Fresh Rumen Liquid Inoculant Enhances the Rumen Microbial Community Establishment in Pre-weaned Dairy Calves

The development of the functional rumen in calves involves a complex interplay between the host and host-related microbiome. Attempts to modulate rumen microbial community establishment may therefore have an impact on weaning success, calf health, and animal performance later in life. In this experiment, we aimed to elucidate how rumen liquid inoculum from an adult cow, provided to calves during the pre-weaning period, influences the establishment of rumen bacterial, archaeal, fungal, and ciliate protozoan communities in monozygotic twin calves (n = 6 pairs). The calves were divided into treatment (T-group) and control (C-group) groups, where the T-group received fresh rumen liquid as an oral inoculum during a 2–8-week period. The C-group was not inoculated. The rumen microbial community composition was determined using bacterial and archaeal 16S ribosomal RNA (rRNA) gene, protozoal 18S rRNA gene, and fungal ITS1 region amplicon sequencing. Animal weight gain and feed intake were monitored throughout the experiment. The T-group tended to have a higher concentrate intake (Treatment: p < 0.08) and had a significantly higher weekly weight gain (Treatment: p < 0.05), but no significant difference in volatile fatty acid concentrations between the groups was observed. In the T-group, the inoculum stimulated the earlier establishment of mature rumen-related bacterial taxa, affecting significant differences between the groups until 6 weeks of age. The inoculum also increased the archaeal operational taxonomic unit (OTU) diversity (Treatment: p < 0.05) but did not affect the archaeal quantity. Archaeal communities differed significantly between groups until week 4 (p = 0.02). Due to the inoculum, ciliate protozoa were detected in the T-group in week 2, while the C-group remained defaunated until 6 weeks of age. In week 8, Eremoplastron dilobum was the dominant ciliate protozoa in the C-group and Isotricha sp. in the T-group, respectively. The Shannon diversity of rumen anaerobic fungi reduced with age (Week: p < 0.01), and community establishment was influenced by a change of diet and potential interaction with other rumen microorganisms. Our results indicate that an adult cow rumen liquid inoculum enhanced the maturation of bacterial and archaeal communities in pre-weaning calves’ rumen, whereas its effect on eukaryotic communities was less clear and requires further investigation.

Landscape configuration affects probability of apex predator presence and community structure in experimental metacommunities

Biodiversity is declining at an unprecedented rate, highlighting the urgent requirement for well-designed protected areas. Design tactics previously proposed to promote biodiversity include enhancing the number, connectivity, and heterogeneity of reserve patches. However, how the importance of these features changes depending on what the conservation objective is remains poorly understood. Here we use experimental landscapes containing ciliate protozoa to investigate how the number and heterogeneity in size of habitat patches, rates of dispersal between neighbouring patches, and mortality risk of dispersal across the nonhabitat ‘matrix’ interact to affect a number of diversity measures. We show that increasing the number of patches significantly increases γ diversity and reduces the overall number of extinctions, whilst landscapes with heterogeneous patch sizes have significantly higher γ diversity than those with homogeneous patch sizes. Furthermore, the responses of predators depended on their feeding specialism, with generalist predator presence being highest in a single large patch, whilst specialist predator presence was highest in several-small patches with matrix dispersal. Our evidence emphasises the importance of considering how top-down effects can drive community responses to patch configuration.

Rumen protozoa shape microbiome composition and metabolic output of fermentation

BackgroundEukaryotic ciliate protozoa are an integral part of the rumen microbiome where they account for up to half of the microbial biomass. Protozoa are known to reside in tight association with their surrounding prokaryotic community – either as predators or involved in mutualistic interactions. Nonetheless, the extent of the ecological effect of protozoa on the microbial community as well as their effect on the rumen metabolic output remains largely understudied.ResultsOur study shows that ciliate protozoa determine the metabolic output of the rumen microbiome as well as impose ecological effects on the prokaryotic community. By conducting microcosms experiments over time we find that volatile fatty acids and methane production are highly increased in the presence of protozoa. Analyzing the structure of the prokaryotic community in the presence of protozoa shows that predation enables several species to colonize previously occupied ecological niches. Furthermore, we observe specificity in predation-resistant species across all treatments, while predation susceptible species depends mainly on the source environment. Our results suggest that ecological models describing predation dynamics are applicable when studying host-associated communities.ConclusionsWe conclude that protozoa have a large impact on the rumen ecosystem structure that may determine the overall rumen productivity. Our study further provides insights into natural dynamics as well as the multifaceted role of microbial eukaryotes in host-associated habitats. Thus, when studying the rumen microbial ecosystem, cross-domain interactions between protozoa and prokarya need to be taken into consideration.

