Immobilized <Emphasis Type="Italic">Kluyveromyces marxianus</Emphasis> cells in carboxymethyl cellulose for production of ethanol from cheese whey: experimental and kinetic studies

Cheese whey fermentation to ethanol using immobilized Kluyveromyces marxianus cells was investigated in batch and continuous operation. In batch fermentation, the yeast cells were immobilized in carboxymethyl cellulose (CMC) polymer and also synthesized graft copolymer of CMC with N-vinyl-2-pyrrolidone, denoted as CMC-g-PVP, and the efficiency of the two developed cell entrapped beads for lactose fermentation to ethanol was examined. The yeast cells immobilized in CMC-g-PVP performed slightly better than CMC with ethanol production yields of 0.52 and 0.49 g ethanol/g lactose, respectively. The effect of supplementation of cheese whey with lactose (42, 70, 100 and 150 g/l) on fermentative performance of K. marxianus immobilized in CMC beads was considered and the results were used for kinetic studies. The first order reaction model was suitable to describe the kinetics of substrate utilization and modified Gompertz model was quite successful to predict the ethanol production. For continuous ethanol fermentation, a packed-bed immobilized cell reactor (ICR) was operated at several hydraulic retention times; HRTs of 11, 15 and 30 h. At the HRT of 30 h, the ethanol production yield using CMC beads was 0.49 g/g which implies that 91.07 % of the theoretical yield was achieved.     

The removal of mercury (II) from water by Ag supported on nanomesoporous silica

In this study, the synthesis of SBA-15/Ag nanocomposite materials with different amounts of silver (2.5, 5, and 10 %) has been investigated under acidic conditions by using P123 as a template via the direct method. The nanocomposites of SBA-15 were synthesized by the same method and by the addition of silver salt. Finally, the nanocomposite materials were examined for the removal of mercury ions from wastewater as an adsorbent by the reverse titration method. Characterization was carried out through x-ray diffraction analysis (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N₂ adsorption-desorption (Brunauer–Emmett–Teller). XRD spectra confirmed the presence of silver nanoparticles within the amorphous silica matrix of SBA-15. The Barrett–Joyner–Halenda analysis showed that SBA-15 and SBA-15/Ag have a narrow pore size distribution. SEM images demonstrated that the morphology of the matrix of SBA-15 is in spherical state. Furthermore, wavelength dispersive x-ray spectroscopy identified the presence and distribution of silver nanoparticles inside the pore channels and outside of them. Typical TEM images of SBA-15 and SBA-15/Ag (5 wt.%) indicated a regular hexagonal pore structure with long-range order and long channels. In SBA-15/Ag (5 wt.%) sample, the nanoparticles of silver was found into the pores and outside of them. The removal of mercury ions from wastewater using mesoporous silica nanocomposite containing silver nanoparticles was studied by the reverse titration analysis. The best capacity of adsorption of mercury ions from wastewater was obtained for SBA-15/Ag (5 wt.%) sample, which was equal to 42.26 mg/g in 20 min at pH of 7. The Freundlich model was used to explain the adsorption characteristics for the heterogeneous surface, and \( {K}_{\mathrm{f}} \) (adsorption capacity) and n (adsorption intensity) were determined for Hg (II) ion adsorption on SBA-15/Ag nanocomposite materials with different amounts of silver (2.5, 5, and 10 %). The value of R ² was about 0.99, 0.99, 0.98, and 0.98 and K _f was about 42, 48, 58, and 58 mg/g for SBA-15/Ag, SBA-15/Ag (2.5 %), SBA-15/Ag (5 %), and SBA-15/Ag (10 %), respectively. Furthermore, the values of n >1 show a favorable adsorption process for Hg (II) ion adsorption on SBA-15/Ag nanocomposite materials. Moreover, the Langmuir isotherm model evaluation showed that the correlation coefficients for all concentrations were R ² >0.99, indicating that Hg (II) ions were adsorbed on the surface of SBA-15/Ag via chemical and physical interaction. Additionally, the analytic hierarchy process (AHP) and Technique of Order Preference Similarity to the Ideal Solution (TOPSIS) methods that depend on the criteria of the surface area, amount of adsorbent, pore volume, and cost of synthesis were used. The evaluation of results showed that the best sample was SBA-15/Ag (5 wt.%). Furthermore, the research work highlighted the antibacterial nanocomposite with suitable adsorption of Hg (II) ions from water solutions and supported its potential for environmental applications. This nanocomposite can be used in the absorption domain of Hg (II) ions from water solutions.     

