Laccase immobilization on mesostructured cellular foams affords preparations with ultra high activity

Extracellular laccase produced by the wood-rotting fungus Cerrena unicolor was immobilized covalently on the mesostructured siliceous cellular foams (MCFs) functionalised using various organosilanes with amine and glycidyl groups. The experiments indicated that laccase bound via glutaraldehyde to MCFs modified using 2-aminoethyl-3-aminopropyltrimethoxysilane remains very active. In the best biocatalyst activity was about 42,700 U mL^?1 carrier (66,800 U mg^?1 bound protein), and hence significantly higher than ever reported before. Optimisation of the immobilization procedure with respect to protein concentration, pH of coupling mixture and the enzyme purity afforded the biocatalyst with activity of about 90,980 U mL^?1. For the best preparation, thermal- and pH-stability, and activity profiles were determined. Experiments carried out in a batch reactor showed that k_cat/K_m for immobilized enzyme (0.88 min^?1 μM^?1) was acceptable lower than the value obtained for the native enzyme (2.19 min^?1 μM^?1). Finally, potentials of the catalysts were tested in the decolourisation of indigo carmine without redox-mediators. Seven consecutive runs with the catalysts separated by microfiltration proved that adsorption of the dye onto the carrier and enzymatic oxidation contribute to the efficient decolourisation without loss of immobilized enzyme activity.     

Iron containing keratinolytic metallo-protease produced by Chryseobacterium gleum

Chryseobacterium gleum exhibited complete dissolution of whole chicken-feathers (10 g l^?1, pH 8) after 72 h at 30 °C through synthesis of keratinolytic protease when inoculated at 1% (v/v). This enzyme was purified to 67-fold with yield of 2.25% having a specific activity of 1670 U mg^?1 and ～36 kDa Mw. MALDI-TOF MS of this keratinase showed some similarity with the keratinase peptides of Bacillus subtilis (BOFXJ2). The keratinase action was inhibited by EDTA, iodoacetamide and metal ions like mercury, copper and zinc (1 mM each), while it was enhanced by iron and calcium. Keratinase showed presence of 3 mM of Fe M^?1 as tested by atomic absorption spectroscopy and addition of Fe in its apoenzyme retained about 79% of original residual feather degradation activity which portrayed it to be metalloprotease. Purified keratinase revealed significant degradation (85%) of feather concentrate (20 g l^?1) to 3.9 μM ml^?1 of free amino groups in 24 h at an initial pH of 8.0, 30 °C and 120 rpm shaking. This keratinase activity can be controlled precisely by presence of chemical or metal ions which could be of use in biotechnology industry while the culture can be used in poultry waste management.     

Inulin hydrolysis and citric acid production from inulin using the surface-engineered Yarrowia lipolytica displaying inulinase

The INU1 gene encoding exo-inulinase cloned from Kluyveromyces marxianus CBS 6556 was ligated into the surface display plasmid and expressed in the cells of the marine-derived yeast Yarrowia lipolytica which can produce citric acid. The expressed inulinase was immobilized on the yeast cells. The activity of the immobilized inulinase with 6 × His tag was found to be 22.6 U mg^?1 of cell dry weight after cell growth for 96 h. The optimal pH and temperature of the displayed inulinase were 4.5 and 50 °C, respectively and the inulinase was stable in the pH range of 3–8 and in the temperature range of 0–50 °C. During the inulin hydrolysis, the optimal inulin concentration was 12.0% and the optimal amount of added inulinase was 181.6 U g^?1 of inulin. Under such conditions, over 77.9% of inulin was hydrolyzed within 10 h and the hydrolysate contained main monosaccharides and disaccharides, and minor trisaccharides. During the citric acid production in the flask level, the recombinant yeast could produce 77.9 g L^?1 citric acid and 5.3 g L^?1 iso-citric acid from inulin while 68.9 g L^?1 of citric acid and 4.1 g L^?1 iso-citric acid in the fermented medium were attained within 312 h of the 2-L fermentation, respectively.     

