The Effect Of
Some Heavy Metals And Gibberellic Acid On Growth Of The Fungus Monoascus
Ruber, Teigh
ABDULAZIZ
Q. Al-SARRANI
Department
of Biology, College of Science,
King
Abdulaziz University,
P.O.
Box 30002, Medina Munawwara, Saudi Arabia
تأثير بعض المعادن
الثقيلة وحمض الجبريلليك على نمو فطر "مونواسكس ربر"
أجريت دراسة عن أثر استخدام التركيزات المختلفة لتسعة من المعادن الثقيلة (هي الحديد، والفضة، والألومنيوم، والمنجنيز، والكوبلت، والنحاس، والزنك، والنيكل، والكادميوم)، على نمو فطر مونوأسكس ربر، عندما تضاف منفردة على هيئة أملاح الكبريت لمنبت زبك دوكس آجار. كما استخدم حمض الجبريليك كمنشط للنمو عند تركيزات مختلفة، حيث تمت اضافته الى تلك البيئات المحضرة سابقا في وجود المعادن. ولقد بينت النتائج أن ثمَّة إختلافات في إستجابة الفطر لسمية المعادن الثقيلة، سواء أكانت مضافة للمنبت على إنفراد، أو مصاحبة لحمض الجبريليك. ولقد ثبط معدن الحديد نمو الفطر، بينما الأخير أستحث بإضافة حمض الجبريليك. وثبط معدن الفضة نمو الفطر، بينما حمض الجبريليك لم يحدث وقاية للفطر من سميته. واستحث معدن الألمنيوم نمو الفطر، عدا التركيزات العالية منه (200–400 ميكروجرام/مل)، بينما حمض الجبريليك لم يستحث النمو الفطري إلاّ عند التركيزات المنخفضة منة (10-100 ميكروجرام/مل). وثبط معدن المنجنيز النمو الفطري، بينما لم يتأثر نمو الأخير في وجود حمض الجبريليك. وثبط كل من معدن الكوبلت، ومعدن النحاس نمو الفطر، بإضافة كل منهما على إنفراد، وأيضا عندما يضاف كل منهما مصاحبا حمض الجبريليك (عدا النحاس وحمض الجبريليك عند تركيز 10 ميكروجرام/مل، وفترة حضانة 4 أيام). وثبط معدن الزنك نمو الفطر، بينما أستحث النمو الفطري بإضافة حمض الجبريليك، عدا التركيزات العالية منة (100-400 ميكروجرام/مل). وثبط معدن النيكل نمو الفطر، سواء أضيف للمنبت على إنفراد، أو كان مصاحبا لحمض الجبريليك. كما ثبط معدن الكادميوم نمو الفطر، سواء عندما أضيف للمنبت على إنفراد، أو كان مصاحبا حمض الجبريليك عند التركيزات 50-400 ميكروجرام/مل.
Studies were carried out on the effect of different concentrations of 9 heavy metals (Fe, Ag, Al, Mn, Co, Cu, Zn, Ni and Cd) on mycelial radial growth of Monoascus ruber, Teigh, when supplied singly in the form of sulfate salts to Czabek Dox,s Agar medium. Gibberellic acid (GA3) was also added as a growth substance, at different concentrations to the media, previously supplied singly with the used heavy metals, for protecting the fungal growth from heavy metal toxicity. The results revealed variable responses to these metals i.e. iron inhibited the fungal growth, but the latter was stimulated by the addition of GA3. Silver inhibited the fungal growth, and was not affected by the addition of GA3; Aluminum stimulated the fungal growth, except at high concentrations (200-400 mg/ml), and the addition of GA3 did not enhance the fungal growth, except at a low concentrations (10-100 mg/ml). Manganese inhibited fungal growth, however, it was not affected by the addition of GA3. Cobalt and copper inhibited the fungal growth when supplied singly, or in combination with GA3 (except Cu and GA3 at 10 mg/ml, after an incubation period of 4 days). Zinc inhibited the fungal growth, and the latter was not affected by the addition of GA3, except at high concentrations (100-400 mg/ml). Nickel inhibited the fungal growth when supplied singly and in combination with GA3. Cadmium inhibited the fungal growth when supplied singly or in combination with GA3, at concentrations of 50-400 mg/ml.
