title: Toxigenic genes, spoilage potential, and antimicrobial resistance of Bacillus cereus group strains from ice cream.
abstract: Bacillus spp. can be recovered from almost every environment. It is also found readily in foods, where it may cause food spoilage and/or food poisoning due to its toxigenic and pathogenic nature, and extracellular enzymes. In this study, 29 Bacillus cereus group strains from ice cream were examined for the presence of following virulence genes hblC, nheA, cytK and ces genes, and tested for a range of the extracellular enzymes, and antimicrobial susceptibility. The strains were found to produce extracellular enzymes: proteolytic and lipolytic activity, gelatin hydrolysis and lecithinase production (100%), DNase production (93.1%) and amylase activity (93.1%). Of 29 strains examined, 24 (82.8%) showed hemolytic activity on blood agar. Beta-lactamase enzyme was only produced by 20.7% of B. cereus group. Among 29 B. cereus group from ice cream, nheA was the most common virulence gene detected in 44.8% of the strains, followed by hblC gene with 17.2%. Four (13.8%) of the 29 strains were positive for both hblC gene and nheA gene. Contrarily, cytK and ces genes were not detected in any of the strains. Antimicrobial susceptibility of ice cream isolates was tested to 14 different antimicrobial agents using the disc diffusion method. We detected resistance to penicillin and ampicillin with the same rate of 89.7%. Thirty-one percent of the strains were multiresistant to three or more antibiotics. This study emphasizes that the presence of natural isolates of Bacillus spp. harboring one or more enterotoxin genes, producing extracellular enzymes which may cause spoilage and acquiring antibiotic resistance might hold crucial importance in the food safety and quality.
authors.affiliation: Abant Izzet Baysal University, Faculty of Arts and Sciences, Department of Biology, Gölköy 14280, Bolu, Turkey. Electronic address: arslan_s3@ibu.edu.tr.
authors.forename: Seza
authors.initials: S
authors.lastname: Arslan
authors.affiliation: Abant Izzet Baysal University, Faculty of Arts and Sciences, Department of Biology, Gölköy 14280, Bolu, Turkey.
authors.forename: Ayla
authors.initials: A
authors.lastname: Eyi
authors.affiliation: Abant Izzet Baysal University, Faculty of Arts and Sciences, Department of Biology, Gölköy 14280, Bolu, Turkey.
authors.forename: Rümeysa
authors.initials: R
authors.lastname: Küçüksarı
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001409:Bacillus cereus / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics* / Q000302:isolation & purification; D001427:Bacterial Toxins / Q000235:genetics* / Q000378:metabolism; D024881:Drug Resistance, Bacterial; D004798:Enzymes / Q000032:analysis; D007054:Ice Cream / Q000382:microbiology*; D008826:Microbial Sensitivity Tests; D037521:Virulence Factors / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D001427:Bacterial Toxins; D004798:Enzymes; D037521:Virulence Factors
keywords: Antimicrobial susceptibility; Bacillus cereus group; Extracellular enzyme; Ice cream; Toxin gene