ABSTRAK Telah dilakukan penelitian yang bertujuan memperoleh identitas dua isolat bakteri
termofilik dari geiser. Isolat LC2-23 diperoleh dari serasah pada geiser di
Cisolok, Jawa Barat, Indonesia, dan isolat RKB-2 diperoleh dari serasah pada
geiser di Onikobe, Miyagi, Jepang.!!Identifikasi dilakukan berdasarkan gabungan
data fenotipik dan genotipik. Berdasarkan karakterisasi fenotipik, isolat LC2-23
memiliki sel berbentuk batang; menghasilkan endospora; motil; gram positif;
bersifat aerob dan fakultatif aerob; mampu tumbuh pada suhu 60 oC, sedangkan
suhu optimum pertumbuhan 50 oC. Berdasarkan karakterisasi genotipik, data full
sequence gen 16S rRNA isolat LC2-23 memiliki homologi 99,1% terhadap
Brevibacillus agri. Berdasarkan data fenotipik dan genotipik, isolat LC2-23
diidentifikasi sebagai Brevibacillus agri (Family Paenibacillaceae, Order
Bacillales, Class Bacilli, Phylum Firmicutes). Berdasarkan karakterisasi
fenotipik, isolat RKB-2 membentuk miselium vegetatif dan aerial yang
bercabang; menghasilkan spora aerial; gram positif; bersifat aerob; mampu
tumbuh pada suhu 60 oC, sedangkan suhu optimum pertumbuhan 50 oC.
Berdasarkan karakterisasi genotipik, data full sequence gen 16S rRNA isolat
RKB-2 memiliki homologi yang rendah, yaitu 98,4% terhadap spesies
terdekatnya, Thermosporothrix hazakensis (Family Thermosporotrichaceae,
Order Ktedonobacteriales, Class Ktedonobacteria, Phylum Chloroflexi). Hasil
analisis filogenetik menunjukkan posisi isolat RKB-2 terpisah dari T. hazakensis.
Data kemotaksonomi (komposisi asam lemak) dan hasil analisis proteomik
menggunakan MALDI-TOF MS mendukung perbedaan antara isolat RKB-2 dan
T. hazakensis. Berdasarkan perbedaan tersebut isolat RKB-2 diidentifikasi
sebagai spesies baru dari Thermosporothrix. Untuk pengajuan nama spesies baru
diperlukan data hibridisasi DNA-DNA antara isolat RKB-2 dengan T. hazakensis.
ABSTRACT This research was aimed to identify two bacterial isolates obtained from geysers.
Strain LC2-23 was isolated from litters on a geyser in Cisolok, West Java,
Indonesia, and isolate RKB-2 was obtained from litters on a geyser in Onikobe,
Miyagi Prefecture, Japan. Identification of bacteria was based on integrated data
of phenotypic and genotypic characterizations. Based on phenotypic
characterizations of isolate LC2-23: it has a rod (bacilli)-shaped cells, forms
endospores; gram positive; motile; aerobic, and able to grow up to a temperature
of 60 oC. Based on genotypic characterizations of isolate LC2-23: the full
sequence of genes 16S rRNA shows 99.1% sequence homology to Brevibacillus
agri. Based on phenotypic and genotypic data, isolate LC2-23 can be identified
as Brevibacillus agri (Family Paenibacillaceae, Order Bacillales, Class Bacilli,
Phylum Firmicutes). Based on phenotypic characterizations of isolate RKB-2:
vegetative and branching aerial mycelia forms, gram positive, aerobic, and able to
grow up to a temperature of 60 oC. Based on genotypic characterizations of
isolate RKB-2: the full sequence of 16S rRNA gene of isolate RKB-2 showed low
homology (98.4%) to Thermosporothrix hazakensis (Family
Thermosporotrichaceae, Order Ktedonobacteriales, Class Ktedonobacteria,
Phylum Chloroflexi). Phylogenetic analysis showed the isolate RKB-2 was
distinct from cluster of Thermosporothrix hazakensis and Ktedonobacteria
bacterium. The genotypic and phylogenetic data, plus chemotaxonomic and
proteomic analysis using MALDI-TOF MS, suggest that isolate RKB-2 represent
novel species of the genus Thermosporothrix. The DNA-DNA hibridization data
is needed for proposal of new species.