Optimation of diatom Haslea ostrearia cultivation in different medium and nutrientSulastri ARSAD*a, Christophe STAVRAKAKISb, Vincent TURPINc, Philippe ROSSAc, Yenny Risjania, Fiddy Semba PRASETIYAd, Jean-Luc MOUGETe

^a Universitas Brawijaya, Jl. Veteran Malang 65145, Indonesia

^b IFREMER, Station Bouin Polder des Champs, 85230 Bouin, France

^c Université de Nantes, 1 Quai de Tourville, 44035 Nantes, France

^d Universitas Padjajaran, Jl. Raya Bandung Sumedang Jatinangor Bandung, Indonesia

^e Le Mans Université, Avenue Olivier Messiaen 72085 Le Mans, France

* Corresponding author: sulastriarsad @ ub.ac.id (sulastriarsad @ ub.ac.id)

Abstract

Haslea ostrearia is a marinediatom that can feed oysters, and green their gills and palps, because of its blue pigment marennine. Marennine is a water-soluble pigment that has been shown to inhibit bacterial growth, and to display antiviral, antioxidant, antiproliferative and allelopathic activities. This study aimed to cultivate H.ostrearia in the following media: seawater (SW), seawater filtered by activated carbon (SW+CA), and drilling water (DW). The three-water media were supplemented with two types of nutrients such as Walne-Conway+silica (CS) and ES-1/3 Provasoli (P) leading to six experiment series. The semi-continuous modes condition was using in the short-term cultures to gain an optimal growth condition of living cells and production of Emn and Imn by regarding their pigment concentration. The cultures were grown in 200 mL and 400 mL. The dilution cycle was each 3-4 day for 200 mL volume and 4-5 days for 400 mL volume for 20-40 days or until the cultures showed the decreasing in growth. Cell growth was observed by using inverted-microscope and followed by calculated cell densities with Nageotte hemocytometer. The concentration of Extracellular marennine (Emn) and Intracellular marennine (Imn) was determined spectrophotometrically. The microalgae exhibited a better growth in SW and SW+CA CS, whereas DW showed diminution number of cells either with CS or P medium. The highest value of Emn with 200 mL volume presented in SW CS medium (1.94 mg L^-1) and Imn remarked in SW+CA CS medium (8.16 mg L^-1), while the lowest value of Emn found in SW+CA CS medium (0.42 mg L^-1) and Imn showed in SW P medium (0.56 mg L^-1). In conclusion, both SW CS and SW+CA CS showed a better performance in growth; even seawater was more stable during the experiment both in 200 mL or 400 mL volume.

Keywords: cultivation, diatom, H.ostrearia, pigment