Antifungal activity of some Mediterranean seaweed against Macrophomina phaseolina and Fusarium oxysporum in Vitro

Abstract

Seaweeds are naturally rich with biological active metabolites that could be promising to be used in the biological control. The present study was conducted to evaluate the antifungal potentiality of metabolites extracted from Ulva fasciata, Ulva lactuca and Cladophora sericea; against Macrophomina phaseolina (Tassi) Goid. and Fusarium oxysporum Schltdl. Four organic solvents hexane, chloroform, acetone and methanol were used for extraction of seaweeds metabolites to assay their biological efficiency on mycelium growth reduction of two candidate soil borne fungal pathogens on potato dextrose agar medium. The highest percentage of F. oxysporum and M. phaseolina growth reduction was observed by acetone extract of U. fasciata and methanol extract of C. sericea. The highest inhibition against M. phaseolina reached up to 28.97% by U. fasciata acetone extract and 24.77% by C. sericea methanol extract. The highest percentage of mycelial growth inhibition of F. oxysporum was observed by U. fasciata acetone extract (23.58%) and C. sericea methanol extract (17.01%). Analysis of acetone extract of U. fasciata by gas chromatography mass spectrophotometer GC/MS revealed the presence of some organic compounds with antifungal properties such as Phenol, 2,2'-methylenebis[6-(1,1-dimethylethyl)-4-methyl-, Di-n-octyl phthalate, 1,2-Benzenedicarboxylic acid, diisodecyl ester, Didecyl phthalate, Phthalic acid, bis (7-methyloctyl) ester, gamma Sitosterol, Cholest-5-en-3-ol, 24-propylidene-, (3. beta.) and Cyclononasiloxane, octadecamethyl-. The results suggest that the studied algal species can be used as potential bio-agent source in biological control of soil borne phytopathogenic fungi.

In vitro efficacy of biologically active compounds derived from Navicula arenaria against soil borne phytopathogenic Macrophomina phaseolina and Fusarium oxysporum

“…Four organic extraction solvents according to polarity; hexane, chloroform, acetone and methanol were used in extraction process of N. arenaria intracellular metabolites by maceration with continuous shaken for 24 hours at 200 rpm. The percentage of each extract was measured as follow [17,18]:…”

“…Extract % = (Weight of extract (g) / Weight of algal sample (g)) * 100 Each crude extract was dissolved in dimethyl sulfoxide (DMSO) then sterilized using micro filters (Millipore, 0.22μm) and stored in refrigerator for further use. The concentration of each extract was calculated [18,19] .…”

“…Antifungal efficiency of N. arenaria extracellular and intracellular metabolites was carried in vitro against M. phaseolina and F. oxysporum by agar diffusion method on potato dextrose agar medium [18,21]. Negative control was DMSO in case of intracellular metabolites and ethyl acetate in case of extracellular metabolites Positive control was performed by using miconazole and nystatin at 0.03 mg/mL.…”

“…Plates were incubated at 30 O C and the results of fungus growth inhibition were recorded after 96 hours in case of M. phaseolina and till 120 hours in case of F. oxysporum. Percentage of mycelium growth inhibition (MGI %) was measured using the following equation [18,22]: MGI% = [(Control − Test)/Control] × 100 (Control= fungus radial growth from the middle of fungal disc toward the negative control well, Test= fungus radial growth from the middle of fungal disc toward the extract well).…”

“…Determination of MIC was achieved by using three diluting concentrations of each extract (75, 50 and 25%) [18]. All experiments were performed in triplicate.…”