SCREENING BIOSURFACTANT-PRODUCING BACTERIA FOR POTENTIAL APPLICATION IN CD-REMOVAL VIA SOIL WASHING BIOREMEDIATION

• Main Author: Suherman, Donny
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/76051
• Institution: Institut Teknologi Bandung

<p align="justify">Heavy metals that accumulate in the environment such as arsenic (As), cadmium (Cd), chromium (Cr)(VI), mercury (Hg), and lead (Pb), are heavy metals that can be highly toxic and are also known as most problematic heavy metals. Cd metal is also a metal that is known to be difficult to degrade naturally in the environment. Cd metal in the environment as a pollutant comes from many agricultural and industrial activities. Bioremediation is currently recognized as a decontamination technology that is safer, relatively cheap, more effective, easy to do, has high efficiency, and is environmentally friendly. Biosurfactants are surface-active amphiphilic compounds consisting of hydrophobic and hydrophilic components. Biosurfactants or natural surfactants can be produced extracellularly by various microorganisms including bacteria, fungi, and yeast. Biosurfactants are categorized based on their forming microbes or chemical composition such as fatty acids, antibiotics, peptides, glycolipids, phospholipids, lipopeptides. Biosurfactants have a mechanism in heavy metal remediation by interacting with metal ions, forming biosurfactant-metal complexes through electrostatic interactions, binding of opponent ions, precipitation, and ion exchange. It is a method that is being developed in heavy metal bioremediation. In this study, biosurfactants produced by indigenous bacteria of petroleum well x Jatibarang were selected for their potential as bioremediation agents for cadmium metal. Biosurfactant production was carried out on Stone Mineral Salt Solution (SMSSe) liquid media supplemented with 2.12% (w/v) molasses, 0.01% (w/v) KH2PO4 and 0.41% (w/v) urea. Biosurfactants were then extracted from the production media using the chloroform:methanol (2:1) acid precipitation method. Drop collapsing test, charge test, and emulsification index test were conducted. Five anionic biosurfactant producing isolates were obtained, namely BS4, BS14, BS16, BS30, and BS33 with emulsification ability of 40%, 50%, 57%, 46% and 53% respectively. Adsorption test of heavy metal cadmium by each anionic biosurfactant was conducted under unoptimized conditions using Atomic Absorption Spectroscopy (SSA) analysis and obtained anionic biosurfactants BS4, BS14, BS16, BS30, and BS33 with a decrease in cadmium concentration of 0.1 ppm, 0.077 ppm, 0.184 ppm, 0.151 ppm, and 0.293 ppm, respectively. Calculation of adsorption capacity (qe) after being treated with a contact time of 15 minutes obtained the largest adsorption capacity of BS33 with an adsorption capacity value of 0.0228 and the smallest adsorption capacity value of 0.0065 is BS14 Identification of anionic biosurfactant-producing bacterial isolates was carried out by 16S rRNA sequencing method and characterization of biosurfactants by FT-IR and LC-MS methods. The biosurfactant-producing bacterial isolate BS33 was identified as Bacillus subtilis strain TPB23 with the compound structure of BS33 biosurfactant identified as a glycolipid compound that has at least 4 peak peaks of IR spectrum analysis results reinforced by the results of LC-MS analysis of BS33 biosurfactant which identifies it as a glycolipid type biosurfactant. Then biosurfactant BS33 was measured Critical Micelle Concentration (CMC) and obtained a value of 100 mg/L.