Microbes in marine ecosystems are known to produce secondary metabolites. One of which are carotenoids, which have numerous industrial applications, hence their demand will continue to grow. This review highlights the recent research on natural carotenoids produced by marine microorganisms. We discuss the most recent screening approaches for discovering carotenoids, using in vitro methods such as culture-dependent and culture-independent screening, as well as in silico methods, using secondary metabolite Biosynthetic Gene Clusters (smBGCs), which involves the use of various rule-based and machine-learning-based bioinformatics tools. Following that, various carotenoids are addressed, along with their biological activities and metabolic processes involved in carotenoids biosynthesis. Finally, we cover the application of carotenoids in health and pharmaceutical industries, current carotenoids production system, and potential use of synthetic biology in carotenoids production.

Virgibacillus salarius 19.PP.SC1.6 is a coral symbiont isolated from Indonesia's North Java Sea; it has the ability to produce secondary metabolites that provide survival advantages and biological functions, such as ectoine, which is synthesized by an ectoine gene cluster. Apart from being an osmoprotectant for bacteria, ectoine is also known as a chemical chaperone with numerous biological activities such as maintaining protein stability, which makes ectoine in high demand in the market industry and makes it beneficial to investigate V. salarius ectoine. However, there has been no research on genome-based secondary metabolite and ectoine gene cluster characterization from Indonesian marine V. salarius. In this study, we performed a genomic analysis and ectoine identification of V. salarius. A high-quality draft genome with total size of 4.45 Mb and 4426 coding sequence (CDS) was characterized and then mapped into the Cluster of Orthologous Groups (COG) category. The genus Virgibacillus has an "open" pangenome type with total of 18 genomic islands inside the V. salarius 19.PP.SC1.6 genome. There were seven clusters of secondary metabolite-producing genes found, with a total of 80 genes classified as NRPS, PKS (type III), terpenes, and ectoine biosynthetic related genes. The ectoine gene cluster forms one operon consists of ectABC gene with 2190 bp gene cluster length, and is successfully characterized. The presence of ectoine in V. salarius was confirmed using UPLC-MS/MS operated in Multiple Reaction Monitoring (MRM) mode, which indicates that V. salarius has an intact ectoine gene clusters and is capable of producing ectoine as compatible solutes.

Premature aging can be triggered by free radicals from UV rays, since exposure to these rays can cause the skin to experience oxidative stress. Oxidative stress induces intracellular DNA damage, protein denaturation, and lipid peroxidation that lead to cell death. However, cell death can be prevented with antioxidants such as carotenoids, which are among the potential natural compounds for its treatment. Sources of carotenoids include microbial symbionts associated with Sinularia sp., one of which is the bacterium Virgibacillus salarius strain 19.PP.Sc1.6, a carotenoid-producing bacteria. This study aims to explore the utilization of carotenoids from the bacterium V. salarius strain 19.PP.Sc1.6 for the preparation of anti-aging creams. Furthermore, the method employed three formulations (vs, ow, and wo) containing different types of cream tested for stability, and antioxidant and sunscreen abilities. The results obtained established that the carotenoid extract from V. salarius strain 19.PP.Sc1.6 was more stable in the cream vs. the oil-in-water type cream with an anionic emulsifier.

The extreme conditions of the deep-sea environment, including limited light, low oxygen levels, high pressure, and nutrient scarcity, create a natural habitat for deep-sea bacteria. These remarkable microorganisms have developed unique strategies to survive and adapt to their surroundings. However, research on the diversity of deep-sea bacteria, both culture-dependent and culture-independent, in Indonesian waters remains insufficient. This study focused on exploring the biodiversity of deep-sea bacteria, specifically in the Makassar and Lombok Strait, the main Indonesian throughflow pathway characterized by relatively fertile water, which serves as an important deep-sea region. High-throughput DNA sequencing of full-length 16S rRNA was employed to construct a genomic database. The results of the bioinformatic analysis revealed that two stations, 48 and 50 (Makassar Strait), exhibited a more similar community structure of deep-sea bacteria than did station 33 (Lombok Strait). Among the predominant phyla found at a depth of 1000 m, the top ten were Proteobacteria, Firmicutes, Bacteroidetes, Actinobacteria, Planctomycetes, Acidobacteria, Nitrospinae, Verrucomicrobia, Candidatus Melainabacteria, and Cyanobacteria. Furthermore, the genera Colwellia, Moritella, Candidatus Pelagibacter, Alteromonas, and Psychrobacter consistently appeared at all three stations, albeit with varying relative abundance values. These bacterial genera share common characteristics, such as psychrophilic, halophilic, and piezophilic tendencies, and are commonly found in deep-sea ecosystem. The environmental conditions at a depth of 1000 m were relatively stable, with an average pressure 10 MPa, temperature 4.68 °C, salinity 34.58 PSU, pH 8.06, chlorophyll-a 0.29 µg/L, nitrate 3.19 µmol/L, phosphate 6.32 µmol/L and dissolved oxygen (DO) 2.90 mg/L. The bacterial community structures at the three sampling stations located at the same depth (1000 m) exhibited similarities, as indicated by the closely aligned similarity index values.

