Fungistatic activity of iron-free bovin lactoferrin against several fungal plant pathogens and antagonists

Abstract

Lactoferrin (LF) is a member of the transferrin family of iron-binding glycoproteins. It is also a multifunctional protein of 80 kDa that is synthesized by glandular epithelial cells and secreted into mucosal fluid. High levels of LF are present in colostrom and milk and low levels in tears, saliva, and gastrointestinal and reproductive secretions. Data regarding the antifungal effects of LF are limited. Studies have been performed on Candida albicans, which demonstrated that LF inhibits the growth of this fungus. This study reports the results of experiments carried out in order to evaluate the effects of LF on the growth of 11 fungi, which were isolated from plants and soils. These experiments employed the methods of amended agar utilizing nine different concentration levels of LF (0, 0.001, 0.01, 0.1, 1, 10, 100, 1000, 5000 mg L⁻¹). The effects of LF on the growth of these fungi were based on measures of the radial growth of the fungal colonies expressed both as percentage of inhibition and as IC₅₀ values (the concentration at which the fungal growth was inhibited by 50% relative to controls). LF had no effects on Alternaria alternata, Gliocladium roseum, Fusarium solani and Colletotrichum lindemuthianum. It did, however, inhibit the growth of Aspergillus niger, Trichoderma viride, Sclerotinia sclerotiorum, Sclerotium rolfsii, Rhizoctonia solani and Phoma exigua to the point that their IC₅₀ values ranged from 31.1 mg L⁻¹ for S. sclerotiorum to 952 mg L⁻¹ for T. viride.

Keywords:

• Fungistasis
• Bovine lactoferrin
• Soil-borne pathogens, antagonists
• IC50 values