Polyvinyl alcohol–silica nanohybrids: An efficient carrier matrix for amylase immobilization

Polyvinyl alcohol (PVA)–silica nanohybrids have been synthesized in a modified Stöber process. The bioactivities of the enzyme loaded hybrids were monitored and the optimum activity sample (H) was calcined at 300 °C in N₂ to obtain hybrid gel (H₃) with improved performance. The synthesized hybrids have been characterized by Fourier Transform Infra Red spectroscopy, X-ray diffraction, scanning electron microscopy, thermogravimetric analysis and BET surface area analysis. Under the optimized conditions, the bioactivity of the enzyme impregnated H₃ (H₃-Enz) was 21.823 U/mg. On recycling, H₃-Enz retained 88% of its initial bioactivity in the sixth cycle. The kinetic parameters of soluble starch hydrolysis for the immobilized (K_M = 4.137 mg mL^?1; V_max = 5.95 mg mL^?1 min^?1) and free enzyme (K_M = 10.667 mg mL^?1; V_max = 6.0557 mg mL^?1 min^?1) indicated that the immobilization has nearly doubled the enzyme's affinity for the substrate, while the maximum rate of the enzymatic reaction at the saturation point was not much affected. The immobilized enzyme showed greater shelf life in comparison to the free enzyme.     

A novel immobilization method for nuclease P1 on macroporous absorbent resin with glutaraldehyde cross-linking and determination of its properties

Microbial nuclease P₁ from Penicllium citrinum was immobilized on macroporous absorbent resins: strong polar poly (styrene-co-DVB) resin (SPPSD), polymethacrylic ester resin and poly (styrene-co-DVB)-Br resin. The results showed that SPPSD was the best carrier. Three methods of glutaraldehyde cross-linking were used and simultaneous immobilization and cross-linking (CIS) was demonstrated to be the best method. The functional properties of immobilized nuclease P₁ were studied and compared to those of the free enzyme. The highest enzyme activities of free and immobilized nuclease P₁ were obtained in 0.2 M acetate buffer at pH 4.5 and a temperature of 70 °C. An increase in K_m (from 3.165 to 18.125 mg mL^?1) and a decrease in V_max (from 1667.18 to 443.95 U min^?1 mL^?1) were recorded after immobilization. SPPSD-glutaraldehyde-nuclease P₁ exhibited better thermal stability than the free enzyme. The apparent activation energy (E_a) of the free and immobilized nuclease P₁ was 137.04 kJ mol^?1 and 98.43 kJ mol^?1, respectively, implying that the catalytic efficiency of the immobilized enzyme was restricted by mass-transfer rather than kinetic limit.     

Glucose isomerase production on a xylan-based medium by Bacillus thermoantarcticus

Effects of medium components on intracellular glucose isomerase (GI) production were investigated by Bacillus thermoantarcticus. The highest GI activity was obtained as 1630 U dm^?3 in the medium containing (g dm^?3): 10.6, birchwood-xylan; 5.6, yeast extract; 5.9 (NH₄)₂SO₄ at T = 55 °C in 33 cm^?3 shake-flasks. When birchwood-xylan was replaced with oat spelt- or beechwood-xylan, GI activity decreased to 1372 and 1308 U dm^?3, respectively. Effects of pH at uncontrolled-pH (pH_UC = 6.0) and controlled-pH (pH_C = 6.0) operations, and oxygen transfer at the air inlet rate of 0.5 vvm and agitation rates of 300, 500 and 700 min^?1, were investigated in 3.0 dm³ bioreactor system with 1.65 dm³ working volume in the designed medium. The highest GI activity was attained at 500 min^?1, 0.5 vvm, pH_UC = 6 as 1840 U dm^?3 where cell concentration was 2.3 g dm^?3. The use of agricultural waste xylan, as the carbon source resulted in concomitant production of xylanase and GI. The highest xylanase activity was attained as 9300 U dm^?3 at 500 min^?1 and 0.5 vvm. K_La varied between 0.008–0.033 s^?1 whereas the highest oxygen uptake rate was 0.002 mmol dm^?3 s^?1. Initially biochemical reaction limitations were effective; thereafter, mass transfer resistances became more effective.     

