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Kusumaningrum H.D.,Bogor Agricultural University | Kusumaningrum H.D.,Southeast Asia Food and Agricultural Science and Technology Center | Nofrianti R.,Bogor Agricultural University | Faridah D.N.,Bogor Agricultural University | Faridah D.N.,Southeast Asia Food and Agricultural Science and Technology Center
International Food Research Journal | Year: 2017

Staphylococcal enterotoxin A (SEA) is one of enterotoxins produced by Staphylococcus aureus that widely involved in food intoxication. The sea gene is an enterotoxin-encoding gene that responsible for production of this toxin. The effect of crude alkaloids towards cells and expression of sea gene of four S. aureus isolates from food was studied. Crude alkaloid extracts were extracted from freeze-dried young papaya leaves. A short alkaloid exposure of 2 hours was conducted to generate an insignificant effect to the cell numbers. The relative quantification of the expressed gene was carried out using qRT-PCR technique. The results showed that exposure of crude alkaloid at concentration of 0.25 mg/mL and 0.5 mg/mL for 2 hours did not significantly reduce the cell numbers of S. aureus. The relative expression of sea gene, however, decreased varied among isolates, in a range of 1.8 to 27 times after exposure to 0.25 mg/mL and in a range of 13.6 to 33.2 after exposure to 0.5 mg/mL. This study showed that young papaya leaves contained crude alkaloids that affected the sea gene expression consistently in four S. aureus isolates. © All Rights Reserved.


Kusumaningrum H.D.,Bogor Agricultural University | Kusumaningrum H.D.,Southeast Asia Food and Agricultural Science and Technology Center | Suliantari,Bogor Agricultural University | Suliantari,Southeast Asia Food and Agricultural Science and Technology Center | And 2 more authors.
International Food Research Journal | Year: 2012

A total of 125 samples, consisting of 40 samples of chicken cuts, 30 samples of beef cuts and minced beef, 29 samples of fish, and 26 samples of vegetables were examined for aerobic plate counts and the presence of Salmonella. The samples were collected from the open market and from a supermarket in Bogor Indonesia. Based on the total plate counts, 35.2% of the fresh products showed a good to average quality. Salmonellae were detected in 24.8% of the samples examined. Chicken cuts were found as the most contaminated (52.5%), followed by beef (16.7%), fish (10.3%) and vegetables (7.7%). Serotyping of the isolates identified four serotypes: Salmonella Weltevreden, S. Kentucky, S. Typhimurium and S. Paratyphi C. Most of the isolates (n=15) exhibited resistance to erythromycin. Only one isolate of S. Kentucky, isolated from chicken cuts, showed intermediate resistance to chloramphenicol. Ten isolates showed resistance to at least two antibiotics. One strain of S. Weltevreden isolated from beef cuts demonstrated resistance to four antimicrobial agents (erythromycin, tetracycline, sulfamethoxazole, and streptomycin). © 2008 IFRJ, Faculty of Food Science & Technology, UPM.


Imelda F.,Bogor Agricultural University | Faridah D.N.,Bogor Agricultural University | Faridah D.N.,Southeast Asia Food and Agricultural Science and Technology Center | Kusumaningrum H.D.,Bogor Agricultural University | Kusumaningrum H.D.,Southeast Asia Food and Agricultural Science and Technology Center
International Food Research Journal | Year: 2014

Leaves of Polygonum minus Huds. contain some bioactive compounds which are potential as natural antibacterial agent. The performance of two extraction techniques, i.e. conventional maceration and ultrasound assisted extraction (UAE), for extraction of bioactive compounds of P. minus leaves were evaluated. The antibacterial activities of the extracts were also evaluated towards Escherichia coli and Staphylococcus aureus by agar disc diffusion in combination with TLC-bioautography and by observing the cell membrane leakage. Extraction with UAE provided higher extraction yields and reduced the extraction time in comparison to the conventional maceration. Ethanolic extract of P. minus showed the strongest inhibitory effect for both E. coli and S. aureus. The Minimal Inhibitory Concentration (MIC) of the ethanolic extract, determined by macro-dilution method, was 25 mg/mL for E. coli and 30 mg/mL for S. aureus. TLC-bioautography detected that fractions of ethanolic extract of P. minus with Rf4 = 0.30 and Rf5 = 0.37 demonstrated the most noticeable antibacterial activity for both E. coli and S. aureus. Leakage of cytoplasmic membrane was observed, indicated by the release of cells materials, measured at 260 and 280 nm using UV - Vis spectrophotometer.

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