Keywords: Monoascus ruber, gibberellic acid, heavy metals.
INTRODUCTION
The
toxicity effect of heavy metals on the growth of some fungi was studied by many
investigators (Lokesha & Somashekar 1991; Colpaert & Van-assche 1993
and Rozycki 1993). However, protection
of fungi from heavy metals toxicity by addition of plant growth substances to
their media, still needs further investigations.
Therefore,
the present studies were carried out to throw some light upon the effect of
certain heavy metals on the growth of the fungus Monoascus ruber, Teigh,
which has been previously isolated from hot sauce of red pepper by Al-Sarrani
(1998), as well as its growth in
presence of the plant growth promoting gibberellic acid (GA3).
MATERIALS
AND METHODS
TEST
ORGANISM
Monoascus
ruber,
Teigh, a fungus previously isolated from hot sauce of red pepper Capsicum
annum (Al-Sarrani 1998) was used in the present studies.
INOCULUM
PREPARATION
Czabek Dox,s Agar medium (CDA) was used. It has the
following composition (g/l): Sucrose, 10; Sodium nitrate, 2; Potassium
dihydrogen phosphate, 1; Magnesium sulfate, 0.01; Agar, 15 and distilled water,
1000ml. The pH value of the medium was adjusted at 4.5 after autoclaving at 1.5
atm. for 15 minutes. CDA medium was also used for subculturing of the test
organism as well as for preparation of fungal inoculum. This was prepared in
the form of fungal culture discs each of 5 mm diameter using 7 days old
culture. CDA medium was also used as control medium for measuring the toxicity
of heavy metals on fungal growth.
HEAVY
METALS EXPERIMENTAL MEDIA
This was prepared using CDA medium free from
magnesium sulfate. It was supplied singly by different salts of 9 heavy metals
to give a final concentration of 10,50, 100, 200, 300 and 400 (mg/ml). The heavy metals were supplied as
follows: iron as (FeSO4.7H2O); silver as
(Ag2SO4); aluminum as (Al2 (SO4)3 .18H2O); manganese as (MnSO4.H2O);
cobalt as (CoSO4.7H2O); copper as (CuSO4.5H2O); zinc as (ZnSO4.7H2O); nickel as
(NiSO4.6H2O) and cadmium as (CdSO4.8H2O), while GA3 was used at a final
concentration of 10, 50, 100, 200, 300 and 400 (mg/ml).
EXPRESSION
OF RESULTS
Fungal growth was determined by measuring the
diameter of colony radial growth in mm. Data were recorded in triplicates after
4 and/ or 8 days of incubation at 25oC. Results were expressed as percentage
difference from control (% DFC).
RESULTS
AND DISCUSSION
Results presented in Table 1 show that the
addition of iron inhibited the growth of Monoascus ruber, after the incubation periods
of 4 and/or 8 days at 25oC. Also the reduction in fungal growth was increased
by increasing iron concentrations. However, a protective effect against iron
toxicity was observed by the addition of GA3 to the fungal basal growth medium
(Table 1a).
Table 1.
Growth of Monoascus ruber on Czabek Dox,s
agar medium
supplied with different concentrations of Fe++
|
Fe++
Conc. (mg /ml) |
*Fungal
Growth (in mm) |
|||
|
4
Days |
8
Days |
|||
|
Growth |
%DFC |
Growth |
%DFC |
|
|
0.0
(Cont) 10 50 100 200 300 400 |
41.3
± 0.6 28.0
± 1.0 27.6
± 0.6 27.3
± 0.6 25.7
± 0.6 20.0
± 1.0 19.0 ± 1.0 |
- -32.2 -33.2 -33.9 -37.8 -51.6 -54.0 |
80.2
± 0.3 62.7
± 0.6 50.6
± 0.3 63.8
± 0.7 61.3
± 0.6 58.3
± 0.6 56.5 ± 0.5 |
- -21.8 -36.9 -20.4 -23.6 -27.3 -29.5 |
* = Mean values of triplicates.
