Highly efficient homologous integration via tandem exo-beta-1, 3-glucanase genes in the common mushroom, Agaricus bisporus.

Homologous integration was studied in the common mushroom, Agaricus bisporus, using a plasmid (pHAG3-1) carrying the hygromycin-resistance gene and a 3.2-kb genomic fragment from A. bisporus. Homologous integration was found in 30-60% of the transformants obtained with pHAG3-1 linearized at three different positions within the homologous sequence, generating either blunt, 5'- or 3'-protruding ends. The genomic fragment was found to contain two homologous open reading frames in tandem, which showed 60% similarity to exo-beta-1,3-glucanases from Saccharomyces cerevisiae and Candida albicans. The level of the corresponding mRNA is low in the vegetative mycelium and relatively high in fruiting bodies. In the vegetative mycelium of a transformant with tandemly integrated pHAG3-1 plasmids at the homologous position, exoglucanase mRNA was strongly increased without any apparent effect on growth rate or morphology.

Cloning, sequence and expression in Escherichia coli of the gene encoding phosphofructokinase from Bacillus macquariensis.

A chromosomal DNA fragment containing the Bacillus macquariensis (Bm) ATP-dependent phosphofructokinase-encoding gene (pfk) was cloned from a subgenomic library in pUC19 using a PCR-derived probe. The region containing pfk, including flanking sequences, was sequenced and the deduced amino acid sequence (aa) was found to be homologous to other PFK, but it contained two single-aa changes conserved in a range of other organisms from pro- and eukaryotic origins. Enzymatic studies with PFK purified from overproducing Escherichia coli (Ec) host cells showed that the Bm enzyme is similar to B. stearothermophilus (Bs) PFK in many respects and that it is relatively cold stable.

Transformation of the cultivated mushroom, Agaricus bisporus, to hygromycin B resistance.

Application of biotechnology to the cultivated mushroom, Agaricus bisporus, has been hampered thus far by the lack of a transformation system. Here, transformation of both a homo- and a heterokaryotic strain of A. bisporus to hygromycin B resistance is described. Transforming DNA was integrated into the A. bisporus genome and stably maintained throughout vegetative growth. Transformants of the heterokaryotic strain formed transgenic fruiting bodies. Promoters derived from the unrelated ascomycete Aspergillus nidulans and from A. bisporus itself, were able to drive expression of the hygromycin B resistance gene. Expression controlled by a fragment of 265 bp from the A. bisporus GPD promoter was sufficient to generate transformants. However, transformation efficiency was not enhanced by using this homologous promoter.

Investigation into the Presence of Pyrrolizidine Alkaloids in Eupatorium cannabinum by Means of Positive and Negative Ion Chemical Ionization GC-MS.

It is demonstrated that the combination of positive ion chemical ionization and negative ion chemical ionization GC-MS analyses of herb and root extracts of EUPATORIUM CANNABINUM L. offers a rapid, tentative structure elucidation of pyrrolizidine alkaloids (PAs). Compounds identified in aerial parts of E. CANNAHIMUM in this way are four echinatine isomers, like lycopsamine and intermedine, and a number of their beta-acetyl, beta-angelyl/tiglyl and beta-(iso)valeryl esters. PAs without a substituent at C-7 were tentatively identified as supinine and amabiline. In addition to a number of these alkaloids, some beta-(iso)butyryl, beta-angelyl/tiglyl, and beta-(iso)valeryl esters of supinine or amabiline were detected in subterranean parts of the plant. PAS with a saturated necine base like the three trachelanthamine isomers and some beta-anglyl/tiglyl esters could be detected in the root material only. A C-9-viridifloryl/trachelanthyl ester of a saturated amino-alcohol like turneforcidine and one of its beta-angelyl/tiglyl esters have also been found. The latter 2 compounds, the beta-(iso)butyryl, the beta-(iso)valeryl, and the beta-angelyl/tiglyl esters of supinine or amabiline and the beta-(iso)valeryl ester of an echinatine isomer have not been described in nature before.

