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Indonesia has a high biodiversity, which can be relied upon as a potential source of medicinal materials. One of the medicinal plants in Indonesia is Kaempferia galanga, which demonstrates various pharmacological properties, including antibacterial, anti-inflammatory, antioxidant, anticancer, and antiangiogenic effects. However, directly extracting active compounds from plants requires a considerable amount of biomass. To address this challenge, utilizing endophytic bacteria associated with these plants presents a promising alternative. Consequently, the antibacterial activity of endophytic bacterial isolates from K. galanga leaves needs to be investigated. This study is an experimental laboratory investigation conducted in vitro. Two isolates demonstrated antibacterial activity: isolate code DR4 inhibited the growth of Escherichia coli (3 ± 0.5 mm), while isolate DR10 inhibited the growth of four bacteria: Bacillus subtilis (5 ± 0 mm), Staphylococcus aureus (1.5 ± 0.5 mm), Escherichia coli (1 ± 0 mm), and Pseudomonas aeruginosa (1 ± 0 mm). Disc diffusion tests using ethyl acetate extracts of isolate DR10 showed the highest antibacterial activity at a concentration of 10,000 ppm. The Minimum Inhibitory Concentration (MIC) was determined to be 156.2 ppm against B. subtilis, while the Minimum Bactericidal Concentration (MBC) was >625 ppm. Molecular identification showed that isolate DR 10 had 100% similarity to Bacillus sp. TS8. The active compound suspected to have antibacterial properties is pyrrolo[1,2-a]pyrazine-1,4-dione, hexahydro-3-(2-methylpropyl)-, with the highest abundance.

The global increase in multidrug-resistant (MDR) bacterial infection has rapidly gained concern globally. This study aimed to investigate antibacterial and antibiofilm potential of 25 soil actinomycete strains against MDR strains including Escherichia coli strain M4, Pseudomonas aeruginosa strain M19, Klebsiella pneumoniae strain M19, Bacillus subtilis strain M18, and Methicillin Resistant Staphylococcus aureus (MRSA). In this study, three actinomycete isolates encoded APM-7, APM-11, and APM-21 showed a strong and broad antibacterial spectrum. The minimum inhibitory concentration (MIC) of extracts derived from these isolates was ranged from 78 μg/ml to 10,000 μg/ml. In addition, The extracts also displayed significant biofilm inhibition values ranging from 6.06 to 72.4%. Based on the results, APM-21 extract had the best antibacterial and antibiofilm activities with the strongest values against MRSA. According to the nucleotide sequencing of the 16S rRNA gene, APM-7, APM-11, and APM-21 strains possessed similar identities with Streptomyces cyaneus, Streptomyces coerulescens, and Streptomyces panayensis, respectively. Based on Liquid Chromatography Tandem-Mass Spectrometry (LC-MS/MS) analysis, two antibacterial compounds, namely rancimanycin III, and enteromycin were detected in all those three extracts. Interestingly, APM-21 extract also contained two prominent antibacterial substances including paramagnetoquinone C, and caerulomycin I, suggesting their contribution to the most potential activities. Moreover, new insights were provided into a promising candidate for use in an active compound combating strategy to control MDR bacterial strain infection.

Soil bacteria could be the promising source of secondary metabolites with diverse pharmacological activities. Bacteria coded as P1 and M7 were isolated from soil obtained from Muna Island, Southeast Sulawesi. This research aimed to evaluate the antioxidant activity, cytotoxic property, and identify the chemical profile of the extract derived from soil bacteria P1 and M7. Based on 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, extract derived from P1 isolate was moderately active against ABTS free radical with IC50 of 126.22±10.82 µg/mL, and less active on DPPH (IC50: 721.95±16.59 µg/mL), while M7 extract was less active towards DPPH and ABTS. Interestingly, these extracts in the concentration of 100 µg/mL were cytotoxic to breast cancer cell (MCF-7), as tested by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. MCF-7 viability was decreased up to 69.83±1.46 % and 61.49±0.76 % after treated with P1 and M7 extract, respectively. The extracts were also induced membrane disruption and apoptosis of MCF-7 cells. The extracts contained phenol (9.52±0.22 and 10.41±0.09 mg EAG/g extract, for P1 and M7, respectively) and flavonoids (9.16±0.16 and 9.29±0.24 mg EQ/g extract, for P1 and M7, respectively). According to Gas Chromatography Mass Spectrometry (GC-MS) analysis, Pyrrolo[1,2-a] pyrazine-1,4-dione, hexahydro-3-(2-methylpropyl) that previously well known as antioxidant and cytotoxic compounds, were found in the M7 and P1 extract. This compound may play a vital role in the radical scavenging and cytotoxic properties of P1 and M7 extracts. The results of this study indicate that P1 and M7 extracts could be the potential source of antioxidant and cytotoxic compounds and need to be further developed for pharmaceutical use.

