Assessing efficacy of N-Acetyl-L-Cysteine-Sodium Hydroxide on bacterial viability and enhanced recovery of Mycobacterium avium subsp. paratuberculosis from bovine colostrum

The standard procedure for the improved cultural recovery of viable Mycobacterium spp. from diverse samples mainly depends on reducing the viability of background microbiota using different chemical compounds. This study was designed to i) evaluate the efficacy and comparison between N-Acetyl-L-Cysteine-Sodium hydroxide (NALC-2% NaOH) and hexadecylpyridinium chloride (0.75% HPC) treatment and exposure time on reducing the viability of undesirable microorganisms with minimal impact on colostrum consistency; and ii) assess the impact of NALC-2% NaOH on improved and enhanced recovery of Mycobacterium avium subsp. paratuberculosis (MAP) in spiked postpartum colostrum samples and consistency of colostrum. A total of 40 samples, each treated with NALC-2% NaOH for 15 min or 0.75% HPC for 5 h, were investigated for total mesophilic aerobic bacteria (MAB) and enterobacteria (EB) (CFU mL(-1)). The results showed that treatment of colostrum samples with NALC-2% NaOH completely eliminated EB and significantly reduced MAB (3.6 log io CFU mL(-1)). Conversely, samples treated with 0.75% HPC produced a complex mixture following interaction with the colostrum protein and showed non-significant and variable results. In addition, the spiked colostrum treated with NALC-2% NaOH for 15 min revealed recovery of viable MAP cells with a minimum limit of detection of 1.36 log io CFU 10 mL(-1) where no change in the consistency of colostrum was observed. In conclusion, 15-min NALC-2% NaOH treatment of colostrum may significantly reduce the viability of undesirable microorganisms and help to enhance the efficient recovery of MAP without impacting the consistency of high quality postpartum colostrum. This rapid procedure is suitable for efficient recovery and early detection of MAP as well as preventing its transmission to neonates and young calves in MAP infected herds.