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Abstract 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.

Sludge oil contains 30%–50% hydrocarbon fractions that comprise saturated fractions, aromatics, resins, and asphaltene. Asphaltene fraction is the most persistent fraction. In this research, the indigenous bacteria that can degrade asphaltene fractions from a sludge oil sample from Balikpapan that was isolated using BHMS medium (Bushnell-Hass Mineral Salt) with 0.01% (w/v) yeast extract, 2% (w/v) asphaltene extract, and 2% (w/v) sludge oil. The ability of the four isolates to degrade asphaltene fractions was conducted by the biodegradation asphaltene fractions test using liquid cultures in a BHMS medium with 0.01% (w/v) yeast extract and 2% (w/v) asphaltene extract as a carbon source. The parameters measured during the process of biodegradation of asphaltene fractions include the quantification of Total Petroleum Hydrocarbon (g), log total number of bacteria (CFU/ml), and pH. There are four bacteria (isolates 1, 2, 3, and 4) that have been characterized to degrade asphaltic fraction and have been identified as Bacillus sp. Lysinibacillus fusiformes, Acinetobacter sp., and Mycobacterium sp., respectively. The results showed that the highest ability to degrade asphaltene fractions is that of Bacillus sp. (isolate 1) and Lysinibacillus fusiformes (Isolate 2), with biodegradation percentages of asphaltene fractions being 50% and 55%, respectively, and growth rate at the exponential phase is 7.17x107 CFU/mL.days and 4.21x107 CFU/mL.days, respectively.

Streptomyces aureofaciens widely produces the antibiotic tetracycline and many other compounds during fermentation. The compounds have yet to be known for their antibacterial potential. This work aims to determine new antibiotics or other possible antibacterial compounds produced by marine S.aureofaceiens A3 through an in silico molecular docking method. The ethyl acetate (EA) extracts from fermented marine S. aureofaciens A3 in ISP4 medium enriched with seawater components showed strong antibacterial activity. The antibacterial activity of EA extracts during 6-12 days of fermentation was carried out by the Kirby-Bauer method and the compounds of EA extracts were analyzed by GC/MS. Compounds identified by GC/MS were ligands for an in silico molecular docking study against four target proteins (DNA gyrase, topoisomerase IV, PBP 1a, and DHFR) of pathogenic bacteria. The drug-likeness of selected chemicals as antibacterial agents was assessed using Lipinski's Rule of Five. The results showed the prospective compounds as a narrow-spectrum antibacterial, including 3,5-di-tert-Butyl-4-hydroxyphenylpropionic acid against PBP 1a and Benzenepropanoic acid, and 3,5-bis (1,1-dimethyl ethyl)-4-hydroxy-, methyl esters against DHFR. Substances with broad-spectrum antibacterial activity, such as 3-Acetylphenanthrene and 3-(p-Ethoxyphenyl)-5-(O-tolyloxymethyl)-2-oxazolidone, against multitarget DNA gyrase B and DHFR, 7,9-Di-tert-butyl-1-oxaspiro (4,5) Deca-6,9-diene-2,8-dione against PBP1a and DHFR, and isobenzofuro [5,6-b] benzofuran-8-carboxylic acid, 1,3-dihydro-7,10-dimethoxy-9-methyl-1-oxo-, methyl ester against DNA gyrase B, PBP 1a, and DHFR. On the 12th day of fermentation, two compounds were identified: isobenzofuro[5,6-b] benzofuran-8-carboxylic acid, 1,3-dihydro-7,10-dimethoxy-9-methyl-1-oxo-, methyl ester, and 3-(p-Ethoxyphenyl)-5-(O-tolyl oxy methyl)-2-oxazolidone. This is the first report that these two compounds, known as potential drugs like antibiotics through in silico molecular docking, were first produced by Streptomyces species. [ABSTRACT FROM AUTHOR]

Biosurfactant is widely used in the petroleum industry since it can increase oil recovery. However, its productivity remains economically inefficient. Through the adaptation laboratory evolution (ALE), it is possible to improve the biosurfactant productivity of targeted bacteria. This study aimed to enhance biosurfactant production by bacteria through the ALE and characterize the biosurfactant properties. Cetyltrimethylammonium bromide (CTAB) was used as a mutagen at concentrations ranging from 3.9 ppm to 10 ppm. The biosurfactant characterizations conducted were: 1) interfacial surface tension (IFT), 2) emulsification index (E24), and 3) biosurfactant structure. The biosurfactant activity from the CTAB-resistant strain (KG7') had 3.3 folds higher IFT reduction with increasing production yield (Yp/x) up to 2.6 folds (18.75 ± 1.53 mg/108 CFU) compared to wildtype (WT) (7.07 ± 0.89 mg/108 CFU). The KG7', which was resistant at 4.5 ppm CTAB (KG7'b), was stable after the extension of the ALE process and had higher biosurfactant activity than WT. The structural properties of WT and mutant biosurfactants were both belong to the lipopeptide class. As a result, the ALE offers a potential tool for enhancing bacterial biosurfactant production. [ABSTRACT FROM AUTHOR]