The effects of sterol mutants of the yeast Saccharomyces cerevisiae on the outcome of competition between Drosophila melanogaster and D. simulans

The effect of different yeast variants of the yeast Saccharomyces cerevisiae on the outcome of competition between Drosophila simulans and D. melanogaster was investigated. In all experiments differential birth rate was the effective mode of species competition. Addition of live yeast and especially mixtures of yeast strains improved the competition situation of a species, but could not prevent the extinction.     

A PCR survey of psychrotrophic Clostridium botulinum-like isolates for the presence of BoNT genes

Isolates (259) of psychrotrophic Clostridium spp. associated with either blown pack spoilage (five isolates) or slaughter stock (254 isolates) were screened for the presence of botulinum neurotoxin (BoNT) genes using degenerate PCR primers capable of amplifying A, B, E, F and G BoNT genes. No BoNT gene amplification products were detected using DNA templates from the 259 psychrotrophic isolates, including 249 isolates that showed the same 16S rRNA gene Restriction Fragment Length Polymorphism (RFLP) patterns as authentic Cl. botulinum type B. It is concluded that although the growth of such microorganisms in vacuum-packed chilled meat leads to product spoilage, it does not prejudice product safety.     

Zum Auftreten von Phoma nigrificans (P. Karst.) comb. nov. (Teleomorph Didymella macropodii Petrak) an Winterraps (Brassica napus L. var. oleifera Metzger)

On the occurrence of Phoma nigrificans (P. Karst.) comb. nov. (teleomorph Didymella macropodii Petrak) on winterrape (Brassica napus L. var. oleifera Metzger) With a screening for resistence of winterrape to Phoma lingam (teleomorph Leptosphaeria maculans), in various places in North Germany, another species of Phoma was repeatedly isolated from plants with blackleg symptoms. This Phoma species could easily be distinguished from P. lingam by its larger conidia and its lower optimal temperature. Comparative study with isolates in the Phoma-collection of the “Plantenziektenkundige Dienst” (Wageningen) showed that it, represents the anamorph of Didymella macropodii, an Eurasian Ascomycete occurring on different wild crucifers and originally described from Macropodium nivale in Siberia. The Phoma-anamorph of this fungus was first described in Finl, and from Armoracia rusticana as Sphaeronaema nigrificans. This binomial is now transferred to Phoma (“section Sclerophomella”). Inoculation of rape seedlings with Phoma nigrificans (Didymella macropodii) resulted, in dark discolorations and constrictions of the hypocotyls of the seedlings.