The rice blast fungus Magnaporthe oryzae is the most important pathogen on cultivated rice because of its economic relevance and destructiveness. 1 Blast disease caused by this heterothallic ascomycete destroys about 10-30% rice yield every year. 2 In order to infect and colonize the host plant Oryza sativa, conidia of the fungus attach to the leaf surface and germinate by sending out a germ tube. Induced by the hard hydrophobic surface, appressoria required for penetration differentiate. Within the specialized infection structure compatible solutes, for example, glycerol, accumulate. 3 The solutes are retained within the cell by a melanin layer. As a consequence, water flows into the infection structure to generate turgor required for a mechanically penetration of the plant cuticle. As the functionality of the appressorium is an essential prerequisite for a successful infection of the host plant, the melanin layer is a pathogenicity factor in M. oryzae. Agrochemicals interfering with the biosynthesis of the biopolymer, for example, tricyclazole, have been successfully used in the past as protective agents. 4 After penetration, the hyphae disperse within the plant to form conidiophores and conidia. The spores are spread in the field via wind and water. 2 Due to the resistance development against commercially available fungicides, there is a demand for lead structures for the development of novel fungicides. 4 Secondary metabolites from nature have in the past been used as lead structures for successful pesticides. The widely used class of QoI (quinone outside inhibitor)-fungicides is based on the structure of strobilurin A, a secondary metabolite found in cultures of the basidiomycete Strobilurus tenacellus. 5 As fungi represent an almost inexhaustible reservoir for natural compounds, screening approaches are conducted for the identification of new secondary metabolites interfering either with pathogenic differentiation or fungal vegetative growth. In this course, compound GKK1032A 2 (1) was identified from cultures of the fungus Penicillium sp. IBWF-029-96. The compound has been described as a metabolite from fungal cultures. In this note, we describe a biological activity of this compound, which has not been reported before. 6,7 M. oryzae strain 70-15 was obtained from the Fungal Genetics Stock Centre, Kansas City, KS, USA. The strain was cultured on complete medium (CM) medium as described previously. 8 Botrytis cinerea, Fusarium graminearum and Phytophthora infestans were provided by BASF SE. EXPERIMENTAL PROCEDURE Organisms Fermentation and isolationThe strain Penicillium sp. IBWF-029-96 was fermented in yeast malt glucose medium in a 20-l fermenter (Biostat A-20, Braun Melsungen, Melsungen, Germany) at room temperature with aeration (4.5 l min À1 ) and agitation (120 r.p.m.). A well-grown culture (200 ml) in the same medium was used as inoculum. Daily samples were withdrawn to measure pH, glucose and maltose content as well as mycelial dry weight and in order to quantify the bioactive secondary metabolite ...
It is accepted practice to disinfect microbiological safety cabinets with formaldehyde vapour particularly before such operations as filter changing. For some years at Shrewsbury the method described in PHLS Monograph No 61 in which 200 ml of an equal volume of commercial formalin and water were boiled away in a sealed cabinet and left undisturbed overnight has been used. The directions imply that the extra water is added to raise the humidity and so enhance the lethal effect of the formaldehyde. Unfortunately one of the effects of the extra water is to cause the inside of the cabinet to become wet from condensation. Because condensation on the load and in the chamber of low temperature steam/formaldehyde sterilisers is known to be a common cause of sterilisation failure,2 we tested our cabinet disinfection procedures.Among the many and varied recommendations for disinfecting safety cabinets (Table 1)' 3-6 only one quotes recent supportive experimental details.6 Because of the varied advice and the relative lack of published results we describe the tests we undertook and the results obtained.
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