Exocellular Carbohydrase Formation by Rumen Holotrich Ciliates

Ciliated protozoa in the rumen of Turkish domestic cattle (Bos taurus L.)

Rumen contents obtained from 28 domesticated cattle (Bos taurus L.) slaughtered at abatoirs near Izmir, Turkey were surveyed for ciliate protozoa. Protozoa are known to make an appreciable contribution to ruminal fiber digestion in many different geographical areas; however, little if any information is available on their occurrence in Turkish cattle. As a result of our survey, 13 genera including 52 species were identified. Nine of the species were further divided into 36 forma. The average ciliate density in our cattle (52.44 X 10(4)/ml) was higher than that of Turkish domestic sheep and other domestic cattle reported previously from different geographical areas. Entodinium basoglui, Entodinium williamsi f. williamsi, E. williamsi f. turcicum, E. dalli f. rudidorsospinatum, Entodinium imai, Entodinium oektemae, Eudiplodinium dehorityi, Epidinium graini, Ophryoscolex purkynjei f. bifidobicinctus, and Ophryoscolex purkynjei f. bifidoquadricinctus have previously been reported from Turkey and appear to be endemic. All ofthe remaining species represent a new host record for domestic Turkish cattle. This study also reports for the second time the presence of Entodinium constrictum in herbivorous mammals, and is the first record of its occurrence in domesticated cattle.

Molecular cloning, expression, and characterization of an endo-beta-1,4-glucanase cDNA from Epidinium caudatum1

An endo-beta-1,4-glucanase gene (epi3) from the rumen ciliated protozoan Epidinium caudatum was cloned from a cDNA library constructed by using the lambda ZAP II vector. The enzymatic activity of the gene product was detected by the Congo red assay, using carboxymethyl cellulose (CMC) as substrate. The nucleotide sequence of epi3 revealed 1,253 nucleotides with an open reading frame for a protein (Epi3) of 356 amino acids (Mr -41,014). Epi3 shows high homology with family 5 endoglucanase genes and with genes from protozoa isolated from sources other than the rumen. The specific activity of Epi3 produced in Escherichia coli was 5.544, 2.754, and 0.295 mmol of glucose min(-1) mg(-1) protein when the substrates used were CMC, beta-glucan, and xylan, respectively. A beta-1,4-linked trisaccharide of glucose was the preferred substrate of Epi3, as determined by analysis with the p-nitrophenyl form of the substrate. To our knowledge, this is the first report of the isolation of an endoglucanase gene from a rumen protozoan.