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Abstrak :
The aims of this study are to provide data regarding the taxonomic study of thermophilic Actinobacteria based on 16S rRNA gene sequences, description, and assessment for secondary metabolite biosynthetic gene clusters (BGCs) in the genome of novel taxa, and its antibacterial activity. Thirty-one isolates of thermophilic Actinobacteria were isolated from soil samples in Cisolok geothermal area, West Java. The 16S rRNA gene sequence-similarity search against all related species was performed using EzTaxon-e database. The sequences of 31 isolates showed similarity to member of family Micromonosporaceae, Nocardiaceae, Pseudonocardiaceae, Streptomycetaceae, Streptosporangiaceae, and Thermomonosporaceae. Six isolates displayed high similarity to genera in the family Pseudonocardiaceae, and most closely related to the genus Thermotunica, T. guangxiensis AG2-7T with similarity values from 94.6 to 95.2%. Phenotypic features and phylogenetic data differentiated strain SL3-2-4T from members of the family Pseudonocardiaceae. Therefore, the strain SL3-2-4T is proposed as a representative of a novel species in a novel genus, Gandjariella thermophila gen. nov., sp. nov. The genome of SL3-2-4T contained 21 antiSMASH-identified secondary metabolite regions harboring BGCs. These BGCs were for polyketide synthase, non-ribosomal peptide synthase, and ribosomally synthesized and post-translationally modified peptide family clusters. Thirteen and five regions displayed low (4–35%) and no similarity with known BGCs for secondary metabolites, respectively. Screening for antibacterial activity showed that strains SL3-2-4T and SL3-2-7 on MM 2 medium solidified with gellan gum at 45°C for 14 days demonstrated inhibitory activity against all Gram-positive, but not Gram-negative bacteria. Strain SL3-2-10 on ISP 3 gellan gum medium incubated for seven-days only active against K. rhizophila NBRC 12078. The results indicated that novel taxa have the potential for the discovery of active secondary metabolites.

Abstrak :
Kelompok Actinobacteria berfilamen merupakan bakteri Gram positif yang beberapa anggotanya diketahui memiliki kemampuan mendegradasi selulosa dengan menghasilkan selulase. Penelitian ini bertujuan untuk mengetahui kemampuan tumbuh isolat Actinobacteria-like GL1-2, GL1-9, dan GL1-12 pada variasi media agar (ISP 1, ISP 2, ISP 3, dan modified Bennett’s) dan suhu (25, 30, 35, 40, 45, 50, dan 55°C), serta mengetahui kemampuan selulolitiknya pada substrat 1% CMC di berbagai suhu (30, 35, 40, 45, 50, dan 55°C). Kemampuan selulolitik diuji dengan menginokulasi biakan pada medium agar minimal (Mm) dengan penambahan 1% CMC, kemudian diinkubasi pada berbagai suhu selama 3, 7, dan 14 hari. Kemampuan selulolitik diamati dengan terbentuknya zona bening di sekitar koloni setelah ditetesi 0,1% Congo red dan dibilas dengan larutan NaCl 1 M. Isolat GL1-2 dan GL1-9 menunjukkan pertumbuhan miselium substrat dalam jumlah banyak pada semua medium yang diuji, namun sporulasi penuh hanya teramati pada medium ISP 1 agar dan MBA. Isolat GL1-12 menunjukkan pertumbuhan miselium substrat yang baik kecuali pada medium ISP 2 agar, namun sporulasi hanya teramati pada medium ISP 3 agar. Suhu pertumbuhan isolat GL1-2 dan GL1-9 berkisar antara 30--55°C, sedangkan GL1-12 berkisar antara 35--55°C. Hasil uji kemampuan selulolitik menunjukkan bahwa isolat GL1-2 dan GL19 memiliki kemampuan mendegradasi 1% CMC pada suhu 30, 35, 40, 45, 50, dan 55°C. Isolat GL1-12 memiliki kemampuan selulolitik pada suhu 40, 45, 50, dan 55°C. Hasil penelitian menunjukkan bahwa ketiga isolat Actinobacteria-like dari serasah di kawasan sumber air panas gunung Galunggung memiliki potensi menghasilkan enzim selulase di berbagai suhu yang diuji. ......Members of Gram-positive filamentous Actinobacteria are some recognized for their ability to degrade cellulose by producing cellulase. This study aimed to determine the growth ability of three Actinobacteria-like isolates (designated isolates GL1-2, GL19, and GL1-12) obtained from litter samples of mount Galunggung hot spring, Tasikmalaya, West Java, on various agar media (ISP 1, ISP 2, ISP 3, and modified Bennett’s) and temperatures (25, 30, 35, 40, 45, 50, 55°C), along with their cellulolytic ability on 1% carboxymethyl cellulose (CMC) as substrate. Cellulolytic ability was tested by inoculating the cultures on minimal (Mm) agar plates with the addition of 1% CMC, and incubated at various temperatures (30, 35, 40, 45, 50, and 55°C) for 3, 7, and 14-days. Cellulolytic ability was observed as formation of clear zone surrounding the colonies after being flooded with 0.1% Congo red and rinsed with 1 M NaCl solution. The results showed that isolates GL1-2 and GL1-9 have abundant substrate mycelia formation on all media tested, while optimal sporulation was only observed on ISP 1 agar and MBA. Isolate GL1-12 showed good growth of substrate mycelia except on ISP 2 agar, however sporulation was poorly observed only on ISP 3 agar. Growth temperatures of isolates GL1-2 and GL1-9 were ranging from 30 to 55°C, while GL112 was ranging from 35 to 55°C. Isolates GL1-2 and GL1-9 have the ability to degrade 1% CMC at 30, 35, 40, 45, 50, and 55°C. Isolate GL1-12 has celulolytic ability at temperatures of 40, 45, 50, and 55°C. This study revealed that Actinobacteria-like isolates obtained from litter samples of mount Galunggung hot spring, Tasikmalaya are potential cellulase-producers on various tested temperatures.