Cloning and heterologous expression of a novel ligninolytic peroxidase gene from poroid brown-rot fungus Antrodia cinnamomea

A novel ligninolytic peroxidase gene (ACLnP) was cloned and characterized from a poroid brown-rot fungus, Antrodia cinnamomea. The genomic DNA of the fungus harboured two copies of ACLnP, with a length of 2111 bp, interlaced with 12 introns, while the full-length cDNA was 1183 bp, with a 66 bp signal peptide and an ORF of 990 bp. The three-dimensional molecular structure model was comparable to that of the versatile peroxidase of Pleurotus eryngii. ACLnP was cloned into vector pQE31, successfully expressed in Escherichia coli strain M15 under the control of the T5 promoter and produced a non-glycosylated protein of about 38 kDa, pI 5.42. The native and recombinant ACLnP was capable of oxidizing the redox mediator veratryl alcohol, and also decolorized bromophenol blue and 2,6-dimethoxyphenol dyes, implicating a functional extracellular peroxidase activity. The significance of discovering a functional ACLnP gene in A. cinnamomea in terms of wood degradation and colonization capacity in its unique niche is discussed.

Characterization of allergens from Penicillium oxalicum and P. notatum by immunoblotting and N-terminal amino acid sequence analysis

BACKGROUND

Penicillium species are important causative agents of extrinsic bronchial asthma. However, little is known about the allergens of these ubiquitous fungal species. Objective The object was to analyse the composition, the allergenic cross-reactivity and the N-terminal sequences of allergens from two prevalent airborne Penicillium species, P. oxalicum and P. notatum.

METHODS

The allergenic composition and the immunoglobulin (Ig)E cross-reactivity were analysed by immunoblot and immunoblot inhibition, respectively, using sera from asthmatic patients. The N-terminal amino acid sequences of major allergens were determined by Edman degradation. Allergens identified were also characterized by immunoblotting using monoclonal antibody (MoAb) PCM39 against the alkaline serine proteinase major allergen of P. citrinum.

RESULTS

Among the 70 asthmatic sera tested, 18 (26%) and 17 (24%) had IgE immunoblot reactivity towards components of P. oxalicum and P. notatum, respectively. Major allergens (> 80% frequency of IgE-binding) from both species are the 34 and 30 kDa proteins of P. oxalicum and the 34 and 32 kDa proteins of P. notatum. IgE cross-reactivity among these major allergens and the 33 kDa major allergen of P. citrinum can be detected by immunoblot inhibition studies. The N-terminal amino acid sequences of the 34 kDa allergen of P. oxalicum and of the 32 and the 28 kDa allergens of P. notatum share homology with sequences of the vacuolar serine proteinase from Aspergillus fumigatus. The N-terminal amino acid sequence of the 34 kDa allergen of P. notatum shows sequence homology with that of alkaline serine proteinase from P. citrinum. Results obtained from immunoblotting showed that MoAb PCM39 reacted with the 34, 30 and 16 kDa IgE-binding components of P. oxalicum, and with the 34, 32 and 28 kDa IgE-binding components of P. notatum.

CONCLUSIONS

Results obtained suggest that the 34 kDa major allergen of P. oxalicum may be a vacuolar serine proteinase. The 34 and the 32 kDa major allergens of P. notatum may be the alkaline and the vacuolar serine proteinases of P. notatum, respectively. The 30 and 16 kDa IgE-binding components of P. oxalicum and the 28 kDa IgE-binding component of P. notatum may be breakdown products of the 34 and the 32 kDa major vacuolar serine proteinase allergens of P. oxalicum and P. notatum, respectively.

The repB gene required for production of extracellular enzymes and fluorescent siderophores in Pseudomonas viridiflava is an analog of the gacA gene of Pseudomonas syringae

Two genes, designated repA and repB, are involved in the regulation of the synthesis of extracellular pectate lyase, protease, and alginate in Pseudomonas viridiflava. The repA gene has been shown to encode a protein highly homologous to several bacterial sensors in the two-component regulator family including the LemA of Pseudomonas syringae. In this study, the repB locus, initially identified in a 6.3-kb EcoRI genomic fragment of P. viridiflava, was further characterized. Results obtained from restriction mapping, deletion subclonings, and mini-Mu-LacZ fusions indicated that the repB gene was contained within a 0.8-kb HindIII-PstI region. Sequence analysis of this repB region revealed the presence of an open reading frame, which was predicted to encode a protein similar or identical to the gacA response regulator found in P. syringae and Pseudomonas fluorescens. The repB gene of P. viridiflava also regulated the production of fluorescent siderophores, in addition to the aforementioned extracellular enzymes and alginate. The repB or gacA homologs were detected in the genomes of nine other strains of P. viridiflava, P. fluorescens, and P. syringae included in the study. The data presented here and earlier indicate that the repA/repB gene regulatory system of P. viridiflava is analogous to the lemA/gacA system of P. syringae and P. fluorescens.

