Investigation of Secondary Metabolites and its Bioactivity from Sarocladium kiliense SDA20 Using Shrimp Shell Wastes

Introduction: In this study we isolated bioactive compounds using different chromatographic techniques from culture filtrate of Sarocladium kiliense SDA20 grown in fermentation media containing shrimp shell waste as substrate under optimum conditions. Antibacterial and antibiofilm activities of crude extract and purified compounds were evaluated. Methods: The test fungi strain Sarocladium kiliense SDA20 was isolated from Egyptian soil and identified by18 S ribosomal RNA. Optimization conditions were carried out in fermentation media containing shrimp shell waste as sole carbon source, inoculated by 10⁶ spores/ml of Sarocladium kiliense SDA20 at pH 7.0 produce 84.5% of the total toxins. Different chromatographic techniques for ethyl acetate extract of culture filtrate of fungi were used resulting in isolation of pure compounds were elucidated spectroscopically and comparing their data in literature. GC/MS analysis of extract was used for identification of other chemical compounds. Antibacterial and biofilm activity was evaluated using MTT assay. Results: Five compounds for the first time were identified: Cholest-5-en-3-ol (C1), Palmitic acid (C2), Oleic acid (C3), Nicotinamide (C4), Tricin (C5). GC-MS analysis showed the presence of twenty-seven compounds. Antibacterial activity of crude and pure compounds displayed a strong inhibitory activity against Bacillus subtilis. C1, C4, C5 showed moderate activity against Escherichia coli, followed by C2, C3. Meanwhile, Staphylococcus aureus was less susceptible to pure compounds with low activity of C3, C5. The crude extract and pure compounds displayed biofilm inhibition activity against four pathogenic bacterial strains. Conclusion: Shrimp shell wastes are one of the economic bioproducts used for the production of bioactive secondary metabolites from fungi.