Background/Objectives: The rise in antimicrobial resistance is one of the major challenges to global health systems, which necessitates the development of new antibacterial compounds. The bioactive compounds of brown seaweed Sargassum duplicatum have demonstrated potential antibacterial activity. This study applied metabolomic profiling and molecular networking in combination with antibacterial screening assays to assess the antimicrobial properties of S. duplicatum extracts against multidrug-resistant bacteria. Methods: Two extraction methods, i.e., maceration and microwave extraction, were used. Therewith, untargeted metabolomic profiling was performed using Liquid Chromatography–High Resolution Mass Spectrometry (LC-HRMS). Molecular networks (MNs) were established and compound dereplication was conducted using the spectral database of the Global Natural Products Social Molecular Networking platform (GNPS). Additionally, antimicrobial assays were conducted against Gram-positive and Gram-negative bacterial strains, including multidrug-resistant bacteria, i.e., methicillin-resistant Staphyloccocus aureus ATCC 33592 (MRSA) and β-lactamase, producing Escherichia coli ATCC 35218 (TEM-1 positive strain). Result: Dereplication resulted in the prediction of six compounds with reported antimicrobial properties, i.e., 13-docosenamide, 9-octadecenamide, pheophorbide A, ouabain, sarmentoside B and AC1L1X1Z. Antibacterial screening of the extracts revealed that the ethyl acetate maceration extracts exhibited the strongest inhibitory activity, with inhibition values between 85 and 98% against S. aureus ATCC 33592. Conclusions: This metabolomics study requires further research to isolate, purify, confirm, and validate the dereplicated compounds that may have potential antibacterial activity.

Gracilaria edulis, a red seaweed that is widely known as an agar-producing seaweed, has a unique biosynthetic pathway for producing bioactive compounds. However, most of the bioactive compounds of this species have not explored yet. The environmental conditions as well as the extraction method might influence the bioactive compound production. Hence, this study aimed to explore untargeted liquid chromatography–high resolution mass spectrometry (LCHRMS)-based metabolomics profiling of G. edulis (Gracilariales, Rhodophyta) from three different beaches along the southern part of the Special Region of Yogyakarta (Java Island, Indonesia), which has different environmental characteristics. We also observed the effect of extraction solvent on metabolomic profiling of G. edulis extract using three different solvents with the different polarity. Metabolomic profiling was performed using an LC-HRMS instrument and analyzed using the Global Natural Product Social Molecular Networking (GNPS) database. The results revealed differences in the metabolomic profiles of G. edulis’s extracts based on coastal location and solvent. G. edulis from Kukup Beach exhibited the highest metabolomic diversity (277 nodes), followed by G. edulis from Sepanjang Beach (268) and G. edulis from Krakal Beach (204). Among the solvents, n-hexane was the most effective, extracting 311 nodes, followed by methanol (293) and ethyl acetate (197). Nine tentatively dereplicated compounds were found, i.e., pumilacidine C, pumilacidine E, lichenysin, cholesterol, AC1L1X1Z, sarmentoside B, 7-dehydrocholesterol, pheophytin A and porphyra-334. Some dereplicated compounds were found in a specific area. For example, lichenysin and pumilacidin compounds were produced by G. edulis from Sepanjang Beach, while cholesterol and AC1L1X1Z were found in from G. edulis extract, which were collected from Sepanjang and Kukup Beaches, and 7-dehydrocholesterol and sarmentoside B compounds from all beach locations, while pheophytin A and porphyra-334 from Krakal Beach. Further research is needed to obtain pure compounds that have the potential to be antibacterial, as well as antioxidant, anti-inflammatory, and photoprotective compounds.

