Endo-polygalacturonase production from untreated lemon peel byAspergillus sp. CH-Y-1043

Summary Endo-polygalacturonase (endo-PG) production byAspergillus sp. CH-Y-1043 using untreated lemon peel as the sole carbon source was investigated. This strain was observed to produce more activity of endo-PG at 37°C than at 29°C. Untreated lemon peel proved to be a beeter substrate than citrus pectin for endo-PG production. Modification of the culture medium and lowering of the initial pH to 2.8 caused a 10-fold increase in the production of endo-PG activity using lemon peel.     

Isolation of endopolygalacturonase hyperproducing mutants ofAspergillus sp. CH-Y-1043

Summary With the aim of obtaining hyperproducing strains of pectinases,Aspergillus sp. CH-Y-1043 was mutated with NTG and mutants resistant to glycerol catabolic repression were selected. Among the mutants obtained, CH-SS/ M63 produced an endo-PG activity 400% higher than the wild type, using lemon peel as the sole carbon source.     

Constitutive exo-pectinase produced byAspergillus sp. CH-Y-1043 on different carbon source

Summary The production of a constitutive exo-pectinase byAspergillus sp. CH-Y-1043 grown on glucose, sucrose, fructose, glycerol and galacturonic acid is reported. The specific activity was found to be in the range of 26% to 75% of that produced with pectin or poly-galacturonic acid. The production of this exo-pectinase is strictly correlated to the exponential growth phase and it is highly sensitive to the pH of the culture medium     

Hydrolysis of orange peel by a pectin lyase-overproducing hybrid obtained by protoplast fusion between mutant pectinolytic Aspergillus flavipes and Aspergillus niveus CH-Y-1043

Pectin lyases cleave the internal glycosidic bonds of pectin by β-elimination, producing non-saturated galacturonic oligomers. Genetic improvement of pectin lyase-overproducing strains is still necessary to improve industrial processes based on this enzyme. In the present study hybrids were obtained by protoplast fusion between mutant pectinolytic Aspergillus flavipes and Aspergillus niveus CH-Y-1043 strains. Prototrophic segregants showed different isoenzymatic profiles and produced increased levels of pectin lyase in cultures containing lemon peel as a sole carbon source. Hybrid HZ showed an increase of 450% and 1300% in pectin lyase production compared with that of A. niveus CH-Y-1043 and A. flavipes, respectively. Pectin lyase produced by the hybrid HZ was partially purified and used for the hydrolysis of orange peel. Pectin lyase was able to hydrolyze 56% of orange peel biomass. However, addition of 2 RFU and 20 U of endo- and exo-polygalacturonase, respectively, induced the hydrolysis of 92% of orange peel solids. In conclusion HZ is a pectin lyase-overproducing hybrid with potential applications in the pectin industry.     

Stabilization of Adenosine-producing Mutants Derived from Bacillus sp. No. 1043

In the case of fermentative production of adenosine by the mutants derived from a Bacillus strain, abnormal fermentations due to the instability of mutants were frequently observed, and therefore studies were performed on the stabilization of mutants.

Among the genetic characteristics of adenosine-producing mutants, the xanthine-requirement was the most important factor and the adenosine productivity was found to decrease significantly as the number of revertants on this genetic marker increased. By using the media supplemented with excess amount of guanine sources, the increase of xanthine-non-requiring revertants both during the transfers on slants and in the preservation periods was perfectly suppressed. Secondly, an attempt was made to derive mutants in which no revertants would appear. Such mutants (‘NB-strains’) were selected by using a medium on which revertants appeared in a high frequency. One strain of the above mutants was found defective in XMP aminase.     

Pectin lyase of Penicillium paxilli

Summary A Penicillium paxilli strain afforded a depolymerase specific for high-methoxyl pectin: pectin lyase EC 4.2.2.10, capable of macerating potato and cucumber tissues.     

