Molecular characterization of Balantioides coli in pigs from Shaanxi province, northwestern China.

Balantioides coli (syn. Balantidium coli) is an important zoonotic but usually neglected protozoa infecting human and a great number of animals, and the pig was considered to be the most important natural host and reservoir. However, no information about the infection of B. coli in pigs in northwestern China was available. In the present study, the prevalence and genetic diversity of B. coli in pigs in Shaanxi province were investigated. A total of 560 fecal samples were collected from pigs of four age groups in five different geographical regions and analyzed by using PCR targeting the ITS1-5.8S rRNA-ITS2 gene fragment. The infection of B. coli was detected in all age groups and regions, with the total prevalence of 16.8% (94/560). Significant differences (P < 0.01) in prevalence were found among four investigated age groups, with the highest in fatteners (38.8%) and the lowest in adults (5.7%). The prevalence was also significantly (P < 0.01) different among pigs from five sampling regions. Sequence analysis revealed two genetic variants, namely, A and B, in these investigated pigs, and both of them were detected in all age groups and regions, with the latter as the predominant one. Further, sixty-eight different haplotypes were found, with 19 and 49 belonged to genetic variants A and B, respectively. The findings in the present study indicated wide distribution and high diversity of B. coli in pigs in Shaanxi province and provided fundamental data for implementing control strategies on B. coli infection in pigs as well as other hosts in this province.

Rumen methanogen and protozoal communities of Tibetan sheep and Gansu Alpine Finewool sheep grazing on the Qinghai-Tibetan Plateau, China.

BACKGROUND: Tibetan sheep (TS) and Gansu Alpine Finewool sheep (GS) are both important plateau sheep raised and fed on the harsh Qinghai-Tibetan Plateau, China. Rumen methanogen and protozoal communities of plateau sheep are affected by their hosts and living environments, and play important roles in ruminant nutrition and greenhouse gas production. However, the characteristics, differences, and associations of these communities remain largely uncharacterized. RESULTS: The rumen methanogen and protozoal communities of plateau sheep were investigated by 16S/18S rRNA gene clone libraries. The predominant methanogen order in both sheep species was Methanobacteriales followed by Methanomassiliicoccales, which is consistent with those seen in global ruminants. However, the most dominant species was Methanobrevibacter millerae rather than Methanobrevibacter gottschalkii seen in most ruminants. Compared with GS and other ruminants, TS have more exclusive operational taxonomic units and a lower proportion (64.5%) of Methanobrevibacter. The protozoa were divided into Entodiniomorphida and Vestibuliferida, including nine genera and 15 species. The proportion of holotrich protozoa was much lower (1.1%) in TS than ordinary sheep. The most predominant genus was Entodinium (70.0%) in TS and Enoploplastron (48.8%) in GS, while the most common species was Entodinium furca monolobum (43.9%) and Enoploplastron triloricatum (45.0%) in TS and GS, respectively; Entodinium longinucleatum (22.8%) was only observed in TS. LIBSHUFF analysis indicated that the methanogen communities of TS were significantly different from those of GS, but no significant differences were found in protozoal communities. CONCLUSION: Plateau sheep have coevolved with unique rumen methanogen and protozoal communities to adapt to harsh plateau environments. Moreover, the host appears to have a greater influence on rumen methanogen communities than on rumen protozoal communities. The observed associations of methanogens and protozoa, together with the findings of previous studies on methane emissions from ruminant livestock, revealed that the lower proportion of Methanobrevibacter and holotrich protozoa may be responsible for the lower methane emission of TS. These findings facilitate our understanding of the rumen microbial ecosystem in plateau sheep, and could help the development of new strategies to manipulate rumen microbes to improve productivity and reduce the emission of greenhouse gases.

First molecular identification of Buxtonella ciliates from captive-bred mangabeys (Cercocebus torquatus) from China.

Buxtonella species are large cyst-forming ciliates that infect ruminants and monkeys, and are morphologically similar to Balantidium coli ciliates that infect pigs, humans, monkeys, and other animals. In this study, we isolated spherical cysts of ciliates that were similar to those of Balantidium and Buxtonella species within collared mangabeys (Cercocebus torquatus) from the Wangcheng Zoo of Luoyang in the Henan Province of central China. The cysts were further identified and designated as belonging to the Buxtonella monkey genotype based on molecular analyses of 18S rRNA, 5.8S rRNA, and ITS1-5.8S rRNA-ITS2 genetic markers. To our knowledge, this is the first report of Buxtonella monkey genotype within monkeys in China. These results will help clarify the classification of species of cyst-forming ciliate infections in monkeys.

Impact of high-concentrate feeding and low ruminal pH on methanogens and protozoa in the rumen of dairy cows.

Non-lactating dairy cattle were transitioned to a high-concentrate diet to investigate the effect of ruminal pH suppression, commonly found in dairy cattle, on the density, diversity, and community structure of rumen methanogens, as well as the density of rumen protozoa. Four ruminally cannulated cows were fed a hay diet and transitioned to a 65% grain and 35% hay diet. The cattle were maintained on an high-concentrate diet for 3 weeks before the transition back to an hay diet, which was fed for an additional 3 weeks. Rumen fluid and solids and fecal samples were obtained prior to feeding during weeks 0 (hay), 1, and 3 (high-concentrate), and 4 and 6 (hay). Subacute ruminal acidosis was induced during week 1. During week 3 of the experiment, there was a significant increase in the number of protozoa present in the rumen fluid (P=0.049) and rumen solids (P=0.004), and a significant reduction in protozoa in the rumen fluid in week 6 (P=0.003). No significant effect of diet on density of rumen methanogens was found in any samples, as determined by real-time PCR. Clone libraries were constructed for weeks 0, 3, and 6, and the methanogen diversity of week 3 was found to differ from week 6. Week 3 was also found to have a significantly altered methanogen community structure, compared to the other weeks. Twenty-two unique 16S rRNA phylotypes were identified, three of which were found only during high-concentrate feeding, three were found during both phases of hay feeding, and seven were found in all three clone libraries. The genus Methanobrevibacter comprised 99% of the clones present. The rumen fluid at weeks 0, 3, and 6 of all the animals was found to contain a type A protozoal population. Ultimately, high-concentrate feeding did not significantly affect the density of rumen methanogens, but did alter methanogen diversity and community structure, as well as protozoal density within the rumen of nonlactating dairy cattle. Therefore, it may be necessary to monitor the rumen methanogen and protozoal communities of dairy cattle susceptible to depressed pH when methane abatement strategies are being investigated.