Biodegradation of Mixed Phenolic Compounds Under High Salt Conditions and Salinity Fluctuations by <Emphasis Type="Italic">Arthrobacter</Emphasis> sp. W1

High salt concentration and salinity fluctuations in wastewater challenge the efficiency of microbial strains used for cleanup of pollutants. In this study, it was investigated that the new isolated Arthrobacter sp. W1 degraded mixed phenolic compounds under complex salt conditions. The results showed that Arthrobacter sp. W1 was able to utilize various phenolic compounds as carbon source under high salt conditions. It can degrade phenol and p-cresol mixture at 10% NaCl, although rates of degradation and cell growth were lower compared to 5% NaCl. The presence of trace p-cresol significantly inhibited phenol biodegradation. When salinity fluctuations were between 1% and 10% NaCl, strain W1 was able to degrade substrates and survived. It was also suggested that the presence of salts (i.e., NaCl, KCl, Na₂SO₄, and K₂SO₄) had almost no effects on the microbial growth and biodegradation process. Therefore, Arthrobacter sp. W1 would be a promising candidate for bioremediation of phenolic compounds under complex salt conditions.     

Study of structure properties of organized silica sorbents synthesized on polymeric templates

Mesoporous silica materials were synthesized by applying Pluronic type polymers as pore creating agents. The composition of a reacting mixture and the process conditions were changed in a synthesis procedure. These changes differentiated the characteristics of porous structure of obtained sorbents. The parameters characterizing the pore structure were estimated and the changes of pore arrangement of obtained materials being a result of different synthesis conditions were investigated. The small-angle XRD results indicate that F cubic structure was formed what confirms the cage-like ordering of the synthesized silicas.     

羧甲基纤维素水凝胶生物降解动力学研究

用氯化铝对羧甲基纤维素进行交联,制得了水凝胶.考察了底物浓度、酶浓度以及降解温度对该水凝胶降解速率的影响,探讨了酶降解动力学及“表观”活化能对酶浓度的依赖关系.结果表明,该酶促反应最佳温度为37 ℃,降解反应对底物浓度和酶浓度的反应级数分别为1级和1.2级;得到了与传统的Michaelis-Menten动力学机制不同的非均相酶促反应动力学模型,确定了“表观”活化能与酶浓度之间的定量关系.     

Genome Annotation and Validation of Keratin-Hydrolyzing Proteolytic Enzymes from <Emphasis Type="Italic">Serratia marcescens</Emphasis> EGD-HP20

Stabilization and utilization of poultry waste demand efficient biodegradation either by mixture of enzymes or by microbial system that can produce different types of protein-hydrolyzing enzymes. For utilization of this keratinous biomass, in the present study, genome was sequenced and annotated for a bacterium having multiple enzymatic options for hydrolysis of different soluble and insoluble protein fractions of poultry waste. Among the soluble protein substrates, optimum production of enzyme and soluble protein was observed in case of casein, whereas among the insoluble protein substrates, maximum production of enzyme was achieved when broken nails were used. Conditions for enhanced enzyme activity with concurrent degradation of keratin-rich poultry feather waste to protein-rich hydrolysate were optimized for different growth parameters. The bacterium grew well and highest protease production occurred in 144 h at mesophilic temperature (30 °C) and alkaline condition (pH 8–10) with enzyme activities of 134 and 168 U/mL, respectively.     

聚羟基烷酸酯酶降解动力学研究

研究了羟基丁酸 羟基戊酸共聚物 (PHBV)在脂肪酶中的降解行为 ,用滴定法测定降解速度并进行酶促反应动力学研究 .探讨了降解速度与酶浓度和底物浓度的数学关系和Michaelis Menten常数 ,从实验上和理论上证实了PHBV的物理形态和几何尺寸对酶降解过程的影响 ,以及实验数据与非均相动力学模型的拟合     

