidin were equally good for the demonstration of acid phosphatase but for alkaline phosphatase the celloidin method was superior. The gelatine embedded material did not produce consistently good results. Celloidin-impregnated tibiae could be stored without marked deterioration of the enzyme content for longer than gelatine-embedded tibiae.     

Pectinase production by Bacillus subtilis and its potential application in biopreparation of cotton and micropoly fabric

An alkaline and thermostable pectinase production from Bacillus subtilis SS was optimized under submerged fermentation and its application was tested in textile industry for desizing and bioscouring of cotton and micropoly fabrics. Desizing of fabric was the best with 5 U/g pectinase treatment for 120 min at pH 9.5 and 65 °C. Under optimized conditions of bioscouring, desized cotton showed highest reducing sugar liberation and weight loss than desized micropoly. Along with enzyme, addition of chelating (EDTA) and wetting agent markedly enhanced the weight loss compared to single use of enzyme or EDTA alone. Agitation (50 ± 2) enhanced the weight loss values of cotton (1.9%) and micropoly fabric (1.7%) at pH 9.5 after treatment time of 2 h. Bioscouring of fabrics with pectinase resulted in enhancement of various physical properties of fabrics viz. whiteness (1.2%), tensile strength (1.6%) and tearness (3.0%) over conventionally alkaline scoured fabrics.     

Discovery of pectin-degrading enzymes and directed evolution of a novel pectate lyase for processing cotton fabric

There is a growing need in the textile industry for more economical and environmentally responsible approaches to improve the scouring process as part of the pretreatment of cotton fabric. Enzymatic methods using pectin-degrading enzymes are potentially valuable candidates in this effort because they could reduce the amount of toxic alkaline chemicals currently used. Using high throughput screening of complex environmental DNA libraries more than 40 novel microbial pectate lyases were discovered, and their enzymatic properties were characterized. Several candidate enzymes were found that possessed pH optima and specific activities on pectic material in cotton fibers compatible with their use in the scouring process. However, none exhibited the desired temperature characteristics. Therefore, a candidate enzyme was selected for evolution. Using Gene Site Saturation Mutagenesistrade mark technology, 36 single site mutants exhibiting improved thermotolerance were produced. A combinatorial library derived from the 12 best performing single site mutants was then generated by using Gene Reassemblytrade mark technology. Nineteen variants with further improved thermotolerance were produced. These variants were tested for both improved thermotolerance and performance in the bioscouring application. The best performing variant (CO14) contained eight mutations and had a melting temperature 16 degrees C higher than the wild type enzyme while retaining the same specific activity at 50 degrees C. Optimal temperature of the evolved enzyme was 70 degrees C, which is 20 degrees C higher than the wild type. Scouring results obtained with the evolved enzyme were significantly better than the results obtained with chemical scouring, making it possible to replace the conventional and environmentally harmful chemical scouring process.     

Metabolic characteristics of sea cucumber Apostichopus japonicus (Selenka) during aestivation

Metabolic characteristics of the sea cucumber Apostichopus japonicus (Selenka) during aestivation were studied in the laboratory. The effects of water temperature on oxygen consumption rate (OCR) and ammonia-N excretion rate (AER) in A. japonicus were determined by the Winkler and Hypobromite methods, respectively. Mature (large, 148.5 ± 15.4 g, medium 69.3 ± 6.9 g) and immature (small, 21.2 ± 4.7 g) individuals aestivated at water temperatures of 20 and 25 °C, respectively. The metabolic characteristics of mature individuals were different from immature individuals during this period. The OCR of mature sea cucumbers peaked at 20 °C, and then dropped significantly at higher temperatures, whereas the OCR of the immature animals continued to increase slightly, even beyond the aestivation temperature. The AER of mature individuals peaked at 20 °C, while that of the immature animals peaked at 25 °C. The relationships between dry weight (DW) and absolute oxygen consumption (R) and absolute ammonia-N excretion (N) could be described by the regression equation R or N = aW^b. With the exception of 15 °C, the O / N ratios (calculated in atomic equivalents) of large size sea cucumbers was close to 20 across the temperatures used in this study, indicating that their energy source was a combination of lipid and protein. On the other hand, apart from small individuals maintained at 10 °C, the O / N ratios of the medium and small sea cucumbers were close to 10, indicating that protein was their major energy source. The O / N ratios in all size groups remained unchanged after aestivation was initiated.     

