Spontaneous variability of glucose oxidase-producing fungus <Emphasis Type="Italic">Penicillium adametzii</Emphasis> LF F-2044

The glucose oxidase-producing fungus Penicillium adametzii LF F-2044 was studied for natural variability. Four variants of the fungus differed in morphological characteristics and glucose oxidase synthesis. The synthesis of extracellular glucose oxidase and the productivity of morphological variants P. adametzii LF F-2044.1 and P. adametzii LF F-2044.2 were 127–146 and 95–159% higher, respectively, than the control. Highly active morphological variants of the fungus were chosen for further selection experiments.     

Isolation and characterization of extracellular glucose oxidase from Penicillium adametzii LF F-2044.1

Hydroxides of magnesium and zinc, aluminum oxide, zinc phosphate, and co-precipitated Ca3(PO4)2 and Mg(OH)2 were efficient in binding extracellular glucose oxidase (GO) of P. adametzii LF F-2044.1 in a culture liquid filtrate (CLF). Basic Al2O3 was the most appropriate adsorbent for GO isolation from the CLF of the fungus. A GO isolation method was developed, which allowed for obtaining an enzyme with a high degree of purification. Spectral properties of the enzyme, its catalytic activity, and stability were characterized. The GO of P. adametzii LF F-2044.1 exhibited high pH stability, retaining activity within the range 4.5-9.0. The rate that GO-catalyzed D-glucose oxidation increased as the temperature increased (up to approximately 60 degrees C). The catalytic activity and thermal stability of GO depended on its concentration in the medium. Under optimum conditions, the fractions GO-1 and GO-2 were characterized by KM values of 1.56 x 10(-2) and 2.19 x 10(-2) M, respectively; the corresponding values of kcat equaled 235.1 and 318.2 s(-1).     

Growth characteristics and glucose oxidase production by mutant Penicillium funiculosum strains

The main parameters of growth and glucose oxidase production by the mutant Penicillium funiculosum strains BIM F-15.3, NMM95.132, and 46.1 were studied. The synthesis of extracellular glucose oxidase by these strains was constitutive and occurred following the phase of exponential growth. The mutant strains also synthesized extracellular invertase and cell-associated catalase and glucose oxidase. The syntheses of invertase, the cell-associated enzymes, and extracellular glucose oxidase were found to be maximum between 14 and 18 h, between 48 and 52 h, and by the 96th h of cultivation, respectively. Among the mutants studied, P. funiculosum 46.1 showed the maximal rates of growth and glucose oxidase synthesis.     

Growth Characteristics and Glucose Oxidase Production in Mutant Penicillium funiculosum Strains

The main parameters of growth and glucose oxidase production by the mutant Penicillium funiculosum strains BIM F-15.3, NMM95.132, and 46.1 were studied. The synthesis of extracellular glucose oxidase by these strains was constitutive and occurred following the phase of exponential growth. The mutant strains also synthesized extracellular invertase and cell-associated catalase and glucose oxidase. The syntheses of invertase, the cell-associated enzymes, and extracellular glucose oxidase were found to be maximum between 14 and 18 h, between 48 and 52 h, and by the 96th hour of cultivation, respectively. Among the mutants studied, P. funiculosum 46.1 showed the maximal rates of growth and glucose oxidase synthesis.     

Isolation and characterization of extracellular glucose oxidase from Penicillium adametzii LF F-2044.1

Hydroxides of magnesium and zinc, aluminum oxide, zinc phosphate, and co-precipitated Ca₃(PO₄)₂ and Mg(OH)₂ were efficient in binding extracellular glucose oxidase (GO) of P. adametzii LF F-2044.1 in a culture liquid filtrate (CLF). Basic Al₂O₃ was the most appropriate adsorbent for GO isolation from the CLF of the fungus. A GO isolation method was developed, which allowed for obtaining an enzyme with a high degree of purification. Spectral properties of the enzyme, its catalytic activity, and stability were characterized. The GO of P. adametzii LF F-2044.1 exhibited high pH stability, retaining activity within the range 4.5–9.0. The rate that GO-catalyzed D-glucose oxidation increased as the temperature increased (up to approximately 60°C). The catalytic activity and thermal stability of GO depended on its concentration in the medium. Under optimum conditions, the fractions GO-1 and GO-2 were characterized by K _M values of 1.56 × 10^?2 and 2.19 × 10^?2 M, respectively; the corresponding values of k _cat equaled 235.1 and 318.2 s^?1.     