The effect of pectinase on the bubble fractionation of invertase from α-amylase

Fermentation broth normally contains many extracellular enzymes of industrial interest. To separate such enzymes on-line could be useful in reducing the cost of recovery as well as in keeping their yield at a maximum level by minimizing enzyme degradation from broth proteases (either the desired enzymes or the proteases could be removed selectively or both removed together and then separated). Several large-scale separation methods are candidates for such on-line recovery such as ultrafiltration, precipitation, and two-phase partitioning. Another promising technique for on-line recovery is adsorptive bubble fractionation, the subject of this study. Bubble fractionation, like ultrafiltration, does not require contaminating additives and can complement ultrafiltration by preconcentrating the enzymes using the gases normally present in a fermentation process. A mixture of enzymes in an aqueous bubble solution can, in principle, be separated by adjusting the pH of that solution to the isoelectric point (pI) of each enzyme as long as the enzymes have different pIs. The model system investigated here is comprised of three enzyme separations and the problem is posed as the effect of pectinase (a charged enzyme) on the bubble fractionation of invertase (a relatively hydrophilic enzyme) from α-amylase (a relatively hydrophobic enzyme). The primary environmental variable studied, therefore, is the pH in the batch bubble fractionation column. Air was used as the carrier gas. This prototype mixture exemplifies an aerobic fungal fermentation process for producing enzymes. The enzyme concentration here is measured as total protein concentration by the Coomassie Blue (Bradford) solution method (1), both as a function of time and column position for each batch run. Since, from a previous study (2), it was found that invertase and α-amylase in a two-enzyme system can be partially separated in favor of one vs the other at two different pHs (pH 5.0 and 9.0) with significant separation ratios, emphasis is placed on the effect of pectinase at these pHs. In this study, the addition of pectinase reduced the total separation ratio of the α-amylase-invertase mixture at both pHs.     

Sol–gel synthesis and structure of silica hybrid materials

In this work the research results on the sol–gel synthesis and structure of silica nanocomposites, containing carrageenan and their application as carriers for cell immobilization were described. The samples were prepared at room temperature by replacing different quantity of the inorganic precursor with κ-carrageenan. For studying the structure of the synthesized hybrids the following methods were used: FT-IR, XRD, BET-Analysis, SEM, AFM and Roughness Analysis. The influence of the type of silicon precursors, nature and quantity of organic component on the structure, surface area, design and size of nanostructures was established. The possibility of application of the synthesized biocatalysts in an enzyme degradation process of the toxic, carcinogenic and mutagenic substances benzonitrile, fumaronitrile, o-, m-, and p-tolunitriles was investigated at batch experiments. A two-step biodegradation process in a column bioreactor of fumaronitrile was followed. After operation of the system for 8 h at a flow rate 45 mL h^?1 and at 60 °C, the overall conversion was 89%, showing a good stability of the developed process.     

Synthesis of novel N-protected β-amino nitriles: study of their hydrolysis involving a nitrilase-catalyzed step

Several commercially available nitrilases were investigated with regard to their potential to hydrolyze N-protected β³-amino nitriles into their corresponding N-protected β³-amino acids.The biotransformations were obtained in different proportions depending on the nitrilase involved. The best hydrolysis results were achieved for the N-Cbz-β³-amino nitrile from l-alanine using the NIT-107, in a phosphate buffer at 0.05 M. However, no biotransformation into the corresponding acids was observed for the N-sulfonylamide β³-amino nitriles. Two simple and efficient procedures to prepare the β³-amino nitriles from their analogous α-amino acids are described. Thirty four new substances were synthesized and characterized over the course of this work.     

Biodegradation of Chlorinated and Non-chlorinated VOCs from Pharmaceutical Industries

Biodegradation studies were conducted for major organic solvents such as methanol, ethanol, isopropanol, acetone, acetonitrile, toluene, chloroform, and carbon tetrachloride commonly used in pharmaceutical industries. Various microbial isolates were enriched and screened for their biodegradation potential. An aerobic mixed culture that had been previously enriched for biodegradation of mixed pesticides was found to be the most effective. All the organic solvents except chloroform and carbon tetrachloride were consumed as primary substrates by this mixed culture. Biodegradation rates of methanol, ethanol, isopropanol, acetone, acetonitrile, and toluene were measured individually in batch systems. Haldane model was found to best fit the kinetics of biodegradation. Biokinetic parameters estimated from single-substrate experiments were utilized to simulate the kinetics of biodegradation of mixture of substrates. Among the various models available for simulating the kinetics of biodegradation of multi-substrate systems, competitive inhibition model performed the best. Performance of the models was evaluated statistically using the dimensionless modified coefficient of efficiency (E). This model was used for simulating the kinetics of biodegradation in binary, ternary, and quaternary substrate systems. This study also reports batch experiments on co-metabolic biodegradation of chloroform, with acetone and toluene as primary substrates. The Haldane model, modified for inhibition due to chloroform, could satisfactorily predict the biodegradation of primary substrate, chloroform, and the microbial growth.     

