Identification and optimization of growth media of microalgae originated from Cipanas hot spring water West Java that is potential for biodiesel source

Abstract

The increasing use of fossil fuel leads to the depletion of fuel sources and increases CO2 emission level into the environment that affects global warming. Microalgae is an alternative biodiesel source that is renewable and environmentally friendly. The objective of the research was to identify and optimize the growth media of microalgae isolate originated from Cipanas hot spring water. Identification was done based on morphological and 18S rDNA gene sequence approaches. Growth media experiment was designed as a factorial randomized block design. First factor was water media composition containing aquades and hot spring water with five level of aquades:hot spring water ratio, which were 1:0, 0:1, 1:1, 2:1, and 1:2 (v/v). The second factor was P concentration, which were 40, 80 and 120 ppm. The result showed that the morphologically a microalgae isolate had similarity to Chroococcus sp prokaryotic, but molecular data indicated that the microalgae was similar to uncultured freshwater eukaryote clones. The highest cell density of microalgae culture was 2.19 and 2,21 which were achieved when microalgae was cultured in aquades:hot spring water medium 1:2 (v/v) and in P concentration 120 ppm, respectively. The highest dry weight average of biomass (175 mg) was obtained in aquades:hot spring water 1:0 (v/v) with P concentration 120 ppm. Hot spring water could be substituted by aquades to gain high lipid content microalgae. Growth media containing aquades:hot spring water 1:0 (v/v) with P concentration 40 ppm produced the highest average of lipid content (21%) and highest average of lipid productivity, 17 mg l-1 day-1.

Salah satu cara untuk mengatasi ketergantungan terhadap bahan bakar fosil adalah dengan menggunakan bahan bakar alternatif seperti biodiesel yang terbarukan dan ramah lingkungan. Mikroalga dapat dijadikan alternatif sumber bahan baku biodiesel yang lebih efisien dalam pemanfaatan lahan. Untuk dapat dikembangkan lebih lanjut sebagai bahan baku biodiesel, maka identitas isolat mikroalga harus diketahui dengan pasti, dan lingkungan tumbuh yang optimum juga harus tersedia. Penelitian ini bertujuan untuk melakukan identifikasi isolat mikroalga berdasarkan ciri morfologi dan molekuler menggunakan sekuen gen 18S rDNA serta optimasi media tumbuh melalui modifikasi komposisi air media tumbuh dan konsentrasi P untuk menghasilkan pertumbuhan dan kandungan lipid yang tinggi pada isolat mikroalga yang berasal dari sumber air panas Cipanas di Jawa Barat. Penelitian dilaksanakan pada bulan Juli 2010 sampai bulan Juni 2011 di Laboratorium Fisiologi Tumbuhan, Laboratorium Terpadu, dan Laboratorium Taksonomi Tumbuhan Departemen Biologi FMIPA IPB Bogor. Identifikasi morfologi dilakukan berdasarkan buku identifikasi yang berjudul “The Freshwater Algae“ (Prescot 1978) dan buku “Introduction to the Algae Structure and Reproduction second edition” (Bold & Wyne 1985), sedangkan identifikasi molekuler dilakukan berdasarkan sekuen gen 18S rDNA.