Effect of mechanical agitation on the production of cellulases by Trichoderma reesei RUT-C30 in a draft-tube airlift bioreactor

With the aim to produce cellulases and to study the effect of mechanical agitation, a 35 L draft-tube airlift bioreactor equipped with a mechanical impeller was developed and validated to grow Trichoderma reesei RUT-C30 in a cellulose culture medium with lactose and lactobionic acid as fed batch. Cultures carried out without mechanical agitation resulted in higher volumetric enzyme productivity (200 U L⁻¹ h⁻¹), filter paper activity (17 U mL⁻¹), carboxymethyl cellulase activity (11.8 U mL⁻¹) and soluble proteins (3.2 mg mL⁻¹) when compared to those with agitation. Stereo and polarized light microscopy analyses reveal that mechanical agitation resulted in shorter mycelial hyphae and larger numbers of tips.     

Crucial factors affecting the nitrile hydratase production of Mesorhizobium sp. F28

Mesorhizobium sp. F28 contains cobalt-NHase, which effectively converts acrylonitrile into acrylamide. When urea was added to the culture medium, the NHase activity was 62.3 U ml^?1 (R2A–R2A/urea) after 22.5 h of cultivation, which was similar to that in the medium without addition (R2A–R2A, 70.0 U ml^?1). The relative activity of the purified NHase was 100%, 92%, 94%, and 92% in the medium containing, respectively, 0 mM, 2 mM, 5 mM, and 10 mM of urea. Urea had no significant effect on the purified NHase activity of Mesorhizobium sp. F28. This research did not observe the NHase production by Mesorhizobium sp. F28 when acrylonitrile was supplemented in the culture medium except that cobalt ions existed. The highest enzyme activity was 328.5 U ml^?1 as cobalt ions were added in the pre-culture and culture medium after 22.5 h of cultivation (R2A/Co-R2A/Co); compared to media without cobalt ions (R2A–R2A, 22.5 h, 70.5 U ml^?1) this is an almost five-fold enhancement. It can be concluded that culture media containing cobalt ions was beneficial for the formation of active NHase of Mesorhizobium sp. F28.     

Microencapsulation of Bacillus subtilis B99-2 and its biocontrol efficiency against Rhizoctonia solani in tomato

Biological control is a promising approach to protecting plants from disease. Bacillus subtilis has been widely used in agriculture for promoting plant growth and biocontrol. However, their short shelf life limits the application of biological pesticides. The objectives of this study were to develop a microencapsulation procedure of B. subtilis B99-2 using maltodextrin and gum arabic as wall materials to determine the optimum conditions of spray-drying in microencapsulation, evaluate storage stability of microcapsules, and assess their biocontrol efficiency against Rhizoctonia solani in tomato under field conditions. We microencapsulated the Bacillus thallus by spray-drying with various concentrations of the wall material. Maltodextrin was found to be an efficient wall material, especially at concentrations higher than 80%, while gum arabic did not affect the bacterial survival rate. The mean survival rate of B. subtilis was more than 90%, when spray drying was performed at 145 °C, with a feed flow rate of 550 mL h⁻¹, and a spray pressure of 0.15 MPa. B. subtilis microcapsule survival rate was 87.53% after 540 d of storage, which was a longer shelf life than that of wettable powders. Moreover, its biocontrol efficacy reached 79.91% when a dosage of 300 g hm⁻² was used, the microcapsule showed higher control efficacy than Thiram wettable powder against R. solani in tomato under field conditions. All these characteristics indicated that B. subtilis microcapsules have the potential to become a successful biocontrol product.     

