PRELIMINARY IN VITRO STUDY ON ANTIFUNGAL ACTIVITY OF SOME LOCAL LACTOBACILLI AND LACTIC STREPTOCOCCI ISOLATES

Document Type : Research articles.

Author

Agriculture Microbiology Dept., Fac. of Agric., Fayoum University, Egypt

Abstract

The agar – well diffusion method was used to assay in vitro
the antifungal activity (AA) of the metabolites of five lactobacilli
(Lb) and five Lactic streptococci (LSt) isolates obtained from
samples of Egyptian dairy products towards four indicator
phytopathogenic fungi: Rhizoctonia solani, Sclerotuim
cepivorum, Fusarium oxysporum and Penicillium sp.The AA
was expressed as percent of fungal growth inhibition ( % FGI ) .
The results revealed that the crude cell-free culture
supernatants (crude CFCS) of both Lb and LSt isolates showed
variations in their AA , and the ranges were 48 – 63 % FGI and
38 – 52 % FGI for Lb and LSt isolates , respectively .Also ,the
four indicator fungi showed differences in their sensitivity to the
CFCS of the tested bacteria . The Penicillium sp. was the most
sensitive indicator fungi with 60% FGI and 54% FGI for Lb and
LSt isolates, respectively.
In general, the AA of Lb isolates was relatively higher
(54% FGI is average) than that of LSt isolates (44% FGI in
average). Neutralization (pH 6.5) of crude CFCS, elimination of
H2O2 or both caused a decrease in AA in most cases indicating a
role of organic acids and H2O2 in AA.
Treatment of the neutralized, H2O2 – free CFCS with the
proteolytic enzymes , Pronase completely inactivated the AA in
most cases and slightly reduced it in some cases, indicating the
presence of a proteinaceous antifungal substances in the crude
CFCS of both Lb and LSt isolates . This study has proven the in
vitro potential of some local Lb and LSt isolates to inhibit
growth of some plant pathogenic fungi.

Keywords

Files

Share

How to cite

Statistics