High cell density cultivation on Hendersonia sp. for the application of biological control

Abstract

Malaysia is one the world’s biggest producers and exporters of oil palm products. In 2011, Malaysia has exported 24.27 million tonnes of oil palm products, which accounted for RM 80.4 billion in total export revenue. However, the oil palm is susceptible to plant diseases, especially Basal Stem Rot caused by Ganoderma. This disease has caused tremendous losses to the economy. Hendersonia sp. is a novel fungus strain that has shown effective results in controlling Ganoderma infection. The aim of this study was to establish a comprehensive Hendersonia cultivation platform for industrial-scale production. In an agar medium screening study, the best medium was composed of (g/L): Malt Extract, 20; Glucose, 20; Peptone,1; Yeast Extract, 5; Agar powder, 20. Based from the shake flask media screening study, the medium composed of (g/L): Malt extract, 20; Glucose, 20; Peptone, 1; Yeast extract, 5, gave the highest CDW of 7.45±0.6 g/L. This is followed by the medium composed of (g/L): Sucrose, 40; KH2PO4, 1; MgSO4.7H2O, 1.0; KCl, 0.5; FeSO4, 0.01; Yeast Extract, 2, which resulted with CDW of 6.15±0.14 g/L. The optimization of the medium was applied by using Response Surface Methodology. The new optimized medium formulation was composed of (g/L): Sucrose, 60; K2HPO4, 0.5; Yeast Extract, 3; MgSO4.7H2O, 1; KCl, 0.5; FeSO4, 0.01. For the 150-L bioreactor cultivation, by utilizing un-controlled pH throughout the cultivation, 13.55 g/L of CDW was obtained. In addition, the effects of agitation speed on the cell mass during the 150-L bioreactor cultivation were studied. The highest CDW (15.6 g/L) was obtained with agitation speed of 250 rpm at 70 h. In conclusion, the present study has proposed a reliable and cost-effective approach in mass producing Hendersonia in industrial scale.