Effect of salts and Triton X-100 on ultrafiltration purification and properties of extracellular glucose oxidase from <Emphasis Type="Italic">Penicillium adametzii</Emphasis> LF F-2044.1

We compared the effectiveness of glucose oxidase isolation from the culture fluid of Penicillium adametzii LF F-2044.1 in the presence of ammonium sulfate, ammonium chloride, and Triton X-100. Ammonium chloride inhibited glucose oxidase in the culture fluid. This compound increased K _M (by 1.2–1.3 times), but decreased V _max for D-glucose oxidation (by 1.7–1.8 times). Ammonium sulfate had little effect on kinetic parameters. Combined treatment with salts and Triton X-100 was followed by a significant increase in the effectiveness of ultrafiltration purification of the culture fluid. The samples of glucose oxidase were electrophoretically characterized. The dependence of kinetic parameters on glucose oxidase concentration during oxidation of D-glucose was evaluated. The catalytic constant and k _cat/K _M ratio for glucose oxidase samples from the culture fluid isolated in the presence of additives significantly surpassed those for enzyme samples, which were obtained by ultrafiltration of the culture fluid with no additives and chromatography on aluminum oxide. The activity of glucose oxidase isolated from the culture fluid in the presence of ammonium chloride was lower compared to that of the enzyme obtained in the presence of ammonium sulfate. This agent is preferable for ultrafiltration of the culture fluid.     

Mechanism of Action of the Fungicide Thiabendazole, 2-(4′-Thiazolyl) Benzimidazole

Thiabendazole, 2-(4'-thiazolyl) benzimidazole (TBZ) inhibited the growth of Penicillium atrovenetum at 8 to 10 mug/ml. Oxygen consumption with exogenous glucose was inhibited at 20 mug/ml, but endogenous respiration required more than 100 mug/ml. TBZ inhibited completely the following systems of isolated heart or fungus mitochondria: reduced nicotinamide adenine dinucleotide oxidase, succinic oxidase, reduced nicotinamide adenine dinucleotide-cytochrome c reductase, and succinic-cytochrome c reductase at concentrations of 10, 167, 10, and 0.5 mug/ml, respectively. Cytochrome c oxidase was not inhibited. Antimycin A and sodium azide caused the usual inhibition patterns for both fungus and heart terminal electron transport systems. In the presence of antimycin, the fungicide inhibited completely succinate-dichloro-phenolindophenol reductase and succinate-2, 2-di-p-nitrophenyl-(3, 3-dimethoxy-4, 4-biphenylene-5, 5-diphenylditetrazolium)-reductase at 2 and 4 mug of TBZ per ml, respectively. Coenzyme Q reductase required 15 mug/ml. TBZ reduced the uptake by P. atrovenetum of glucose and amino acids and decreased the synthesis of various cell components. At 120 mug/ml, the incorporation of labeled carbon from amino acids-U-(14)C was decreased: lipid, 73%; nucleic acids, 80%; protein, 80%; and a residual fraction, 89%. TBZ did not inhibit peptide synthesis in a cell-free protein-synthesizing system from Rhizoctonia solani. Probably the primary site of inhibition is the terminal electron transport system and other effects are secondary.     

Isolation and screening of glucose oxidase producing microorganisms from natural sources.

Among 1486 mould strains isolated from natural sources (screened for extracellular glucose oxidase) only 119 (Aspergillus and Penicillium) showed this enzyme activity. As the best glucose oxidase producer, A. niger 0-1 was isolated from decaying tree. The dynamics of glucose oxidase synthesis in A. niger 0-1 during its culture by submerged method show that the intracellular activity of this enzyme is 10-times higher than its extracellular level. Some properties of the crude glucose oxidase preparation, isolated from the postculture liquids by lyophilization, were examined.     

