Showing papers in "Applied Biochemistry and Microbiology in 2002"
TL;DR: Data on the inhibitory effect of chitosan on viral infections in animals, plants, and microorganisms are reviewed and possible mechanisms of the inhibitors effect are discussed.
Abstract: Data on the inhibitory effect of chitosan on viral infections in animals, plants, and microorganisms are reviewed The effects of the physicochemical parameters and structure of chitosan on its antiviral activity are analyzed Possible mechanisms of the inhibitory effect of chitosan on viral infections are discussed
258 citations
TL;DR: A new nomenclature of cellulases and relative enzymes based on their structural classification is reviewed and some opportunities of cellulase improvement by means of protein engineering are discussed.
Abstract: Compositions of cellulase-hemicellulase systems of aerobic fungi (hyphomycetes, ascomycetes, and basidiomycetes), aerobic bacteria, actinomycetes, as well as anaerobic fungi and bacteria, are considered in the context of the modern structural classification of glycosyl hydrolases. A new nomenclature of cellulases and relative enzymes based on their structural classification is reviewed. Some opportunities of cellulase improvement by means of protein engineering are discussed.
127 citations
TL;DR: Kartolin-4, a preparation with cytokinin-like activity, partially prevented the drought-induced inhibition of the photosynthetic assimilation of carbon dioxide and carboxylation activities of ribulose-1,5-bisphosphateCarboxylase/oxygenase (EC 4.1.39), the key enzyme of carbon metabolism in plants.
Abstract: Parameters of photosynthesis, heat-resistance, and osmotic pressure of cell exudate of leaves of the drought-sensitive cultivarLyutestsens 758 of wheat, Triticum aestivum, were studied under conditions of normal water supply, soil drought, and subsequent rehydration The plants preliminarily treated with kartolin-4 were compared to untreated plants Kartolin-4, a preparation with cytokinin-like activity, partially prevented the drought-induced inhibition of the photosynthetic assimilation of carbon dioxide and carboxylation activities of ribulose-1,5-bisphosphate carboxylase/oxygenase (EC 41139), the key enzyme of carbon metabolism in plants Upon subsequent rehydration, kartolin-4 stimulated the reparation reactions and facilitated the rapid recovery of normal photosynthetic activity Kartolin-4 also increased the plant resistance to overheating and water deficiency
99 citations
TL;DR: Chitin isolated enzymatically from Antarctic krill shells was dissolved in aqueous NaOH by freezing and thawing to create homogeneous conditions as mentioned in this paper, where the degree of deacetylation, molecular weight, and dynamic viscosity of solutions were estimated in chitosan samples.
Abstract: Chitin isolated enzymatically from Antarctic krill shells was dissolved in aqueous NaOH by freezing and thawing to create homogeneous conditions. Deacetylation was performed at room temperature or under heating. The degree of deacetylation, molecular weight, and dynamic viscosity of solutions were estimated in chitosan samples. Deacetylation of chitin under homogeneous conditions was optimized. Chitosans with molecular weights of 180–220 and 250–300 kDa were obtained from the chitins of Antarctic krill and northern shrimp, respectively.
47 citations
TL;DR: It was shown that the lytic activity of strains VK2 and VK21 was not related to the synthesis of hydrolytic enzymes and the maximum level of antimicrobial activity in the growth medium was found to correspond to the beginning of the stationary growth phase.
Abstract: A collection of thermophilic strains of the genus Bacillus was made. The strains were screened for antimicrobial activity. Strains VK2 and VK21 isolated from thermal springs of the Kamchatka Peninsula, and antagonistic to several gram-positive bacterial species were chosen for further investigation of antibiotics produced by them. Restriction analysis of DNA coding for 16S rRNA showed that both strains can be assigned to Bacillus licheniformis. It was shown that the lytic activity of strains VK2 and VK21 was not related to the synthesis of hydrolytic enzymes. The maximum level of antimicrobial activity in the growth medium was found to correspond to the beginning of the stationary growth phase. Addition of manganese sulfate induced sporulation and altered significantly the time course of antibiotic production in both strains. Active metabolites were extracted with n-butanol. They survived boiling for 30 min and were resistant to trypsin and chymotrypsin but were partly hydrolyzed by pronase. They were stable at a pH range of 2.0–9.0.
