Methanogenesis in rumen ciliate cultures ofEntodinium caudatum andEpidinium ecaudatum after long-term cultivation in a chemically defined medium

Abstract

The methanogenic activity in the presence of Entodinium caudatum and Epidinium ecaudatum was well preserved after long-term cultivation. Microscopic observation revealed that methane production in the presence of E. caudatum was probably caused by their intracellular methanogenic activity, while methane production in the presence of E. ecaudatum f caudatum et ecaudatum could be attributed to both the methanogenic bacterial fraction of their external surface and their intracellular activity. Methane production per protozoan cell of E. caudatum and E. ecaudatum was 2.1 nmol per cell per d and 6.0 nmol per cell per d, respectively. E. caudatum was responsible for almost the entire methane production in the culture. The activity of free methanogens constituted approximately 50% of the total methane production in the E. ecaudatum culture. Decrease of digestibility of substrates and differences in the fermentation end products accompanied the inhibition of methanogenesis in both cultures by penicillin G, streptomycin, chloramphenicol, 2-bromoethanesulfonate, and pyromellitic diimide. E. caudatum appeared to be more sensitive than E. ecaudatum to the compounds tested. Hydrogen recoveries based on both volatile fatty acids and methane production suggested that the methanogenic population appeared not to be fully able to consume hydrogen produced in the protozoan cultures. The culture conditions tested were found to be suitable for experiments on the relationship between rumen ciliates and rumen bacteria.

In vitro methane formation and carbohydrate fermentation by rumen microbes as influenced by selected rumen ciliate species

“…In the present study, the ciliate concentration in the preand post-incubation medium was much lower than in vivo (Zeitz et al 2012), which is, however, often the case in ciliate cultures (Kisidayova et al 2000). Therefore, the influence of the ciliates on microbial fermentation in the present study was probably lower than under conditions which more closely resemble in vivo conditions in terms of ciliate concentration.…”

“…This might be one explanation for the observation that the presence of ciliates in the microbial cultures did not clearly enhance the intensity of fermentation compared to the cultures of ruminal prokaryotes alone. Different from that, Kisidayova et al (2000), using the same ciliate removal technique and with similar ciliate concentrations in the cultures, described that the absence of the ciliates in former in vitro ciliate cultures may lead to a clearly lower gas formation. Furthermore, it has to be stated that, due to the isolation procedure used for the prokaryote cultures in the present study, it could not be avoided that certain large bacteria were also removed and thus were absent in the supernatant used as ciliate-free prokaryote culture.…”

“…Besides these ciliate cultures (i.e., ciliates plus prokaryotes), prokaryotic cultures free of ciliates were tested. These cultures were prepared by removing the ciliates just before the incubation started through using the supernatant after centrifuging the ciliate cultures for 3 min at 2147 × g at ambient temperature (Kisidayova et al 2000). From each of the ciliate-prokaryotic co-cultures (n = 7) and the ciliate-free cultures (n = 4 only, due to technical problems) 20 mL were then transferred into incubation bottles.…”

“…However, similar gas and total SCFA production by both ciliate-prokaroytic and ciliate-free cultures might also illustrate the presence of a strong competition for feed between ruminal ciliates and prokaryotes, with the latter being able to replace ciliates in fermentation in vitro within few hours. It is known that ciliates can control fermentation by the rapid ingestion of feed particles like entire starch granules, thus impeding bacterial accession to feed (Kisidayova et al 2000), and store them for eventual degradation. This shall help prevent a fast decline in ruminal pH by slowing down fermentation.…”

Plant components with specific activities against rumen methanogens

“…Regensbogenova et al (2004) demonstrated that M. mobile occurs mainly in singlespecies cultures of Metadinium medium, Entodinium furca monolobum and Diplodinium dentatum, while Kamra (2005) named four species of rumen ciliates of the group Entodiniomorpha, which are in close symbiosis with the methanogens: Entodinium elonginucleatum, Entodinium bursa, Eudiplodinium maggii and Eremoplastron bovis. Other researchers (Finlay et al, 1994;Kisidayova et al, 2000;Cieslak et al, 2006) added to the list Dasytricha ruminantium, Entodinium caudatum, E. f. monolobum, D. dentatum, Eremoplastron dilobum, Epidinium ecaudatum and Ophryoscolex caudatus. It is presumed that the species preferences of the methanogens result from differences in the protozoal cell surface (Vogels et al, 1980).…”