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Preliminary study on the requirements of Entodinium exiguum and E. caudatum for live or dead bacteria when cultured
1Departamento de Producción Animal y Ciencia de los Alimentos, Universidad de Zaragoza, Spain. mfonde@posta.unizar.es
Abstract:
Whether live bacteria are required to culture the rumen protozoa Entodinium exiguum and E. caudatum in vitro was studied. Treatments were protozoa plus antibiotics (PA), PA plus autoclaved bacteria (PAB) or protozoa plus live bacteria (PLB). Generation times at 24 h were 22.8 and 31.0 h for E. exiguum and E. caudatum. Protozoal concentrations were unaffected by the absence of bacteria up to 48 h. After 72 h, E. exiguum, concentrations were higher in PLB than PA or PAB. With E. caudatum differences between PLB and PA were only observed at 96 h. Thus, a requirement for live bacteria appears to be manifested in culture periods longer than 48 (E. exiguum) and 72 (E. caudatum) h. Although differences between PLB and PAB indicate a metabolic dependence for bacteria or a long-term antibiotic effect, non-significant differences between PAB and PA suggest that the effect is also related to a nutritive bacterial contribution.
Insights
Live bacteria are essential for long-term in vitro cultures of rumen protozoa Entodinium exiguum and E. caudatum, providing a nutritive contribution for sustained growth.
Area of Science:
- Rumen microbiology
- Protozoology
- In vitro culture techniques
Background:
- Rumen protozoa play a crucial role in ruminant digestion.
- Understanding their in vitro culture requirements is vital for research.
- The necessity of live bacteria for culturing specific protozoa remains unclear.
Purpose of the Study:
- To investigate the requirement of live bacteria for in vitro cultivation of Entodinium exiguum and E. caudatum.
- To determine the duration of bacterial absence before significant effects on protozoal growth are observed.
Main Methods:
- Rumen protozoa were cultured in vitro under three conditions: protozoa plus antibiotics (PA), PA plus autoclaved bacteria (PAB), and protozoa plus live bacteria (PLB).
- Protozoal growth and generation times were monitored over extended culture periods (up to 96 hours).
- Comparisons were made between treatments to assess the impact of live versus autoclaved bacteria and antibiotic presence.
Main Results:
- Protozoal concentrations remained unaffected by the absence of live bacteria for up to 48 hours.
- After 72 hours, Entodinium exiguum concentrations were significantly higher in PLB compared to PA and PAB.
- Entodinium caudatum showed significant differences between PLB and PA only at 96 hours, suggesting a longer requirement for live bacteria.
Conclusions:
- Live bacteria are required for sustained in vitro culture of E. exiguum and E. caudatum beyond 48-72 hours.
- The results indicate a potential nutritive contribution from live bacteria, alongside possible metabolic dependence or long-term antibiotic effects.
- Further investigation is needed to fully elucidate the specific roles of live bacteria in protozoal nutrition and growth.