± = Standard Deviation.
% DFC= Percentage differences from control.
Table 1a. Growth
of Monoascus ruber on
Czabek Dox,s agar medium
supplied with different concentrations of Fe++ and
GA3
|
Fe++and
GA3 Conc. (mg /ml) |
*Fungal
Growth (in mm) |
|||
|
4
Days |
8
Days |
|||
|
Growth |
%DFC |
Growth |
%DFC |
|
|
0.0
(Cont.) 10 50 100 200 300 400 |
41.3
± 0.6 46.2
± 0.7 46.8
± 0.7 46.7
± 0.7 46.4
± 1.0 46.3
± 0.7 45.2 ± 0.2 |
- +11.9 +13.3 +13.1 +12.3 +12.1 +9.4 |
80.2
± 0.3 85.0
± 0.0 85.0
± 0.0 85.0
± 0.0 85.0
± 0.0 85.0
± 0.0 85.0 ± 0.0 |
- +6.0 +6.0 +6.0 +6.0 +6.0 +6.0 |
* = Mean values of triplicates.
± = Standard Deviation.
% DFC= Percentage differences from control.
Results presented in Table 2 show that the addition of silver strongly inhibited the fungal growth obtained after the incubation periods of 4 and/or 8 days. Also the inhibitory effect was increased by increasing silver concentrations. The present results differ from those obtained by Olasupo et al. (1993), who found that both of the yeast’s Saccharomyces carisbergensis and Saccharomyces cerevisae showed resistance to the toxicity of silver up to 9 mmol/L.
Table 2. Growth
of Monoascus ruber on
Czabek Dox,s agar medium
supplied with different concentrations of Ag++
|
Ag++
Conc. (mg /ml) |
*Fungal
Growth (in mm) |
|||
|
4
Days |
8
Days |
|||
|
Growth |
%DFC |
Growth |
%DFC |
|
|
0.0
(Cont.) 10 50 100 200 300 400 |
41.3
± 0.6 35.8
± 0.7 33.3
± 0.3 32.3
± 0.3 30.6
± 0.3 23.3 ± 0.3 22.0 ± 1.4 |
- -13.3 -19.4 -21.8 -25.9 -43.6 -46.7 |
80.2
± 0.3 73.3
± 1.5 70.3
± 1.5 65.7
± 1.2 60.3
± 0.6 50.7 ± 1.6 43.0 ± 2.7 |
- -8.6 -12.3 -18.1 -24.8 -36.8 -46.4 |
* = Mean values of triplicates.
± = Standard Deviation.
% DFC= Percentage differences from control.
Results obtained, as presented in Table 2a, showed that GA3 did not exert any protective effect against silver ion toxicity except at 10 mg/ml, and the inhibition of fungal growth was increased by combining silver with GA3 at higher concentrations. However, these results still need further investigations.
Table 2a. Growth
of Monoascus ruber on
Czabek Dox,s agar medium
supplied with different concentrations of Ag++ and
GA3
|
Ag++and
GA3 Conc. (mg /ml) |
*Fungal
Growth (in mm) |
|||
|
4
Days |
8
Days |
|||
|
Growth |
%DFC |
Growth |
%DFC |
|
|
0.0
(Cont.) 10 50 100 200 300 400 |
41.3
± 0.6 44.7
± 0.2 21.0
± 0.0 19.2
± 0.1 0.0
± 0.0 0.0
± 0.0 0.0 ± 0.0 |
- +8.2 -49.1 -53.5 -100.0 -100.0 -100.0 |
80.2
± 0.3 85.0
± 0.0 44.9
± 2.0 32.5
± 0.4 28.5
± 1.8 24.3
± 0.6 17.5 ± 0.5 |
- +6.0 -44.0 -59.1 -64.5 -69.7 -78.2 |
* = Mean values of triplicates.
± = Standard Deviation.
% DFC= Percentage differences from control.
