ORCID Profile
0000-0002-6019-9854
Current Organisation
Wilmar International Ltd
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Publisher: Public Library of Science (PLoS)
Date: 31-07-2014
Publisher: Springer Science and Business Media LLC
Date: 19-10-2016
Publisher: Wiley
Date: 18-01-2016
Abstract: Symbiotic associations are ubiquitous in the microbial world and have a major role in shaping the evolution of both partners. One of the most interesting mutualistic relationships exists between protozoa and methanogenic archaea in the fermentative forestomach (rumen) of ruminant animals. Methanogens reside within and on the surface of protozoa as symbionts, and interspecies hydrogen transfer is speculated to be the main driver for physical associations observed between the two groups. In silico analyses of several rumen methanogen genomes have previously shown that up to 5% of genes encode adhesin-like proteins, which may be central to rumen interspecies attachment. We hypothesized that adhesin-like proteins on methanogen cell surfaces facilitate attachment to protozoal hosts. Using phage display technology, we have identified a protein (Mru_1499) from Methanobrevibacter ruminantium M1 as an adhesin that binds to a broad range of rumen protozoa (including the genera Epidinium and Entodinium). This unique adhesin also binds the cell surface of the bacterium Butyrivibrio proteoclasticus, suggesting a broad adhesion spectrum for this protein.
Publisher: Microbiology Society
Date: 03-2016
DOI: 10.1099/MIC.0.000245
Abstract: Only limited information is available on the roles of different rumen ciliate community types, first described by Eadie in 1962, in enteric methane (CH4) formation by their ruminant hosts. If the different types were differentially associated with CH4 formation, then ciliate community typing could be used to identify naturally high and low CH4-emitting animals. Here we measured the CH4 yields [g CH4 (kg feed dry matter intake, DMI)(-1)] of 118 sheep fed a standard pelleted lucerne diet at two different times, at least 2 weeks apart. There were significant differences (P < 2.2 × 10(-16), Wilcoxon rank sum test) in the CH4 yields (± sd) from sheep selected as high [16.7 ± 1.5 g CH4 (kg DMI)(-1)] and low emitters [13.3 ± 1.5 g CH4 (kg DMI)(-1)]. A rumen s le was collected after each of the two measurements, and ciliate composition was analysed using barcoded 454 Titanium pyrosequencing of 18S rRNA genes. The genera found, in order of mean relative abundance, were Epidinium, Entodinium, Dasytricha, Eudiplodinium, Polyplastron, Isotricha and Anoplodinium-Diplodinium, none of which was significantly correlated with the CH4 emissions ranking associated with the rumen s le. Ciliate communities naturally assembled into four types (A, AB, B and O), characterized by the presence and absence of key genera. There was no difference in CH4 yield between sheep that harboured different ciliate community types, suggesting that these did not underlie the natural variation in CH4 yields. Further research is needed to unravel the nature of interactions between ciliate protozoa and other rumen micro-organisms, which may ultimately lead to contrasting CH4 emission phenotypes.
Publisher: American Society for Microbiology
Date: 10-03-2017
DOI: 10.1128/MICROBIOLSPEC.FUNK-0038-2016
Abstract: The ersity and abundance of zoosporic true fungi have been analyzed recently using fungal sequence libraries and advances in molecular methods, such as high-throughput sequencing. This review focuses on four evolutionary primitive true fungal phyla: the Aphelidea, Chytridiomycota, Neocallimastigomycota, and Rosellida (Cryptomycota), most species of which are not polycentric or mycelial (filamentous), rather they tend to be primarily monocentric (unicellular). Zoosporic fungi appear to be both abundant and erse in many aquatic habitats around the world, with abundance often exceeding other fungal phyla in these habitats, and numerous novel genetic sequences identified. Zoosporic fungi are able to survive extreme conditions, such as high and extremely low pH however, more work remains to be done. They appear to have important ecological roles as saprobes in decomposition of particulate organic substrates, pollen, plant litter, and dead animals as parasites of zooplankton and algae as parasites of vertebrate animals (such as frogs) and as symbionts in the digestive tracts of mammals. Some chytrids cause economically important diseases of plants and animals. They regulate sizes of phytoplankton populations. Further metagenomics surveys of aquatic ecosystems are expected to enlarge our knowledge of the ersity of true zoosporic fungi. Coupled with studies on their functional ecology, we are moving closer to unraveling the role of zoosporic fungi in carbon cycling and the impact of climate change on zoosporic fungal populations.
Publisher: Cold Spring Harbor Laboratory
Date: 06-06-2014
Abstract: Ruminant livestock represent the single largest anthropogenic source of the potent greenhouse gas methane, which is generated by methanogenic archaea residing in ruminant digestive tracts. While differences between in idual animals of the same breed in the amount of methane produced have been observed, the basis for this variation remains to be elucidated. To explore the mechanistic basis of this methane production, we measured methane yields from 22 sheep, which revealed that methane yields are a reproducible, quantitative trait. Deep metagenomic and metatranscriptomic sequencing demonstrated a similar abundance of methanogens and methanogenesis pathway genes in high and low methane emitters. However, transcription of methanogenesis pathway genes was substantially increased in sheep with high methane yields. These results identify a discrete set of rumen methanogens whose methanogenesis pathway transcription profiles correlate with methane yields and provide new targets for CH 4 mitigation at the levels of microbiota composition and transcriptional regulation.
No related grants have been discovered for Sandra Kittelmann.