ANALYSIS OF CHEMICAL COMPOSITION OF CACTUS PEAR (OPUNTIA FICUS-INDICA L.) CLADODE EXTRACT AND ITS ROLES IN THE PREPARATION OF FUNGAL CULTURE MEDIA

The present study was aimed at analyzing the chemical composition of the crude extract of cactus pear (Opuntia ficus-indica L.) cladode and examine its suitability for fungal culture media. For this purpose cactus pear cladode samples were collected from Haramaya University campus Model School area. The chemical composition analysis was done according to standard procedures. The growth of five fungal species (R. stoloinfer ATCC 1052, P. digitatum ATCC 2560, A. niger ATCC 1232, T. aureoviride ATCC 2156, and S. cerevisiae ATCC 234) on cactus pear cladode agar (CPCA) w/v (2, 1.6, 1.33, and 1.14 %) were evaluated. Radial growth of the fungal colonies were measured at 72 h interval of time and then compared with the results obtained on standard potato dextrose agar (PDA). The chemical analysis of cactus pear cladode powder extract revealed the presence of carbohydrate (186%), crude fiber (46%), ash (20%), crude protein (9.6%), and moisture content (4.8%). In addition, GC/MS also showed the fatty acid consisted of Octadecanoic acid methyl esters, 7-Octadecanoic methyl ester, and 9-Octadecanoic (Z) methyl ester (68.49%), hexadecanoic acid methyl ester (13.36%), methyl stearate (8.95%), and 9, 12-octadecanoic (Z, Z) methyl ester and 10-trans, 12-cis-octadecadienoate methyl ester (8.89%) in the crude extract. Based on the atomic absorption spectroscopy analysis, macro-elements such as Na, K, Mg, and Ca were identified and these amounted 2.00, 1.98, 0.12, and 0.05 ppm respectively. Micro-elements including Cu, Fe, Mn, and Zn were investigated and quantified as 2.05, 1.76, 1.75, and 0.54 ppm respectively. Vanadate colorimeter analysis showed the concentration of total phosphorus (P) of the extract was 1.00%. R.stoloinfer grew fast and covered the whole diameter of the petriplates in 24 h. Higher radial growth recorded in TS1 (33.08±0.89, 22.33±0.66, and 16.33±0.57) followed by TS2 (30.25±0.54, 15.85±0.59, and 11.58±0.63) for A.niger, P.digitatum and T. aureoviride respectively, after nine days. P.digitatum and T. aureoviride showed significantly (p≤0.05) higher radial growth in TS1 (22.33±0.68, and 14.17±0.28) than in PDA (18.83±0.17 and 10.83±0.52) after nine days. A.niger resulted in comparable radial growth in TS1 (33.08±0.89) and PDA (34.08±0.76). However, S.cerevisiae produced less radial growth on TS1 (16.33±0.57) than on PDA (20.42±0.88) after nine days. In conclusion, higher fungal radial growth was observed on TS1-CPCA (4:200) indicating that the medium has a huge potential to substitute the PDA but other growth performance evaluation parameters are crucial to elucidate the suitability of the medium for commercial purpose.