Results presented in Table 3 show that aluminum exerted a stimulatory effect at low concentrations up to 100 mg /l. However, at higher concentrations (200 - 400 mg/l), fungal growth was completely inhibited.
Results obtained, as presented in Table 3a, showed that a slight reduction in the fungal growth was also obtained by the addition of GA3, at low concentrations of both aluminum and GA3 (10-50mg/ml), especially after an incubation period of 4 days. However, fungal growth was inhibited at high concentrations (100 - 400 mg/ml). The resistance of fungi to aluminum toxicity was also recorded by Hashem & Parves (1994). They found that the presence of 16 fungal species belonging to 5 genera, Aspergillus (species), Alternaria and Fusarium (3 species of each), and Penicillium and Ulocladium (2 species of each), in aluminum rich soil indicated that they could tolerate high aluminum concentrations and also they claimed that such tolerance may be due to the alkaline nature of their mother soils.
Table 3. Growth
of Monoascus ruber on
Czabek Dox,s agar medium
supplied with different concentrations of Al+++
|
Al+++
Conc. (mg /ml) |
*Fungal
Growth (in mm) |
|||
|
4
Days |
8
Days |
|||
|
Growth |
%DFC |
Growth |
%DFC |
|
|
0.0
(Cont.) 10 50 100 200 300 400 |
41.3
± 0.6 49.4
± 0.5 48.1
± 0.2 45.0
± 0.0 0.0
± 0.0 0.0
± 0.0 0.0 ± 0.0 |
- +19.6 +16.5 +9.0 -100.0 -100.0 -100.0 |
80.2
± 0.3 85.0
± 0.0 84.7
± 0.6 84.7
± 0.5 0.0
± 0.0 0.0
± 0.0 0.0 ± 0.0 |
- +6.0 +5.6 +5.6 -100.0 -100.0 -100.0 |
* = Mean values triplicates.
± = Standard Deviation.
% DFC= Percentage differences from control.
Table 3a. Growth of Monoascus ruber on Czabek Dox,s agar medium
supplied with different concentrations of Al+++ and GA3
|
Al+++
and GA3 Conc. (mg /ml) |
*Fungal
Growth (in mm) |
|||
|
4
Days |
8
Days |
|||
|
Growth |
%DFC |
Growth |
%DFC |
|
|
0.0
(Cont.) 10 50 100 200 300 400 |
41.3
± 0.6 47.8
± 0.2 45.4
± 1.0 43.9
± 1.0 34.2
± 0.2 27.2
± 1.4 22.3 ± 0.3 |
- +15.7 +9.9 +6.3 -17.2 -34.1 -46.0 |
80.2
± 0.3 85.0
± 0.0 85.0
± 0.0 84.3
± 0.6 76.4
± 1.0 63.4
± 3.3 56.6 ± 0.4 |
- +6.0 +6.0 +5.1 -4.7 -20.9 -29.4 |
* = Mean values of triplicates.
± = Standard Deviation.
% DFC= Percentage differences from control.
A marked reduction in the fungal growth after incubation periods of 4 and/or 8 days was also recorded (Table 4) by the addition of manganese. These results differ to some extent from those obtained by Olasupo (1993), who found that Saccharomyces carisbergensis and Saccharomyces cerevisae, isolated from sugary substrates such as orange, palm and pineapple, showed resistance to 16 - 20 mmol/l manganese. Also it was found that Aspergillus ochraceus, Aspergillus niger and Penicillium digitatum tolerated manganese when grown either on solid or liquid media (Metwally & Abou-Zeid 1996). However, results presented in Table 4a showed the protective effect of GA3 against manganese toxicity on the growth of the fungus.
