A rapid turbidometric microplate bioassay for accurate quantification of lactic acid bacteria bacteriocins.
A 1 day turbidometric microplate bioassay (TMB) was developed for the rapid, accurate and precise quantification of lactic acid bacteria (LAB) bacteriocins (nisin Z and pediocin PA-1). Parameters such as the concentration of the indicator strains and the incubation time were optimized for each bacteriocin. A high correlation coefficient (r(2)=0.992+/-0.004) was obtained for the exponential regression in the nisin Z concentration range of 20-120 ng/ml with 1 x 10(7) CFU indicator strain (Pediococcus acidilactici UL5) and an incubation time of 3 h. Using these parameters, the detection limit was estimated at 80 ng/ml (3.2 IU/ml), compared to 300 ng/ml for the agar diffusion assay (ADA). High precision (<7%) and accuracy (10%) were obtained for all nisin Z concentrations tested. Similar results were obtained with pediocin PA-1 with r(2)=0.993+/-0.005, a precision (8.2%) and an accuracy lower than 15%.
Turcotte
Carl
C
Dairy Research Centre STELA, Pavillon Paul Comtois, Université Laval, Québec, PQ, Canada G1K7P4.
Lacroix
Christophe
C
Kheadr
Ehab
E
Grignon
Louis
L
Fliss
Ismaïl
I
D000900:Anti-Bacterial Agents / Q000032:analysis* / Q000096:biosynthesis; D001430:Bacteriocins / Q000032:analysis* / Q000096:biosynthesis; D001681:Biological Assay; D015169:Colony Count, Microbial; D005520:Food Preservatives / Q000032:analysis; D007700:Kinetics; D009391:Nephelometry and Turbidimetry / Q000379:methods*; D009561:Nisin / Q000031:analogs & derivatives* / Q000032:analysis* / Q000096:biosynthesis; D000070017:Pediocins; D010376:Pediococcus / Q000254:growth & development / Q000378:metabolism*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D000900:Anti-Bacterial Agents; D001430:Bacteriocins; D005520:Food Preservatives; D000070017:Pediocins; C074288:pediocin PA-1; D009561:Nisin; C071364:nisin Z