Immobilized Cyclodextrin Glycosyl Transferase for the Continuous Production of Cyclodextrins

Cyclodextrin glycosyl transferase (E.C: 2.4.1.19) from Bacillus, macerans and from a Bacillus sp. isolate was immobilized by two methods, viz. to epoxy-activated Sepharose and to alkylamine silica treated with glutaraldehyde. Because of the ready availability, low cost ($0.01/g), good surface area (30 M²/g) and ease of operation of a continuous cylindrical reactor, the high silica fabric was chosen. The immobilized enzyme had a pH optimum shifted to the alkaline side (from 6.5 to 7.5) and had a reduced temperature optimum (from 60°C to 50-55°C). Reuse efficiency showed 65% reduction in the overall activity of the immobilized enzyme after 10 cycles of 48 h each. Continuous operation at 55°C of a cylindrical reactor of 141 ml capacity, using the immobilized enzyme (80 g of high - silica fabric containing 114 mg of purified enzyme) gave a maximum productivity of 10.2 g of cyclodextrins L^-1 h,^-1, at a dilution rate of 0.32 h^-1 and a substrate concentration of 20 g L^-1. The half life of the biocatalyst was found to be 22 days, which could be further improved by using a lower operating temperature. Over the useful life time of the immobilized biocatalyst (22 days), the total Cyclodextrin produced was of the order of 88 Kg.     

Lipase-catalyzed acylation of naringin with palmitic acid in highly concentrated homogeneous solutions

Acylation reactions of naringin with palmitic acid were performed by a lipase after formation of highly concentrated homogeneous solutions. Their initial naringin concentration was 840–950 mM, which is 20–60 times greater than that in organic solvent media. The overall productivity of highly concentrated solutions was more than 15 times greater than those of organic phase media. The addition of DMSO (20–40%, w/w) to substrate mixtures lowered the melting temperature of a naringin–palmitic acid mixture (1:1 molar ratio) to about 40 °C. Reactions at 80 °C apparently followed Michaelis–Menten kinetics despite extremely high substrate concentrations. As the temperature increased from 60 °C to 80 °C, the apparent viscosity of the highly concentrated solution decreased remarkably from 4.31 Pa s to 0.063 Pa s. An activation energy of 7.65 kcal/mol obtained in a range of 60–75 °C suggests a diffusion-control. On the other hand, an activation energy of 17.09 kcal/mol in a range of 75–90 °C indicates a reaction-control. The highest product conversion yield of 33% (mol/mol) was obtained in a 10 h reaction at 80 °C. Addition of activated molecular sieves to the highly concentrated solution increased the product conversion yield by 7% (mol/mol), suggesting that the original equilibrium was disrupted by removing water and then a new equilibrium was reached.     

The influence of pH on the viscous behavior of starch-poly(ethylene-co-acrylic acid) complexes

Starch-poly (ethylene-co-acrylic acid) (EAA) complexes were prepared by jet-cooking mixtures of either cornstarch, waxy cornstarch or high amylose cornstarch with aqueous ammonia dispersions of EAA (4% EAA based on the weight of starch). Viscosities (η) were determined at temperatures ranging from 80°C to 22°C, and plots of log η versus 1/T (K⁻¹) were prepared. When cooked with EAA, cornstarch and waxy cornstarch showed major changes in viscous behavior between 50°C and 60°C. Above 50–60°C, viscosity increased markedly with a reduction in temperature; however, viscosity increased slowly below 50–60°C with an apparent activation energy for the process approximating that of water itself. The temperature dependence of the measured viscosity from 80°C to 60°C could be attributed to the large increase in size and complexity of the flowing particles as individual amylopectin molecules were bound together by complexed EAA. Apparently, complexing is essentially complete at 50°C. When high amylose cornstarch was cooked in the absence of EAA, retrogradation produced a sharp increase in log η at temperatures below about 50°C. However, if EAA is present, association between amylose molecules apparently takes place via complex formation rather than retrogradation, since log η increases sharply at about 70–80°C. Also, in contrast to cornstarch and waxy cornstarch, log η versus 1/T plots for high amylose cornstarch did not level off at low temperatures. In general, viscosities increased with the pH of the system, particularly when η was measured at high temperatures. This could result from improved complexing ability of EAA under high pH conditions, possibly due to reduced micelle size and maximum extension of polymer chains from micelle surfaces.     