Intracellular glucose oxidase from Penicillium funiculosum 46.1

A method for isolating extracellular glucose oxidase from the fungus Penicillium funiculosum 46.1, using ultrafiltration membranes, was developed. Two samples of the enzyme with a specific activity of 914-956 IU were obtained. The enzyme exhibited a high catalytic activity at pH above 6.0. The effective rate constant of glucose oxidase inactivation at pH 2.6 and 16 degrees C was 2.74 x 10(-6) s-1. This constant decreased significantly as pH of the medium increased (4.0-10.0). The temperature optimum for glucose oxidase-catalyzed beta-D-glucose oxidation was in the range 30-65 degrees C. At temperatures below 30 degrees C, the activation energy for beta-D-glucose oxidation was 6.42 kcal/mol; at higher temperatures, this parameter was equal to 0.61 kcal/mol. Kinetic parameters of glucose oxidase-catalyzed delta-D-glucose oxidation depended on the initial concentration of the enzyme in the solution. Glucose oxidase also catalyzed the oxidation of 2-deoxy-D-glucose, maltose, and galactose.     

Search for lactate oxidase producer microorganisms

Using the method of enrichment cultures, eight lactate oxidase producer strains of the fungus Geotrichum candidum were identified. The microorganisms were isolated from diverse specimens of fermented vegetables and manure. Variation in the content of glucose and lactate and the degree of aeration made it possible to attain lactate oxidase activities of up to 130-140 U per 11 grown medium containing microbial cells.     

Glucose oxidase as the antifungal principle of talaron from Talaromyces flavus

Analysis of an authentic sample of the antifungal antibiotic talaron from the biocontrol fungus Talaromyces flavus indicated that approximately 40% of the solid sample was glucose oxidase. High-performance liquid chromatography elution profiles of the antimicrobial activity of talaron coeluted with those of glucose oxidase. Fluorescence emission and excitation wavelength maxima for talaron were similar to those of glucose oxidase from Aspergillus niger. The molecular weight of talaron was 152,000 with a subunit molecular weight of 71,000. The isoelectric point of talaron was pH 4.2. Mobilities of talaron on native, sodium dodecylsulfate, and isoelectric focusing polyacrylamide gels were identical with those of glucose oxidase produced by T. flavus. Furthermore, talaron had antimicrobial activity only in the presence of glucose. Hydrogen peroxide produced by the action of glucose oxidase is toxic to Verticillium dahliae. This study indicates that the antifungal activity of authentic talaron resulted from glucose oxidase produced by T. flavus.     

Production of extracellular H2O2 and L-lysine-α-oxidase during bulk growth of the fungus Trichoderma cf. aureoviride Rifai VKM F-4268D under salt stress

In this article, we report on Some physiological aspects of the synthesis of extracellular L-lysine-??-oxidase (LO) by the fungus Trichoderma cf. aureoviride Rifai VKM F-4268D under salt stress conditions and discuss the possible role of this enzyme for the producer. It has been shown that The synthesis of extracellular LO and proteolytic enzymes is induced in the fungus T. cf. aureoviride Rifai VKM F-4268D during submerged cultivation on wheat bran under salt stress. It has been shown that LO biosynthesis is accompanied by H₂O₂ accumulation in the growth medium. It seems that the extracellular LO synthesis followed by hydrogen peroxide production under stress conditions provides an adaptive advantage for the producer fungus in its competition with other organisms.     

Production of alkyl glucoside from cellooligosaccharides using yeast strains displaying Aspergillus aculeatus β-glucosidase 1

For efficient alkyl glucoside production from cellooligosaccharides, we constructed a yeast strain for alkyl glucoside synthesis by genetically inducing the display of β-glucosidase 1 (BGL1) from the filamentous fungus Aspergillus aculeatus No. F-50 on the cell surface. The localization of BGL1 on the cell surface was confirmed by immunofluorescence microscopy. The yeast strain displaying BGL1 catalyzed alkyl glucoside synthesis from p-nitrophenyl β-d-glucoside and primary alcohols. The highest yield of alkyl glucoside was 27.3% of the total sugar. The substrate specificities of the BGL1-displaying yeast strain and almond β-glucosidase were compared using different-chain-length cellooligosaccharides. The BGL1-displaying yeast showed efficient alkyl glucoside production from not only glucose but also cellohexaose. This yeast is applicable as a whole-cell biocatalyst for alkyl glucoside production from cellulose hydrolysates.     

Regulatory factors affecting alpha-amylase production in bacillus licheniformis.

