Abstract. Dikson, Victor H, Jong D, Sanjaya A, Samantha A, Jo J, Pinontoan R. 2022. Whole-genome analysis of Bacillus subtilis G8 isolated from natto. Biodiversitas 23: 1293-1300. Bacillus subtilis-fermented soy-based food is associated with multiple health benefits. Various bacterial strains have been isolated from it, includingB. subtilisG8, recent isolation from Japanese natto commercially available in Indonesia. Both 16S rRNA gene sequencing and fibrinolytic activity characterization have been performed and published in prior studies. After comparison to the genome of a natto-isolated reference strain (i.e., B. subtilisBEST195), the B. subtilis G8 genome showed a similar guanine-cytosine (GC) content, predicted number of coding sequences (CDS) and predicted number of tRNA genes, but had a shorter sequence length and fewer predicted rRNA genes. Further analysis using multiple genome alignment with Mauve, average nucleotide identity (ANI) matrix calculation, and phylogenetic inference indicated that B. subtilis G8 was more related to natto-derived B. subtilis than to cheonggukjang-derived B. subtilis and B. subtilis 168. Finally, sequence analyses of a gene encoding nattokinase as well as two genes regulating poly-gamma-glutamic acid (?-PGA) production in B. subtilis G8, B. subtilis BEST195 and B. subtilis 168 clearly indicated that B. subtilis G8 is able to produce nattokinase and ?-PGA, which both contribute to natto’s fermentation process. Therefore, it is proposed that B. subtilis G8 should be reclassified as B. subtilis subsp. natto G8 to reflect that it is a natto-derived B. subtilis strain.

Abstract. Anastasia L, Kodrat EA, Victor H, Sanjaya A, Pinontoan R. 2022. Isolation and characterization of indigenous amylolytic enzyme-producing Aspergillus sp. from sweet-flavored tapai. Biodiversitas 23: 5580-5586. Aspergillus sp. are able to produce abundant amylolytic enzymes that may have a crucial role in producing the sweet flavor of tapai. This study was aimed to evaluate the amylolytic activity of Aspergillus sp. isolated from a widely known sweet tapai from Jember, East Java, Indonesia. The fungi isolated from sweet tapai were identified under notable morphological parameters, and its amylolytic activities were evaluated by utilizing various starch-based media, such as potato peel, potato dextrose broth, cassava, and maize. Optimum pH and temperature of partially purified amylolytic enzymes were evaluated using DNS assay. The result of this study suggested that TM3 fungal isolate isolated from sweet tapai belonged to Aspergillus sp. section Nigri. Aspergillus sp. TM3 grown in the potato peel medium displayed the highest amylolytic activity, followed by those grown in maize, potato dextrose broth, and cassava media. Further characterization of partially purified amylolytic enzymes from the isolate showed that optimal pH for the amylolytic activity was at pH 4.59 while the optimal temperature was around 54°C. Furthermore, analysis by thin-layer chromatography revealed that the amylolytic enzymes starch hydrolysis yielded dextrose as the main product and oligosaccharides as the side product, which indicated that Aspergillus sp. TM3 may have both alpha-amylase and glucoamylase involved in its amylolytic activity. This study explored the role of Aspergillus sp. TM3 in producing the sweet flavor of tapai.

Abstract. Sugata M, Arviana N, Tampubolon L, Widjajakusuma J, Victor H, Jan TT. 2022. Identification and characterization of calcite producing bacteria isolated from soils in West Java, Indonesia. Biodiversitas 23: 3921-3927. Bio-mediated soil improvement as an interdisciplinary application of geotechnical engineering and microbiology has gained attention due to its environmentally friendly and sustainable properties. This study aimed to isolate indigenous bacteria from soils in Indonesia and evaluate their ability to precipitate calcium carbonate. Fifty-seven colonies were isolated from three soil samples of different locations in Indonesia (Cikarang, Medang, and Karawang). Screening of calcite-producing bacteria was carried out using B4 agar medium incubated for 7-14 days. Only twenty isolates showed the potential ability to form precipitate on B4 agar medium. All the twenty isolates were characterized morphologically and biochemically. For molecular analysis, two isolates, LK3 and NC7, were chosen based on the morphological similarities with Bacillus: Gram-positive, spore-forming rod bacteria. According to 16S rRNA gene sequence analysis using the Basic Local Alignment Search Tool (BLAST), LK3 was identified as Bacillus subtilis LK3 and NC7 was identified as Bacillus cereus NC7. At a temperature of 30 °C, B. cereus NC7 showed the highest growth and produced the most calcite precipitates. In addition, pH 9 was the optimum condition for crystal formation by these bacteria. In conclusion, B. cereus NC7 as indigenous bacteria might be feasible to be used for local soil improvement.