Microbial diversity changes in soybean sprouts treated with enterocin AS-48.
Seed sprouts may act as vehicles for foodborne pathogenic bacteria. In the present study, the effect of washing treatment with the enterococcal bacteriocin enterocin AS-48 on the microbiota of two batches of soybean sprouts was studied by culture-dependent and independent methods throughout storage at 10 degrees C. Viable cell counts of bacteriocin-treated samples revealed some modifications only for lactic acid bacteria and enterococci during storage. In the control samples from batch 1, the culture-independent DGGE analysis revealed species from genera Rahnella and Serratia as the predominant bacteria at early stages. Several bands corresponding to other genera (two Pantoea bands, one Escherichia band, and five Enterobacter bands) were also detected during storage of control samples, especially at days 3 and 5, while one Rahnella band disappeared. By contrast, some of the enterobacteria (Pantoea Escherichia and Enterobacter) were not detected or showed very faint bands in batch 1 bacteriocin-treated samples, in which two new and intense bands corresponding to genera Enterococcus and Leuconostoc were detected. Batch 2 showed a more homogeneous bacterial population, composed mainly by species of genus Enterobacter together with Pantoea. The major modifications detected in the bacteriocin-treated samples from batch 2 included the loss of one genus Enterobacter band at days 3, 5 and 7, and the detection of a new band corresponding to genus Leuconostoc at days 5 and 7. These results suggest that bacteriocin treatment disturbs the microbial balance in sprouts, producing changes in the microbial profile that cannot be detected by culture-dependent methods. The results also encourage the use of culture-independent methods to gain more insights into the global effects of bacteriocins in food systems.
Cobo Molinos
Antonio
A
Area de Microbiología, Departamento de Ciencias de la Salud, Facultad de Ciencias Experimentales, Universidad de Jaén, 23071-Jaén, Spain.
Abriouel
Hikmate
H
Ben Omar
Nabil
N
López
Rosario Lucas
RL
Gálvez
Antonio
A
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001419:Bacteria / Q000145:classification / Q000187:drug effects / Q000302:isolation & purification*; D001430:Bacteriocins / Q000494:pharmacology*; D001431:Bacteriological Techniques; D044822:Biodiversity; D015169:Colony Count, Microbial / Q000379:methods*; D003257:Consumer Product Safety; D003470:Culture Media; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods; D005516:Food Microbiology; D005519:Food Preservation / Q000379:methods; D018525:Germination; D006801:Humans; D013025:Glycine max / Q000382:microbiology*; D013696:Temperature; D013997:Time Factors
D000900:Anti-Bacterial Agents; D001430:Bacteriocins; D003470:Culture Media; C466236:enterocin AS-48, Enterococcus faecalis