Possible factors regulating alpha-mylase synthesis in wild-type Bacillus licheniformis and in mutants producing elevated levels of the enzyme were studied in terms of catabolite repression, apparent temperature-sensitive repression, induction, and culture age. The synthesis of alpha-amylase in the parent strain occurred long after the culture reached the stationary phase of growth as a result of de novo protein synthesis, occurred only at high temperature around 50 C and not below 45 C, appeared to be induced in the presence of oligosaccharides with some linkage of alpha-1,4-, beta-1,4, beta-1,6-glucosyl glucose, or alpha-1,6-galactosyl glucose, and was repressed by the addition of exogenous glucose or low-molecular-weight metabolites. The addition of cyclic adenosine 3',5'-monophosphate stimulated alpha-amylase accumulation in growing cultures of the parent strain, but neither shortened the long lap period prior to the start of alpha-amylase synthesis nor mitigated the repressive effect of glucose. Mutant strains derived from the parent strain showed variation in the pattern of alpha-amylase synthesis, and some of them such as F-12s and F-14 produced alpha-amylase constitutively and without sensitivity to catabolite repression or transient repression from the moment of cell growth. These results are discussed in relation to possible regulatory mechanisms that might account for the observed characteristics of alpha-amylase synthesis in this facultative thermophilic microorganism.     

Glucose oxidase and catalase activities ofPenicillium variabile P16 immobilized in polyurethane sponge

Conidia ofPenicillium variabile P16 were immobilized in polyurethane sponge and used in repeated-batch processes in a fluidized-bed reactor. Optimal conditions for production of glucose oxidase and catalase were: inoculum size, 10%; glucose concentration, 80 g L^–1; Ca-carbonate concentration, 15 g L^–1; temperature, 28°C and aeration rate, 4 VV^–1 min^–1. In an extended repeated-batch process, glucose oxidase activity was highest after the fourth batch and catalase activity was highest after the fifth batch. Scanning electron microscopy showed that the fungus grew only in the interior of carrier particles.     

Purification and properties of Penicillium glucose 6-phosphate dehydrogenase

1. Glucose 6-phosphate dehydrogenase was isolated and partially purified from a thermophilic fungus, Penicillium duponti, and a mesophilic fungus, Penicillium notatum. 2. The molecular weight of the P. duponti enzyme was found to be 120000+/-10000 by gelfiltration and sucrose-density-gradient-centrifugation techniques. No NADP(+)- or glucose 6-phosphate-induced change in molecular weight could be demonstrated. 3. Glucose 6-phosphate dehydrogenase from the thermophilic fungus was more heat-stable than that from the mesophile. Glucose 6-phosphate, but not NADP(+), protected the enzyme from both the thermophile and the mesophile from thermal inactivation. 4. The K(m) values determined for glucose 6-phosphate dehydrogenase from the thermophile P. duponti were 4.3x10(-5)m-NADP(+) and 1.6x10(-4)m-glucose 6-phosphate; for the enzyme from the mesophile P. notatum the values were 6.2x10(-5)m-NADP(+) and 2.5x10(-4)m-glucose 6-phosphate. 5. Inhibition by NADPH was competitive with respect to both NADP(+) and glucose 6-phosphate for both the P. duponti and P. notatum enzymes. The inhibition pattern indicated a rapid-equilibrium random mechanism, which may or may not involve a dead-end enzyme-NADP(+)-6-phosphogluconolactone complex; however, a compulsory-order mechanism that is consistent with all the results is proposed. 6. The activation energies for the P. duponti and P. notatum glucose 6-phosphate dehydrogenases were 40.2 and 41.4kJ.mol(-1) (9.6 and 9.9kcal.mol(-1)) respectively. 7. Palmitoyl-CoA inhibited P. duponti glucose 6-phosphate dehydrogenase and gave an inhibition constant of 5x10(-6)m. 8. Penicillium glucose 6-phosphate dehydrogenase had a high degree of substrate and coenzyme specificity.     

Regulation of tyramine oxidase synthesis in Klebsiella aerogenes.

