title: Staphylococcal enterotoxin A gene-carrying Staphylococcus aureus isolated from foods and its control by crude alkaloid from papaya leaves.
abstract: Staphylococcus aureus is a known pathogen causing intoxication by producing enterotoxins in food. Staphylococcal enterotoxin A is one of the enterotoxins commonly implicated in staphylococcal food poisoning. The ability of crude alkaloid extract from papaya leaves to inhibit the growth of S. aureus and staphylococcal enterotoxin A synthesis was investigated. Staphylococcal enterotoxin A gene-carrying S. aureus was isolated from raw milk and ready-to-eat foods. Crude alkaloid was extracted from ground, dried papaya leaves using ultrasonic-assisted extraction, and a MIC of the alkaloid was determined by the broth macrodilution method. Furthermore, S. aureus isolate was exposed to the crude alkaloid extract at one- and twofold MIC, and the expression of sea was subsequently analyzed using a quantitative reverse transcription real-time PCR. Ten isolates of S. aureus were obtained, and nine of those isolates were sea carriers. The yield of crude alkaloid extract was 0.48 to 1.82% per dry weight of papaya leaves. A MIC of crude alkaloid to S. aureus was 0.25 mg/ml. After exposure to the alkaloid at 0.25 and 0.5 mg/ml for 2 h, a significant increase in cycle threshold values of sea was observed. The sea was expressed 29 and 41 times less when S. aureus was exposed to crude alkaloid at one- and twofold MIC, respectively. This study revealed that crude alkaloid of papaya leaves could control staphylococcal enterotoxin A gene-carrying S. aureus by suppressing the expression of sea, in addition to the ability to inhibit the growth of S. aureus. The expression of sea was successfully quantified.
authors.affiliation: Food Science Study Program, Department of Food Science and Technology, Bogor Agricultural University, Campus IPB Darmaga, P.O. Box 220, Bogor 16002, Indonesia.
authors.forename: Lita
authors.initials: L
authors.lastname: Handayani
authors.affiliation: Food Science Study Program, Department of Food Science and Technology, Bogor Agricultural University, Campus IPB Darmaga, P.O. Box 220, Bogor 16002, Indonesia; Southeast Asian Food and Agricultural Science and Technology (SEAFAST) Center, Bogor Agricultural University, SEAFAST Center Building, Jl. Puspa No 1, Campus IPB Darmaga, Bogor 16680, Indonesia.
authors.forename: Didah Nur
authors.initials: DN
authors.lastname: Faridah
authors.affiliation: Food Science Study Program, Department of Food Science and Technology, Bogor Agricultural University, Campus IPB Darmaga, P.O. Box 220, Bogor 16002, Indonesia; Southeast Asian Food and Agricultural Science and Technology (SEAFAST) Center, Bogor Agricultural University, SEAFAST Center Building, Jl. Puspa No 1, Campus IPB Darmaga, Bogor 16680, Indonesia. h_kusumaningrum@ipb.ac.id.
authors.forename: Harsi D
authors.initials: HD
authors.lastname: Kusumaningrum
mesh_terms: D000470:Alkaloids / Q000494:pharmacology*; D000818:Animals; D029441:Carica / Q000737:chemistry*; D002417:Cattle; D004768:Enterotoxins / Q000378:metabolism*; D057140:Fast Foods / Q000382:microbiology*; D008892:Milk / Q000382:microbiology*; D010936:Plant Extracts / Q000494:pharmacology*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D000470:Alkaloids; D004768:Enterotoxins; D010936:Plant Extracts; C026066:enterotoxin A, Staphylococcal