Aspergillus bertholletius sp. nov. from Brazil Nuts

During a study on the mycobiota of brazil nuts (Bertholletia excelsa) in Brazil, a new Aspergillus species, A. bertholletius, was found, and is described here. A polyphasic approach was applied using morphological characters, extrolite data as well as partial β-tubulin, calmodulin and ITS sequences to characterize this taxon. A. bertholletius is represented by nineteen isolates from samples of brazil nuts at various stages of production and soil close to Bertholletia excelsa trees. The following extrolites were produced by this species: aflavinin, cyclopiazonic acid, kojic acid, tenuazonic acid and ustilaginoidin C. Phylogenetic analysis using partial β-tubulin and camodulin gene sequences showed that A. bertholletius represents a new phylogenetic clade in Aspergillus section Flavi. The type strain of A. bertholletius is CCT 7615 ( = ITAL 270/06 = IBT 29228).     

Aspergillus siamensis sp. nov. from soil in Thailand

A new species of Aspergillus section Fumigati, Aspergillus siamensis, isolated from coastal forest soil in Samaesarn island, Chonburi province, Eastern Thailand, is described and illustrated. This species is characterized by its broadly lenticular ascospores with two wide equatorial crests and finely spinulose and rugose convex surfaces and produced pale pinkish exudates after 14 d incubation on Czapek agar. The validation of this new species was supported further by analyses of the β-tubulin, calmodulin and actin gene sequences.     

Aspergillus insulicola sp. nov.

A strain of Aspergillus sp. is described and proposed as a new species under the name ‘Aspergillus insulicola sp. nov.’ Montemayor & Santiago, 1973. This strain was isolated from soil samples taken in ‘Aves Island’ during a scientific expedition. — Aves Island, situated at 15°, 40′, 42″ N and 63°, 36′, 47″ W, about 665 Km of the coast of Venezuela, has very special ecological conditions. Due to its smallness: 550 m long and 40 to 120 m across and to its low profile only 3 m over sea level, it is swept by the sea during the periodical storms and hurricanes in the area. It has thus a very interesting fauna and flora. We took a series of soil samples to study its mycological flora. Forty samples were inoculated by dilution method. In this first paper a species is described and proposed as a new species because of its macroscopic and microscopic characteristics, as well as by its biological properties, under the name ‘Aspergillus insulicola sp. nov.’. In its study we have tried to follow as closely as possible the methods recommended by Kennet B. Raper & Dorothy Fenell, world authorities on the genera Aspergillus and Penicillium. The strain is being kept in USB under the number T1, and has been sent to ATCC & CBSC to be incorporated in their collections.     

Aspergillus asperescens n. sp.

Summary A newAspergillus species,Aspergillus asperescens, is described. Three strains of this fungus have been isolated from soil and dung of bats in caves in Great-Britain and Poland. It is characterized by a yellow green colour, radiate conidial heads, two series of sterigmata, a brown conidiophore, hülle cells and subglobose conidia, which are smooth in young and rough in old cultures.     

Isolation and characterization of isocitrate lyase from a thermophilic Bacillus sp.

Isocitrate lyase was isolated in homogeneous state from a thermophilic Bacillus. The enzyme has a mol.wt. of 180000 and a pI of 4.5 and contains threonine as the N-terminal residue. It resembles in size the cognate enzyme from the mesophilic bacterium Pseudomonas indigofera, but is smaller than the enzyme from the eukaryotic fungus Neurospora crassa. All three lyases are tetramers and similar in amino acid composition, but the thermophile enzyme is distinctive from its mesophilic coutnerparts in possessing a lower catalytic-centre activity, greater resistance to chemical and thermal denaturation and fewer thiol groups and in being strongly activated by salts. Salt activation, by 0.4M-KCl, is about 3-fold at 30 degrees C and pH 6.8 and weakens progressively as the temperature or pH is raised. The activation is probably due to a change in the enzyme conformation caused by the electrolyte modifying the interaction between charged groups or between hydrophobic groups in protein. The possible significance of the salt activation, of the relative paucity of thiol groups and of the greater resistance to chemical denaturants is discussed. Besides its effect on the Vmax., KCl produces large increases in the magnitude of several kinetic parameters. A rise in reaction temperature from 30 to 55 degrees C produces a somewhat similar result. In view of these peculiar features, the patterns of inhibition of enzyme activity by compounds such as succinate and phosphoenolpyruvate were examined at 30 and 55 degrees C in the presence and absence of KCl.     