41 citations
TL;DR: The antimicrobial activity of the ethanol extract of resins obtained from the roots and stems of Cedrus libani and Abies cilicia is studied, using the disc diffusion method.
Abstract: The antimicrobial activity of the ethanol extract of resins obtained from the roots and stems of Cedrus libani and Abies cilicia has been studied, using the disc diffusion method. The results obtained indicate that crude extracts of the resins of both plants are highly efficient in preventing the growth of microorganisms.
41 citations
TL;DR: It is recommended to add iron-containing clay, as an inexpensive and easily available iron source, in amounts providing the binding of the long-chain fatty acids present in wastewaters.
Abstract: Effects of iron compounds on methanogenic fermentation in water polluted with fatty acids were studied. A natural readily available source of iron applicable to biological treatment of liquid wastes was searched for. A positive effect of iron on the methanogenic fermentation of fats and their degradation products—long-chain fatty acids—in aqueous media was demonstrated. It is recommended to add iron-containing clay, as an inexpensive and easily available iron source, in amounts providing the binding of the long-chain fatty acids present in wastewaters.
37 citations
TL;DR: The optimal parameters for the producer growth were as follows: pH 7.0, 33–35°C, growth duration 72 h, and the presence of reduced mineral nitrogen or organic nitrogen was necessary for the enzyme biosynthesis.
Abstract: Biosynthesis of extracellular inulinase by bacteria Bacillus polymyxa 29,B. polymyxa 722, and B. subtilis 68 was studied. The optimal parameters for the producer growth were as follows: pH 7.0, 33–35°C, growth duration 72 h. The presence of reduced mineral nitrogen or organic nitrogen was necessary for the enzyme biosynthesis. The inulinase biosynthesis was sharply activated in the presence of carbohydrates. B. polymyxa 722 and B. polymyxa 29 displayed the maximum activities on a starch-containing culture medium; the maximum activity of B. subtilis 68 was in the presence of sucrose. Inulin did not induce inulinase biosynthesis by the strains studied. The time course of bacteria growth and enzyme biosynthesis was studied.
34 citations
TL;DR: In this article, β-glucosidase and β-xylosidases were characterized at pH 20−25 and 30, respectively, with the maximum activity at 65°C and were stable in a wide pH range and at high temperatures.
Abstract: β-Glucosidase and β-xylosidase production by a yeastlike Aureobasidium sp was carried out during solid-state and submerged fermentation using different carbon sources and crude enzymes were characterized β-Glucosidase and β-xylosidase exhibited optimum activities at pH 20–25 and 30, respectively These enzymes had the maximum activities at 65°C and were stable in a wide pH range and at high temperatures
30 citations
Journal Article•
TL;DR: Parameters of photosynthesis, heat-resistance, and osmotic pressure of cell exudate of leaves of the drought-sensitive cultivar Lyutestsens 758 of wheat, Triticum aestivum, were studied and kartolin-4 stimulated the reparation reactions and facilitated rapid recovery of normal photosynthetic activity.
Abstract: Parameters of photosynthesis, heat-resistance, and osmotic pressure of cell exudate of leaves of the drought-sensitive cultivar Lyutestsens 758 of wheat, Triticum aestivum, were studied under conditions of normal water supply, soil drought, and subsequent rehydration. The plants preliminarily treated with kartolin-4 were compared to untreated plants. Kartolin-4, a preparation with cytokininlike activity, partially prevented the drought-induced inhibition of the photosynthetic assimilation of carbon dioxide and carboxylation activities of ribulose-1,5-bisphosphate carboxylase/oxygenase (EC 4.1.1.39), the key enzyme of carbon metabolism in plants. Upon a subsequent rehydration, kartolin-4 stimulated the reparation reactions and facilitated rapid recovery of normal photosynthetic activity. Kartolin-4 also increased plant resistance to overheating and water deficiency.
29 citations
TL;DR: The results indicate that neurosporaxanthin possesses photoprotective properties in Neurospora crassa and in Blakeslea trispora (+/–) fungi, β-carotene acts as a major antioxidant during inactivation of enzymes that detoxify reactive oxygen species.