Laser light-scattering studies of poly(caprolactone-b-ethylene oxide-b-caprolactone) nanoparticles and their enzymatic biodegradation

Water-insoluble triblock poly(caprolactone-b-ethylene oxide-b-caprolactone) (PCL-PEO-PCL) was micronized into narrowly distributed nanoparticles stable in water. Using a combination of static and dynamic laser light scattering (LLS), we characterized the resultant nanoparticles and studied their biodegradation in the presence of enzyme lipase PS. The results revealed that the biodegradation rate was mainly dependent on the enzyme concentration. The scattering intensity decreased as the degradation proceeded, but there was no change in size of the remaining nanoparticles, indicating that the degradation of each particle was fast and the enzyme consumed the nanoparticles individually. We also found that different copolymer compositions, i.e., different PCL–PEO molar ratios, led to different biodegradation rates. The pH and temperature dependence of the biodegradation rate were also studied. All results indicated that the biodegradation rate can be well controlled and the biodegradation essentially involves two processes: adsorption of lipase PS onto the nanoparticles, and enzymatic hydrolysis of the PCL blocks. The biomedical application of the enzymatic biodegradation of the copolymer nanoparticles is also envisioned. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 3288–3293, 1999     

Lipase-catalyzed production of short-chain acids terpenyl esters of interest to the food industry

The production of low molecular weight esters as flavor compounds by biotechnological processes has a potential interest for the food industry. The use of natural available substrates and enzymes is an essential part of the process design, because the products may obtain natural label. In this study, direct esterification of citronellol and geraniol with short-chain fatty acids catalyzed by free lipase from Mucor miehei was performed with high yields in n-hexane. The effects of the acid:alcohol ratio on the bioconversion rate of increasing chain length esters was investigated. To reach the optimum yield, substrates and enzyme concentration were determined. The inhibiting effects of acid are strongly attenuated by reducing the quantity of acid and increasing the amount of enzyme in media following the optimum values. Improvements have been made to increase the ester purity. The consumption of excess substrate by adding calculated amounts of acid gives a 10% yield enhancement, and leads to 100% pure terpenyl esters. The first steps to a scale-up application were attempted using a reactor that allowed us to produce ester quantities up to 100 cm³. Separation and purification of the products were treated with success, underlining the lipase stability and efficiency under the conditions of this study. The ability to recover the enzyme, and reusing it in bioconversions, plays a major role in reducing the cost of the overall process.     

Antimicrobial anilinium polymers: The properties of poly(N,N‐dimethylaminophenylene methacrylamide) in solution and as coatings

Antimicrobial polymers have been widely reported to exert strong biocidal effects against bacteria. In contrast with antimicrobial polymers with aliphatic ammonium groups, polymers with anilinium groups have been rarely studied and applied as biocidal materials. In this study, a representative polymer with aniline side functional groups, poly(N,N‐dimethylaminophenylene methacrylamide) (PDMAPMA), was explored as a novel antimicrobial polymer. PDMAPMA was synthesized and its physicochemical properties evaluated. The methyl iodide‐quaternized polymer was tested against the Gram‐positive Staphylococcus aureus, with a minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of 16–32 and 64–128 μg mL^?1, respectively. Against the Gram‐negative Escherichia coli, the MIC and MBC were both 64–128 μg mL^?1. To broaden the range of applications, PDMAPMA was coated on substrates via crosslinking to endow the surface with contact‐kill functionality. The effect of charge density of the coatings on the antimicrobial behavior was then investigated, and stronger biocidal performance was observed for films with higher charge density. This study of the biocidal behavior of PDMAPMA both in solution and as coatings is expected to broaden the application of polymers containing aniline side groups and provide more information on the antimicrobial behavior of such materials. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1908–1921     