Evaluation of ethanol production and bioadsorption of heavy metals by various red seaweeds

The objective of this study was to evaluate ethanol production and bioadsorption with four red seaweeds, Gelidium amansii, Gracilaria verrucosa, Kappaphycus alvarezii and Eucheuma denticulatum. To produce ethanol, thermal acid hydrolysis, enzymatic saccharification and fermentation was carried out. After pretreatment, 38.5, 39.9, 31.0 and 27.5 g/L of monosaccharides were obtained from G. amansii, G. verrucosa, K. alvarezii and E. denticulatum, respectively. Ethanol fermentation was performed with Saccharomyces cerevisiae KCCM 1129 adapted to 80 g/L galactose. The ethanol productions by G. amansii, G. verrucosa, K. alvarezii and E. denticulatum were 18.8 g/L with Y _EtOH = 0.49, 19.1 g/L with Y _EtOH = 0.48, 14.5 g/L with Y _EtOH = 0.47 and 13.0 g/L with Y _EtOH = 0.47, respectively. The waste seaweed slurries after the ethanol fermentation were reused to adsorb Cd(II), Pb(II) and Cu(II). Using langmuir isotherm model, Cu(II) had the highest affinity for waste seaweeds with the highest q _max and electronegativity values among three heavy metals.     

Effect of glycerol and PEGMA coating on the efficiency of cell holding in alginate immobilized <Emphasis Type="Italic">Synechococcus elongatus</Emphasis>

Synechococcus elongatus cells were immobilized in alginate beads, and the effects of increasing the cross-linker concentration from 2 to 4 % CaCl₂ were evaluated, as well as the effects of coating the beads with either glycerol or poly(ethylene glycol) methyl ether methacrylate (PEGMA)—not previously reported for immobilized microalgae—to improve the holding time of the immobilized cells. S. elongatus cells remain metabolically active after coating with glycerol or PEGMA. There is an inverse relation between the glycerol concentration and the chlorophyll a content for the alginate beads cross-linked with 2 % CaCl₂. PEGMA diminishes the rate of liberation of cells as its concentration increases, although results suggest the ability of S. elongatus to degrade PEGMA, which increases the growth rate of the liberated cells, because of PEGMA being used as carbon source.     

Decolorization of textile dye RB19 using volcanic rock matrix immobilized <Emphasis Type="Italic">Bacillus thuringiensis</Emphasis> cells with surface displayed laccase

A triplicate volcanic rock matrix–Bacillus thuringiensis–laccase WlacD (VRMs–Bt–WlacD) dye decolorization system was developed. WlacD was displayed on the B. thuringiensis MB174 cell surface to prepare a whole-cell laccase biocatalyst by using two repeat N-terminal domains of autolysin Mbg (Mbgn)₂ as the anchoring motif. Immunofluorescence microscopic assays confirmed that the fusion protein (Mbgn)₂–WlacD was anchored on the surface of the recombinant B. thuringiensis MB174. After optimization by a single factor test, L ₉(3⁴)-orthogonal test, Plackett–Burman test, steepest ascent method, and Box–Behnken response surface methodology, the whole-cell specific laccase activity of B. thuringiensis MB174 was improved to 555.2 U L^?1, which was 2.25 times than that of the primary culture condition. Optimized B. thuringiensis MB174 cells were further adsorbed by VRMs to prepare VRMs–Bt–WlacD, an immobilized whole-cell laccase biocatalyst. Decolorization capacity of as-prepared VRMs–Bt–WlacD toward an initial concentration of 500 mg L^?1 of an textile dye reactive blue 19 (RB19) aqueous solution reached 72.36% at a solid-to-liquid ratio of 10 g–100 mL. Repeated decolorization-activation operations showed the high decolorization capacity of VRMs–Bt–WlacD and have the potential for large-scale or continuous operations.     