Optimization and immobilization of amylase obtained from halotolerant bacteria isolated from solar salterns

The objective of the present study was to isolate halotolerant bacteria from the sediment sample collected from Marakanam Solar Salterns, Tamil Nadu, India using NaCl supplemented media and screened for amylase production. Among the 22 isolates recovered, two strains that had immense potential were selected for amylase production and designated as P1 and P2. The phylogenetic analysis revealed that P1 and P2 have highest homology with Pontibacillus chungwhensis (99%) and Bacillus barbaricus (100%). Their amylase activity was optimized to obtain high yield under various temperature, pH and NaCl concentration. P1 and P2 strain showed respective, amylase activity maximum at 35 °C and 40 °C; pH 7.0 and 8.0; 1.5 M and 1.0 M NaCl concentration. Further under optimized conditions, the amylase activity of P1 strain (49.6 U mL^?1) was higher than P2 strain. Therefore, the amylase enzyme isolated from P. chungwhensis P1 was immobilized in sodium alginate beads. Compared to the free enzyme form (49.6 U mL^?1), the immobilized enzyme showed higher amylase activity as 90.3 U mL^?1. The enzyme was further purified partially and the molecular mass was determined as 40 kDa by SDS–PAGE. Thus, high activity of amylase even under increased NaCl concentration would render immense benefits in food processing industries.     

Purification and characterization of a thermostable endo-β-1,4-glucanase from a novel strain of Penicillium purpurogenum

A novel endo-β-1,4-glucanase (EG)-producing strain was isolated and identified as Penicillium purpurogenum KJS506 based on its morphology and internal transcribed spacer (ITS) rDNA gene sequence. P. purpurogenum produced one of the highest levels of EG (5.6 U mg-protein^?1) with rice straw and corn steep powder as carbon and nitrogen sources, respectively. The extracellular EG was purified to homogeneity by sequential chromatography of P. purpurogenum culture supernatants on a DEAE sepharose column, a gel filtration column, and then on a Mono Q column with fast protein liquid chromatography. The purified EG was a monomeric protein with a molecular weight of 37 kDa and showed broad substrate specificity with maximum activity towards lichenan. P. purpurogenum EG showed t_1/2 value of 2 h at 70 °C and catalytic efficiency of 118 ml mg^?1 s^?1, one of the highest levels seen for EG-producing microorganisms. Although EGs have been reported elsewhere, the high catalytic efficiency and thermostability distinguish P. purpurogenum EG.     

Characterization of the toxicity of Cochlodinium polykrikoides isolates from Northeast US estuaries to finfish and shellfish

Harmful algal blooms caused by Cochlodinium polykrikoides are annual occurrences in coastal systems around the world. In New York (NY), USA, estuaries, bloom densities range from 10³ to 10⁵ mL^?1 with higher densities (≥10⁴ cells mL^?1) being acutely toxic to multiple fish and shellfish species. Here, we report on the toxicity of C. polykrikoides strains recently isolated from New York and Massachusetts (USA) estuaries to juvenile fish (Cyprinodon variegates) and bay scallops (Argopecten irradians), as well as on potential mechanisms of toxicity. Cultures of C. polykrikoides exhibited dramatically more potent ichthyotoxicity than raw bloom water with 100% fish mortality occurring within ～1 h at densities as low as 3.3 × 10² cells mL^?1. More potent toxicity in culture was also observed in bioassays using juvenile bay scallops, which experienced 100% mortality during 3 days exposure to cultures at cell densities an order of magnitude lower than raw bloom water (～3 × 10³ cells mL^?1). The toxic activity per C. polykrikoides cell was dependent on the growth stages of cultures with early exponential growth cultures being more potent than cultures in late-exponential or stationary phases. The ichthyotoxicity of cultures was also dependent on both cell density and fish size, as a hyperbolic relationship between the death time of fish and the ratio of algal cell density to length of fish was found (～10³ cells mL^?1 cm^?1 yielded 100% fish mortality in 24 h). Simultaneous exposure of fish to C. polykrikoides and a second algal species (Rhodomonas salina or Prorocentrum minimum) increased survival time of fish, and decreased the fish mortality suggesting additional cellular biomass mitigated the ichthyotoxicity. Frozen and thawed-, sonicated-, or heat-killed-, C. polykrikoides cultures did not cause fish mortality. In contrast, cell-free culture medium connected to an active culture through a 5 μm nylon membrane caused complete mortality in fish, although the time required to kill fish was significantly longer than direct exposure to the whole culture. These results indicate that ichthyotoxicity of C. polykrikoides isolates is dependent on viability of cells and that direct physical contact between fish and cells is not required to cause mortality. The ability of the enzymes peroxidase and catalase to significantly reduce the toxicity of live cultures and the inability of hydrogen peroxide to mimic the ichthyotoxicity of C. polykrikoides isolates suggests that the toxicity could be caused by non-hydrogen peroxide, highly reactive, labile toxins such as ROS-like chemicals.     

