Screening and Bioplastic Production Using Palm Oil as Carbon Source by Halophilic Bacteria Isolated from Bledug Kuwu Mud Crater

• Main Author: Gautama, Maykel
• Format: Final Project
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/38049
• Institution: Institut Teknologi Bandung

Plastic is a material that it is found in various areas in everyday life. Plastic is typically synthesized from petrochemicals as raw materials and it is difficult to be degraded in nature, thereby imposing negative impact to the environment. In order to overcome such problem, the alternative of raw material to make plastic products more biodegradable is increasingly demanded. One of these alternatives is using raw materials synthesized by microbes. Polyhydroxyalkanoate (PHA) is a raw material for bioplastic production produced by a certain type of bacteria as a secondary metabolite when the bacteria is grown in a carbon-rich medium. One type of bacteria that produce bioplastic is halophilic bacteria, class of extremophile that can adapt against high salinity environmental. In this study, a halophilic bacteria sampled from Bledug Kuwu mud crater, Purwodadi, Central Java, was explored its potential as PHA producer. The potential bacteria is selected by growing them in a medium containing Nile red such that it will react to PHA produced by the potential bacteria to give bright-orange bacterial colony when exposed to ultraviolet (UV) light. Among those bacterial exhibited positive PHA producer, the best one that showing the most bright-orange colony was selected. After that, the species of the selected halophilic bacterium was identified by determining the sequence of its 16S rRNA gene. The phylogenetic analysis based on the gene sequences revealed that the bacterial species was closer to Staphylococcus arlettae. Therefore, we named it in this study as Staphylococcus arlettae BK-HRG1. The next stage is the production of PHA by growing the bacteria in a medium containing two types of carbon as sources i.e. glucose and palm oil. The result showed that the use palm oil as carbon source gave better yield than glucose, hence the further production of PHA only uses it as a the main carbon source. The result of optimization for PHA production showed that the optimum production was achieved when growing the bacteria in the medium containing 2% of palm oil as a source of carbon, 7% of NaCl and aeration at 150 rpm for 24 hours. The resulted PHA was characterized its structure by using Fourier Transform Infrared (FT-IR), and its thermal properties by using Differential Scanning Calorimetry (DSC). The results of structural characterization verified that the PHA sample has typical FT-IR functional groups that similar to those of the standard polyhydroxybutirate (PHB), namely - OH group (3500 cm-1), C-H (2900 cm-1), C=O groups (1600 cm-1) and -CH3 (1400 cm-1). The results of DSC revealed that the PHB sample has a melting point at 169 °C and a crystallinity about 36.5%. This study, thus, showed that the local halophilic bacteria, Staphylococcus arlettae BK-HRG1, was a potential bioconvertor for palm oil into PHB.