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The Prevalence and Concentration of Salmonella in Poultry Litter and the Effects of Ammonia and Microflora on Its Survival in Litter- [electronic resource]

자료유형: 학위논문파일 국외

최종처리일시: 20240214095846

ISBN: 9798380604130

DDC: 641

저자명: Gutierrez, Alan.

서명/저자: The Prevalence and Concentration of Salmonella in Poultry Litter and the Effects of Ammonia and Microflora on Its Survival in Litter - [electronic resource]

발행사항: [S.l.]: : University of Florida., 2021

발행사항: Ann Arbor : : ProQuest Dissertations & Theses,, 2021

형태사항: 1 online resource(185 p.)

주기사항: Source: Dissertations Abstracts International, Volume: 85-04, Section: B.

주기사항: Advisor: Schneider, Keith R.

학위논문주기: Thesis (Ph.D.)--University of Florida, 2021.

사용제한주기: This item must not be sold to any third party vendors.

초록/해제: 요약n the United States, Salmonella is often associated with foodborne outbreaks in fresh produce. The use of animal manures, or biological soil amendments of animal origin, as soil fertilizers presents a risk for the pre-harvest contamination of produce. Determining the prevalence and concentration of Salmonella in Florida poultry litter and examining the influence of microflora and ammonia on the survival of Salmonella in litter may help mitigate these pre-harvest risks. Poultry litter samples were collected from 18 commercial poultry farms. The prevalence of Salmonella in litter samples was 61.1% (n = 54), with a geometric mean of 0.21 MPN/g, and S. Typhimurium was the most common serovar. S. Typhimurium was inoculated into irradiated (sterilized) and natural poultry litter to investigate the influence of indigenous microflora on its survival. Salmonella populations declined similarly in both litter treatments with no significant differences (P 0.05) between them, and their inactivation kinetics were best fitted to the Weibull model. In the absence of antagonistic interactions with litter microflora, the effects of ammonia on Salmonella in poultry litter were investigated. This was first studied by inoculating S. Typhimurium into buffer solutions to characterize the pH dependency, minimum antimicrobial concentration, and production efficacy of unionized ammonia (NH3). This study showed that the antimicrobial activity of NH3 was dependent on alkaline conditions (pH ≥ 9), where concentrations ≥ 0.04 M NH3 resulted in significant Salmonella reductions. With 1% urea added into solutions, Corynebacterium urealyticum rapidly produced NH3 which reduced Salmonella. The inactivation kinetics of Salmonella in these NH3 solutions were best fitted to Weibull, double Weibull, and Weibull with tailing effects models. The final study examined the effects of ammonia, water activity (aw), and C. urealyticum on the survival of S. Typhimurium in poultry litter. In this study, Salmonella populations in litter fell below 1 log CFU/g within 5 days, at 0.84 and 0.92 aw, regardless of ammonia treatments. C. urealyticum produced ammonia at 0.92 and 0.96 aw with 1% urea added. Lastly, a minimum of 1,643 ppm NH3 reduced Salmonella populations, but this was dependent on aw levels of 0.96 aw in litter.