title: Estimation of Mycobacterium avium subsp. paratuberculosis growth parameters: strain characterization and comparison of methods.
abstract: The growth rate of Mycobacterium avium subsp. paratuberculosis was assessed by different methods in 7H9 medium supplemented with OADC (oleic acid, albumin, dextrose, catalase), Tween 80, and mycobactin J. Generation times and maximum specific growth rates were determined by wet weight, turbidometric measurement, viable count, and quantitative PCR (ParaTB-Kuanti; F57 gene) for 8 M. avium subsp. paratuberculosis strains (K10, 2E, 316F, 81, 445, 764, 22G, and OVICAP 49). Strain-to-strain differences were observed in growth curves and calculated parameters. The quantification methods gave different results for each strain at specific time points. Generation times ranged from an average of 1.4 days for viable count and qPCR to approximately 10 days for wet weight and turbidometry. The wet-weight, turbidometry, and ParaTB-Kuanti qPCR methods correlated best with each other. Generally, viability has been assessed by viable count as a reference method; however, due to M. avium subsp. paratuberculosis clumping problems and the presence of noncultivable M. avium subsp. paratuberculosis cells, we conclude that qPCR of a single-copy gene may be used reliably for rapid estimation of M. avium subsp. paratuberculosis bacterial numbers in a sample.
authors: Animal Health Department, Neiker-Tecnalia, Berreaga, 1, 48160 Derio, Bizkaia, Spain.
authors: Natalia
authors: N
authors: Elguezabal
authors: Felix
authors: F
authors: Bastida
authors: Iker A
authors: IA
authors: Sevilla
authors: Nuria
authors: N
authors: González
authors: Elena
authors: E
authors: Molina
authors: Joseba M
authors: JM
authors: Garrido
authors: Ramón A
authors: RA
authors: Juste
mesh_terms: D001431:Bacteriological Techniques / Q000379:methods*; D018533:Biomass; D015169:Colony Count, Microbial / Q000379:methods; D003470:Culture Media / Q000737:chemistry; D016927:Mycobacterium avium subsp. paratuberculosis / Q000254:growth & development*; D009391:Nephelometry and Turbidimetry / Q000379:methods; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods
chemical_list: D003470:Culture Media