Thermogravimetric characteristics and kinetic of co-pyrolysis of olive residue with high density polyethylene

The co-pyrolytic behaviour of olive residue/high-desity polyethylene mixture was examined with a thermogravimetric analyser. The experiments were done over the temperature range of room temperature to 1273 K at various heating rates (2, 10, 20 and 50 K min⁻¹) and in a nitrogen atmosphere. The results indicated that mass loss process of mixture consists of three distinct stages and the increase of the heating rate shifts in the maximum rate loss to higher temperature. The difference of mass loss (Δm) between experimental and theoretical, calculated as algebraic sums of the mixture for different heating rates of 2, 10, 20 and 50 K min⁻¹, is about 7–11% at 740–900 K. These experimental results indicate a significant synergistic effect during co-pyrolysis of olive residue with high-density polyethylene. In addition, a kinetic analysis was performed to fit thermogravimetric data, the mixture is considered as multi-stage process. A reasonable fit to the experimental data was obtained for all materials and their mixture by isoconversional Friedman method.     

Three‐Dimensional Ultralarge‐Pore Ia3d Mesoporous Silica with Various Pore Diameters and Their Application in Biomolecule Immobilization

Highly ordered mesoporous three‐dimensional Ia3d silica (KIT‐6) with different pore diameters has been synthesized by using pluronic P123 as surfactant template and n‐butanol as cosolvent at different synthesis temperatures in a highly acidic medium. The materials were characterized by XRD and N₂ adsorption. The synthesis temperature plays a significant role in controlling the pore diameter, surface area, and pore volume of the materials. The material prepared at 150 °C, KIT‐6‐150, has a large pore diameter (11.3 nm) and a high specific pore volume (1.53 cm³ g^?1). We also demonstrate immobilization of lysozyme, which is a stable and hard protein, on KIT‐6 materials with different pore diameters. The amount of lysozyme adsorbed on large‐pore KIT‐6 is extremely large (57.2 μmol g^?1) and is much higher than that observed for mesoporous silicas MCM‐41, SBA‐15, and KIT‐5, mesoporous carbons, and carbon nanocages. The effect of various parameters such as buffer concentration, adsorption temperature, concentration of the lysozyme, and the textural parameter of the adsorbent on the lysozyme adsorption capacity of KIT‐6 was studied. The amount adsorbed mainly depends on solution pH, ionic strength, adsorption temperature, and pore volume and pore diameter of the adsorbent. The mechanism of adsorption on KIT‐6 under different adsorption conditions is discussed. In addition, the structural stability of lysozyme molecules and the KIT‐6 adsorbent before and after adsorption were investigated by XRD, nitrogen adsorption, and FTIR spectroscopy.     

Production of oligocellouronates by biodegradation of oxidized cellulose

The biodegradation of β-(1,4)-polyglucuronic acids from cellulose acetate oxidation utilizing the TEMPO/NaBr/NaOCl system was investigated using a glucuronan lyase isolated from Trichoderma strain GL2. Products of the β-elimination mechanism catalyzed by this enzyme were then purified by size-exclusion chromatography and characterized by ESI-Q/TOF-mass spectrometry and ¹H-NMR spectroscopy. The analyses prove the complete biodegradation of this category of cellulose derivates and open the way to the large-scale production of oligouronides.     

Spectral and chromatographic study of the effect of UV preirradiation on the biodegradation of phenols

The effect of UV radiation of a KrCl excilamp on the biodegradation of 4-nitrophenol, 2,5-dinitrophenol, and their mixture by a Penicillium tardum H-2 isolate strain and microbiocenosis of activated sludge was studied. It was shown that the efficiency of the successive photodegradation and biodegradation of nitrophenols depended on the initial concentration and the time of UV preirradiation. UV irradiation increased the efficiency of the biodegradation of 2,5-dinitrophenol with respect to the biodegradation alone. Preliminary UV irradiation inhibited the subsequent biodegradation of 4-nitrophenol by a Penicillium tardum H-2 isolate strain and activated sludge.     

