Chitinase production and antifungal potential of endophytic Streptomyces strain P4

The endophytic actinomycete P4 strain, previously isolated from sweet pea root, wasidentified as Streptomyces sp. by full 16S rRNA sequencing. It is mostly related to Streptomycesgriseoflavus with a 99.7% identity score. The Streptomyces sp. P4 was tested for its hydrolyticactivities by plate method. The result showed the presence of chitinase. The extent of chitinase activitywas assessed by spectrophotometric method along with growth monitoring. Chitinase production wasgrowth-associated and showed the highest activity on the fifth day. The dual culture method revealedthat the strain was effective in restricting the radial growth of Fusarium oxysporum f.sp. lycopersici, animportant phytopathogen of tomato. Scanning electronic microscopic analysis showed that the ruptureof the F. oxysporum mycelial cell wall occurred at the area of interaction between F. oxysporum andStreptomyces sp. P4. This was possibly due to the chitinolytic activity of the P4. Thus, thisactinomycete has the potential for being used as a biocontrol agent, thereby reducing the use ofchemical fungicides.