A stable immobilized d-psicose 3-epimerase for the production of d-psicose in the presence of borate

Maximal activity of the immobilized d-psicose 3-epimerase from Agrobacterium tumefaciens on Duolite A568 beads was achieved at pH 9.0 and 55 °C with borate, and at pH 8.5 and 50 °C without borate. The half-lives of the immobilized enzyme at 50 °C with and without borate were increased 4.2- and 128-fold compared to that of the free enzyme without borate, respectively. The immobilized enzyme with borate produced 441 g l^?1 psicose from 700 g l^?1 fructose at pH 9.0 and 55 °C, whereas 193 g l^?1 psicose was produced without borate at pH 8.5 and 50 °C after 120 min in a batch reaction. The immobilized enzyme in a packed-bed bioreactor without borate was produced continuously 325 g l^?1 psicose from 500 g l^?1 fructose at a dilution rate of 1.62 h^?1 over a 236 h period with productivity of 527 g l^?1 h^?1 while that without borate produced 146 g l^?1 psicose at 4.15 h^?1 over a 384-h period with productivity of 606 g l^?1 h^?1. The operational half-lives of the enzyme with and without borate in the bioreactor were 601 and 645 h, respectively. In the present study, psicose was produced stably with high productivity using the immobilized d-psicose 3-epimerase in the presence of borate.     

Production of specific-molecular-weight hyaluronan by metabolically engineered Bacillus subtilis 168

Low-molecular-weight hyaluronan (LMW-HA) has attracted much attention because of its many potential applications. Here, we efficiently produced specific LMW-HAs from sucrose in Bacillus subtilis. By coexpressing the identified committed genes (tuaD, gtaB, glmU, glmM, and glmS) and downregulating the glycolytic pathway, HA production was significantly increased from 1.01 g L⁻¹ to 3.16 g L⁻¹, with a molecular weight range of 1.40×10⁶–1.83×10⁶ Da. When leech hyaluronidase was actively expressed after N-terminal engineering (1.62×10⁶ U mL⁻¹), the production of HA was substantially increased from 5.96 g L⁻¹ to 19.38 g L⁻¹. The level of hyaluronidase was rationally regulated with a ribosome-binding site engineering strategy, allowing the production of LMW-HAs with a molecular weight range of 2.20×10³–1.42×10⁶ Da. Our results confirm that this strategy for the controllable expression of hyaluronidase, together with the optimization of the HA synthetic pathway, effectively produces specific LMW-HAs, and could also be used to produce other LMW polysaccharides.     

Isolation and identification of a novel Rhodococcus sp. ML-0004 producing epoxide hydrolase and optimization of enzyme production

Rhodococcus sp. ML-0004, a novel strain for producing epoxide hydrolase, was isolated from soil in this study. The epoxide hydrolase can catalyze the stereo-specific hydrolysis of cis-epoxysuccinic acid to generate l(+)-tartaric acid. By examining physiological, biochemical characteristics and comparing its 16S rDNA gene sequence, it was identified as Rhodococcus opacus, and named R. opacus ML-0004. The optimal conditions for epoxide hydrolase production from R. opacus ML-0004 were also investigated. Propanediol and (NH₄)₂SO₄ were selected as carbon source and nitrogen source, respectively, for the production of R. opacus ML-0004 epoxide hydrolase. The optimal conditions for epoxide hydrolase production were fermentation temperature = 28 °C, pH 7.0, and cultivation time = 26 h. Under these conditions, the maximum epoxide hydrolase activity reached 10.5 U mL⁻¹.     