Nickel-Impregnated Silica Nanoparticle Synthesis and Their Evaluation for Biocatalyst Immobilization

In the present investigation, impact of nickel-impregnated silica paramagnetic particles (NSP) as biocatalyst immobilization matrices was investigated. These nanoparticles were synthesized by sol–gel route using a nonionic surfactant block co polymer [poly (ethylene glycol)-block-poly-(propylene glycol)-block-poly (ethylene glycol)]. Diastase enzyme was immobilized on these particles (enzyme-impregnated NSP) as model enzyme and characterized using Fourier-transform infrared spectroscopy and X-ray crystallography. Analysis of enzyme-binding nature with these nanoparticles at different physiological conditions revealed that binding pattern and activity profile varied with the pH of the reaction mixture. The immobilized enzyme was further characterized for its biocatalytic activity with respect to kinetic properties such as Km and Vmax and compared with free enzyme. Paramagnetic nanoparticle-immobilized enzyme showed more affinity for substrate compared to free one. The nature of silica and nickel varied from amorphous to crystalline nature and vice versa upon immobilization of enzyme. To the best of our knowledge, this is the first report of its kind for change of nature from one form to other under normal temperatures upon diastase interaction with NSP.     

Synthesis of functional polycarbonates by lipase-catalyzed ring-opening polymerization

Poly(5-benzyloxy-trimethylene carbonate) (PBTMC), a new functional polycarbonate was synthesized by enzymatic ring-opening polymerization in bulk at 150°C using Porcine pancreas lipase (PPL) or Candida rugosa lipase (CL) as catalyst. Influences of different polymerization conditions such as the source of enzyme, enzyme concentration and polymerization time on the molecular weight and yield were studied. The results showed that PPL exhibited higher activity than CL. Both higher molecular weight(Mn, 18953) and yield(98%) could be obtained by the use of PPL as catalyst. ¹H NMR spectrum showed no decarboxylation occurrence during the ring-opening polymerization.     

Sol–gel silica hybrid biomaterials for application in biodegradation of toxic compounds

The purpose of the present work is the sol–gel synthesis, structure characterization and potential application of hybrid biomaterials based on silica precursor (MTES) and natural polymers such as gelatin or pectin. The structure formation in the biomaterials was investigated by XRD, FTIR, BET and AFM. The results showed that all studied hybrid biomaterials have an amorphous structure. The FT-IR spectra of the obtained materials with MTES showed chemical bonds at 2,975, 1,255, 880 and 690 cm⁻¹ due to the presence of Si–O–R (CH₃ and C₂H₅) and Si–C bonds. In the samples synthesized with TEOS the inorganic and organic components interact by hydrogen bonding, Van der Waals or electrostatic forces. Surface area of investigated samples decreases with increasing of the natural polymers content. The structure evolution was studied by AFM and roughness analysis. Depending on the chemical composition a different design and size of particles and their aggregates on the surface structure were established. The hybrid biomaterials were used for immobilization of bacterial cells and applied in the biodegradation of the toxic compound 4-chlorobutyronitrile, possible constituent of waste water effluents in a laboratory glass bioreactor. Optimization of the process at different temperatures was carried out.     

Studies on the biodegradation of fosfomycin: synthesis of 13C-labeled intermediates, feeding experiments with Rhizobium huakuii PMY1, and isolation of labeled amino acids from cell mass by HPLC

Racemic (1R*,2R*)‐1,2‐dihydroxy‐[1‐¹³C₁]propylphosphonic acid and 1‐hydroxy‐[1‐¹³C₁]acetone were synthesized and fed to R. huakuii PMY1. Alanine and a mixture of valine and methionine were isolated as their N‐acetyl derivatives from the cell hydrolysate by reversed‐phase HPLC and analyzed by NMR spectroscopy. It was found that the carbon atoms of the respective carboxyl groups were highly ¹³C‐labeled (up to 65 %). Hydroxyacetone is therefore considered an obligatory intermediate of the biodegradation of fosfomycin by R. huakuii PMY1.