The nitrite reductase activity of horse heart carboxymethylated-cytochrome <Emphasis Type="Italic">c</Emphasis> is modulated by cardiolipin

Horse heart carboxymethylated cytc (CM-cytc) displays myoglobin-like properties. Here, the effect of cardiolipin (CL) liposomes on the nitrite reductase activity of ferrous CM-cytc [CM-cytc-Fe(II)], in the presence of sodium dithionite, is reported between pH 5.5 and 7.6, at 20.0 °C. Cytc-Fe(II) displays a very low value of the apparent second-order rate constant for the NO₂ ^?-mediated conversion of cytc-Fe(II) to cytc-Fe(II)-NO [k _on = (7.3 ± 0.7) × 10^?2 M^?1 s^?1; at pH 7.4], whereas the value of k _on for NO₂ ^? reduction by CM-cytc-Fe(II) is 1.1 ± 0.2 M^?1 s^?1 (at pH 7.4). CL facilitates the NO₂ ^?-mediated nitrosylation of CM-cytc-Fe(II) in a dose-dependent manner, the value of k _on for the NO₂ ^?-mediated conversion of CL–CM-cytc-Fe(II) to CL–CM-cytc-Fe(II)-NO (5.6 ± 0.6 M^?1 s^?1; at pH 7.4) being slightly higher than that for the NO₂ ^?-mediated conversion of CL–cytc-Fe(II) to CL–cytc-Fe(II)-NO (2.6 ± 0.3 M^?1 s^?1; at pH 7.4). The apparent affinity of CL for CM-cytc-Fe(II) is essentially pH independent, the average value of B being (1.3 ± 0.3) × 10^?6 M. In the absence and presence of CL liposomes, the nitrite reductase activity of CM-cytc-Fe(II) increases linearly on lowering pH and the values of the slope of the linear fittings of Log k _on versus pH are ?1.05 ± 0.07 and ?1.03 ± 0.03, respectively, reflecting the involvement of one proton for the formation of the transient ferric form, NO, and OH^?. These results indicate that Met80 carboxymethylation and CL binding cooperate in the stabilization of the highly reactive heme-Fe atom of CL–CM-cytc.     

Mercury(II) complex formation with glutathione in alkaline aqueous solution

The structure and speciation of the complexes formed between mercury(II) ions and glutathione (GSH = L-glutamyl-L-cysteinyl-glycine) have been studied for a series of alkaline aqueous solutions (\( C_{{{\text{Hg}}^{{2 + }}}}\,{\sim18\,{\rm{mmol}}\,{\rm{{dm^{-3}}}}}\) and C _GSH = 40–200 mmol dm^?3 at pH ～10.5) by means of extended X-ray absorption fine structure (EXAFS) and ¹⁹⁹Hg NMR spectroscopy at ambient temperature. The dominant complexes are [Hg(GS)₂]^4? and [Hg(GS)₃]^7?, with mean Hg–S bond distances of 2.32(1) and 2.42(2) Å observed in digonal and trigonal Hg–S coordination, respectively. The proportions of the Hg²⁺–glutathione complexes were evaluated by fitting linear combinations of model EXAFS oscillations representing each species to the experimental EXAFS spectra. The [Hg(GS)₄]^10? complex, with four sulfur atoms coordinated at a mean Hg–S bond distance of 2.52(2) Å, is present in minor amounts (<30%) in solutions containing a large excess of glutathione (C _GSH ≥ 160 mmol dm^?3). Comparable alkaline mercury(II) cysteine (H₂Cys) solutions were also investigated and a reduced tendency to form higher complexes was observed, because the deprotonated amino group of Cys^2? allows the stable [Hg(S,N-Cys)₂]^2? chelate to form. The effect of temperature on the distribution of the Hg²⁺–glutathione complexes was studied by comparing the EXAFS spectra at ambient temperature and at 25 K of a series of glycerol/water (33/67, v/v) frozen glasses with \( C_{{{\text{Hg}}^{{2 + }} }} \,{\sim7\,{\rm{mmol}}\,{\rm{{dm^{-3}}}}} \) and C _GSH = 16–81 mmol dm^?3. Complexes with high Hg–S coordination numbers, [Hg(GS)₃]^7? and [Hg(GS)₄]^10?, became strongly favored when just a moderate excess of glutathione (C _GSH ≥28 mmol dm^?3) was used in the glassy samples, as expected for a stepwise exothermic bond formation. Addition of glycerol had no effect on the Hg(II)–glutathione speciation, as shown by the similarity of the EXAFS spectra obtained at room temperature for two parallel series of Hg(II)-glutathione solutions with \( C_{{{\text{Hg}}^{{2 + }} }} \,{\sim7\,{\rm{mmol}}\,{\rm{{dm^{-3}}}}},\) with and without 33% glycerol. Also, the ¹⁹⁹Hg NMR chemical shifts of a series of ～18 mmol dm^?3 mercury(II) glutathione solutions with 33% glycerol were not significantly different from those of the corresponding series in aqueous solution.     

