CHITIN EXTRACTION FROM GREEN MUSSEL SHELL USING ACID AND PROTEASE PRODUCING BACTERIA

• Main Author: Maya, Fransiska
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/71383
• Institution: Institut Teknologi Bandung

Green mussels are one of the marine commodities that are quite common in Indonesia with 70-80% of the total product being shell waste which can be a source of chitin (or chitosan) which contains about 9-20% (w/w). Chitin can be extracted from mussel shells through demineralization and deproteination processes. Chitin extraction by chemical treatment uses strong acids such as HCl for demineralization and strong bases such as NaOH for deproteination. Meanwhile, by biological treatment, it is known that acid-producing bacteria such as Lactobacillus plantarum are used as demineralizing agents and protease-producing bacteria such as Seratia marcescens or Bacillus sp. are used as deproteination agents. In this study, extraction of green mussel shells was carried out by biological treatment using indigenous bacteria and chemical treatment as a control/comparison. The method used in this study consisted of three major stages. The first stage is the preparation of mussel shell powder (tck). Green mussel shells were prepared to obtain sizes of 60 mesh and 100 mesh and then analyzed by proximate test and Energy-dispersive X-ray Spectroscopy (EDS) to determine their components. The second stage is to obtain indigenous bacteria for tck fermentation. Bacteria that were successfully isolated from mussel shells were selected using LAB and protease selective media, catalase test, Gram staining, and then identified based on 16S rRNA. Age of selected inoculum was determined through the growth curve. The final stage is tck extraction, which is carried out by biological and chemical treatments. In the biological treatment, tck extraction was carried out by selected isolates and Lactobacillus plantarum was used as a comparison bacterium. In optimizing extraction with bacteria, tck concentrations of 5%, 10%, and 15% (w/v) were used in extraction medium consisting of glucose 10% (w/v) and half dose of NB. During fermentation, the number of bacteria was observed using the viable cell count method and the pH of the medium with a pH meter every 24 hours. At the end of fermentation, the tck was weighed and the change in this weight became an indicator of the successful reduction of minerals and protein from tck. In chemical treatment, HCl solution is used for demineralization and NaOH for deproteination. Tck used for extraction has an ash content of 90,78%. Based on the isolation results, two isolates were obtained that were able to produce acid and had protease activity from 36 isolated bacteria. One of these isolates is isolate 27 which produce acid and protease, belongs to Gram positive bacteria and catalase positive. Based on the analysis of the 16S rRNA gene, isolate 27 has 99,86% percent identity with Corynebacterium casei LMG S-19264 and was selected for the tck fermentation. Chitin fermentation using C. casei and L. plantarum showed tck weight reduction efficiency in medium with tck 5% are 9,3% and 34%, respectively. However, this value is still lower than the reduced weight extracted by chemical treatment (52%).