66 Jurnal Natur Indonesia 10 (2): 66-69 Zainuri, et al. Jurnal Natur Indonesia 10 (2), April 2008: 66-69 ISSN 1410-9379, Keputusan Akreditasi No 55/DIKTI/Kep./2005 Microbiological and Ecophysiological Characterization of Green Algae Dunaliella sp. for Improvement of Carotenoid Production Muhammad Zainuri 1) , Hermin P. Kusumaningrum 2) , Endang Kusdiyantini 2) 1) Laboratory of Biological Oceanography Laboratory, Department of Marine Sciences, Faculty of Fisheries and Marine Sciences, Diponegoro University e-mail: muhammad.zainuri@yahoo.co.id 2) Microbiogenetics Laboratory, Faculty of Mathematics and Natural Sciences, Diponegoro University Jl. Prof. Soedarto, UNDIP, Tembalang, Semarang. 50275. Diterima 08-01-2008 Disetujui 25-03-2008 ABSTRACT An isolate of green algae Dunaliella sp. from BBAP Jepara is usually used as a source for carotenoid supplement for marine animal cultivation in the local area. In order to improve carotenoid production especially detection of biosynthetic pathway from the organisms investigated in this study, the main purpose of this study is characterizing Dunaliella sp. based on it’s microbiological and ecophysiological characters. The research was done by characterize the growth, the cell and colonies microbiologically, total pigment production, and also characterize all of the ecophysiological factors affecting the algal growth and survival. The results of this research showed that Dunaliella sp. posseses typical characteristic of green eucaryote alga, in their growth and ecological condition. The extreme characters which was toleration ability to high salinity environment of was used to conclude Dunaliella sp. as Dunaliella salina. Keywords: algae, characterization, Dunaliella sp., eco-physiological, microbiological. INTRODUCTION Green algae are simple photosynthetic eukaryotes which are responsible for up to 50% of the planet’s atmospheric carbon fixation. The recent discoveries of health related beneficial properties attributed to algal carotenoids have spurred great interest in their production. Carotenoids, some of which are provitamin A, have range of diverse biological function and actions, such as species specific coloration, photo protection, and light harvesting, and they serve as precursors of many hormones (Vershinin 1999 in Lee & Schmidt- Dannert 2002). Carotenoids are used commercially as food colorants, animal feed supplements, and more recently, as nutraceuticals for cosmetic and pharmaceutical purposes. The demand and market for carotenoids are anticipated to change drastically with the discovery that carotenoids exhibit significant anti- carcinogenic activity and play an important role in the prevention of chronic diseases (Lee & Schmidt-Dannert 2002). For many years, it was accepted that carotenoid was synthesized through the well known acetate/ mevalonate pathway. However, recent studies have demonstrated photosynthetic organisms including green algae, such as Scenedesmus obliquus, Chlorella fusca, Chlamydomonas reinhardii use a new non- mevalonate pathway known as deoxyxylulose 5- phosphate (DXP) pathway for their carotenoid biosynthesis. The exclusive occurrence of the non-MVA pathway for the biosynthesis of plastidic isoprenoids and of sterols might represent a general feature of many green algae (Lois et al, 1998; Lichtenthaler 1999). A local isolate of an algal species from BBPAP Jepara, called Dunaliella sp., was found potentially useful as source of carotenoids in food additives or as food supplement in fish farming. Thus, it was of great interest to know if this local isolate of algae would also follow the non-MVA pathway for carotenoid biosynthesis. This indigenous algae has been successfully cultivated. Therefore, it is important to examine species identification based on eco-physiological and morphological characteristics microbiologically, needed to support improvement of their carotenoid production. MATERIAL AND METHODS Culture Media. The Walne medium was used for culturing Dunaliella sp. modified from Bidwell & Spotte (1983). The medium consist of EDTA 45 g/l, FeCl 3 .6H 2 O 1.3 mg/l, H 3 BO 3 33.6 g/l, MnCl 2 .4H 2 O 0.36 g/l, NH 4 NO 3 100 g/l, Na 2 PO 4 20 g/l, B 12 vitamin 0.001 ppm, distilled water until 1 l. Sterilization was done by autoclaving at 15 lb/in 2 (103 kPa and 120 o C). The medium was using