Reproduction of the beet cyst nematode Heterodera schachtii Schm. on transformed root cultures of Beta vulgaris L.

Transformed hairy root cultures of Beta vulgaris L., grown in petri-dishes, were inoculated with a suspension of surface-sterilized larvae of the beet cyst nematode Heterodera schachtii Schm. Larvae developed into both male and female adults. Juvenile larvae were hatched from the newly-formed cysts, indicating that fertilization had occurred. Results of a glasshouse test showed that H. schachtii did not lose its pathogenicity after being cultured on transformed roots. This technique can be developed further for the mass-propagation of sedentary nematodes and for the in vitro storage of isclates.

Induction of phenoloxidase in cell suspension cultures of Mucuna pruriens L. : Effects on accumulation of L-3,4-dihydroxyphenylalanine and biotransformation capacity.

The effects of limitating nitrogen-containing compounds in the medium and of adding the amino-acid analogues p-fluorophenylalanine and ethionine on both phenoloxidase activity and the accumulation of L-3,4-dihydroxyphenylalanine (L-DOPA) are reported for cell suspension cultures of Mucuna pruriens. Nitrogen limitation of the cultures, or the addition of p-fluorophenylalanine or ethionine to the culture medium resulted in an increased phenoloxidase activity. There appeared to be an inverse relationship between phenoloxidase activity and the acccumulation of L-tyrosine into L-DOPA by alginate-entrapped cells occurred at a higher rate when phenoloxidase activity was increased.

Optimization of the biotransformation of L-tyrosine into L-dihydroxyphenylalanine (DOPA) by alginate-entrapped cells of Mucuna pruriens.

The optimization of the biotransformation of L-tyrosine into L-dihydroxyphenylalanine (DOPA), and of formyl-tyrosine into formyl-DOPA by alginate-entrapped cells of Mucuna pruriens is reported. This optimization is discussed in terms of parameters that are relevant for the entrapped cell system (charge of the beads with cells, bead diameter, permeation of the cells) and some parameters that are relevant for the enzymatic transformation (pH, pO2, concentration of ascorbate). The optimization experiments resulted in the description of a biotransformation system which operates at a constant redox potential. With this transformation system a transformation efficiency of 70% could be obtained, at a biotransformation-rate of 435 µmol·h(-1)·g(-1) (DW of cells) at a substrate concentration of 19 mM.

Purification and properties of a phenol oxidase derived from suspension cultures of Mucuna pruriens.

From cells of Mucuna pruriens, grown in suspension, a monophenol monooxygenase (EC 1.14.18.1) was purified to homogeneity, as deduced from sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme appeared to have a native molecular weight of 90000±5000 dalton, and consisted of two subunits, each of 42000±1000 dalton. High-performance liquid chromatography with electrochemical detection for specific measurement of catecholes, was used to determine separately the tyrosinehydroxylating and catecholase activities of the enzyme. For the enzymatic activities, pH optima of, respectively, 7.5 and 5.5-6.5 were found; the effects of some inhibitors on both activities appeared to be different. Michaelis-Menten characteristics for some mono-and o-dihydroxysubstrates were determined.

The effect of some environmental factors on the production of L-DOPA by alginate-entrapped cells of Mucuna pruriens.

In-vitro-grown cells of Mucuna pruriens, immobilized in calcium-alginate gels, were able to transform the precursor L-tyrosine into L-dihydroxyphenylalanine (L-DOPA). After the immobilization in alginate the plant cells released 90% of the produced L-DOPA into the medium; supplementation of the medium with calcium inhibited both the transformation of L-tyrosine into L-DOPA and the release of L-DOPA into the medium. Continuous illumination of the beads had a slight beneficial effect on the synthesis of L-DOPA. A simple production medium for the transformation of L-tyrosine into L-DOPA was designed. This medium contained only sucrose and sodium chloride as osmotic stabilizers, a low concentration of calcium chloride for stabilization of the alginate beads, and L-tyrosine as the precursor.