Biosurfactants are a class of amphipathic molecules that various microorganisms can produce. Biosurfactants are used as biopesticides and biocontrol agents because they have antimicrobial activity, especially as antifungal agents in several species of fungal pathogens such as Ganoderma boninense and Fusarium sp. that attack crops. This study aims to detect the biosurfactant activity of Bacillus sp. and its potential as an antifungal agent against the fungi Ganoderma boninense and Fusarium sp. Biosurfactants were produced in mineral salt medium (MSM) by harvesting cell-free supernatants. Screening of biosurfactant-producing isolates was carried out using an oil-spreading assay, a hemolysis assay, and an emulsification index. The antifungal activity of the isolates was then tested using the agar diffusion method. The LP04 isolate was closely related to Bacillus thuringiensis with a 99% similarity level. It has the potential to have biosurfactant activity, which is characterized by a positive result on the oil spreading assay test and has an emulsification index of 48.33±2.87%. The cell-free supernatants of the bacterial isolate were able to inhibit the growth of Ganoderma boninense and Fusarium sp. with growth inhibition rates of 51.11% and 56.92%, respectively.

Aeromonas spp. causes the human diseases including diarrhea, gastroenteritis, and bacteremia. Aeromonas spp. can be found in kitchen sponge, one of the reservoirs for food-borne bacterial pathogens. Virulence study of Aeromonas spp. in vivo in animal model is important since the animal model can mimic manifestasions in human infections. Omphisa fuscidentalis was chosen for alternative virulence model, since they are in the same taxonomical order with the well-known infections model, Galleria mellonella. Bacterial isolation and selection of kitchen sponge used Brain Heart Infusion agar and Endo Agar, respectively. Bacterial virulence of KS-1 was injected into Omphisa fuscidentalis larvae. Survival percentage and melanization score of infected larvae were evaluated. Hemolymph of larvae with melanization score of 1 and 4 were stained with Giemsa method to observe the hemocyte changes. Bacterial identification of isolate KS-1 based on 16S rRNA sequence resulted in 96.9% identity to Aeromonas spp. strain VS7. Isolate KS-1 injection to O. fuscidentalis revealed higher bacterial dosage resulting more severe symptoms to the larvae according to survival percentage and melanization score. However, statistical analysis showed evaluation of melanization score could distinguish larvae with 106 and 107 CFU/larva dosage injection, while evaluation of survival percentage could not. Hemocyte of larvae with melanization score 1 had larger and more cytoplasmic vacuolization than the score 4 (healthy larvae). Omphisa fuscidentalis is an alternative of insect model for bacterial infections with survival percentage and melanization score as the evaluation. Cytoplasmic vacuolization of hemocyte can be used as larvae’s health indicator in a cellular level.

Paederia foetida Linn. is a rich source of active compounds, yet its antioxidant and cytotoxic properties remain poorly studied. This current research aimed to investigate the chemical profiles of a crude extract derived from P. foetida leaves, its fractionated substances, and their antioxidant and cytotoxic properties on MCF-7 cells, a breast carcinoma cell. Six fractionated substances have been separated in thin layer chromatography (TLC) plate. Five fractions showed antioxidant properties, as indicated by the formation of the yellowish band on the TLC plate after spraying with the DPPH reagent. Furthermore, crude extract of P. foetida leaves and its fractions are also characterized by antioxidant properties against 2, 2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radicals. F1 fraction exhibited the most potent antioxidant activity with IC50 values of 10.94±2.67 and 50.04±0.48 µg/ml, respectively, toward DPPH and ABTS radicals. Crude extract and all six fractions also varied in their cytotoxic properties against MCF-7 cells, with IC50 values ranging from 410.24±0.30 to 831.57±6.91 µg/ml. F3 fractions showed the strongest cytotoxicity (IC50 value: 410.24±0.30 µg/ml). Methanolic extract and active plant leaf fractions contained flavonoid and phenolic compounds, as measured by aluminum chloride and Folin-Ciocalteu reagent, respectively. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis showed that phenol, flavonoid, alkaloid, limonoid, and steroid were the major compound found in the crude extract and fractions. In conclusion, the present study proved that crude extract of P. foetida leaves and its fractionated substances were potential as antioxidant and cytotoxic agents.