Free and encapsulated chitinase and laminarinase as biological agents against Fusarium oxysporum

Abstract

In order to seek an environmentally-friendly alternative to chemical fungicide, the aims of this paper were: 1) to assess the enzymatic and antifungal activity of free and microencapsulated enzymes (laminarinase and chitinase from Trichoderma sp.) and their mixtures against F. oxysporum in soil in the presence or absence of thiabendazole; 2) to analyze remarkable variants resulting from soil testing in ad planta assay with tomato crops (L. esculentum Mill) and the pathogen F. oxysporum. To evaluate the effect of applied treatments to the fungus, the quantity of colony forming units (CFU) was deter-mined. Enzyme activities were measured spectrophotometrically using laminarin and of p-nitrophenyl-β-D-N-acetyl-glucosamide as laminarinase and chitinase substrates, respectively. An inhibiting effect to fungus growth (fungistatic effect) of both enzymes applied separately and together, as well as the treatment with liposomes only was demonstrated in vitro and ad planta assays. Enzyme application permitted a decreasing of chemical fungicide level and allowed the achievement of partial (90-98%) or total inhibition of fungus growth. Microencapsulation led to increase enzyme stability in the presence of thiabendazole. The growth of tomato plant was higher in the presence of applied treatments. The increase of fungistatic effect was revealed in the case of mixture of encapsulated enzymes and enzymes with thiabendazole. Encapsulation of chitinase and laminarinase in soya lecithin liposomes was useful to maintain enzymatic activity for the control of phytopathogenic fungus F. oxysporum. Thus, it confirmed the idea regarding the use of free or encapsulated (in soya lecithin liposome) mycolytic enzymes for the control of phytopathogen fungus growth in the presence and absence of chemical fungicide in vitro and ad planta assays.   Key words: Fungistatic effect, mycolytic enzymes, soya lecithin liposomes.