Isolation and Visualisation of Helicobacter Strains from a Bengal Tiger
Five single Helicobacter-like colonies (called SB-1 to SB-5) from diarrheic fecal samples of a captive Bengal tiger from Thailand were grown under microaerobic growth conditions using either Columbia agar plates with 5% sheep blood or GC agar plates with 10% horse serum. Gram-staining indicated that these bacteria were Gram-negative. Scanning electron microscopic investigation revealed spiral-shaped Helicobacter-like organisms (Fig. 1A), about 0.25–0.45 µm in diameter and 2.5–6 µm in length. The majority of these bacteria contained 1–4 monopolar flagella with lengths of about 1.5–4.5 µm, although some were non-flagellated (Fig. S1). This suggests that some bacteria may have lost their flagella during sample processing. Negative stained samples revealed similar results (Fig. 1B). The visualized flagella were commonly sheathed and about 43–48 nm in diameter, although non-sheathed flagella (15–17 nm in diameter) were also observed. In addition, we often found that the flagella ends were thickened and had a bulb-like shape (see enlargement panels in Fig. 1B, arrows).