Abstract. Ardhi A, Sidauruk AN, Suraya N, Pratiwi NW, Pato U, Saryono. 2020. Molecular identification of amylase-producing thermophilic bacteria isolated from Bukit Gadang Hot Spring, West Sumatra, Indonesia. Biodiversitas 21: 994-1000.  Amylase is one of the hydrolytic enzymes that is widely used in a wide number of industrial processes such as food, fermentation, textile, paper, detergent, and pharmaceutical industries. Amylase produced by thermophilic bacteria may be thermostable, which is very beneficial in several applications requiring high temperature, for example, the process of gelatinization, liquefaction, and saccharification are performed in high temperature involved in the starch processing. In this study, the amylase-producing ability of thermophilic bacteria isolated from Bukit Gadang hot spring, West Sumatra, Indonesia, was checked and followed by molecular identification. Thirteen isolates that were successfully isolated from the hot springs were microscopically and macroscopically characterized, biochemically tested, and determined their amylase enzyme activity both qualitatively and quantitatively. The isolate that performed the best amylase activity was identified using the molecular technique. The DNA sequencing was carried out in 16S rRNA and continued with BLAST search for species identification. The result of molecular identification showed that the isolate with the best amylase activity was identified as Bacillus licheniformis. The optimum amylase production  (231.33 U/ml)  and the best enzyme-specific activity  (101.79 U/mg) were obtained at the incubation time of 36 hours.

Fusarium oxysporum is one of endophyte microbes isolated from dahlia tuber (Dahlia variabilis) which has the ability to produce secondary metabolites. In this research, optimization of chemichal and physical fermentation conditions were carried out. Corn, potato, and sweet potato with particle size of 80 mesh were used as corbon sources to produce secondary metabolite for 5, 10, 15, 20, and 25 days respectively with ethyl acetate was used to extract secondary metabolites. The assessment of antimicrobial activity was then performed against Candida albican, Escherichia coli and Staphylacoccus aureus. A serial of metabolite concentrations 5.7 mg/ml, 3.8 mg/ml, and 1.9 mg/ml were used. The optimum inhibition against microbial pathogen growth was corn for 15 day fementation (C15). The inhibition zone against Candida albicans, E.coli, and S. aureus were 7.62±0.32, 14.15±0.09, and 15.24±0.24 mm respectively at 5.7 mg/ml metabolite concentration. The result of metabolites screening showed overall extract secondary metabolites comprised terpenoid group. The separation of the active ingredients was performed using both Thin Layer Chromatoghraphy and High Performance Liquid Chromatoghraphy (HPLC) depicted 4 component.

Fusarium oxysporum LBKURCC41 is one of endophyte fungi which is able to produce secondary metabolites. The purpose of this research was to discover an antioxidant agent from F. oxysporum LBKURCC41extract that was fermented in Huang medium for 15 d with of corn and potato with particle size of 80 mesh as carbon sources. The ethyl acetate extract from the cultured medium showed four dominant component with retentiont time of 3.24, 3.44, 17.02 and 18.889 min. The F. oxysporum LBKURCC41 extract containing compounds with functional group O-H, C-H and C-O, and it had a IC 50 value of 435,157±12,009 a . ABSTRAKJamur Fusarium oxysporum LBKURCC41 adalah salah satu jamur endofit yang mampu menghasilkan metabolit sekunder. Tujuan penelitian ini adalah untuk menemukan suatu agen antioksidan dari F. oxysporum LBKURCC41 yang difermentasi dengan media Huang selama 15 hari dengan menggunakan jagung dan kentang dengan ukuran partikel 80 mesh sebagai sumber karbon. Ekstrak metabolit yang telah diekstraksi dengan etil asetat menunjukkan adanya 4 komponen dengan waktu retensi 3,24; 3,44; 17,02 dan 18,889 menit. Ekstrak metabolit dari F. oxysporum LBKURCC41Hasil FTIR ekstrak mengandung beberapa gugus fungsi seperti O-H, C-H, dan C-O , dan memiliki nilai IC 50 sebesar 435,157±12,009 a .Kata kunci: antioksidan, fermentasi, Fusarium oxysporum, metabolit sekunder. PENDAHULUANJamur endofit merupakan jamur yang hidup dalam jaringan tanaman dengan cara simbiosis mutualisme (Simarmata et al. 2007). Jamur endofit masuk ke dalam jaringan tanaman bisa melalui beberapa cara diantaranya dengan menghasilkan enzim ekstraseluler dan dapat juga melalui jaringan yang luka.

