Abstract

This experiment was performed to test the suitability of other starch containing tubers (sweet potato varieties [purple and whitish], yam and cocoyam varieties [edible and non-edible]) as substitutes for Irish potato in potato dextrose agar (PDA) in varying concentrations (100, 200, 300, and 400 g/L) and alternating between dextrose and glucose in concentration range of 10, 20, and 30 g/L. Potato dextrose agar (PDA) served as the control. Aspergillus niger and Aspergillus carbonarius were used as test organisms. Test organisms were aseptically inoculated into the ten different formulated media including PDA and allowed to grow. Spores were harvested after five days of growth and counted using haemocytometer. The results were subjected to analysis of variance (ANOVA) (P Ë‚ 0.05). The purple sweet potato variety on an average showed good mycelial growth when compared to other formulated media and sometimes PDA. Purple sweet potato variety can be used as an alternative to Irish potato for fungal growth. However further studies may be required to determine appropriate concentrations and conditions.

Key words: culture media, fungi, potato dextrose agar (PDA), sweet potato, cocoyam, yam.