Table 4. Growth of Monoascus ruber on Czabek Dox,s agar medium
supplied with different concentrations of Mn++
|
Mn++
Conc. (mg /ml) |
*Fungal
Growth (in mm) |
|||
|
4
Days |
8
Days |
|||
|
Growth |
%DFC |
Growth |
%DFC |
|
|
0.0
(Cont.) 10 50 100 200 300 400 |
41.3
± 0.6 33.1
± 0.5 32.9
± 0.6 31.7
± 0.4 31.4
± 0.4 31.2
± 0.1 30.6 ± 0.4 |
- -19.8 -20.3 -23.2 -24.0 -24.5 -25.9 |
80.2
± 0.3 47.7
± 0.6 67.3
± 2.1 68.3
± 1.2 66.0
± 1.0 67.5
± 1.0 66.6 ± 1.2 |
- -6.9 -16.1 14.8 -17.7 -16.5 -17.0 |
* = Mean values of triplicates.
± = Standard Deviation.
% DFC= Percentage differences from control.
Table 4a. Growth of Monoascus ruber on Czabek Dox,s agar medium
supplied with different concentrations of Mn++ and GA3
|
Mn++
and GA3 Conc. (mg /ml) |
*Fungal
Growth (in mm) |
|||
|
4
Days |
8
Days |
|||
|
Growth |
%DFC |
Growth |
%DFC |
|
|
0.0
(Cont.) 10 50 100 200 300 400 |
41.3
± 0.6 45.0
± 1.4 45.9
± 0.6 46.6
± 0.4 46.7
± 2.0 46.2
± 0.7 46.1 ± 1.0 |
- +9.0 +11.1 +12.8 +13.1 +11.9 +11.6 |
80.2
± 0.3 85.0
± 0.0 85.0
± 0.0 85.0
± 0.0 85.0
± 0.0 85.0
± 0.0 85.0 ± 0.0 |
- +6.0 +6.0 +6.0 +6.0 +6.0 +6.0 |
* = Mean values of triplicates.
± = Standard Deviation.
% DFC= Percentage differences from control.
A marked reduction in fungal growth was also obtained in the presence of cobalt especially at high concentrations, as indicated in Table 5. Similar results were obtained by Al-Obaid & Hashem (1996), using Aspergillsus candidus, Dechslera rostrata and Ulocladium atrum. Also GA3 did not show any protective effect over cobalt toxicity, especially at high cobalt concentrations (Table 5a).
Table 5. Growth of Monoascus ruber on Czabek Dox,s agar medium
supplied with different concentrations of Co++
|
Co++
Conc. (mg /ml) |
*Fungal
Growth (in mm) |
|||
|
4
Days |
8
Days |
|||
|
Growth |
%DFC |
Growth |
%DFC |
|
|
0.0
(Cont.) 10 50 100 200 300 400 |
41.3
± 0.6 24.3
± 0.7 11.3
± 0.6 0.0
± 0.0 0.0
± 0.0 0.0
± 0.0 0.0 ± 0.0 |
- -41.2 -71.6 -100.0 -100.0 -100.0 -100.0 |
80.2
± 0.3 49.0
± 1.0 15.7
± 1.2 11.7
± 0.6 0.0
± 0.0 0.0
± 0.0 0.0 ± 0.0 |
- -38.9 -80.4 -85.4 -100.0 -100.0 -100.0 |
* = Mean values of triplicates.
± = Standard Deviation.
% DFC= Percentage differences from control.
Table 5a. Growth of Monoascus ruber on Czabek Dox,s agar medium
supplied with different concentrations of Co++ and GA3
|
Co++ and GA3 Conc. (mg /ml) |
*Fungal
Growth (in mm) |
|||
|
4
Days |
8
Days |
|||
|
Growth |
%DFC |
Growth |
%DFC |
|
|
0.0
(Cont.) 10 50 100 200 300 400 |
41.3
± 0.6 34.1
± 1.0 11.1
± 1.0 0.0 ±
0.0 0.0 ±
0.0 0.0 ±
0.0 0.0 ± 0.0 |
- -17.4 -73.1 -100.0 -100.0 -100.0 -100.0 |
80.2
± 0.3 65.4
± 0.5 16.8
± 0.7 9.0 ±
1.0 0.0 ±
0.0 0.0 ±
0.0 0.0 ± 0.0 |
- -18.4 -79.0 -88.8 -100.0 -100.0 -100.0 |
* = Mean values of triplicates.
