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HERAWATI PRAYITNO

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Abstrak (Bhs. Indonesia)

Bakteri asam laktat (BAL) merupakan kelompok bakteri yang mampu memfermentasikan karbohidrat menjadi asam laktat dan diketahui memiliki manfaat di bidang pangan maupun kesehatan. Isolat BAL telah diisolasi dari lingkungan sedimen mangrove di Pantai Logending. Karakterisasi secara fenetik terhadap isolat BAL belum mampu mengidentifikasi sampai dengan tingkat spesies. Salah satu pendekatan identifikasi adalah menggunakan pendekatan genotipik yaitu analisis sekuen gen 16S rRNA. Identifikasi molekuler menggunakan 16S rRNA memiliki akurasi tinggi dalam menentukan taksonomi suatu bakteri. Sekuens rRNA khususnya 16S rRNA menjadi acuan utama dalam studi evolusi dan ekologi bakteri, termasuk determinasi hubungan filogenetik di antara taxa, eksplorasi keanekaragaman bakteri di lingkungan dan kuantifikasi kelimpahan relatif taksa dari berbagai tingkatan. Identifikasi bakteri berdasarkan marka 16S rRNA memerlukan teknik PCR (Polymerase Chain Reaction). Tujuan penelitian kali ini adalah untuk mengetahui identitas dari bakteri asam laktat yang diisolasi dari sedimen mangrove Pantai Logending dan hubungan filogenetiknya.
Penelitian dilakukan dengan metode survei. Tahapan kerja terdiri atas isolasi DNA, konfirmasi isolat BAL (penanaman pada medium MRSA+CaCO3 pewarnaan gram, uji katalase-oksidase dan pewarnaan endospora), amplifikasi gen 16S rRNA dengan metode Polymerase Chain Reaction (PCR) menggunakan primer universal 27F dan 1492R, sekuensing hasil PCR, analisis hasil sekuensing menggunakan Basic Local Alignment Search Tool (BLAST). Paramater yang diamati  adalah ukuran dan urutan nukleotida sekuen gen 16Sr RNA, persentase kemiripan urutan basa nukleotida pada bakteri. Data hasil BLAST dianalisis kemiripan dengan data yang ada di GenBank dan hubungan filogenetiknya menggunakan metode UPGMA, Neighbour joining, Maximum Parsimony, Maximum Likelihood.
Hasil penelitian didapatkan tiga isolat terpilih dan teridentifikasi hingga tingkat spesies yaitu LG 3 memiliki kemiripan dengan Bacillus aerius strain 24 K sebesar 100%, isolat LG-15 memiliki kemiripan dengan Bacillus cereus sebesar 99,80% isolat LG-71 memiliki kemiripan dengan Bacillus tropicus strain MCCC 1A01406 sebesar 99,24% serta dua isolat lain hanya mampu teridentifikasi hingga tingkat spesies yaitu isolat isolat LG-17 memiliki kemiripan dengan Bacillus wiedmanni strain FSL W8-0169 sebesar 98,80%, isolat LG-114 memiliki kemiripan dengan Bacillus tropicus strain MCCC 1A01406 sebesar 98,41%. Adapun kekerabatan masing-masing isolat Bacillus tropicus strain MCC 1A01406, Bacillus cereus ATCC14579 dan Bacillus tropicus strain MCCC berada pada satu klade yang berarti menandakan bahwa spesies tersebut merupakan spesies yang sangat mirip. Bakteri Bacillus aerius strain 24K memiliki yang cukup jauh dengan dua isolat pembanding yaitu Leunostoc lactis dan Ligilactobacillus salivarus. Sedangkan Bacillus wiedmannii strain  FSL w8-0169 menjadi outgroup dari semua isolat sampel yang diuji.

Abtrak (Bhs. Inggris)

Lactic Acid Bacteria (LAB) is a group of bacteria that can ferment carbohydrates to become lactic acid and is known to have functions in food and health sectors. The isolates of LAB had been isolated from the environment of mangrove sediment in the Logending coast.  The characterization of LAB's isolates genetically has not yet been able to identify them at the species level. One of the identification approaches is utilizing the genotypic approach which is the analysis of the gene 16S rRNA sequence. Molecular identification using 16S rRNA has a high accuracy to determine the taxonomy of a certain bacteria. rRNA sequences, specifically 16S rRNA, become the main reference in the study of bacteria evolution and ecology, including the determination of phylogenetic relation among taxa, exploration of the bacteria variety in the environment, and quantification of relative abundance of taxa from various levels. Identification of bacteria based on marker 16S rRNA requires the PCR (Polymerase Chain Reaction) technique. The purpose of the research is to know the identity of lactic acid bacteria which was isolated from mangrove sediment in the Logending coast and its phylogenetic relation.
	The research was conducted using a survey method. The working steps consisted of DNA isolation, confirmation of LAB’s isolates (cultivation in MRSA+CaCO3 staining gram medium, catalase-oxidation test, and endospore staining), amplification of gene 16S rRNA with Polymerase Chain Reaction (PCR) method utilizing universal primer 27F and 1492R, sequencing of PCR result, analysis of sequencing result using Basic Local Alignment Seach Tool (BLAST). The observed parameters are the size and nucleotide sequence of gene 16S rRNA sequence, and the similarity percentage of sequence of nucleotide bases in bacteria. The result data of BLAST were analyzed in terms of similarity to the data in the GeneBank and its phylogenetic relation using the UPGMA method, Neighbor Joining, Maximum Parsimony, and Maximum Likelihood.
	The result of the research found there were 5 selected and identified isolates to the species level, which were LG3 isolate which had similarity to Bacillus aerius strain 24K of 100%, LG-15 isolate which had similarity to Bacillus cereus of 99,80%,  LG-17 isolate which had similarity to Bacillus wiedmanni strain FSL W8-0169 of 98,80%, LG-71 isolate which had similarity to Bacillus tropicus strain MCCC 1A01406 of 99,24%, and LG-114 isolate which had similarity to Bacillus tropicus strain MCCC 1A01406 of 98,41%. Regarding the genetic relationship of each Bacillus tropicus strain MCC 1A01406 isolate, Bacillus cereus ATCC14579 and Bacillus tropicus strain MCCC were in one clade which gave a sign that those species are very similar. Bacteria Bacillus aerius strain 24K had a quite far similarity to the two compared isolates which were Leunostoc lactis and homofermentative. On the other hand, Bacillus wiedmannii strain FSL w8-0169 became the outgroup of all isolate samples that were tested.

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