ISOLATION AND CHARACTERIZATION OF BIOSILICA FROM NITZSCHIA SP. NPI1 CULTURES

• Main Author: Riptanto, Irsanda
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/49344
• Institution: Institut Teknologi Bandung

Diatom-(Bacillariophyceae) have a distinctive cell wall made of silica with nanosized pores known as frustule. Biosilica isolated from diatom can be used as a support material for separation columns, catalysts, and drug delivery systems. Nitzschia sp. is a species of diatom that is commonly found in Indonesian waters which contains silica-rich frustule. This study aims to cultivate Nitzschia sp. NPI1 in the laboratory and to obtain pure biosilica from its frustule. Cultivation of Nitzschia sp. NPI1 was carried out in a modified artificial seawater enriched with nitrate, phosphate, silicate, and iron solution. The culture conditions were maintained at a salinity of ± 22 ppt, lighting of ± 3000 lx, and a light-dark photoperiod of 12:12 hours. Observations under a light microscope showed that Nitzschia sp. NPI1 has pennate-shaped cells with a length of 20 – 28 µm and greenish yellow in color. Wet biomass weighing 38.9 g of culture was separated from the growth media after being cultured for 8 days by centrifugation. The wet biomass productivity of culture value is 0.83 g ml-1 day-1 . The salinity variation did not give a significant effect on the growth of Nitzschia sp. NPI 1. Furthermore, the isolation of biosilica from wet biomass was carried out by washing with nitric acid (HNO3), oven-drying, followed by calcination at a temperature of 550 oC for 10 hours. This treatment resulted in 0.66 g of biosilica with a yield of 1.69% w/w of biosilica relative to the wet biomass. The white powder of biosilica is obtained. Characterization of the biosilica was performed with SEM-EDS. SEM observations show that the frustule features striae with pores ranging from 40 – 80 nm. Based on EDS analysis, biosilica from the culture of Nitzschia sp. NPI1 only contains silicon and oxygen, indicating that pure biosilica was obtained.