Abstract: The addition of menadione into the medium during cultivation of Neurospora crassa in the dark activated its constitutive superoxide dismutase. Exposure to light not only activated superoxide dismutase and catalase, but also increased the content of neurosporaxanthin. Superoxide dismutase activity in the mixed (+/-) mycelium of Blakeslea trispora synthesizing beta-carotene in the dark was much lower than that in Neurospora crassa. The superoxide dismutase activity further decreased in oxidative stress. The catalase activity decreased with an increase in the content of beta-carotene. Our results indicate that neurosporaxanthin possesses photoprotective properties in Neurospora crassa. In Blakeslea trispora (+/-) fungi, this compound acts as a major antioxidant during inactivation of enzymes that detoxify reactive oxygen species.
TL;DR: Using a synthetic medium supplemented with biphenyl (a polycyclic aromatic hydrocarbon), a new bacterial strain of Citrobacter freundii was isolated from enrichment cultures containing soil and industrial wastewater samples of the Serpukhov Condenser Factory and was found to be capable of degrading bipenyl under anaerobic conditions in the course of nitrate reduction.
Abstract: Using a synthetic medium supplemented with biphenyl (a polycyclic aromatic hydrocarbon), a new bacterial strain of Citrobacter freundiiwas isolated from enrichment cultures containing soil and industrial wastewater samples of the Serpukhov Condenser Factory. This strain was found to be capable of degrading biphenyl under anaerobic conditions in the course of nitrate reduction. When the initial concentration of biphenyl in the culture medium equaled 150 mg/ml, the culture with a titer of 109 cells/ml degraded up to 26–28% of biphenyl in 3 days (28°C). At 250 mg/ml, the culture with a titer of 107 cells/ml degraded 15% of biphenyl in 21 days. Approximately 10% of the substrate consumed was utilized completely, whereas the remainder underwent transformation.
TL;DR: Data on the lipid composition and carbohydrate composition of Aspergillus niger conidia make it possible to characterize the individual germination stages and differentiate between the conidia capable of germination and those that lost the germination capacity.
Abstract: Data on the lipid composition and carbohydrate composition of Aspergillus niger conidia make it possible to characterize the individual germination stages and differentiate between the conidia capable of germination and those that lost the germination capacity. The following criteria are proposed: the ratio of phosphatidylcholine and phosphatidylethanolamine, the ratio of mannitol and arabitol, and the levels of sterols and free fatty acids. The role of these compounds in the biochemical background of cell transition from dormancy to active metabolism and their use as indices of the quality of inocula in biotechnological processes are discussed.
TL;DR: Physicochemical properties of pigments isolated from the naturally occurring sterile form of Inonotus obliquus(Fr.) Pil.
Abstract: Physicochemical properties of pigments isolated from the naturally occurring sterile form of Inonotus obliquus(Fr.) Pil. known as Chagi and comprising the major constituent of the medicine befungin were compared with those of melanins synthesized by this fungus in the culture in order to develop a new medicine. Elemental and functional group analyses, as well as UV-visible, IR, and EPR spectra, and thermolysis studies revealed structural differences in these pigments and allowed for assignment of the naturally produced melanin to allomelanins, whereas that of cultivated fungus was assigned to eumelanins.
TL;DR: Two versions of a group-specific enzyme immunoassay based on the heterologous combination of solid-phase antigens are described and sensitivity, 0.01 ng/ml, is described.
Abstract: Formation kinetics, specificity, and analytical potential of polyclonal antibodies raised in rabbits against BSA conjugates of zearalanone carboxymethyloxime (CMO-ZAN) and zearalenone carboxymethyloxime (CMO-ZEN) have been studied. Preparation of the conjugates involved conversion of CMO-ZAN and CMO-ZEN into activated esters or carbodiimide condensation. Two versions of a group-specific enzyme immunoassay (for zearalenone/α-zearalenol and zearalanone/α-zearalanol) based on the heterologous combination of solid-phase antigens are described (sensitivity, 0.01 ng/ml).
TL;DR: The stability of HRP and its immunoglobulin, cortisol, and progesterone conjugates were compared in these two media and the protein-based medium displayed a greater stabilizing effect particularly on HRP-steroid conjUGates.
