Lignolytic Activity of Bacteria Isolated from Mangrove Sediment in Tirang Beach, Semarang as a Consortium Agent for Bioremediation of Methylene Blue Dyes

Department of Marine Science Faculty of Fisheries and Marine Science, Diponegoro University, 50275 Semarang, Indonesia

^* Corresponding author: delianispringgenies@lecturer.undip.ac.id

Abstract

Lignin is an abundant phenolic compound that has –OH groups and is found in many sources such a tree. Lignolytic enzyme plays an important role in dye bioremediation. Methylene blue is a dye generally applied in the industry to produce a blue color. However, it also causes pollution and waste. To prevent environmental pollution, it is necessary to process this waste. Bioremediation is an environmentally friendly method for dealing with dye waste. This research aims to isolate bacteria from mangrove sediment that can break down lignin and remove methylene blue color. The research methods include isolating and purifying the bacteria, testing for lignin-degrading enzymes, decolorization test were performed with a spectrophotometer at 650 nm wavelength, and analyzing bacteria’s genetic information. The results of the isolation process showed that 17 potential bacteria were isolated from mangrove sediments. Among them, 6 bacteria were tested positive for lignin-degrading enzymes, with degrading zone sizes ranging from 6.5 to 14 mm. The decolorization test, conducted at a wavelength of 650 nm, revealed that 3 selected bacteria had decolorization rates of 88% for isolate 4.1.1, 74% for isolate 3.2.1, and 82% for isolate 2.2.1. The consortium of bacteria achieved a decolorization rate of 90%. Molecular identification using 16s RNA identified the species as Exiguobacterium profundum, Vibrio alginolyticus, and Pseudomonas aeruginosa.