Effects of heat treatment and dehydration on bioactive polysaccharide acemannan and cell wall polymers from Aloe barbadensis Miller

Physico-chemical modifications promoted by heat treatment and dehydration at different temperatures (30–80 °C) on acemannan, a bioactive polysacharide from aloe vera (Aloe barbadensis Miller) parenchyma, were evaluated. Modification of acemannan, a storage polysaccharide, was particularly significant when dehydration was performed above 60 °C. Heating promoted marked changes in the average molecular weight (MW) of the bioactive polysaccharide, increasing from 45 kDa, in fresh aloe, to 75 and 81 kDa, for samples dehydrated at 70 and 80 °C, respectively. This could be attributed to structural modifications, such as deacetylation and losses of galactose-rich side-chains from the mannose backbone. These structural modifications were reflected by the significant changes occurring in the related functional properties, such as swelling, water retention capacity, and fat adsorption capacity, which exhibited a significant decrease as the temperature of dehydration increased. Further, dehydration also promoted significant modification of the main type of cell wall polysaccharides present within the aloe parenchyma tissues. Pectic polysaccharides from the cell wall matrix were affected by heating, probably due to either β-elimination processes or enzyme-catalysed degradation. The influence that these physico-chemical modifications might have on the bioactivity and properties of processed products from A. barbadensis Miller needs to be considered.     

Purification and kinetics of two novel thermophilic extracellular proteases from Lactobacillus helveticus, from kefir with possible biotechnological interest

Two thermophilic extracellular proteases, designated Lmm-protease-Lh (29 kDa) and Hmm-protease-Lh (62 kDa), were purified from the Lactobacillus helveticus from kefir, and found active in media containing dithiothreitol; the activity of Lmm-protease-Lh was increased significantly in media containing also EDTAK₂. Both novel proteases maintained full activity at 60 °C after 1-h incubation at 10 °C as well as at 80 °C, showing optimum k_cat/K_m values at pH 7.00 and 60 °C. Only irreversible inhibitors specific for cysteine proteinases strongly inhibited the activity of both novel enzymes, while they remained unaffected by irreversible inhibitors specific for serine proteinases. Both enzymes hydrolyzed the substrate Suc-FR-pNA via Michaelis–Menten kinetics; conversely, the substrate Cbz-FR-pNA was hydrolyzed by Lmm-protease-Lh via Michaelis–Menten kinetics and by Hmm-protease-Lh via substrate inhibition kinetics. Valuable rate constants and activation energies were estimated from the temperature-(k_cat/K_m) profiles of both enzymes, and useful results were obtained from the effect of different metallic ions on their Michaelis–Menten parameters.     

Thermoregulatory use of heat increment of feeding in the tawny owl (Strix aluco)

The heat increment of feeding (HIF) was investigated in the tawny owl (Strix aluco) in central Norway (63°N, 10°E), close to the northern limit of its distribution. HIF was measured as the increase in heat production (measured as oxygen consumption) after force-feeding the owls with laboratory mice at thermoneutral conditions (20 °C) and during cold-exposure (5 °C and −5 °C). The basal metabolic rate of the owls (mean mass 419 g) was 4.39 kJ h⁻¹ and the lower critical temperature was approximately 16 °C. During cold conditions, HIF substituted for thermogenesis, and at an ambient temperature of −5 °C the substitution was complete. Calculations indicate that the substitution by HIF may save the owls as much as 60% of their daily thermoregulatory costs. This corresponds to about 10% of their total daily energy budget.     

Characterization of the thermophilic isoamylase from the thermophilic archaeon Sulfolobus solfataricus ATCC 35092

Isoamylase catalyzes the hydrolysis of -1,6-glucosidic linkages of starch and related polysaccharides. In this study, the treX gene (GenBank accession no. AE006815 REGION: 9279 … 11435) encoding the thermophilic isoamylase was PCR-cloned from the genomic DNA of Sulfolobus solfataricus ATCC 35092 to an expression vector with a T7lac promoter. Both wild-type and His-tagged isoamylases were expressed in Escherichia coli. The wild-type isoamylase was purified sequentially using heat treatment, nucleic acid precipitation, ion-exchange chromatography, and gel filtration chromatography while the His-tagged isoamylase was purified from the cell-free extract directly by metal chelating chromatography. Both enzymes were active only under their homo-trimer forms. In the absence of NaCl, both enzymes became inactive monomers. In addition, both enzymes were more stable when being stored at room temperature than at 4 °C. They had an apparent optimal pH of 5 and an optimal temperature at 75 °C. The enzyme activities remained unchanged after a 2 h incubation at 80 and 75 °C for the wild-type and His-tagged enzymes, respectively. These thermophilic isoamylases showed a potential to be used in industry to degrade the branching points of starch at a high temperature.     