± = Standard Deviation.
% DFC= Percentage differences from control.
As regards the effect of copper on the fungal growth, results presented in Table 6 show that fungal growth was decreased by increasing copper concentrations. A similar finding was also obtained by Miersch et al. (1997), who found that on a solid medium copper reduced redial growth of 10 strains of aquatic hyphomycetes by 50% at concentrations between 150 – 400 mM. However, the presence of copper in solid and liquid media had no inhibitory effect on the growth of Aspergillus ochraceus (Metwally & Abou-Zaid 1996).
Table 6. Growth of Monoascus ruber on Czabek Dox,s agar medium
supplied with different concentrations of Cu++
|
Cu++
Conc. (mg/ml) |
*Fungal
Growth (in mm) |
|||
|
4
Days |
8
Days |
|||
|
Growth |
%DFC |
Growth |
%DFC |
|
|
0.0
(Cont.) 10 50 100 200 300 400 |
41.3
± 0.6 37.4
± 0.1 28.8
± 0.1 26.3
± 0.1 19.0
± 1.0 18.3
± 0.1 14.0 ± 1.0 |
- -9.4 -30.3 -36.3 -54.0 -55.7 -66.1 |
80.2
± 0.3 77.1
± 2.2 67.4
± 1.9 64.3
± 1.0 38.4
± 2.1 33.9
± 1.0 32.1 ± 1.7 |
- -3.9 -16.0 -19.8 -52.1 -57.7 -60.0 |
* = Mean values of triplicates.
± = Standard Deviation.
% DFC= Percentage differences from control.
It was also found that copper at 500 mg/ml stimulated the growth of Alternaria alternata, Cladosporium herbarium, Penicillium notatum, Aspergillus candidus, Dechslera rostrata, Ulocladium atrum and Fusarium moniliforme (Al-Obaid & Hashem 1996). In the present studies however, the addition of GA3 did not show any protective effect on copper toxicity as shown in Table 6a. These results, however, need further investigations.
Table 6a. Growth
of Monoascus ruber on Czabek Dox,s
agar medium
supplied with different concentrations of Cu++ and
GA3
|
Cu++ and GA3 Conc. (mg/ml) |
*Fungal
Growth (in mm) |
|||
|
4
Days |
8
Days |
|||
|
Growth |
%DFC |
Growth |
%DFC |
|
|
0.0
(Cont.) 10 50 100 200 300 400 |
41.3
± 0.6 43.3
± 0.3 40.4
± 0.5 37.6
± 1.4 23.3
± 0.1 19.3
± 0.1 10.6 ± 0.6 |
- +4.8 -2.2 -9.0 -43.6 -53.3 -74.3 |
80.2
± 0.3 75.3
± 0.3 70.5
± 0.9 68.3
± 1.0 42.9
± 0.4 33.5
± 0.8 16.2 ± 4.9 |
- -6.1 -12.1 -14.8 -46.5 -58.2 -79.8 |
* = Mean values of triplicates.
± = Standard Deviation.
% DFC= Percentage differences from control.
Results presented in Table 7 show the effect of zinc on the fungal growth. In general, an inhibitory effect was obtained which increased by increasing zinc concentrations. The inhibitory effect of zinc to growth of some fungi was also recorded by Miersch et al. (1997), who found that the inhibitory effect of zinc was much less severe to the radial growth of 10 strains of aquatic hyphomycetes. However, both of the yeasts Saccharomyces carisbergensis and Saccharomyces cerevisae showed resistance to 16 – 19 mmol/l of zinc concentrations (Olasupo 1993). Also, it was claimed that higher concentrations of zinc (3000 mg/ml) did not inhibit the growth of Aspergillus candidus and Dechslera rostrata (Al-Obaid & Hashem 1996).
The addition of GA3 to the basal medium supplied with zinc (Table 7a) slightly stimulated the growth of the test fungus, at low concentrations of both zinc and GA3 (10 and 50 mg/ml after an incubation period of 4 days and 10–100 mg/ml after an incubation period of 8 days). Inhibition of fungal growth was also obtained at high concentrations of both zinc and GA3 and increased by increasing their concentrations.
