Bacterial community structure in the rhizosphere of fungi-infected Amorphophallus titanum.

The rhizosphere is a narrow soil area directly affected by plant root exudates. Microbes inhabiting the rhizosphere have been widely studied for their beneficial effects on plant nutrition, growth, and disease prevention. Many factors affect the rhizosphere microbial composition, including plant pathogen infection. Here, we analyzed the bacterial community structure in the rhizosphere of fungi-infected Amorphophallus titanum. Soil samples were collected from rhizosphere and non-rhizosphere areas of fungi-infected A. titanum. The 16S metagenomic analysis was conducted to investigate the bacterial community of the samples by amplifying the V3-V4 region. The results showed that the phylum Firmicutes was prevalent in the rhizosphere, whereas the phyla Proteobacteria, Acidobacteria, and Actinobacteria were limited. Some major fungal genera were isolated from infected tubers and rhizosphere soil of A. titanum, including Trichoderma sp., Aspergillus sp., Perenniporia sp., and Cerrena sp. The fungal-isolate Aspergillus spp. is a well-known agricultural pest in several reports. While Cerrena sp. was reported to be pathogenic in plants, including the family of Arecaceae. Overall, the data revealed a potential relationship between fungal infections and the dominant bacterial community in the rhizosphere of A. titanum. Additionally, this research may contribute to the development of microbe-based technology to mitigate diseases in A. titanum.

Gastroprotective activities of Peperomia pellucida L. and Pachyrhizus erosus L. extracts combination on ethanol-induced rats.

Gastroprotective is an effect caused by the compounds that have the capability of protecting the gastric mucosa. Peperomia pellucida L. plants contain alkaloids, flavonoids, saponins, tannins, and terpenoids, while Pachyrhizus erosus L. contains flavonoids, alkaloids, tannins, and saponins. Peperomia pellucida L. reportedly contains dillapiole compounds with a gastroprotective effect. Moreover, its isolation result from Pachyrhizus erosus L. indicates the presence of dulcitol, gentisic acid, and formononetin, which has antioxidant activity. This study aims to determine the gastroprotective effect of the combination of Peperomia pellucida L. and Pachyrhizus erosus L. extract on rats with gastric ulcer models by looking at the ulcer index, percentage of inhibition, and histopathology. The research method used in this study was by making a combination of Peperomia pellucida L. and Pachyrhizus erosus L. extract. The combined extract was then given to five treatment groups. Group I as a negative control, group II as a positive control was given sucralfate, groups III, IV, and V were given a combination of Peperomia pellucida L. and Pachyrhizus erosus L. extract of 100, 200, and 400 mg/kg BW. The treatment was given orally for 14 days, after 1 h of treatment on the 14th day, 96% ethanol induction was given orally at a dose of 5 mg/kg BW. The animal dissection was performed 24 h after the induction. The results from observations showed an increase in body weight before and after the treatment. The ulcer index produced by negative control, positive control in the treatment with doses of 100, 200, and 400 were 4.18; 2.98; 2.42; 2.04; and 1.07. This study showed that the combination of Peperomia pellucida L. and Pachyrhizus erosus L. extract has a gastroprotective effect.

Potential Antimicrobe Producer of Endophytic Bacteria from Yellow Root Plant (Arcangelisia flava (L.)) Originated from Enggano Island.

Exploration studies of endophytic bacteria from Arcangelisia flava (L.) and their potential have not much been conducted. This research aims to explore and characterize the antimicrobial activity of endophytic bacteria in A. flava against pathogenic bacteria. This research consists of several steps including the isolation of bacteria, screening of the antimicrobial activity assay using the dual cross streak method, molecular identification through 16s rDNA analysis, and characterization of bioactive compound production through PKS-NRPS gene detection and GC-MS analysis. There are 29 endophytic bacteria that were successfully isolated from A. flava. The antimicrobial activity showed that there are four potential isolates AKEBG21, AKEBG23, AKEBG25, and AKEBG28 that can inhibit the growth of pathogenic bacteria such as Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. The 16S rDNA sequence analysis showed that these isolates are identified as Bacillus cereus. These four isolates are identified as able to produce the bioactive compounds through the detection of polyketide synthase (PKS) and nonribosomal peptide synthase (NRPS)-encoding genes. B. cereus AKEBG23 has the highest inhibition against pathogenic bacteria, and according to the GC-MS analysis, five major compounds are allegedly involved in its antimicrobial activity such as butylated hydroxytoluene (BHT), diisooctyl phthalate, E-15-heptadecenal, 1-heneicosanol, and E-14-hexadecenal. This result suggested that B. cereus AKEBG23 as the endophytic bacterium from A. flava has a beneficial role as well as the plant itself. The bacterium produces several bioactive compounds that are allegedly involved in its antimicrobial activity against pathogenic bacteria.