Complete nucleotide sequence of Beauveria bassiana 5.8s rRNA coding gene and flanking internal transcribed spacers

The nucleotide sequence of two clones of Beauveria bassiana in 5.8s rRNA coding gene and ITS regions were completely sequenced. The overall sequence similarity of these two clones is 96%. The identities of internal transcribed spacer (ITS) regions are 91 % (ITSI) and 100% (ITSII), respectively. Both of 5.8s rRNA sequences have 98% homology.

Production of type II ribotoxins by Aspergillus species and related fungi in Taiwan

A molecular investigation was conducted on the production of type II ribotoxin of the species Aspergillus and related fungi in Taiwan. Species that carried ribotoxin were confirmed by (1) cross-reactivity to anti-alpha-sarcin serum; (2) Southern dot hybridization; (3) PCR amplification of genomic DNA with specific primers; and (4) analysis of ribotoxic activity. Five new strains, A. clavatus, A. oryzae var. effusus, A. ostianus, A. tamarii, and Neosartorya fischeri var. spinosa, were identified to contain an alpha-sarcin-like ribotoxin. These positive strains exhibit ribotoxic activity by cleaving ribosomes and generating an alpha-fragment.

Spore germination and the life cycle of Frankia in vitro

Bacterial spores of Frankia produced in defined culture media were collected by filtration after washing in amounts approximating 106 spores/mL. Frankia strains UFGCeI5 from Casuarina equisetifolia and UFGCgI1 from C. glauca showed spontaneous release of spores in culture; strains HFPCcI3 from C. cunninghamiana and HFPAllI1 from Allocasuarina lehmanniana showed low spore release in culture unless homogenized. Spore germination was tested on plates of agar nutrient media under different physical and chemical environments. Strain CeI5 showed about 15% germination within 2 days in a defined (BAP) medium with an optimum pH of 6.0–6.8 at 28–35 °C. Under these conditions, strain CcI3 germinated less than 0.5%. In a series of trials with increasingly complex media, strain CeI5 showed 75% spore germination in 3 days at 28 °C and pH 6.7 in the most complex medium tested. Additions of specific single organic compounds to BAP medium caused either strong inhibition or slight stimulation of spore germination. Frankia strains that showed spontaneous spore release germinated better than strains that did not release. Spore germination in Frankia strains is markedly influenced by their strain origin and by the physical and chemical environment in which they are placed.Key words: Casuarina, Frankia, life cycle, spore germination.

A new predatory hyphomycete capturing bdelloid rotifers in soil

Cephaliophora navicularis, a hyphomycete capable of capturing bdelloid rotifers by using specialized adhesive pegs, is described as new. Canoe-shaped conidia are produced synchronously on ovoid- to club-shaped ampullae that arise more or less directly from the vegetative hyphae. In the presence of rotifers conidia develop short, adhesive appendages by which they attach to the host cuticle. After adhesion, germination and penetration occur and tortuous assimilative hyphae develop in the host. Vegetative hyphae from parasitized rotifers break out to the exterior and produce adhesive pegs which catch additional rotifers.

A subcuticular endoparasite impaling bdelloid rotifers using three-pronged spores

Triacutus subcuticularis is described as an endoparasite of bdelloid rotifers. The infection hypha does not establish in the visceral tissue but grows in the pseudocoel between the cuticle and the epidermis. In this location the thallus grows and divides repeatedly to produce numerous unicellular assimilative segments which pack the subcuticular space of the living host. After death, each hyphal segment produces one or several filiform extensions which bear solitary one-celled, three-pronged spores at the apex. Infection is initiated by the spore impaling the rotifers in the mouth region.

Species of Phytophthora and Pythium as Nematode-destroying Fungi

Pythium monospermum,, P. aphanidermatum, and Phytophthora palmivora were found to be capable of destroying certain nonstylet-bearing nematodes through endozoic parasitism by hyphae from ingested zoospores. Hyphae of P. monospermum parasitized nematode eggs but could not capture or otherwise prey upon living nematodes. We suggest that endoparasitism of free-living nematodes may be common among Oomycetes in nature.

Schizophyllum commune Fr. as a destructive mycoparasite

Schizophyllum commune Fr. was shown, by light, scanning, and transmission electron microscopy, to be a destructive mycoparasite on several phytopathogenic and nematode-trapping fungi. The hyphae of S. commune coiled around host hyphae and fruiting structures and penetrated them by means of either unspecialized hyphae or by penetration pegs that developed from terminal appressoria. The host cell walls were usually chemically degraded after which the parasite grew through an electron-dense, papillate, reaction region and its underlying membrane(s) produce trophic hyphae inside the host cells.