Abstract. Saryono, Octarina N, Yuharmen, Pratiwi NW, Ardhi A. 2017. Antifungal activity of the extracts and fractions of dahlia tuber (Dahlia variabilis) against pathogenic skin fungi. Nusantara Bioscience 9: 146-151. Dahlia plant (Dahlia variabilis) can be easily found in the highlands in Indonesia and its tuber has been reported to have some bioactive compounds which are potential to be utilized as an antimicrobial agent. This study aimed to determine antifungal activity and minimum inhibitory concentration (MIC) of n-hexane and methanol extracts and fractions of red-flowered dahlia tubers against pathogenic skin fungi Candida albicans and Microsporum gypseum using disc diffusion method. The n-hexane and methanol extracts and fractions of dahlia tuber showed their antifungal activity against C. albicans and M. gypseum, with the larger activity, was found in both extracts and fractions of methanol. The best fractions of n-hexane and methanol were chosen and determined their minimum inhibitory concentration; which the F5 n-hexane fraction and the F2 methanol fraction gave the MIC of 1.50% and 0.50% against C. albicans respectively, whereas both F1 n-hexane and F2 methanol fraction gave the MIC of 0.50% against M. gypseum. The high antifungal activity of F2 of methanol extract against C. albicans and M. gypseum allowed this fraction to be utilized as a medicinal drug for candidiasis and other fungal skin infections.

Abstract. Ardhi A, Ahmad KC, Novrianti H, Husna EY, Yulis M, Pratiwi NW, Saryono. 2019. Hydrolytic enzymes-producing ability of species of actinomycetes and bacteria associated with wilted banana plants (Musa sp.). Biodiversitas 20: 1147-1153. Banana plants contain many nutrients that enable microbes to grow and attack them, causing wilting disease. Microbes growing on the stumps and soil around banana plants are believed to have the ability to produce hydrolytic enzymes. The purpose of this study was to determine the ability of actinomycetes and bacteria isolated from the stumps and soil of wilted banana plants in producing hydrolytic enzymes, namely cellulase, inulinase, amylase, and protease. The confirmation tests of hydrolytic enzymes-producing ability were conducted by inoculating the microbes into media containing CMC, inulin, starch, and skim milk, using the method of paper disc diffusion. From the subculture results, there were 18 isolates of actinomycetes which have been identified as Nocardia, Actinobiospora, Nocardiopsis, Streptomyces, Streptoverticillium, Streptosporangium, and Microbiospora, as well as 40 bacterial isolates with 9 genera of bacteria, namely Xanthomonas, Erwinia, Pesudomonas, Proteus, Ralstonia, Escherichia, Staphylococcus, Caulobacter, and Neisseria, were found. As many as 8 actinomycetes and 40 bacterial isolates indicated the ability to degrade amylum, 39 bacterial and 18 actinomycetes isolates could degrade cellulose, 34 bacterial and 13 actinomycetes isolates could degrade inulin. The highest cellulase ratio was shown by Nocardia sp. LBKURCC101 (3.43) and Ralstonia sp. LBKURCC112 (3.90). The actinomycetes isolate of Nocardia sp. LBKURCC104 and bacteria Pseudomonas sp. LBKURCC133 gave the highest inulinase ratio of 3.36 and 3.47 respectively. In selective amylase media, the highest ratio of 3.10 and 3.80 was found in actinomycetes Nocardia sp. LBKURCC104 and bacteria Erwinia sp. LBKURCC125.