Influence of Growth Medium on Diagnostic Characters of Aspergillus and Penicillium Species
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African Journal of Microbiology Research Vol. 3 (5) pp. 280-286 May, 2009 Available online http://www.academicjournals.org/ajmr ISSN 1996-0808 ©2009 Academic Journals Full Length Research Paper Influence of growth medium on diagnostic characters of aspergillus and penicillium species M. E. Zain, A. A. Razak, H. H. El-Sheikh, H. G. Soliman and A. M. Khalil Botany and Microbiology Department, Faculty of Science, Al-Azhar University, Cairo, Egypt. Accepted 27 April, 2009 Three fungal strains; namely, Aspergillus terreus, Penicillium janthinellum and Penicillium duclauxii were cultured on different growth media including yeast extract, malt extract, yeast-malt extract, Czapek's Dox, Sabourod's, Harrlod's, and potato dextrose. The growth and secondary metabolites of the three fungal strains were greatly affected by the growth medium. The colour of the culture and secondary metabolites were noticeably altered and changed according to the growth medium used. Key words: Growth medium, Aspergillus, Penicillium, Secondary metabolites, Culture characteristics. INTRODUCTION The taxonomy of the fungi is in a state of rapid flux at on their sexual reproductive structures. Currently, four present, especially due to recent papers based on DNA divisions are recognized (Alexopolous et al., 1996). comparisons, which often overturn the assumptions of On the other hand, secondary metabolites are com- the older systems of classification (Hibbett, 2007). pounds neither essential for growth nor key intermediates The simple morphology, the lack of a useful fossil re- of the organism’s basic metabolism but presumably play- cord, and fungal diversity has been major impediments to ing some other role in the life of fungi. They are usually progress in this field (Berbee and Taylor, 1992). Classi- found as a mixture of closely related molecules with a cally, studies on fungal evolution have been based on peculiar and rare chemical structure (Hawksworth et al., comparative morphology, cell wall composition (Bartnicki; 1995). Bartnicki-Garcia, 1970, 1987) cytologic testing (Taylor, Molds will be affected by all the environmental factors; 1978), ultrastructure (Fuller, 1976; Heath, 1980; Heath, (chemical and physical). Physical and chemical factors 1986) cellular metabolism (Vogel, 1964; Le'John, 1974), have a pronounced effect on diagnostic characters of fun- and the fossil record (Hawksworth et al., 1995). More re- gi. Fungal growth (spore germination, vegetative growth cently, the advent of cladistic and molecular approaches and sporulation) has a specific set of conditions that is has changed the existing situation and provided new optimal. Important conditions in this set are nutrient types insights into fungal evolution (Josep et al., 1999). and concentrations, light, temperature, oxygen and water However, different concepts have been used by myco- availability (Kuhn and Ghannoum, 2003). However, the logists to define the fungal species. The morphological effect of environmental factors on growth of fungi is gene- (phenetic or phenotypic) concept is the classic approach rally less specific and restricted than the effect on se- used by mycologists; in this approach, units are defined condary metabolite production (Northolt and Bullerman, on the basis of morphological characteristics and ideally 1982). by the differences among them (Davis, 1995). The sexual stages are precisely the baseline of fungal MATERIALS AND METHODS taxonomy and nomenclature. It seems evident that in the near future, modern molecular techniques will allow most Fungal strains of the pathogenic and opportunistic fungi to be connected to their corresponding sexual stages and integrated into a The investigated fungi were isolated from soil and identified at the more natural taxonomic scheme (Josep et al., 1999). The Regional Center for Mycology and Biotechnology, Cairo, Egypt. major divisions (phyla) of fungi are mainly classified based Media For isolation, culturing, maintenance of stock cultures, and experi- *Corresponding author. E-mail: [email protected]. mental studies the following range of media were used: Czapek- Zain et al. 281 Dox Agar (Sucrose, 30 g; Sodium nitrate, 2 g; Potassium hydrogen Results revealed that the culture characteristics and orthophosphate, 1 g; Potassium chloride, 0.5 g; Magnesium sul- secondary metabolites profiles of A. terreus, P. janthin- phate, 0.5 g; Ferrous sulphate, 0.002 g; Agar, 20 g; Distilled water, ellum and P. duclauxii were greatly affected by the type 1 L), Malt Extract Agar (Malt extract, 20 g; Peptone, 1 g; Glucose, 20 g; Agar, 20 g; Distilled water, 1 L), Potato Dextrose Agar (Potato of growth medium. extract, 4 g; Glucose, 20 g; Agar, 20 g; Distilled water, 1 L), Yeast Extract Sucrose Agar (Yeast extract, 20 g; Sucrose, 150 g; Agar, 20 g; Distilled water, 1 L), Yeast