Abstract: Effects of pH, enzyme concentration, and various supplements on the catalytic activity, temperature stability, and secondary structure of horseradish peroxidase (HRP) were studied in diluted aqueous solutions. In 5.0 mM citrate-phosphate buffer (pH 4.2) at 55°C and infinite dilution, HRP was inactivated with a rate constant of 2.86 × 10–3 s–1. CaCl2, BSA, and glycerol caused protective effects, whereas KCl, LiCl, maltose, PEG-6000 (at a concentration above 3%), Triton X-100, ethanol, and Kathon CG had an opposite effect and altered the secondary structure of HRP. Two HRP-stabilizing media: the “glycerol-based” one containing 10% ethanol and 20% glycerol, or the “protein-based” one containing 0.1% Kathon CG and 0.2 mg/ml of BSA in 50.0 mM Tris-HCl buffer (pH 7.2) supplemented with 50 mM CaCl2 were developed, and the stability of HRP (0.36 nM) and its immunoglobulin, cortisol, and progesterone conjugates were compared in these two media. The protein-based medium displayed a greater stabilizing effect particularly on HRP-steroid conjugates.
TL;DR: A novel enzymatic photometric assay for ethanol determination using alcohol oxidase and peroxidase is described, which allows detecting ethanol in biological fluids (saliva and blood serum).
Abstract: A novel enzymatic photometric assay for ethanol determination using alcohol oxidase and peroxidase is described. The sensitivity of the method allows detecting ethanol in biological fluids (saliva and blood serum). Secondary alcohols and other organic compounds do not interfere with the assay. General-purpose spectrophotometers and photoelectric colorimeters can be used in the measurements. Methanol and propanol can also be determined by this technique.
TL;DR: Possible mechanisms of various AMEs, possible practical applications of antimutagenic properties of bacteria are discussed, and some of their metabolites attenuate the mutagenic action of several genotoxic agents.
Abstract: Lactic acid and propionic acid bacteria, bifidobacteria, and fecal enterococci associated with the activity of humans and animals caused antimutagenic effects (AME) on many test systems designed for detecting point mutations and chromosomal aberrations. Bacterial cells and some of their metabolites attenuate the mutagenic action of several genotoxic agents, and this effect is mediated by the mechanism of dysmutagenesis and/or bioantimutagenesis. Possible mechanisms of various AMEs and possible practical applications of antimutagenic properties of bacteria are discussed.
TL;DR: The data suggest that, under oxidative stress, oxidative degradation of β- carotene into β-apo-13-carotenone leads to the formation of considerable amounts of trisporic acids.
Abstract: Biotransformation of β-carotene with enzyme preparations isolated from the mycelium of Blakeslea trispora resulted in the formation of its hydroxylated metabolite and apocarotenals, products of oxidative degradation of this compound Based on its spectral, chromatographic, and chemical properties, the β-carotene derivative was identified as 4-hydroxy-β-carotene (isocryptoxanthine) One of the products of oxidative degradation of β-carotene, β-apo-13-carotenone, was modified in the presence of enzyme preparations from Blakeslea trispora to form trisporic acid precursors β-Apo-13-carotenone transformation proceeded more rapidly than β-carotene oxidation at the carbon atom at position 4 The data suggest that, under oxidative stress, oxidative degradation of β-carotene into β-apo-13-carotenone leads to the formation of considerable amounts of trisporic acids
TL;DR: Seasonal changes in the content of alginic acid and fuccidan have been studied in four species of fucus algae from the Barents Sea.
Abstract: Seasonal changes in the content of alginic acid and fuccidan have been studied in four species of fucus algae from the Barents Sea: Fucus vesiculosus, F. distichus, F. serratus, and Ascophyllum nodosum. These polysaccharides are accumulated in the biomass of the algae during summer and autumn. To ensure complete processing of fucus algae it is recommended that the raw material be harvested within this period.
TL;DR: In this article, the use of this compost as a fertilizer for barley growth demonstrated that the changes increased the biological activity of hydrolytic lignin and increased its exchange capacity and the amount of negative charges.
