ANTIFUNGAL STUDY OF Fusarium SPECIES CAUSING SEA TURTLE EGG FUSARIOSIS (STEF)

Abstract

Sea Turtle Egg Fusariosis (STEF) is an emerging disease caused by Fusarium species. This soil-borne pathogenic fungus had been infecting turtle eggs worldwide consequently, reducing their hatching success. Therefore, objectives of this study were to obtain the natural antifungal products that could inhibit Fusarium species and effective to be applied into the nests. All Fusarium species were obtained from Laboratory for Pest, Disease and Microbial Biotechnology (LAPDiM) culture collection originally isolated from eggs and soils of different hatcheries in Pahang and Terengganu. The cultures were subculture on Potato Dextrose Agar (PDA) as working plates. Three species of Fusarium had been selected; F. falciforme, F. oxysporum and F. proliferatum. Antifungal assay by applying turmeric and neem ethanol-based was following the poison plate technique. The concentration of natural antifungal products used were 10%, 20% and 30% with four replicates each. Observation of growth and inhibition percentage were collected every two days for eight consecutive days. Inhibition percentage was calculated using a formula; control plate diameter growth - tested antifungal plate diameter growth/control plate diameter growth x 100%. Since F. oxysporum was found the most abundant, it was tested for sand inoculation technique. Spore suspension with 2.4 – 4.5 x106 inoculum concentration was prepared and pipetted into the universal bottles of damp sterilised sand. Then turmeric and neem were added after a week of fungi incubation and colony-forming unit (CFU) counting was performed. Results from poison plate showed that 10% of turmeric was greater than other treatment to inhibit Fusarium. However, sand inoculation showed that neem was the greatest results to inhibit Fusarium. In conclusion, both neem and turmeric could inhibit Fusarium species and had a potential to reduce STEF issues at the turtle nesting sites. Nevertheless, there is more research work to understand this antifungal to aid sea turtle conservation management.