A new high-alkaline alginate lyase from a deep-sea bacterium Agarivorans sp.

A high-alkaline, salt-activated alginate lyase is produced by Agarivorans sp. JAM-A1m from a deep-sea sediment off Cape Nomamisaki on Kyushu Island, Japan. Purified to homogeneity, as judged by SDS-PAGE, the enzyme (A1m) had a molecular mass of approximately 31 kDa. The optimal pH was around 10 in glycine–NaOH buffer, and the activity was increased to 1.8 times by adding 0.2 M NaCl. However, when the optimal pH in the presence of 0.2 M NaCl was shifted to pH 9.0, the activity was more than 10 times compared with that at pH 9 in the absence of NaCl. A1m showed the optimal temperature at around 30°C and was stable to incubation between pH 6 and 9. The enzyme degraded favorably mannuronate–guluronate and guluronate-rich fragments in alginate. Shotgun cloning and sequencing of the gene for A1m revealed a 930-bp open reading frame, which encoded a mature enzyme of 289 amino acids (32,295 Da) belonging to polysaccharide lyase family 7. The deduced amino acid sequence showed the highest similarity to that of a Klebsiella enzyme, with only 54% identity.     

Purification and characterization of alginate lyase from marine Vibrio sp. YWA

Extracellular alginate lyase secreted by marine Vibrio sp.YWA,isolated from decayedLaminaria japonica,was purified by a combination of ammonium sulfate precipitation and diethylaminoethyl-Sephacel column chromatography.The results show that the molecular mass of alginate lyase wasapproximately 62.5 kDa,with an optimal pH and temperature at pH 7.0 and 25℃,respectively.K_m wasapproximately 72.73 g/L.The activity of the enzyme was enhanced by EDTA and Zn~(2 ),but inhibited by Ba~(2 ).The substrates specificity analysis shows that it was specific for hydrolyzing poly-β-D-1,4-mannuronate inalginate.     

The distinctiveness of ATP:citrate lyase from Aspergillus nidulans

ATP:citrate lyase (ACL), an important enzyme in lipid synthesis, has been purified from Aspergillus nidulans to a specific activity of 19.6 micromol min(-1) mg(-1), almost twice that of any other purified ACL and shown to be distinct from any previously purified ACL. The enzyme is a 371+/-31 kDa hexamer of 3 alpha, 3 beta proteins, unlike the 4 alpha tetramer found in rats or yeasts. The molecular weights of the alpha and beta protein subunits were determined by SDS-PAGE to be 70 and 55 kDa.ACL in A. nidulans (unlike Aspergillus niger) appears to be regulated by the carbon source present in the media. In crude extracts, it was found at high activity (88 micromol min(-1) mg protein(-1)) in glucose-grown cells but only at low activity (10 micromol min(-1) mg protein(-1)) in acetate-grown cells.     

植物细胞离析酶的制备和应用

用 Aspergillus sp．A-19菌经固体发酵研制成一种新的植物细胞离析酶(SeparatasezA—P)。其离析单细胞的酶活力平均为70 767u／g,有效作用的pH在3．0—7．0,温度为20—45℃。发酵培养基配方是麸皮：桔皮粉：(NH₄)₂SO₄(w／w)为100:100:O．63,料水比为1 :2．0,培养适宜条件为25℃、60小时。     

Potato signal molecules that activate pectate lyase synthesis in Pectobacterium atrosepticum SCRI1043

A new type of plant-derived signal molecules that activate extracellular pectate lyase activity in phytopathogenic bacterium Pectobacterium atrosepticum SCRI1043 was revealed. These compounds were characterized and partially purified by means of several approaches including RT-PCR analysis, luminescence bioassay and HPLC fractionation. They were smaller than 1 kDa, thermoresistant, nonproteinaceous, hydrophilic, and slightly negatively charged molecules. Using gene expression analysis and bacterial biosensor assay the mode of activity of revealed compounds was studied. The possibility of their action through quorum sensing- and KdgR-mediated pathways was analyzed.