Buitenzorg: Journal of Tropical Science

In Silico Study of NONEXPRESSOR OF PATHOGENESIS-RELATED GENES 1 (NPR1) Sequence in Citrus Associated with Huanglongbing Resistance

Kristianto Nugroho, Tri Joko Santoso, Mia Kosmiatin, Dewi Sukma, Agus Purwito — Wed, 24 Dec 2025 00:00:00 +0000

The evaluation of citrus resistance to Huanglongbing (HLB) disease is still challenging due to the incapability of the bacteria to be cultured purely in artificial medium, the complexity of inoculation methods, and the long duration required for phenotypic observation. Thus, the use of molecular markers is one of the alternatives to solve this problem. The focuses of this study were to perform in silico analysis of the nucleotide variations in NONEXPRESSOR OF PATHOGENESIS-RELATED GENES 1 (NPR1) gene sequence among several citrus genotypes whose resistance information to HLB have been known previously and to employ phylogenetic analysis among them. The NPR1 gene sequences from 20 genotypes which consisted of 14 citrus and six relative genotypes were collected in silico from Citrus Genome Database and analyzed using multiple sequence alignment program. A total of six interesting SNPs that could distinguish between susceptible and resistant citrus genotypes were detected in this study. As many as five SNPs were non-synonymous, while only one synonymous SNP that did not cause the amino acid change was identified in this study. The phylogenetic analysis also revealed the separation between susceptible and tolerant/resistant citrus genotypes in two main clusters. The SNPs found in this study are expected to be useful for designing new functional markers as a selection tool in future studies.

Keywords: in silico, molecular marker, phylogenetic analysis, selection tool, SNP

A Baseline Study of Nepenthes spp. in Bukit Tangkiling Nature Tourism Park, Palangka Raya, Central Kalimantan, Indonesia

Muhammad Rizki, Helen Oktafiani, Desimaria Panjaitan — Wed, 24 Dec 2025 00:00:00 +0000

Pitcher plants (Nepenthes spp.) are carnivorous plants that flourish in the Bukit Tangkiling Nature Tourism Park (BTNTP), Palangka Raya, Central Kalimantan. Searches of global biodiversity databases and relevant literature revealed no prior records of Nepenthes from this area. This study aimed to document and provide a baseline record of Nepenthes species occurring within BTNTP. The study was conducted from March to May 2022 using exploration and purposive sampling methods to collect plant specimens. Three species, namely Nepenthes gracilis Korth, Nepenthes mirabilis (Lour.) Druce, and Nepenthes rafflesiana Jack, were recorded across various habitats, including scrub forest, heath forest, secondary forest, and peat forest, all below 100 m above sea level. These findings contribute to the species inventory of BTNTP and serve as a scientific reference for future ecological monitoring and management strategies aimed at maintaining habitat quality and supporting long-term Nepenthes conservation efforts in the region.

Keywords: habitat, species record, pitcher plants, Nepenthes, Kalimantan

In Vitro Antibacterial Activity and Preliminary Cytotoxicity of White Turmeric (Curcuma zedoaria) Kombucha

Tobias Hezkel Siregar, Mafrikhul Muttaqin, Syaefudin — Wed, 24 Dec 2025 00:00:00 +0000

White turmeric (Curcuma zedoaria) contains bioactive compounds with antibacterial and cytotoxic potential; however, the quantity of these compounds and their biological activity remain relatively low. Fermentation can enhance these properties by promoting microbial bioconversion. This study evaluated the total flavonoid content as well as antibacterial and cytotoxic activities of C. zedoaria rhizomes fermented using a Symbiotic Culture of Bacteria and Yeast (SCOBY). Antibacterial activity was evaluated against Escherichia coli and Staphylococcus aureus using the disk diffusion method, while cytotoxic activity was analyzed using the Brine Shrimp Lethality Test (BSLT). The results showed that fermentation increased the total flavonoid content by 64% and substantially improved antibacterial performance, producing inhibition zones of 13.7±0.7 mm for E. coli and 12.8±0.4 mm for S. aureus, more than double those of the non-fermented white turmeric. Cytotoxic activity also increased, as indicated by a lower LC₅₀ value (145.3 µg/ml) compared to the non-fermented white turmeric (1,381.8 µg/ml). Overall, the findings demonstrate that fermentation significantly enhances the antibacterial and cytotoxic activities of white turmeric.

Keywords: bioactivity enhancement, fermentation, functional beverage, SCOBY, white turmeric

Community Structure and Association of Crinoidea (Echinodermata) with Coral Reef Lifeforms on the Reef Slopes of Pramuka Island, Seribu Islands

Muhammad Emir Rasyid, Mufti Patria — Wed, 24 Dec 2025 00:00:00 +0000

Class Crinoidea, or sea lilies, are primitive members of the Echinoderm phylum, playing a crucial ecological role as filter feeders and indicating ecosystem health. Pramuka Island is the administrative center of the Seribu Islands Regency, DKI Jakarta, which is experiencing rapid development and becoming a promising tourism site. These anthropogenic activities may influence the survival of the coral reef ecosystem below the island. Thus, further research on crinoid communities and their relationship with coral reef lifeforms is needed to assess the health of the reef ecosystem amidst increasing anthropogenic activities. The research was done using the belt transect method covering an area of 50×5 m at a depth of 10 m at four research stations, calculating the diversity index, evenness index, dominance index, and density. The association of Crinoidea with coral reef lifeforms was analyzed using the chi-square test. The result showed poor value with an average low diversity index, moderate evenness index, and high dominance index. Capillaster sentosus, the most abundant species at every station, indicates habitat suitability rather than ecological disturbance, and serves as a potential bioindicator for Pramuka Island’s reef health, though its dominance might signal a decline in other species due to competition. There were six pairs of Crinoidea–substrates found to be positively associated, and four pairs of Crinoidea–substrates that were negatively associated. The associations between crinoids and coral reefs, influenced by crinoid morphology, reef stability, and current flow, highlight the need for conservation efforts to preserve these crucial relationships for biodiversity.

Keywords: association, community structure, coral reef, crinoids, Pramuka island

CO2 Supplementation Unlocks Biomass, Lipid, and Carotenoid Potentials in Microalgae Coelastrella sp. strain Saripa

Wed, 24 Dec 2025 00:00:00 +0000

Microalgae are a group of photosynthetic microorganisms widely distributed in various habitats, especially in aquatic environment. This study aimed to evaluate the effects of carbon dioxide (CO₂) gas supplementation on the growth and biomass production of the microalgae Coelastrella sp. strain Saripa, as well as the lipid and carotenoid contents produced. Additionally, color changes during the growth process were observed as physiological indicators of the microalgae's response to CO₂ treatments and pH changes during growth. The experiment was conducted using a Completely Randomized Design. CO₂ was supplemented at 0, 25, and 50 ml volumes. The results showed that different CO₂ supplementations influenced the pH change, ranging from 6 to 8.4 during cultivation. The 50 ml CO₂ supplementation at pH 6 resulted in the highest biomass production (0.418±0.022 mg/l), lipid production (46%), and total carotenoids (21%). Under this condition, the culture color changed gradually, correlated with the change of chlorophylls and carotenoid contents. Statistical analysis (α = 0.05) confirmed that CO₂ supplementations significantly affected biomass, lipid, and carotenoid productions. In conclusion, Coelastrella sp. strain Saripa demonstrated potentials in reducing atmospheric CO₂, providing the biomass as lipid and carotenoid bioresources.

Keywords: Coelastrella sp., microalgae, CO₂ gas supplementation