Verrucarin A and roridin E produced on spinach by <Emphasis Type="Italic">Myrothecium verrucaria</Emphasis> under different temperatures and CO<Subscript>2</Subscript> levels

The behavior of Myrothecium verrucaria, artificially inoculated on spinach, was studied under seven different temperature conditions (from 5 to 35 °C) and under eight different combinations of temperature and CO₂ concentration (14–30 °C and 775–870 or 1550–1650 mg/m³). The isolate used for this study was growing well on spinach, and the mycotoxins verrucarin A and roridin E were produced under all tested temperature and CO₂ conditions. The maximum levels of verrucarin A (18.59 ng/g) and roridin E (49.62 ng/g) were found at a temperature of 26–30 °C and a CO₂ level of 1550–1650 mg/m³. Rises in temperature as well as in temperature and CO₂ concentrations had a significant effect by increasing Myrothecium leaf spots on spinach. The biosynthesis of verrucarin A was significantly increased at the highest temperature (35 °C), while roridin E was influenced by the CO₂ concentration. These results show that a positive correlation between climate condition and macrocyclic trichothecene production is possible. However, because of the ability of M. verrucaria to produce mycotoxins, an increase in temperature could induce the spread of M. verrucaria in temperate regions; this pathogen may gain importance in the future.     

Immobilization and stabilization of papain on poly(hydroxyethyl methacrylate-ethylenglycol dimethacrylate) beads grafted with epoxy functional polymer chains via surface-initiated-atom transfer radical polymerization (SI-ATRP)

Poly(hydroxyethyl methacrylate–ethylen glycol dimethacrylate), p(HEMA–EGDMA), beads were prepared by suspension polymerization, and were decorated with fibrous poly(glycidyl methacrylate), p(GMA), via surface initiated-atom transfer radical polymerization (SI-ATRP). The functional epoxy groups of the beads were used for covalent immobilization of papain. The average amount of immobilized enzyme was 18.7 mg/g beads. The immobilized enzyme was characterized by temperature, pH, operational and storage stability experiments. The maximum velocity of the free and immobilized enzymes (V_max) and Michaelis–Menten constant (K_m) values were determined as 10.7 and 8.3 U/mg proteins and 274 and 465 μM, respectively. The immobilized papain was operated in a batch reactor, and it was very effective for hydrolysis of different proteins (i.e., casein and cytochrom c).     