Characteristics of galactomannanase for degrading konjac gel

Galactomannanase (Glmnase) is an enzyme product derived from Aspergillus niger. The activity of Glmnase degrading (hydrolyzing) the konjac gel were investigated. Significant loss in the enzyme activity was found when the temperature above 60 °C. Similar observations were obtained when the reaction pH above 5. Further increase in the pH value resulted in entirely loss of enzyme activity at the alkaline pH region (pH 8.0 and above). The optimal hydrolyzing temperature and pH were at 60 °C and 5.0, respectively. For the stability test, the purified Glmnase increased its thermostability up to 70 °C at pH 5.0, but it retained only about 60% activity after 60 min incubation at this temperature and its activity became zero after 20 min incubation at 80 °C. The Glmnase was stable at the pH range from 3.0 to 7.0 at room temperature and retained at least 80% activity for 60 min. For the storage temperature test, the lyophilized Glmnase still conserved about 90% activity during 7 days at 30 °C, and was higher than about 80% at 4 °C. The K_m and V_max, were 0.018 mg/ml konjac powder and 0.20 mg/ml reducing sugar per min, respectively.     

Metabolic adjustments in the oyster Crassostrea gigas according to oxygen level and temperature

The purpose of this study was to examine the responses of the oyster Crassostrea gigas to oxygen levels at subcellular and whole organism levels. Two experiments were carried out. The first experiment was designed to measure the clearance and oxygen consumption rates of oysters exposed at different concentrations of oxygen at 15, 20 and 25°C for 20 h. The goal of this first part was to estimate the hypoxic threshold for oysters below which their metabolism shifts towards anaerobiosis, by estimating the oxygen critical point (PcO₂) at 15, 20 and 25°C. The second experiment was carried out to evaluate the metabolic adaptations to hypoxia for 20 days at three temperatures: 12, 15 and 20°C. The metabolic pathways were characterized by the measurement of the enzymes pyruvate kinase (PK) and phosphoenolpyruvate carboxykinase (PEPCK), the alanine and succinate content and the adenylate energy charge. Respiratory chain functioning was estimated by the measurement of the activity of the electron transport system (ETS). The values of PcO₂ were 3.02±0.15, 3.43±0.20 and 3.28±0.24 mg O₂ l^-1 at 15, 20 and 25°C, respectively. In whole oysters, hypoxia involved the inhibition of PK whatever the temperature, but PEPCK was not stimulated. Succinate accumulated significantly only at 12°C and alanine at 12 and 15°C. A negative relationship between the PK activity and the alanine content was only found in hypoxic oysters. Finally, hypoxia increased significantly the activity of ETS. With high PcO₂ values, the metabolic depression occurred quickly, showing that oysters had a low capacity to regulate their respiration when oxygen availability is reduced, particularly in the summer.     

Effects of Thermobifida fusca cutinase-carbohydrate-binding module fusion proteins on cotton bioscouring

Previously, we presented a novel approach for increasing Thermobifida fusca cutinase adsorption on cotton fibers by fusing cutinase with a carbohydrate-binding module (CBM). A preliminary study showed that two fusion proteins, namely cutinase-CBM_Cel6A and cutinase-CBM_CenA, with similar stabilities and catalytic properties, had potential applications in bioscouring. In the present study, an indepth analysis of both cutinase-CBMs in bioscouring was explored. Effects of cutinase-CBMs on cotton bioscouring were investigated by characterizing the chemical and physical surface changes in enzyme-treated cotton fabrics. Gas chromatography/mass spectrometry was used to analyze the degradation of the cotton fabric cuticle; Fourier transform infrared microspectroscopy was used to study changes in the chemical composition of the cotton fabric epidermal layer; and scanning electron microscopy was used to monitor minor changes in the morphology of the fiber surface. Our results indicated that cutinase-CBMs in combination with pectinase had a greater effect on cotton fabric than did cutinase. Following scouring with cutinase-CBMs and pectinase, the performance of cotton fabric in terms of its wettability and dyeability was similar to that following alkali scouring. Our study provides a foundation for the further application of cutinase-CBM to bioscouring.     

Surface modification of polyacrylonitrile with nitrile hydratase and amidase from Agrobacterium tumefaciens

A new strain of Agrobacterium tumefaciens (BST05) was found to grow on polyacrylonitrile (PAN; ¹³C labelled) converting the polymer to polyacrylic acid as shown by solid state NMR. When cultivated in a medium containing acetonitrile the bacterium produced nitrile hydratase and amidase activity. Activity recovery after lyophilisation and enzyme stability was significantly enhanced in the presence of 5% sorbitol leading to half life times of 12, 72 and 154 days at 25°C, 4°C and -20°C. The enzymes were able to convert 1.1% of the nitrile groups of PAN-powder to the corresponding acids. PAN fabrics were mainly converted to the amides as shown by an 80% increase of the O/C ratio in ESCA analysis. These data were confirmed by cationic dyeing and FTIR-ATR analysis.