The ubiquity of natural adsorbable organic halogen production among basidiomycetes

 Recently, several species of basidiomycetes were shown to produce de novo high concentrations of chloroaromatic metabolites. Since these lignocellulose-degrading fungi play a major role in the ecosphere, the purpose of this study was to determine the ubiquity of organohalogen production among basidiomycetes. A total of 191 fungal strains were monitored for adsorbable organic halogen (AOX) production when grown on defined liquid media. Approximately 50% of the strains tested and 55% of the genera tested produced AOX. A low production of 0.1–0.5 mg AOX/l was observed among 25% of the strains, a moderate production of 0.5–5.0 mg AOX/l was observed among 16% of the strains and 9% of the strains produced high levels (5–67 mg AOX/l). The latter group was dominated by species belonging to the genera Hypholoma, Mycena and Bjerkandera, showing specific AOX productions in the range 1074–30893 mg AOX/kg dry weight of mycelial biomass. Many highly ecologically significant fungal species were identified among the moderate to high producers. These species were also able to produce AOX when cultivated on natural lignocellulosic substrates. Hypholoma fasciculare and Mycena metata respectively produced up to 132 mg and 193 mg AOX/kg dry weight of forest litter substrate in 6 weeks. Received: 5 October 1995/Received revision: 28 December 1995/Accepted: 12 February 1996     

Effect of culture conditions on astaxanthin production by a mutant of Phaffia rhodozyma in batch and chemostat culture

Temperature and pH had only a slight effect on the astaxanthin content of a Phaffia rhodozyma mutant, but influenced the maximum specific growth rate and cell yield profoundly. The optimum conditions for astaxanthin production were 22°C at pH 5.0 with a low concentration of carbon source. Astaxanthin production was growth-associated, and the volumetric astaxanthin concentration gradually decreased after depletion of the carbon source. The biomass concentration decreased rapidly during the stationary growth phase with a concomitant increase in the cellular content of astaxanthin. Sucrose hydrolysis exceeded the assimilation rates of D-glucose and D-fructose and these sugars accumulated during batch cultivation. D-Glucose initially delayed D-fructose uptake, but D-fructose utilization commenced before glucose depletion. In continuous culture, the highest astaxanthin content was obtained at the lowest dilution rate of 0.043 h^–1. The cell yield reached a maximum of 0.48 g cells·g^–1 glucose utilized between dilution rates of 0.05 h^–1 and 0.07 h^–1 and decreased markedly at higher dilution rates. Correspondence to: J. C. Du Preez