Enhanced isopropanol and <Emphasis Type="Italic">n</Emphasis>-butanol production by supplying exogenous acetic acid via co-culturing two clostridium strains from cassava bagasse hydrolysate

The focus of this study was to produce isopropanol and butanol (IB) from dilute sulfuric acid treated cassava bagasse hydrolysate (SACBH), and improve IB production by co-culturing Clostridium beijerinckii (C. beijerinckii) with Clostridium tyrobutyricum (C. tyrobutyricum) in an immobilized-cell fermentation system. Concentrated SACBH could be converted to solvents efficiently by immobilized pure culture of C. beijerinckii. Considerable solvent concentrations of 6.19 g/L isopropanol and 12.32 g/L butanol were obtained from batch fermentation, and the total solvent yield and volumetric productivity were 0.42 g/g and 0.30 g/L/h, respectively. Furthermore, the concentrations of isopropanol and butanol increased to 7.63 and 13.26 g/L, respectively, under the immobilized co-culture conditions when concentrated SACBH was used as the carbon source. The concentrations of isopropanol and butanol from the immobilized co-culture fermentation were, respectively, 42.62 and 25.45 % higher than the production resulting from pure culture fermentation. The total solvent yield and volumetric productivity increased to 0.51 g/g and 0.44 g/L/h when co-culture conditions were utilized. Our results indicated that SACBH could be used as an economically favorable carbon source or substrate for IB production using immobilized fermentation. Additionally, IB production could be significantly improved by co-culture immobilization, which provides extracellular acetic acid to C. beijerinckii from C. tyrobutyricum. This study provided a technically feasible and cost-efficient way for IB production using cassava bagasse, which may be suitable for industrial solvent production.     

Assessment of the antimicrobial,antioxidant and cytotoxic activities of the wild edible mushroom <Emphasis Type="Italic">Agaricus lanipes</Emphasis> (F.H. Møller &amp; Jul. Schäff.) Hlaváček

The present investigation was undertaken to evaluate the antimicrobial and antioxidant activities of the wild edible mushroom Agaricus lanipes, and also to investigate its cytotoxicity and potential and possible apoptotic effect against the A549 lung cancer cell line in in vitro conditions. Total antioxidant capacity, total phenolic content, total oxidant status, total antioxidant status, lipid hydroperoxides, and total free –SH levels of A. lanipes were found to be 4.55 mg T/g, 14.6 mg GA equivalent/g, 3.10 mg H₂O₂ equivalent/g, 2.25 mg H₂O₂ equivalent/g, and 1.90 µmol/g, respectively. The methanolic extract of A. lanipes had relatively strong antimicrobial activity against seven tested microorganism strains. It also had high anti-proliferative potency and strong pro-apoptotic effects, and this mushroom used as a daily nutrient could be a source for new drug developments and treatment in cancer therapies, and could be a guide for studies in this area.     

Recovery of avocado (<Emphasis Type="Italic">Persea americana</Emphasis> Mill.) plants transformed with the antifungal plant defensin gene PDF1.2

Embryogenic avocado cultures derived from ‘Hass’ protoplasts were genetically transformed with the plant defensin gene (pdf1.2) driven by the CaMV 35S promoter in pGPTV with uidA as a reporter gene and bar, the gene for resistance to phosphinothricin, the active ingredient of the herbicide Finale® (Basta) (Bayer Environmental Science, Research Triangle Park, Durham, NC ). Transformation was mediated by Agrobacterium tumefaciens strain EHA105. Transformed cultures were selected in the presence of 3.0 mg l^?1 phosphinothricin in liquid maintenance medium for 3–4 mo. Liquid maintenance medium consisted of modified MS medium containing (per liter) 12 mg NH₄NO₃ and 30.3 mg KNO₃ and supplemented with 0.1 mg l^?1 thiamine HCl, 100 mg l^?1 myo-inositol, 30 g l^?1 sucrose, 3.0 mg l^?1 phosphinothricin, and 0.41 μM picloram. Somatic embryo development from transformed cultures was initiated on MS medium supplemented with 45 g l^?1 sucrose, 4 mg l^?1 thiamine HCl, 100 mg l^?1 myo-inositol, 10% (v/v) filter-sterilized coconut water, 3.0 mg l^?1 phosphinothricin, and 6.0 g l^?1 gellan gum. Limited plant recovery occurred from somatic embryos on semi-solid MS medium supplemented with 3.0 mg l^?1 phosphinothricin, 4.44 μM 6-benzylaminopurine (BA), and 2.89 μM GA₃; transformed shoots were micrografted on in vitro-grown seedling rootstocks. Approximately 1 yr after acclimatization in the greenhouse, transformed shoots were air-layered to recover transformed roots. Genetic transformation of embryogenic cultures, somatic embryos, and regenerated plants was confirmed by polymerase chain reaction (PCR), Southern blot hybridization, the XGLUC reaction for uidA, and application of the herbicide Finale® to regenerated plants.     