Table 7. Growth of Monoascus ruber on Czabek Dox,s agar medium
supplied with different concentrations of Zn++
|
Zn++
Conc. (mg/ml) |
*Fungal
Growth (in mm) |
|||
|
4
Days |
8
Days |
|||
|
Growth |
%DFC |
Growth |
%DFC |
|
|
0.0
(Cont.) 10 50 100 200 300 400 |
41.3
± 0.6 40.3
± 0.6 37.3
± 2.1 30.0
± 0.0 25.4
± 0.5 24.3
± 1.1 22.4 ± 0.7 |
- -2.4 -9.7 -27.4 -38.5 -41.2 -45.8 |
80.2
± 0.3 85.0
± 0.0 77.6
± 0.8 67.2
± 0.7 61.5
± 1.3 57.0
± 1.7 56.4 ± 0.3 |
- +6.0 -3.2 -16.2 -23.3 -28.9 -29.7 |
* = Mean values of triplicates.
± = Standard Deviation.
% DFC= Percentage differences from control.
Table 7a. Growth of Monoascus ruber on Czabek Dox,s agar medium
supplied with different concentrations of Zn++ and GA3
|
Zn++ and GA3 Conc. (mg/ml) |
*Fungal
Growth (in mm) |
|||
|
4
Days |
8
Days |
|||
|
Growth |
%DFC |
Growth |
%DFC |
|
|
0.0
(Cont.) 10 50 100 200 300 400 |
41.3
± 0.6 48.7
± 0.7 44.2
± 0.5 36.9
± 4.1 37.2
± 0.6 35.6
± 0.6 30.1 ± 3.0 |
- +17.9 +7.0 -10.6 -9.9 -13.8 -27.1 |
80.2
± 0.3 85.0
± 0.0 85.0
± 0.0 84.2
± 0.2 83.1
± 1.0 77.9
± 0.9 74.7 ± 0.6 |
- +6.0 +6.0 +5.0 +3.6 -2.9 -6.9 |
* = Mean values of triplicates.
± = Standard Deviation.
% DFC= Percentage differences from control.
The addition of nickel to the fungal basal medium inhibited the fungal growth due to its severe toxicity, after the incubation periods of 4 and/or 8 days, as shown in Table 8. Microorganisms suffering from nickel toxicity were also recorded by Codina et al. (1993).
In the present study, it was found that GA3 did not show any protective effect over nickel toxicity (Table 8a).
Table 8. Growth of Monoascus ruber on Czabek Dox,s agar medium
supplied with different concentrations of Ni++
|
Ni++
Conc. (mg/ml) |
*Fungal
Growth (in mm) |
|||
|
4
Days |
8
Days |
|||
|
Growth |
%DFC |
Growth |
%DFC |
|
|
0.0
(Cont.) 10 50 100 200 300 400 |
41.3
± 0.6 16.7
± 1.5 0.0 ± 0.0 0.0
± 0.0 0.0 ± 0.0 0.0
± 0.0 0.0 ± 0.0 |
- -59.6 -100.0 -100.0 -100.0 -100.0 -100.0 |
80.2
± 0.3 31.4
± 1.2 0.0 ± 0.0 0.0
± 0.0 0.0 ± 0.0 0.0
± 0.0 0.0 ± 0.0 |
- -60.8 -100.0 -100.0 -100.0 -100.0 -100.0 |
* = Mean values of triplicates.
± = Standard Deviation.
% DFC= Percentage differences from control.
