Fate and Survival of Campylobacter coli in Swine Manure at Various Temperatures

Abstract

Campylobacter coli is the most common Campylobacter species found in pig (95%), but the ability of this bacterium to survive in swine manure as well as the potential for causing human illness are poorly understood. We present here laboratory-scale experiments to investigate the effect of temperature on the survival of C. coli in spiked swine manure samples at temperatures from 4 to 52°C. The survival of C. coli during storage for 30 days was studied by three different methods: bacterial culture (plate counting), DNA qPCR, and mRNA RT-qPCR. The results indicate that C. coli could survive in swine manure up to 24 days at 4°C. At higher temperatures, this bacterium survived only 7 days (15°C) or 6 days (22°C) of storage. The survival of C. coli was extremely short (few hours) in samples incubated at 42 and 52°C. The results from the RT-qPCR method were consistent with the data from the bacterial culture method, indicating that it detected only viable C. coli cells, thus eliminating false-positive resulting from DNA from dead C. coli cells.

Keywords: Campylobacter coli; RT-qPCR; ceuE; mRNA; swine manure.

Figure 1

(A) Melting temperature curve of ceuE qPCR products: (+) control: positive control; arrows represent ceuE melting curves of C. coli strains (4 different strains) and negative signals of non-C. coli strains (14 different strains), un-spiked samples, and water. (B) Agarose gel electrophoresis of qPCR products: Lane 1–4 (four different C. coli strains) with 196-bp band, lane M, 100-bp DNA marker; lane 5–18, 14 non-C. coli strains; lane 19, water; lane 20, un-spiked manure sample.

Figure 2

The standard curve for absolute quantification of C. coli in swine manure. Standard curves produced from 10-fold serial dilutions ranging from 1 × 10² to 1 × 10⁸ CFU/ml swine manure sample of C. coli (CCUG 11283), showing the relationship between C_t-values and CFU/ml for qPCR assays. C_t, cycle threshold.

Figure 3

The detection and quantification of C. coli in swine manure samples incubated at various temperatures (4, 15, 22, 42, and 52°C) by bacterial culture (counting), DNA-based qPCR (DNA), and RT-qPCR (RNA) methods with (A) at 4°C, (B) at 15°C, (C) at 22°C, (D) at 42°C, and (E) at 52°C. Data are means and SE of at least three independent experiments; (**): not detected.