Serum Level of Zinc and Copper in Sudanese Women with Polycystic Ovarian Syndrome

The paper’s objective was to estimate weekly Hg intake from fish meals based on intervention research. Total Hg (THg) concentrations in blood and hair samples collected from men (n = 67) from an intervention study as well as muscular tissues of fresh and after heat-treating fish were determined using the thermal decomposition amalgamation atomic absorption spectrometry method (TDA-AAS) using direct mercury analyzer (DMA-80). The mean of the estimated weekly intake (EWI) was estimated at 0.62 μg/kg bw/week in the range 0.36–0.96 μg/kg body weight (bw) /week through the consumption of 4 edible marine fish species every day (for 10 days) by the participants from the intervention research in Lodz, Poland. The Hg intake in the volunteers in our intervention study accounted for 38.6% of the provisional tolerable weekly intake (PTWI) (1.6 μg/kg bw, weekly) value. The average Hg concentration in the analyzed fish ranged from 0.018 ± 0.006 mg/kg wet weight (Gadus chalcogrammus) to 0.105 ± 0.015 mg/kg wet weight (Macruronus magellanicus). The results for the average consumers were within PTWI of methylmercury (MeHg). Moreover, the average concentration of Hg in the selected fish after heat treatment did not exceed the maximum permitted concentrations for MeHg (MPCs = 0.5 mg/kg wet weight) in food set by the European Commission Regulation (EC/1881/2006). Hence, the risk of adverse effects of MeHg for the participants is substantially low.     

Immobilized CALB Catalyzed Transesterification of Soybean Oil and Phytosterol

Candida antarctica lipase B (CALB) was immobilized on Fe₃O₄/SiO_x-g-P(GMA) polymer carrier to catalyzed the transesterification of soybean oil and phytosterol. The enzyme loading of the obtained particles was 98.7 mg/g supports and the enzyme activity was 1226.5 U/g. The average particle size was 100.5?±?1.30 nm and the magnetization was 15.80 emu/g. The immobilized enzyme showed higher activities at a wider range of pH and temperatures. Its optimum reaction temperature was up to 50 °C; increased by 5 °C compared to the free enzyme. The obtained magnetic immobilized Fe₃O₄/SiO_x-g-P(GMA) lipase was nanoscale. First-grade soybean oils were used as a substrate. System pH was adjusted to 7.0. The optimal reaction temperature was 50 °C and the reaction time was 3 h. The phytosterol concentration of 5% and immobilized CALB of 2% were obtained. The conversion rate of transesterification reaction between soybean oil and phytosterol was 86.2%. The use of magnets can quickly separate the immobilized enzymes from the substrates. The relative activity of the immobilized enzymes was 83.0% when reused seven times. The prepared immobilized CALB can improve efficiently enzyme activity and reutilization.     

Characterisation of lactic acid producing <Emphasis Type="Italic">Sporolactobacillus</Emphasis> strains from tree barks in Thailand

Eight spore-forming lactic acid producing bacteria were isolated from tree barks in Thailand. They were identified as Sporolactobacillus nakayamae (Group I, three isolates), S. terrae (Group II, two isolates), S. kofuensis (Group III, one isolate) and S. inulinus (Group IV, two isolates) based on their phenotypic characteristics and 16S rRNA gene sequence analyses. Four isolates in Groups I and II produced DL lactic acid (89.60–114.61 g/L), while three isolates in Groups III and IV produced D-lactic acid (88.01–113.78 g/L). Isolate BK65-3 identified as S. inulinus produced the highest D-lactic acid concentrations (101.42 g/L), productivity (1.41 g/L/h), yields (84.52%) and optical purity of D-lactic acid (100%).     