Production of the postharvest biocontrol agent Bacillus subtilis CPA-8 using low cost commercial products and by-products

The aim of this research was to identify a low cost medium based on commercial products and by-products that provided maximum Bacillus subtilis CPA-8 growth and maintained biocontrol efficacy. Low cost media combining economical nitrogen and carbon sources such as yeast extract, peptone, soy products, sucrose, maltose and molasses were tested. Tests were carried out in 250-ml flasks containing 50 ml of each tested medium. Maximum cell growth (>3 × 10⁹ CFU ml^?1) was obtained in defatted soy flour 44% combined with sucrose or molasses media. Second, CPA-8 production was scaled up in a 5-l fermenter and CPA-8 population dynamics, pH and oxygen consumption in the optimized medium (defatted soy flour 44% – molasses) was recorded. In these tests, there was a 5-h lag phase before growth, after which exponential growth occurred and maximum production was 3 × 10⁹ CFU ml^?1 after 20 h. Fruit trials with cells and cell free supernatants from CPA-8 grown in optimized medium maintained biocontrol efficacy against Monilinia fructicola on peaches, resulting in disease reductions up to 95%. CPA-8 populations survived in wounds on inoculated peaches, regardless of the culture media used. The results show that B. subtilis CPA-8 can be produced in a low cost medium combining inexpensive nitrogen and carbon sources (40 g l^?1 defatted soy flour 44%, 5 g l^?1 molasses plus mineral trace supplements) in shake flasks and a laboratory fermenter (5 l). The results could be used to provide a reliable basis for scaling up the fermentation process to an industrial level.     

Determination of phenothiazine derivatives in human urine by using ionic liquid-based dynamic liquid-phase microextraction coupled with liquid chromatography

A simple and rapid method for the determination of seven phenothiazines derivatives (chlorpromazine, promethazine, levomepromazine, prochlorperazine, trifluoperazine, fluphenazine and thioridazine) in human urine samples is presented. The analytes are extracted from the sample in 50 μL of the ionic liquid 1-butyl-3-methyl-imidazolium hexafluorophosphate working in an automatic flow system under dynamic conditions. The chemical affinity between the extractant and the analytes allows a good isolation of the drugs from the sample matrix achieving at the same time their preconcentration. The separation and detection of the extracted compounds is accomplished by liquid chromatography and UV detection. The proposed method is a valuable alternative for the analysis of these drugs in urine within the concentration range 0.07–10 μg mL^?1. Limits of detection were in the range from 21 ng mL^?1 (thioridazine) to 60 ng mL^?1 (levomepromazine). The repeatability of the proposed method expressed as RSD (n = 5) varied between 2.2% (levomepromazine) and 3.9% (chlorpromazine).     

Characterization and overproduction of a thermo-alkaline pectate lyase from alkaliphilic Bacillus licheniformis with potential in ramie degumming

A thermo-alkaline pectate lyase (BliPelA) gene from an alkaliphilic Bacillus licheniformis strain was cloned and overexpressed in Escherichia coli. Mature BliPelA exhibited maximum activity at pH 11 and 70 °C, and demonstrated cleavage capability on a broad range of substrates such as polygalacturonic acid, pectins, and methylated pectins. The highest specific activity, of 320 U mg⁻¹, was towards polygalacturonic acid. Significant ramie (Boehmeria nivea) fiber weight loss (21.5%) was obtained following enzyme treatment and combined enzyme-chemical treatment (29.3%), indicating a high ramie degumming efficiency of BliPelA. The total activity of recombinant BliPelA reached 1450.1 U ml⁻¹ with a productivity of 48.3 U ml⁻¹ h⁻¹ under high-cell-density cultivation with a glycerol exponential feeding strategy for 30 h in 1-l fed-batch fermenter, and 1380.1 U ml⁻¹ with a productivity of 57.5 U ml⁻¹ h⁻¹ after 24 h under constant glucose feeding in a 20-l fermenter using E. coli as the host. The enzyme yields reached 4.5 and 4.3 g l⁻¹ in 1-l and 20-l fed-batch fermenters, respectively, which are higher than those of most reported alkaline Pels. Based on these promising properties and high-level production, BliPelA shows great potential for application in ramie degumming in textile industry.     