Table 8a. Growth of Monoascus ruber on Czabek Dox,s agar medium
supplied with different concentrations of Ni++ and GA3
|
Ni++
and GA3 Conc. (mg/ml) |
*Fungal
Growth (in mm) |
|||
|
4
Days |
8
Days |
|||
|
Growth |
%DFC |
Growth |
%DFC |
|
|
0.0
(Cont.) 10 50 100 200 300 400 |
41.3
± 0.6 14.9
± 0.5 0.0
± 0.0 0.0
± 0.0 0.0
± 0.0 0.0
± 0.0 0.0 ± 0.0 |
- -63.9 -100.0 -100.0 -100.0 -100.0 -100.0 |
80.2
± 0.3 28.7
± 1.5 10.3
± 0.6 0.0
± 0.0 0.0
± 0.0 0.0
± 0.0 0.0 ± 0.0 |
- -64.2 -87.2 -100.0 -100.0 -100.0 -100.0 |
* = Mean values of triplicates.
± = Standard Deviation.
% DFC= Percentage differences from control.
Results presented in Table 9 show that cadmium toxicity started at 50 – 400 mg/ml. In general, these results are similar to those obtained by Miersch et al. (1997) who found that cadmium reduced radial growth of aquatic hyphomycetes by 50% at concentrations between 150 – 400 m M. However, Olasupo et al. (1993) found that both Saccharomyces carisbergensis and Saccharomyces cerevisae resisted the toxic effect of cadmium at concentrations of 3–15 mmol/L.
Table 9. Growth of Monoascus ruber on Czabek Dox,s agar medium
supplied with different concentrations of Cd++
|
Cd++
Conc. (mg/ml) |
*Fungal
Growth (in mm) |
|||
|
4
Days |
8
Days |
|||
|
Growth |
%DFC |
Growth |
%DFC |
|
|
0.0
(Cont.) 10 50 100 200 300 400 |
41.3
± 0.6 42.0
± 1.0 27.0
± 1.0 18.3
± 0.6 14.7
± 0.6 12.0
± 1.0 10.8 ± 0.3 |
- +1.7 -34.6 -55.7 -64.4 -70.9 -73.8 |
80.2
± 0.3 83.4
± 1.5 59.6
± 0.3 39.1
± 1.3 30.7
± 1.5 22.8
± 2.5 17.3 ± 0.6 |
- +4.0 -25.7 -51.2 -61.7 -71.6 -78.4 |
* = Mean values of triplicates.
± = Standard Deviation.
% DFC= Percentage differences from control.
Also, it was claimed that Penicillium digitatum tolerated cadmium toxicity but Aspergillus niger was cadmium resistant to the same metal (Metwally & Abou-Zaid 1996). However, Ulocladium atrum showed less colony growth on media containing cadmium at a concentration of 3000 mg/ml (Al-Obaid & Hashem 1996). Hashem & Al-Obaid (1996) worked on Aspergillus flavus and Ulocladium chlamydosporium isolated from apple. When the fungi were grown on a liquid medium containing up to 300 mg/ml cadmium, the fungal growth was stimulated at 100 mg/ml, but inhibited at 200–300 mg/ml. In the present studies, however, it was found that the addition of GA3 did not show any protective effect on cadmium toxicity except at 10 mg /ml (Table 9a).
Table 9a. Growth of Monoascus ruber on Czabek Dox,s agar medium
supplied with different concentrations of Cd++ and GA3
|
Cd++ and GA3 Conc. (mg/ml) |
*Fungal Growth (in mm) |
|||
|
4 Days |
8 Days |
|||
|
Growth |
%DFC |
Growth |
%DFC |
|
|
0.0 (Cont.) 10 50 100 200 300 400 |
41.3 ±
0.6 48.9 ±
1.0 30.2 ±
0.7 24.4 ±
0.5 19.7 ±
0.5 14.2 ±
1.0 10.6 ±
1.4 |
- +18.4 -26.9 -40.9 -52.3 -65.6 -74.3 |
80.2 ±
0.3 84.0 ±
1.0 53.6 ±
0.4 42.9 ±
1.2 33.9 ±
0.5 31.1 ±
1.6 28.4 ±
4.5 |
- +4.7 -33.2 -46.5 -57.7 -61.2 -64.6 |
* = Mean values of triplicates.
± = Standard Deviation.
% DFC= Percentage differences from control.
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(Received 24/1/1420; 10th May 1999, accepted 7/5/1420; 18th August 1999)