Desulfurization with <Emphasis Type="Italic">Thialkalivibrio versutus</Emphasis> immobilized on magnetic nanoparticles modified with 3-aminopropyltriethoxysilane

Objective

Thialkalivibrio versutus D301 cells were immobilized on Fe₃O₄ nanoparticles (NPs) synthesized by an improved chemical coprecipitation method and modified with 3-aminopropyltriethoxysilane (APTES), then the immobilized cells were used in sulfur oxidation.

Results

The prepared Fe₃O₄–APTES NPs had a narrow size distribution (10 ± 2 nm) and were superparamagnetic, with a saturation magnetization of 60.69 emu/g. Immobilized cells had a saturation magnetization of 34.95 emu/g and retained superparamagnetism. The optimum conditions for cell immobilization were obtained at pH 9.5 and 1 M Na⁺. The immobilization capacity of Fe₃O₄–APTES NPs was 7.15 g DCW/g-NPs that was 2.3-fold higher than that of Fe₃O₄ NPs. The desulfurization efficiency of the immobilized cells was close to 100%, having the same sulfur oxidation capacity as free cells. Further, the immobilized cells could be reused at least eight times, retaining more than 85% of their desulfurization efficiency.

Conclusion

Immobilization of cells with the modified magnetic NPs efficiently increased cell controllability, have no effect on their desulfurization activity and could be effectively used in large-scale industrial applications.

     

Molecular docking,PASS analysis,bioactivity score prediction,synthesis, characterization and biological activity evaluation of a functionalized 2-butanone thiosemicarbazone ligand and its complexes

2-Butanone thiosemicarbazone ligand was prepared by condensation reaction between thiosemicarbazide and butanone. The ligand was characterized by ¹H NMR, ¹³C NMR, FT-IR, mass spectrometry and UV spectroscopic studies. Docking studies were performed to study inhibitory action against topoisomerase II (Topo II) and ribonucleoside diphosphate reductase (RR) enzymes. Inhibition constants (K _i ) of the ligand were 437.87 and 327.4 μM for the two enzymes, respectively. The ligand was tested for its potential anticancer activity against two cancer cell lines MDA-MB-231 and A549 using MTT assay and was found to exhibit good activity at higher doses with an IC₅₀ = 80 μM against human breast cancer cell line MDA-MB-231. On the other hand, no significant activity was obtained against the lung carcinoma cell line A549. Antibacterial activity of the ligand was tested against Staphylococcus aureus and E. coli using the disc diffusion method. Ligand did not exhibit any significant antibacterial activity. Four complexes of Co(III), Fe(II), Cu(II), and Zn(II) were prepared with the ligand and characterized by various spectroscopic studies. Low molar conductance values were obtained for all complexes displaying non-electrolyte nature except in Co(III) complex. As expected, complexation with metal ions significantly increased the cytotoxicity of the ligand against the tested cell lines viz. IC₅₀ values of <20 μM for Co, Fe, and Zn complexes and approx. 80 μM against MDA cells versus IC₅₀ value of <20 μM for Co and Cu complexes and that of 30 and 50 μM for Fe and Zn complexes, respectively, against A549 cells. The Cu complex was found to be active against E. coli and S. aureus with MIC values in the range of 6–10 mg/mL. Other than Cu, only Co complex was found to possess antibacterial activity with MIC values of 5–10 mg/mL when tested against S. aureus. Bioactivity score and Prediction of Activity Spectra for Substances (PASS) analysis also depicted the drug-like nature of ligand and complexes.     