A new fungal peroxidase with alkaline-tolerant,chloride-enhancing activity and dye decolorization capacity

A new fungal peroxidase (Pspd) from Perenniporia subacida was purified by ammonium sulfate precipitation, DEAE-cellulose DE52 anionic exchange and Sepharose GL-6B chromatography, resulting in a high specific activity of 9.138 U mg⁻¹, 3.622-fold higher than that of crude enzyme at the same level. Polyacrylamide gel electrophoresis and UV–vis adsorption spectrum analysis showed that the purified enzyme is a heme-containing monomer with a molecular mass of 43.0 kDa. Optimal peroxidase activity was obtained at pH 5.5 and 30 °C when using 100.0 mM n-propanol as substrate, and under these conditions, the catalytic efficiency (k_cat/K_m) is 1.57 s⁻¹ μM⁻¹. Pspd was inhibited by l-cysteine, dithiothreitol, EDTA and sodium azide, but stimulated by Mn²⁺, Na⁺, Mg²⁺ and K⁺. The enzyme is stable over a broad pH range of 7.0–8.5 after incubation for 72 h, which indicated that the enzyme is lasting alkaline-tolerant. It was worth noting that the chloride at relatively low concentrations can enhance the peroxidase activity, with concomitant increase in substrate affinity. Additionally, Pspd performed high decolorization capability toward structurally various dyes and the capability was independent of the oxidizing mediators, with 75.31% of Neutral Red (50.0 mg L⁻¹) being decolorized by 1.5 U mL⁻¹ pure enzyme after incubation for 72 h. These properties demonstrated that Pspd has potentials for textile dyes decolorization applications.     

Knee flexor strength and bicep femoris electromyographical activity is lower in previously strained hamstrings

The aim of this study was to determine if athletes with a history of hamstring strain injury display lower levels of surface EMG (sEMG) activity and median power frequency in the previously injured hamstring muscle during maximal voluntary contractions. Recreational athletes were recruited, 13 with a history of unilateral hamstring strain injury and 15 without prior injury. All athletes undertook isokinetic dynamometry testing of the knee flexors and sEMG assessment of the biceps femoris long head (BF) and medial hamstrings (MHs) during concentric and eccentric contractions at ±180 and ±60° s^?1. The knee flexors on the previously injured limb were weaker at all contraction speeds compared to the uninjured limb (+180° s^?1 p = 0.0036; +60° s^?1 p = 0.0013; ?60° s^?1 p = 0.0007; ?180° s^?1 p = 0.0007) whilst sEMG activity was only lower in the BF during eccentric contractions (?60° s^?1 p = 0.0025; ?180° s^?1 p = 0.0003). There were no between limb differences in MH sEMG activity or median power frequency from either BF or MH in the injured group. The uninjured group showed no between limb differences in any of the tested variables. Secondary analysis comparing the between limb difference in the injured and the uninjured groups, confirmed that previously injured hamstrings were mostly weaker (+180° s^?1 p = 0.2208; +60° s^?1 p = 0.0379; ?60° ^?1 p = 0.0312; ?180° s^?1 p = 0.0110) and that deficits in sEMG were confined to the BF during eccentric contractions (?60° s^?1 p = 0.0542; ?180° s^?1 p = 0.0473). Previously injured hamstrings were weaker and BF sEMG activity was lower than the contralateral uninjured hamstring. This has implications for hamstring strain injury prevention and rehabilitation which should consider altered neural function following hamstring strain injury.