Salt and herbal supplementations in fish feed are expected to promote aquaculture productivity, including for slow-growing fish such as Bonylip barb (Osteochilus vittatus). The objective of this study was to evaluate the growth performance and occurrence of Aeromonas spp. in the intestine of Bonylip barb fed a diet supplemented with salt and herbs. This experiment was conducted using a completely randomized design with four treatments: 1) control, 2) salt 3% supplementation, 3) herbal supplementation, and 4) Salt 3% and herbal supplementation. Growth performance evaluation included weight gain, relative growth rate, and specific growth rate after 30 and 60 days of rearing. Bacterial samples were isolated on trypticase soy agar (TSA) and glutamate starch phenol red agar (GSP) media. Yellow colonies on GSP were counted and confirmed as Aeromonas spp. via molecular identification based on 16S rDNA sequence. Results showed that herbal supplementation, either alone or in combination with 3% salt, insignificantly increased the fish growth performance in the short-term (30 days), but tended to decrease it over the long-term (60 days). Salt supplementation consistently decreased fish growth performance but improved fish survival rates. Aeromonas isolates comprised more than 60 % of the culturable intestinal bacteria in all treatments. Furthermore, herbal supplementation appeared to increase the percentage of Aeromonas spp. in the intestine, with identified species including Aeromonas veronii, Aeromonas caviae, and Aeromonas jandaei.

Gen hormon pertumbuhan (growth hormone, GH) perlu dipelajari untuk mendukung domestikasi ikan sidat Anguilla bicolor di Indonesia. Penelitian ini bertujuan untuk mengisolasi dan mengidentifikasi gen pengkode GH serta menganalisis ekspresinya pada sampel ikan sidat A. bicolor. Primer untuk amplifikasi gen GH ikan sidat A. bicolor didesain berdasarkan sekuen gen GH dari beberapa spesies ikan sidat lain yang tersedia di GenBank. Sampel cDNA hipofisa dan otak ikan sidat digunakan untuk amplifikasi gen GH. Hasil amplifikasi disekuensing dan hasilnya dianalisis menggunakan analisis BLAST, multiple sequences alignment, hormon signature, dan filogenetik. Analisis ekspresi gen GH dilakukan menggunakan teknik realtime PCR dengan metode delta-delta CT pada 14 sampel ikan sidat (23,1 ± 19,6 g; 24,5 ± 4,2 cm). Fragmen DNA sepanjang 486 bp berhasil diamplifikasi dan disekuensing. Sekuen gen GH A. bicolor memiliki similaritas nukleotida sebesar 98,49-99,14% jika dibandingkan dengan gen GH ikan sidat A. anguilla, A. australis, dan A. japonica. Sekuen parsial tersebut secara in silico diketahui mengkode bagian dari protein GH sepanjang 155 asam amino (aa). Sekuen asam amino protein GH A. bicolor sangat mirip dengan sekuen spesies ikan sidat lain dengan hanya tiga perbedaan asam amino dan membentuk satu percabangan pada pohon filogenetik. Tingkat ekspresi gen GH pada sampel ikan sidat memiliki variasi yang tinggi. Hasil penelitian ini dapat menjadi dasar untuk studi selanjutnya khususnya berkaitan dengan peran gen GH dalam pertumbuhan ikan sidat A. bicolor.The growth hormone (GH) gene needs to be studied to support the domestication of the Anguilla bicolor eel in Indonesia. This study aimed to isolate and identify the GH coding gene and analyze its expression in samples of the eel A. bicolor. Primers for amplification of the GH gene of A. bicolor eels were designed based on GH gene sequences from several other eel species available in GenBank. Pituitary and brain cDNA samples of eel were used for GH gene amplification. The amplification results were sequenced and the results were analyzed using BLAST analysis, multiple sequence alignment, hormone signature, and phylogenetic analysis. The GH gene expression analysis was carried out using the real-time PCR technique with the delta-delta CT method on 14 eel samples (23.1 ± 19.6 g; 24.5 ± 4.2 cm). The 486 bp DNA fragment was successfully amplified and sequenced. The GH gene sequence of A. bicolor has a nucleotide similarity of 98.49-99.14% when compared with the GH gene of other eel species A. anguilla, A. australis, and A. japonica. This partial sequence was found in silico to code 155 amino acids (aa) GH protein. The amino acid sequence of the A. bicolor GH protein is very similar to that of other eel species with only three amino acid differences and forms one branch on the phylogenetic tree. The expression level of the GH gene in eel samples had high variations. The results of this study could be a basis for further studies, especially regarding the role of the GH gene in the growth of the eel A. bicolor.Â