1.Metagenome analysis of tempeh production: Where did the bacterial community in tempeh come from?
Rahmadina Radita ; Antonius Suwanto ; Norio Kurosawa ; Aris Tri Wahyudi ; Iman Rusmana
Malaysian Journal of Microbiology 2017;13(4):280-288
Aims: Tempeh is a soy-based traditional food fermented by Rhizopus oligosporus. Although this mold is the main
microorganism responsible for tempeh fermentation, various unknown bacteria presence in tempeh could enhance
tempeh’s nutritional value. This study is aimed to examine the identity of bacteria in tempeh bacterial community by
combining metagenomics analysis and culturable technique.
Methodology and results: Samples were obtained from a tempeh producer which consists of raw soybeans, fresh
water used to soak the beans, soaking water after the beans were soaked for 18 h, dehulled-soybean before inoculation,
starter culture, and fresh tempeh. All samples were plated onto Enterobacteriaceae and Lactic Acid Bacteria agar media,
and the total DNA was extracted for metagenomics analysis based on 16S rRNA gene cloning and High-Throughput
Sequencing (HTS). Metagenomic analysis indicated that Firmicutes and Proteobacteria were the predominant and subdominant
bacteria, respectively, while the culturable technique showed Proteobacteria were the predominant bacteria.
Firmicutes species detected in tempeh were similar to the ones in the soaking water, which were populated by
Lactobacillus. However, another predominant bacteria from tempeh, Enterococcus, was similar to minor population of
Enterococcus detected in dehulled-soybean before inoculation. Based on the cloned 16S rRNA genes, we observed L.
agilis, L. fermentum, and E. cecorum as the predominant bacteria in tempeh. The starter culture, which was dominated
by Clostridium, did not alter bacterial community in tempeh, since its proportion was only 2.7% in tempeh clean reads.
Conclusion, significance and impact of study: The dominant bacteria in tempeh was Lactobacillus from Firmicutes.
The bacterial community in tempeh was not affected by the starter culture used, but mainly because of the soybean
soaking process.
2. Bacillus sp. SAB E-41-derived extract shows antiaging properties via ctt1-mediated oxidative stress tolerance response in yeast Schizosaccharomyces pombe
Muhammad Eka PRASTYA ; Rika I. ASTUTI ; Aris T. WAHYUDI ; Irmanida BATUBARA ; Irmanida BATUBARA
Asian Pacific Journal of Tropical Biomedicine 2018;8(11):533-539
Objective: To analyze potential activation of oxidative stress tolerance systems by SAB E-41 bacterial extract in promoting the life span of yeast Schizosaccharomyces pombe. Methods: In vitro analysis was done to assess antioxidant activity of SAB E-41 bacterial extract. Antiaging property of the particular extract was then assayed through spot test and chronological life span assays. Furthermore, sty1 mitogen-activated protein kinase, pap1 transcriptional factor of oxidative stress response and its downstream genes, ctt1 were evaluated via real time PCR. The protein level of ctt1 was then observed via Western Blot analysis. In addition, accumulation of reactive oxygen species and mitochondrial activity were conducted to understand the effect of SAB E-41 upon oxidative stress response systems in vivo. Results: The IC
3. Phytochemical analysis and antibacterial activities of Eleutherine bulbosa (Mill.) Urb. extract against Vibrio parahaemolyticus
Waode MUNAENI ; Waode WIDANARNI ; Munti YUHANA ; Mia SETIAWATI ; Waode MUNAENI ; Aris WAHYUDI
Asian Pacific Journal of Tropical Biomedicine 2019;9(9):397-404
Objective: To analyze compounds in Eleutherine bulbosa (E. bulbosa) (Mill.) Urb. extract and to determine its antibacterial capability against Vibrio parahaemolyticus (V. parahaemolyticus). Methods: E. bulbosa bulb extract was preprared using 96% ethanol by the maceration method. Phytochemical investigation of E. bulbosa extract was analyzed using GC-MS, spectrophotometry and titrimetry methods. The zone of inhibition was identified by the diffusion agar method. The minimum inhibitory concentration and minimum bactericidal concentration were determined using the plate count method. The inhibitory rate against V. parahaemolyticus was determined by the microdilution method. Cellular leakage was evaluated by spectrophotometry and cellular damage was observed by scanning electron microscopy. Results: GC-MS analysis showed the high compound of the E. bulbosa extract was securixanthone E (7-hydroxy-1,2-dimethoxyxanthone). The compound groups also included fatty acid esters, isoquinolines, naphthalenes, and phenolics. The total phenolic content was (2.50 ± 0.00) mg/g, flavonoid (6.61 ± 0.00) mg/g, and tannin (0.03 ± 0.00)%. The greatest zone of inhibition and inhibitory rate were (11.83 ± 0.06) mm and (91.32 ± 2.76)%, respectively, at 10 mg/mL. The minimum inhibitory concentration was 0.156 mg/mL, while the minimum bactericidal concentration was 10 mg/mL. The E. bulbosa extract caused leakage and cellular damage to V. parahaemolyticus. Conclusions: The E. bulbosa extract possesses inhibitory activities against V. parahaemolyticus and causes cellular leakage and damage.