Functional Proteomics of Nuclear Proteins in Tetrahymena thermophila: A Review

Identification and characterization of protein complexes and interactomes has been essential to the understanding of fundamental nuclear processes including transcription, replication, recombination, and maintenance of genome stability. Despite significant progress in elucidation of nuclear proteomes and interactomes of organisms such as yeast and mammalian systems, progress in other models has lagged. Protists, including the alveolate ciliate protozoa with Tetrahymena thermophila as one of the most studied members of this group, have a unique nuclear biology, and nuclear dimorphism, with structurally and functionally distinct nuclei in a common cytoplasm. These features have been important in providing important insights about numerous fundamental nuclear processes. Here, we review the proteomic approaches that were historically used as well as those currently employed to take advantage of the unique biology of the ciliates, focusing on Tetrahymena, to address important questions and better understand nuclear processes including chromatin biology of eukaryotes.

The South American lungfish Lepidosiren paradoxa as a new host for Trichodina quelenii

Recently, the South American lungfish Lepidosiren paradoxa is being found inside aquaculture ponds, and even though there are a few studies on their parasite fauna, there is still much to be reported. Thus, the objective of this study is to report parasitism by trichodinids in L. paradoxa, as these ciliate protozoa are related to injuries and mortality in fish farming. The lungfish were collected from experimental tanks, had their tegument scraped and the resultant mucus was analyzed under an optical microscope for morphological and morphometrical analyses in Giemsa and silver nitrate stained slides. The species found was identified as Trichodina quelleni. This is the first report of this parasite in L. paradoxa, and the second report in cultivated fish in Brazil.

Estimated ruminal digestion values and digestion end-products of concentrated mix feed after in vitro treatment with propionic acid

This study was aimed at determining the effects of propionic acid supplementation at doses of 0 (control group, PA0), 12, 24, 48 and 96 mM (PA12, PA24, PA48, and PA96) to concentrated mix feed on in vitro cumulative total gas production, methane emission, gas kinetics (potential gas production, (a + b)_gas and gas production rate, c_gas), estimated digestibility, estimated energy value and the end-products and variables of in vitro digestion (total bacteria count, the number of ciliate protozoa, volatile fatty acids, pH value and ammonia-N). Digestion treatments were carried out in an anaerobic in vitro fermenter for up to 96 h. The in vitro cumulative total gas production, (a + b)_gas, estimated metabolic energy, estimated net energy lactation and estimated organic matter digestibility and ammonia-N concentration were decreased by propionic acid up to 96 mM (P < 0.05). In the in vitro fermenter fluid, total bacteria count, the total numbers of ciliate protozoa and the individual numbers of some ciliate protozoa (Entodiniinae, Isotricha spp. and Diplodiniinae) (P < 0.01) decreased linearly with increasing concentrations of dietary propionic acid. The total molar concentrations of volatile fatty acids decreased in response to propionic acid supplementation (P < 0.001). Dietary propionic acid elicited linear increases in the molar concentrations of propionic acid (P < 0.001) and butyric acid (P < 0.01) as proportions of total volatile fatty acids of the in vitro fermenter fluid. In contrast, molar proportions of acetic acid, the c_gas, pH values and the numbers of Dasytricha sp. were not affected by dietary propionic acid supplementation (P > 0.05). The addition of 12–96 mM propionic acid to concentrated mix feed decreased methane emission from the rumen and negatively affected microbiota count, feed digestibility, proteolysis, and molar volatile fatty acid values in the rumen environment.