Competitive reduction of poultry-borne enteric bacterial pathogens in chicken gut with bioactive Lactobacillus casei
SCIENTIFIC REPORTS
Authors: Tabashsum, Zajeba; Peng, Mengfei; Alvarado-Martinez, Zabdiel; Aditya, Arpita; Bhatti, Jacob; Romo, Paulina Bravo; Young, Alana; Biswas, Debabrata
Abstract
In this study, the effect of sustainable probiotics on Campylobacter jejuni colonization and gut microbiome composition was evaluated using chicken as a model organism. Chickens were given Lactobacillus casei over-expressing myosin-cross-reactive antigen (LC+mcra). LC+mcra can generate bioactive compounds in larger quantity including conjugated linoleic acid. A total of 120 chickens were used in duplicate trials to investigate the effectiveness of LC+mcra in decreasing C. jejuni colonization by means of kanamycin resistant strain compared to the control group. We observed that LC+mcra can efficiently colonize various parts of the chicken gut and competitively reduce colonization of natural and challenged C. jejuni and natural Salmonella enterica. LC+mcra was found to reduce C. jejuni colonization in cecum, ileum and jejunum, by more than one log CFU/g when compared to the no-probiotic control group. Furthermore, 16S rRNA compositional analysis revealed lower abundance of Proteobacteria, higher abundance of Firmicutes, along with enriched bacterial genus diversity in gut of LC+mcra fed chicken. Decreased contamination of drinking water by C. jejuni and S. enterica was also observed, suggesting a potential function of reducing horizontal transfer of enteric bacteria in poultry. Outcomes of this study reveal high potential of LC+mcra as sustainable approach to decrease colonization of C. jejuni and S. enterica in poultry gut along with other beneficial attributes.
Rapid estimation of Salmonella enterica contamination level in ground beef - Application of the time-to-positivity method using a combination of molecular detection and direct plating
FOOD MICROBIOLOGY
Authors: Harhay, Dayna M.; Weinroth, Margaret D.; Bono, James L.; Harhay, Gregory P.; Bosilevac, Joseph M.
Abstract
Little progress has been made in decreasing the incidence rate of salmonellosis in the US over the past decade. Mitigating the contribution of contaminated raw meat to the salmonellosis incidence rate requires rapid methods for quantifying Salmonella, so that highly contaminated products can be removed before entering the food chain. Here we evaluated the use of Time-to-Positivity (TTP) as a rapid, semi-quantitative approach for estimating Salmonella contamination levels in ground beef. Growth rates of 14 Salmonella strains (inoculated at log 1 to -2 CFU/g) were characterized in lean ground beef mTSB enrichments and time-to-detection was determined using culture and molecular detection methods. Enrichments were sampled at five timepoints and results were used to construct a prediction model of estimated contamination level by TTP (superscript indicates time in hours) defined as TTP4: >= 5 CFU/g; TTP6: <= 5, >= 1 CFU/g; TTP8: <= 1, >= 0.01 CFU/g; with samples negative at 8 h estimated <= 0.01 CFU/g. Model performance measures showed high sensitivity (100%) and specificity (83% and 93% for two detection methods) for samples with a TTP4, with false negative rates of 0%.