Malt Agar (Yeast extract, 3 g; Malt Aspergillus terreus extract, 3 g; Peptone, 5 g; Glucose, 10 g; Agar, 20 g; Distilled wa- ter, 1 L), Harrold's Agar (Malt extract, 20 g; Yeast extract, 5 g; Su- The surface and reverse culture color, mycelial weight, crose, 400 g; Agar, 20 g; Distilled water, 1 L), and Sabouraud agar colony diameter, and number of spores of A. terreus were (Peptone, 10 g; Glucose, 40 g; Agar, 20 g; Distilled water, 1 L). varied and coined to the type of the growth medium (Table 1 and Figure 1). Yeast extract sucrose and Har- Fungal secondary metabolites rold's media showed the best mycelial fresh, dry weight and colony diameter (7.5 g, 2.0 g, 4.5 cm and 7.0 g, 1.6 The secondary metabolites of the investigated fungal strains were g, 4.0 cm respectively). However, the Sabourod's me- determined according to the method described by Paterson and dium showed the lowest mycelial fresh and dry weight Bridge (1994). The fungal mycelial mat was removed and the filtrate (1.4 g and 0.5 g respectively) (Table 1). of metabolized medium was extracted with chloroform in a separa- On the other hand, the highest number of spores per tion funnel then the extract was evaporated to dryness and then 5 2 redissolved in a 2 ml volume of chloroform. The extract sample was cm2 was obtained on Sabourod's (85 X 10 /cm ), Cza- 5 2 5 2 loaded on thin layer chromatography (TLC) plate (20 × 20cm, pek's- Dox (80 X 10 /cm ), Malt extract (72 X 10 /cm ), Merck aluminum sheet, silica gel G 60, layer thickness 0.2 mm) and Yeast extract (70 X 105 /cm2) media. The potato dex- using volumetric micropipette. Griseofulvin was dissolved in chloro- trose medium showed the lowest number of spores (45 X form/methanol (2:1, v/v) and was used as an external standard. The 105 /cm2). TLC plate was developed in toluene, ethylacetate, 90% formic acid (TEF) (5:4:1, v/v/v). The TLC plates were eluted for 17 cm, removed Interestingly, the surface and reverse culture color of from jar and left at room temperature till dried. The plates were Aspergillus terreus were noticeably changed from one examined under the normal light, long UV light (365 nm), short medium to another (Figure 1). Surface color was gra- UV light (254 nm), and back under long UV light (365 nm). The dually altered from light yellow on yeast extract sucrose characteristics of all spots, that is, color and Rf value were to rosy brown on potato dextrose and Sabourod's media. recorded. The plates were sprayed with 0.5% (v/v) p-anisaldehyde The surface color was old lace on Czapek Dox, tan on in methanol-acetic acid-concentrated sulphoric acid (17:2:1, v/v/v), malt extract, beige on Harrold's, and antique white on heated for 8 min at 105°C and re-examined. yeast malt extract media (Figure 1). The numbers of secondary metabolites produced by A. Counting fungal spores terreus were 11 on yeast extract sucrose, 10 on yeast malt extract and 9 on Harrold's medium. However, only 4 The numbers of fungal spores were estimated by transferring 9 secondary metabolites were detected on potato dextrose mm disc of fungal cultures into 10 ml test tube containing 5 ml distilled water. The tubes were shaked vigorously using vortex medium (Table 2). mixer for 5 min. One-tenth ml of fungal spores suspension was tran- The metabolites Aurofusarin, Secalonic acid and un- sferred into a haemocytometer and then the spores was counted. known (C) were produced on five different growth media; Accordingly, the number of fungal spores in 5 ml was calculated. however, they were produced together on only potato The same procedures were repeated three times and the mean dextrose and Sabourod's media (Table 2). While aurofu- number of spores was considered. sarin was not produced on malt and Harrold's media, the secalonic acid was not produced on yeast extract su- Determination of mycelial dry weight crose and yeast malt extract media and the unknown (C) wan not produced on malt extract and Czapek's Dox Mycelia were harvested by filtration using Buchner funnel. Then the media. However, the terrain was produced on yeast ex- mycelia were washed thoroughly with distilled water and the excess tract sucrose, yeast malt extract, and Harrold's media, the of water was removed by plotting with filter papers. The mycelia of water was removed by plotting with filter papers. The mycelia were phoenicin was produced only on malt extract and then either directly weighted; mycelial fresh weight, or dried at 80°C Czapek's Dox media, and unknown was produced on till constant weight obtained; mycelial dry weight. Sabourod's and Czapek's Dox media. RESULTS Penicillium janthinellum Aspergillus terreus, Penicillium janthinellum, Penicillium Culture characteristics and secondary metabolites of Pe- duclauxii were cultured on different kinds of growth media nicillium janthinellum were significantly affected by the including yeast extract, malt extract, yeast-malt extract, type of the growth medium (Tables 3, 4 and Figure 2).