Deep-sea polymetallic nodules, rich in cobalt, nickel and titanium, are valuable for electronics, aerospace and energy industries. However, the vertical distribution and ecological functions of prokaryotic communities in sediments beneath nodules from the Magellan seamounts, a unique microbial habitat characterized by ultra-slow sedimentation rates (0.4–4 mm ky ⁻¹ ) and heterogeneous metal gradients, remain poorly characterized. In our research, 16S rRNA gene amplicon sequencing and metagenomic analyses of sediment cores (0–20 cm) from the western Pacific polymetallic nodule province revealed statistically significant decreases in prokaryotic diversity (Shannon index: 9.446 to 2.288; P <0.001). Proteobacteria , Crenarchaeota , Chloroflexi and Bacteroidota were the dominant taxa. The microbial co-occurrence network in the surface layer had a longer mean path length (2.11 vs 1 in the bottom layer) and a larger network diameter (11 vs 1), indicating a loose community structure and greater resistance to disturbance, while the bottom microbial network had a higher density (0.037 vs 0.01) and clustering coefficient (0.32 vs 1), suggesting tight microbial interactions. The concentrations of MnO (6.96–9.41 µg g ⁻¹ ) and P₂O₅ (2.55–3.89 µg g ⁻¹ ) gradually decreased with increasing depth. The concentrations of Co and Pb were relatively high in the surface sediments (0–8 cm) but decreased significantly below 8 cm. In contrast, the concentrations of Fe₂O₃ and As increased with depth. The environmental factors depth, MnO, Fe₂O₃ and heavy metals (Cr, Zn and Cu) were found to be the main drivers of the microbial community structure. We assembled 122 metagenome-assembled genomes from the metagenomic data. Gene abundance analysis revealed that sox genes ( soxB / C / D / X / Y / Z ) and assimilatory sulphate reduction genes ( cysC and cysH ) were highly abundant in the surface sediment, whereas the abundance of dissimilatory sulphate reduction genes ( dsrA and dsrB ) was enhanced in the bottom layer, reflecting a hierarchical adaptive strategy for sulphur metabolism. Our study expands current knowledge on the vertical variations of microbial diversity and microbially driven biogeochemical cycling in deep-sea settings underneath polymetallic nodules. Characterizing the microbial community underneath those nodules may provide insights into microbial resilience in extreme oligotrophic environments and valuable insights for future deep-sea mining activities.

The marine environment boasts distinctive physical, chemical, and biological characteristics. While numerous studies have delved into the microbial ecology and biological potential of the marine environment, exploration of genetically encoded, deep-sea sourced secondary metabolites remains scarce. This study endeavors to investigate marine bioproducts derived from deep-sea water samples at a depth of 1,000 m in the Java Trench, Indonesia, utilizing both culture-dependent and whole-genome sequencing methods. Our efforts led to the successful isolation and cultivation of a bacterium Priestia flexa JT4 from the water samples, followed by comprehensive genome sequencing. The resultant high-quality draft genome, approximately 4 Mb, harbored 5185 coding sequences (CDSs). Notably, 61.97% of these CDSs were inadequately characterized, presenting potential novel CDSs. This study is the first to identify the "open-type" (α < 1) pangenome within the genus Priestia. Moreover, our analysis uncovered eight biosynthetic gene clusters (BGCs) using the common genome mining pipeline, antiSMASH. Two non-ribosomal peptide synthetase (NRPS) BGCs within these clusters exhibited the potential to generate novel biological compounds. Noteworthy is the confirmation that the terpene BGC in P. flexa JT4 can produce lycopene, a compound in substantial industrial demand. The presence of lycopene in the P. flexa JT4 cells was verified using Ultra-performance liquid chromatography-mass spectrometry (UPLC-MS/MS) in multiple reaction modes. This study highlights the bioprospecting opportunity to explore novel bioproducts and lycopene compounds from P. flexa JT4. It marks the pioneering exploration of deep-sea bacterium bioprospecting in Indonesia, seeking to unveil novel bioproducts and lycopene compounds through a genome mining approach.