Growth and phosphorus removal by <Emphasis Type="Italic">Synechococcus elongatus</Emphasis> co-immobilized in alginate beads with <Emphasis Type="Italic">Azospirillum brasilense</Emphasis>

This study examined the co-immobilization of the cyanobacterium Synechococcus elongatus with the plant growth-promoting bacterium Azospirillum brasilense in alginate beads and its potential application for the removal of phosphorus from aquaculture wastewater. Co-immobilization of both microorganisms significantly increased the cell density of S. elongatus (2852.5?×?10⁴ cells mL^?1) compared with that of immobilization of cyanobacteria alone (1325.2?×?10⁴ cells mL^?1). Chlorophyll a content was similar in co-immobilized (11.1?±?3.5 pg cell^?1) and immobilized S. elongatus (14.5?±?4.9 pg cell^?1). Azospirillum brasilense showed continuous growth until day 2, after which its cell concentration declined until the end of the assay. Co-immobilized S. elongatus removed more phosphorus (44.8 %) than immobilized cyanobacteria cells alone (32.0 %). In conclusion, phosphate removal was greater with free cells of S. elongatus but overlapped with the values that were obtained with the treatment of co-immobilization of cells. Our results demonstrate that A. brasilense enhances the growth of S. elongatus and improves its removal of phosphorus when they are co-immobilized in alginate beads compared with only immobilization of cyanobacteria cells alone.     

Simultaneous nitrification and denitrification with different mixed nitrogen loads by a hypothermia aerobic bacterium

Microorganism with simultaneous nitrification and denitrification ability plays a significant role in nitrogen removal process, especially in the eutrophic waters with excessive nitrogen loads. The nitrogen removal capacity of microorganism may suffer from low temperature or nitrite nitrogen source. In this study, a hypothermia aerobic nitrite-denitrifying bacterium, Pseudomonas tolaasii strain Y-11, was selected to determine the simultaneous nitrification and denitrification ability with mixed nitrogen source at 15 °C. The sole nitrogen removal efficiencies of strain Y-11 in simulated wastewater were obtained. After 24 h of incubation at 15 °C, the ammonium nitrogen fell below the detection limit from an initial value of 10.99 mg/L. Approximately 88.0 ± 0.33% of nitrate nitrogen was removed with the initial concentration of 11.78 mg/L and the nitrite nitrogen was not detected with the initial concentration of 10.75 mg/L after 48 h of incubation at 15 °C. Additionally, the simultaneous nitrification and denitrification nitrogen removal ability of P. tolaasii strain Y-11 was evaluated using low concentration of mixed NH₄⁺-N and NO₃^?–N/NO₂^?–N (about 5 mg/L-N each) and high concentration of mixed NH₄⁺–N and NO₃^?–N/NO₂^?–N (about 100 mg/L-N each). There was no nitrite nitrogen accumulation at the time of evaluation. The results demonstrated that P. tolaasii strain Y-11 had higher simultaneous nitrification and denitrification capacity with low concentration of mixed inorganic nitrogen sources and may be applied in low temperature wastewater treatment.     

Development of novel robust nanobiocatalyst for detergents formulations and the other applications of alkaline protease

Alkaline protease from alkaliphilic Bacillus sp. NPST-AK15 was immobilized onto functionalized and non-functionalized rattle-type magnetic core@mesoporous shell silica (RT-MCMSS) nanoparticles by physical adsorption and covalent attachment. However, the covalent attachment approach was superior for NPST-AK15 protease immobilization onto the activated RT-MCMSS-NH₂ nanoparticles and was used for further studies. In comparison to free protease, the immobilized enzyme exhibited a shift in the optimal temperature and pH from 60 to 65 °C and pH 10.5–11.0, respectively. While free protease was completely inactivated after treatment for 1 h at 60 °C, the immobilized enzyme maintained 66.5 % of its initial activity at similar conditions. The immobilized protease showed higher k _cat and K _m , than the soluble enzyme by about 1.3-, and 1.2-fold, respectively. In addition, the results revealed significant improvement of NPST-AK15 protease stability in variety of organic solvents, surfactants, and commercial laundry detergents, upon immobilization onto activated RT-MCMSS-NH₂ nanoparticles. Importantly, the immobilized protease maintained significant catalytic efficiency for ten consecutive reaction cycles, and was separated easily from the reaction mixture using an external magnetic field. To the best of our knowledge this is the first report about protease immobilization onto rattle-type magnetic core@mesoporous shell silica nanoparticles that also defied activity-stability tradeoff. The results clearly suggest that the developed immobilized enzyme system is a promising nanobiocatalyst for various bioprocess applications requiring a protease.