Abstract: Composting of hydrolytic lignin by a microbial association changed its molecular-weight composition, acid-base properties, and supramolecular structure. Specifically, by the end of the third month of composting, an increase was observed in its exchange capacity and the amount of negative charges, as well as in the content of phenyl, hydroxyl, and carboxyl groups. The use of this compost as a fertilizer for barley growth demonstrated that the changes increased the biological activity of hydrolytic lignin.
TL;DR: Fractional extraction of chitosan hydrolysate by aqueous ethanol (ethanol:distilled water) yielded fractions with molecular weights in the range 3.2–26.4 kDa.
Abstract: A low-molecular-weight water-soluble chitosan was obtained from high-molecular-weight crab chitosan using the enzyme preparation Celloviridine G20x. Optimum conditions for enzymatic hydrolysis were designed. The reaction should be performed for 4 h in a sodium-acetate buffer (pH 5.2) at 55°C and an enzyme to substrate ratio of 1 : 400. Fractional extraction of chitosan hydrolysate by aqueous ethanol (ethanol:distilled water) yielded fractions with molecular weights in the range 3.2–26.4 kDa.
TL;DR: Correlation of the rate of ATP hydrolysis was found to be correlated with bacterial resistance to toxic arsenic ions and detoxification of arsenate by resistant cultures of bacteria was suggested to be related to an increase in bacterial ATPase activity and the degree of ATPase mobilization.
Abstract: The effects of arsenic in the forms of arsenite and arsenate on bacterial growth and plasma membranes' ATPase activity was studied. Correlation of the rate of ATP hydrolysis was found to be correlated with bacterial resistance to toxic arsenic ions. Detoxification of arsenate by resistant cultures of bacteria was suggested to be related to an increase in bacterial ATPase activity and the degree of ATPase mobilization.
TL;DR: The complete gene xylA that encodes endo-1,4-β-xylanase secreted by Penicillium canescens was cloned and sequenced and nucleotide sequences for binding catabolite repression protein CREA and transactivator protein were detected in the promoter region.
Abstract: The complete gene xylA that encodes endo-1,4-β-xylanase secreted byPenicillium canescens was cloned and sequenced. The coding region of the gene is separated by eight introns. The protein comprises 302 amino acids of the mature protein and 25 amino acids of the signal peptide. The xylanase of P. canescens belongs to the glycosyl hydrolase family 10. Nucleotide sequences for binding catabolite repression protein CREA and transactivator protein were detected in the promoter region. A set of multicopy strains displaying a seven to eightfold increase in xylanase yield was obtained. The fraction of xylanase in most productive strains amounted to 30–50% of the total secreted protein.
TL;DR: In this article, the degradation rates of fuel oil, its components, benzene resins, and petroleum amounting to 17, 26, 10, and 51% were selected.
Abstract: Of 150 cultures capable of degrading petroleum at +6°C, 40 strains growing in a liquid mineral nutrient medium containing petroleum (2%) as the sole source of carbon were selected. Of them, 13 cultures displaying a petroleum degradation rate exceeding 25% were selected. Abilities of these cultures and their associations to utilize fuel oil and its components—oils and benzene resins—were studied. A culture exhibiting degradation rates of fuel oil, its oils, benzene resins, and petroleum amounting to 17, 26, 10, and 51%, respectively, was selected. This culture can be used for cleanup of petroleum pollution under cold climatic conditions.
TL;DR: Lack of cross-reactivity with a series of sulfonyl-/arylurea derivatives and triazines makes it possible to recommend the EIA systems developed for chlorsulfuron determination in the environment.
Abstract: Antibodies against the herbicide chlorsulfuron have been raised and characterized. Enzyme immunoassays (EIAs) for chlorsulfuron, involving labeled antigen or labeled antibodies, have been developed. The kinetics of antigen–antibody interactions in the EIA systems developed has been studied. Both systems exhibit equal sensitivity (1 ng/ml). The values of the coefficient of variation (CV), determined within the range of chlorsulfuron concentrations to be measured by the systems (1–100 ng/ml), are not in excess of 8%. The possibility of using glucose oxidase as a label in EIAs for chlorsulfuron has been demonstrated. Lack of cross-reactivity with a series of sulfonyl-/arylurea derivatives and triazines makes it possible to recommend the EIA systems developed for chlorsulfuron determination in the environment.