Tyramine oxidase in Klebsiella aerogenes is highly specific for tyramine, dopamine, octopamine, and norepinephrine, and its synthesis is induced specifically by these compounds. The enzyme is present in a membrane-bound form. The Km value for tyramine is 9 X 10(-4) M. Tyramine oxidase synthesis was subjected to catabolite repression by glucose in the presence of ammonium salts. Addition of cyclic adenosine 3',5'-monophosphate (cAMP) overcame the catabolite repression. A mutant strain, K711, which can produce a high level of beta-galactosidase in the presence of glucose and ammonium chloride, can also synthesize tyramine oxidase and histidase in the presence of inducer in glucose ammonium medium. Catabolite repression of tyramine oxidase synthesis was relieved when the cells were grown under conditions of nitrogen limitation, whereas beta-galactosidase was strongly repressed under these conditions. A cAMP-requiring mutant, MK54, synthesized tyramine oxidase rapidly when tyramine was used as the sole source of nitrogen in the absence of cAMP. However, a glutamine synthetase-constitutive mutant, MK94, failed to synthesize tyramine oxidase in the presence of glucose and ammonium chloride, although it synthesized histidase rapidly under these conditions. These results suggest that catabolite repression of tyramine oxidase synthesis in K. aerogenes is regulated by the intracellular level of cAMP and an unknown cytoplasmic factor that acts independently of cAMP and is formed under conditions of nitrogen limitation.     

Preparation and characteristics of mutant strains of Penicillium funiculosum--producers of glucose oxidase

After the mutagenesis of Penicillium funiculosum with UV light and N-nitroso-N-methylurea, 83 of 2237 grown colonies were surrounded with increased zones of glucose oxidase diffusion. Analysis of the glucose oxidase activity of selected mutant strains grown in submerged cultures allowed 18 mutant strains to be obtained whose glucose oxidase activity was 5-153% higher (in a medium with glucose) and 4-83% higher (in a medium with sucrose) than that of the parent strain. Two of these mutant strains, UV6.31 and NMU95-132, possessed high glucose oxidase activity when grown in media with glucose or sucrose and produced large amounts of mycelia. The active and morphologically stable mutant P. funiculosum NMU95-132 was chosen for further selection work.     

Endophytic fungus <Emphasis Type="Italic">Cladosporium cladosporioides</Emphasis> LF70 from <Emphasis Type="Italic">Huperzia serrata</Emphasis> produces Huperzine A

A strain LF70 endophytic fungus was isolated from the leaves of Huperzia serrata. The fungus was identified as Cladosporium cladosporioides LF70 according to its morphological characteristics and nuclear ribosomal DNA ITS sequence analysis. The strain could produce Huperzine A (HupA) identified through thin layer chromatography (TLC) and high-performance liquid chromatography (HPLC) with authentic HupA. The amount of HupA produced by this endophytic fungus was quantified to be 56.84 μg/L by HPLC, which was higher than that of other reported endophytic fungi, Acremonium sp., Blastomyces sp., and Botrytis sp. Acetylcholinesterase inhibition activity of HupA produced by strain LF70 was also similar to authentic HupA in vitro. Isolation of such a fungus may provide a promising alternative approach to producing HupA, which is used in treating Alzheimer’s disease and preventing further memory degeneration.     

三株提高刺五加苷E 含量内生真菌的鉴定及其作用方式分析

目的:确定自刺五加分离的内生真菌P109-4、P116-1b和P312-1的分类地位,并初步分析其提高刺五加苷E含量的作用方式。方法:应用形态学及18S rDNA序列分析方法进行鉴定,将菌液回接刺五加浸出液进行发酵培养和将灭活后的菌液注射刺五加后,HPLC法分析刺五加苷含量E的变化。结果:P109-4、P116-1b和P312-1分别与尖孢镰孢菌、葡萄座腔菌和角担菌的形态学特征相符,与各对应种属真菌的18S rDNA序列同源性分别高达99.28%、99.76%和97.23%。活体的3株内生真菌能延长刺五加浸出液中刺五加苷E的存在时间,灭活后P312-1可显著提高刺五加苷E的含量,P109-4和P116-1B无显著作用。结论:P109-4为Fusarium oxysporum,P116-1b为Botryosphaeria dothidea,P312-1为Ceratobasidium spp.。P312-1的作用方式为通过菌体某种不被高温破坏的物质提高刺五加苷E的含量,P116-1b和P109-4仅能对已存在的刺五加苷E发挥作用。