TL;DR: The effects of bacteria belonging to the genera Azotobacter and Bacillus in a mixed culture with Bradyrhizobium japonicumstrains on the formation and function of the legume–rhZobium symbiosis of soybean plants were studied.
Abstract: The effects of bacteria belonging to the genera Azotobacter and Bacillus in a mixed culture with Bradyrhizobium japonicumstrains on the formation and function of the legume–rhizobium symbiosis of soybean plants were studied. The data showed that the bacterial compositions B. japonicum 634b +B. subtilis 5, B. japonicum 634b + A. chroococcum 20, and B. japonicum 10k + A. vinelandii56 with a cell ratio of 1 : 0.1 increased the number and weight of root nodules as well as the height and weight of the aboveground plant parts in almost all cases by 22–105% compared with the control variants. These binary microbial cultures may be used for the development of combined bacterial preparations for soybean.
TL;DR: A promising producer of extracellular amylases, Aspergillus flavipes, was selected from 245 strains of marine fungi and depending on the conditions of growth, this strain produced diverse amylolytic complexes.
Abstract: A promising producer of extracellular amylases, Aspergillus flavipes, was selected from 245 strains of marine fungi Depending on the conditions of growth, this strain produced diverse amylolytic complexes When grown on a medium containing peptone and yeast extract (pH 70), A flavipes synthesized three forms of amylase, differing in pH optimum (55, 60, and 75) A single form of the enzyme was synthesized either in the absence of peptone from the medium or at the initial pH value of the medium, equal to 86 The activity of the isolated amylase forms decreased in the presence of proteolytic enzymes New, highly stable forms of amylase (with pH optima of 55 and 75 and maximum activity at 60–80°C) were synthesized in the presence of diisopropyl fluorophosphate, an inhibitor of proteases
TL;DR: In contrast to polysaccharides, easily metabolizable substrates (cellobiose, mannitol, and glucose) provided the highest rates of secretion of laccase and ligninase and the addition of tangerine pomace (TP), a substrate enriched with aromatic compounds, to the culture medium caused an increase in the rate of biosynthesis.
Abstract: The activities of carboxymethylcellulase and xylanase in the higher basidial fungusCerrena unicolorgrown in avicel-containing medium reached 195 and 150 units per mg protein, respectively, whereas in mannitol-containing medium they ranged from 002 to 004 units per mg protein The activity of fungal β-glucosidase depended on the carbon source in the culture medium and ranged from 21 units per mg protein in the presence of mannitol to 173 units per mg protein in the presence of avicel In contrast to polysaccharides, easily metabolizable substrates (cellobiose, mannitol, and glucose) provided the highest rates of secretion of laccase (527–1235 ncat per mg protein) and ligninase (22–106 units per mg protein) The addition of tangerine pomace (TP), a substrate enriched with aromatic compounds, to the culture medium caused an increase in the rate of biosynthesis of laccase and ligninase to 862 ncat/ ml and 557 units per ml, respectively Aromatic compounds such as p-xylidine and veratric aldehyde increased the laccase activity of C unicolor IBB 62 from 79 to 236 and 183 ncat per mg protein, respectively Veratryl alcohol caused a sevenfold increase in the activity of Mn-dependent peroxidase in the culture medium
TL;DR: It was found that intense biosynthesis of amaranthine, tyrosine, and phenylalanine resulted in a decrease in the contents of lignin, protein, and cellulose in leaves of Valentina by comparison with K-99 and in changes to the morphological traits: color deepening and a decreases in leaf density.
Abstract: The composition and content of secondary compounds produced by the shikimate pathway and the contents of protein and cellulose were determined in leaves of amaranth (Amaranthus tricolor L.) K-99 and the cultivar Valentina raised from it by family selection and enriched in the pigment amaranthine. It was found that intense biosynthesis of amaranthine, tyrosine, and phenylalanine resulted in a decrease in the contents of lignin, protein, and cellulose in leaves of Valentina by comparison with K-99 and in changes to the morphological traits: color deepening and a decrease in leaf density. It is concluded that amaranth biosynthesis is related to nitrogen metabolism and amaranthine is an intermediate involved in conversion of nitrogen compounds in the cell.